Changeset - 94751a00b9b7
[Not reviewed]
0 8 0
mh - 4 years ago 2021-05-31 10:43:41
contact@maxhenger.nl
Better error spans for expressions
7 files changed:
0 comments (0 inline, 0 general)
src/protocol/ast.rs
Show inline comments
 
@@ -1035,550 +1035,582 @@ pub struct MemoryStatement {
 
/// ChannelStatement is the declaration of an input and output port associated
 
/// with the same channel. Note that the polarity of the ports are from the
 
/// point of view of the component. So an output port is something that a
 
/// component uses to send data over (i.e. it is the "input end" of the
 
/// channel), and vice versa.
 
#[derive(Debug, Clone)]
 
pub struct ChannelStatement {
 
    pub this: ChannelStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "channel" keyword
 
    pub from: VariableId, // output
 
    pub to: VariableId,   // input
 
    // Phase 2: linker
 
    pub relative_pos_in_block: u32,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LabeledStatement {
 
    pub this: LabeledStatementId,
 
    // Phase 1: parser
 
    pub label: Identifier,
 
    pub body: StatementId,
 
    // Phase 2: linker
 
    pub relative_pos_in_block: u32,
 
    pub in_sync: SynchronousStatementId, // may be invalid
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct IfStatement {
 
    pub this: IfStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "if" keyword
 
    pub test: ExpressionId,
 
    pub true_body: BlockStatementId,
 
    pub false_body: Option<BlockStatementId>,
 
    pub end_if: EndIfStatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndIfStatement {
 
    pub this: EndIfStatementId,
 
    pub start_if: IfStatementId,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct WhileStatement {
 
    pub this: WhileStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "while" keyword
 
    pub test: ExpressionId,
 
    pub body: BlockStatementId,
 
    pub end_while: EndWhileStatementId,
 
    pub in_sync: SynchronousStatementId, // may be invalid
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndWhileStatement {
 
    pub this: EndWhileStatementId,
 
    pub start_while: WhileStatementId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BreakStatement {
 
    pub this: BreakStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "break" keyword
 
    pub label: Option<Identifier>,
 
    // Phase 2: linker
 
    pub target: Option<EndWhileStatementId>,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ContinueStatement {
 
    pub this: ContinueStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "continue" keyword
 
    pub label: Option<Identifier>,
 
    // Phase 2: linker
 
    pub target: Option<WhileStatementId>,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SynchronousStatement {
 
    pub this: SynchronousStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "sync" keyword
 
    pub body: BlockStatementId,
 
    // Phase 2: linker
 
    pub end_sync: EndSynchronousStatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndSynchronousStatement {
 
    pub this: EndSynchronousStatementId,
 
    pub start_sync: SynchronousStatementId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ReturnStatement {
 
    pub this: ReturnStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "return" keyword
 
    pub expressions: Vec<ExpressionId>,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct GotoStatement {
 
    pub this: GotoStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "goto" keyword
 
    pub label: Identifier,
 
    // Phase 2: linker
 
    pub target: Option<LabeledStatementId>,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct NewStatement {
 
    pub this: NewStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "new" keyword
 
    pub expression: CallExpressionId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ExpressionStatement {
 
    pub this: ExpressionStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan,
 
    pub expression: ExpressionId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
 
pub enum ExpressionParent {
 
    None, // only set during initial parsing
 
    If(IfStatementId),
 
    While(WhileStatementId),
 
    Return(ReturnStatementId),
 
    New(NewStatementId),
 
    ExpressionStmt(ExpressionStatementId),
 
    Expression(ExpressionId, u32) // index within expression (e.g LHS or RHS of expression)
 
}
 

	
 
impl ExpressionParent {
 
    pub fn is_new(&self) -> bool {
 
        match self {
 
            ExpressionParent::New(_) => true,
 
            _ => false,
 
        }
 
    }
 

	
 
    pub fn as_expression(&self) -> ExpressionId {
 
        match self {
 
            ExpressionParent::Expression(id, _) => *id,
 
            _ => panic!("called as_expression() on {:?}", self),
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum Expression {
 
    Assignment(AssignmentExpression),
 
    Binding(BindingExpression),
 
    Conditional(ConditionalExpression),
 
    Binary(BinaryExpression),
 
    Unary(UnaryExpression),
 
    Indexing(IndexingExpression),
 
    Slicing(SlicingExpression),
 
    Select(SelectExpression),
 
    Literal(LiteralExpression),
 
    Cast(CastExpression),
 
    Call(CallExpression),
 
    Variable(VariableExpression),
 
}
 

	
 
impl Expression {
 
    pub fn as_variable(&self) -> &VariableExpression {
 
        match self {
 
            Expression::Variable(result) => result,
 
            _ => panic!("Unable to cast `Expression` to `VariableExpression`"),
 
        }
 
    }
 

	
 
    pub fn span(&self) -> InputSpan {
 
    /// Returns operator span, function name, a binding's "let" span, etc. An
 
    /// indicator for the kind of expression that is being applied.
 
    pub fn operation_span(&self) -> InputSpan {
 
        match self {
 
            Expression::Assignment(expr) => expr.operator_span,
 
            Expression::Binding(expr) => expr.operator_span,
 
            Expression::Conditional(expr) => expr.operator_span,
 
            Expression::Binary(expr) => expr.operator_span,
 
            Expression::Unary(expr) => expr.operator_span,
 
            Expression::Indexing(expr) => expr.operator_span,
 
            Expression::Slicing(expr) => expr.slicing_span,
 
            Expression::Select(expr) => expr.operator_span,
 
            Expression::Literal(expr) => expr.span,
 
            Expression::Cast(expr) => expr.cast_span,
 
            Expression::Call(expr) => expr.func_span,
 
            Expression::Variable(expr) => expr.identifier.span,
 
        }
 
    }
 

	
 
    /// Returns the span covering the entire expression (i.e. including the
 
    /// spans of the arguments as well).
 
    pub fn full_span(&self) -> InputSpan {
 
        match self {
 
            Expression::Assignment(expr) => expr.span,
 
            Expression::Binding(expr) => expr.span,
 
            Expression::Conditional(expr) => expr.span,
 
            Expression::Binary(expr) => expr.span,
 
            Expression::Unary(expr) => expr.span,
 
            Expression::Indexing(expr) => expr.span,
 
            Expression::Slicing(expr) => expr.span,
 
            Expression::Select(expr) => expr.span,
 
            Expression::Assignment(expr) => expr.full_span,
 
            Expression::Binding(expr) => expr.full_span,
 
            Expression::Conditional(expr) => expr.full_span,
 
            Expression::Binary(expr) => expr.full_span,
 
            Expression::Unary(expr) => expr.full_span,
 
            Expression::Indexing(expr) => expr.full_span,
 
            Expression::Slicing(expr) => expr.full_span,
 
            Expression::Select(expr) => expr.full_span,
 
            Expression::Literal(expr) => expr.span,
 
            Expression::Cast(expr) => expr.span,
 
            Expression::Call(expr) => expr.span,
 
            Expression::Cast(expr) => expr.full_span,
 
            Expression::Call(expr) => expr.full_span,
 
            Expression::Variable(expr) => expr.identifier.span,
 
        }
 
    }
 

	
 
    // TODO: @cleanup
 
    pub fn parent(&self) -> &ExpressionParent {
 
        match self {
 
            Expression::Assignment(expr) => &expr.parent,
 
            Expression::Binding(expr) => &expr.parent,
 
            Expression::Conditional(expr) => &expr.parent,
 
            Expression::Binary(expr) => &expr.parent,
 
            Expression::Unary(expr) => &expr.parent,
 
            Expression::Indexing(expr) => &expr.parent,
 
            Expression::Slicing(expr) => &expr.parent,
 
            Expression::Select(expr) => &expr.parent,
 
            Expression::Literal(expr) => &expr.parent,
 
            Expression::Cast(expr) => &expr.parent,
 
            Expression::Call(expr) => &expr.parent,
 
            Expression::Variable(expr) => &expr.parent,
 
        }
 
    }
 
    // TODO: @cleanup
 
    pub fn parent_expr_id(&self) -> Option<ExpressionId> {
 
        if let ExpressionParent::Expression(id, _) = self.parent() {
 
            Some(*id)
 
        } else {
 
            None
 
        }
 
    }
 

	
 
    pub fn get_unique_id_in_definition(&self) -> i32 {
 
        match self {
 
            Expression::Assignment(expr) => expr.unique_id_in_definition,
 
            Expression::Binding(expr) => expr.unique_id_in_definition,
 
            Expression::Conditional(expr) => expr.unique_id_in_definition,
 
            Expression::Binary(expr) => expr.unique_id_in_definition,
 
            Expression::Unary(expr) => expr.unique_id_in_definition,
 
            Expression::Indexing(expr) => expr.unique_id_in_definition,
 
            Expression::Slicing(expr) => expr.unique_id_in_definition,
 
            Expression::Select(expr) => expr.unique_id_in_definition,
 
            Expression::Literal(expr) => expr.unique_id_in_definition,
 
            Expression::Cast(expr) => expr.unique_id_in_definition,
 
            Expression::Call(expr) => expr.unique_id_in_definition,
 
            Expression::Variable(expr) => expr.unique_id_in_definition,
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone, Copy)]
 
pub enum AssignmentOperator {
 
    Set,
 
    Concatenated,
 
    Multiplied,
 
    Divided,
 
    Remained,
 
    Added,
 
    Subtracted,
 
    ShiftedLeft,
 
    ShiftedRight,
 
    BitwiseAnded,
 
    BitwiseXored,
 
    BitwiseOred,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct AssignmentExpression {
 
    pub this: AssignmentExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of the operator
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub left: ExpressionId,
 
    pub operation: AssignmentOperator,
 
    pub right: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BindingExpression {
 
    pub this: BindingExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of the binding keyword
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub bound_to: ExpressionId,
 
    pub bound_from: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ConditionalExpression {
 
    pub this: ConditionalExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of question mark operator
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub test: ExpressionId,
 
    pub true_expression: ExpressionId,
 
    pub false_expression: ExpressionId,
 
    // Validator/Linking
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 
pub enum BinaryOperator {
 
    Concatenate,
 
    LogicalOr,
 
    LogicalAnd,
 
    BitwiseOr,
 
    BitwiseXor,
 
    BitwiseAnd,
 
    Equality,
 
    Inequality,
 
    LessThan,
 
    GreaterThan,
 
    LessThanEqual,
 
    GreaterThanEqual,
 
    ShiftLeft,
 
    ShiftRight,
 
    Add,
 
    Subtract,
 
    Multiply,
 
    Divide,
 
    Remainder,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BinaryExpression {
 
    pub this: BinaryExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of the operator
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub left: ExpressionId,
 
    pub operation: BinaryOperator,
 
    pub right: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 
pub enum UnaryOperator {
 
    Positive,
 
    Negative,
 
    BitwiseNot,
 
    LogicalNot,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct UnaryExpression {
 
    pub this: UnaryExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of the operator
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub operation: UnaryOperator,
 
    pub expression: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct IndexingExpression {
 
    pub this: IndexingExpressionId,
 
    // Parsing
 
    pub span: InputSpan,
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub subject: ExpressionId,
 
    pub index: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SlicingExpression {
 
    pub this: SlicingExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // from '[' to ']';
 
    pub slicing_span: InputSpan, // from '[' to ']'
 
    pub full_span: InputSpan, // includes subject
 
    pub subject: ExpressionId,
 
    pub from_index: ExpressionId,
 
    pub to_index: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SelectExpression {
 
    pub this: SelectExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of the '.'
 
    pub operator_span: InputSpan, // of the '.'
 
    pub full_span: InputSpan, // includes subject and field
 
    pub subject: ExpressionId,
 
    pub field_name: Identifier,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct CastExpression {
 
    pub this: CastExpressionId,
 
    // Parsing
 
    pub span: InputSpan, // of the "cast" keyword,
 
    pub cast_span: InputSpan, // of the "cast" keyword,
 
    pub full_span: InputSpan, // includes the cast subject
 
    pub to_type: ParserType,
 
    pub subject: ExpressionId,
 
    // Validator/linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct CallExpression {
 
    pub this: CallExpressionId,
 
    // Parsing
 
    pub span: InputSpan,
 
    pub func_span: InputSpan, // of the function name
 
    pub full_span: InputSpan, // includes the arguments and parentheses
 
    pub parser_type: ParserType, // of the function call, not the return type
 
    pub method: Method,
 
    pub arguments: Vec<ExpressionId>,
 
    pub definition: DefinitionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone, PartialEq, Eq)]
 
pub enum Method {
 
    // Builtin
 
    Get,
 
    Put,
 
    Fires,
 
    Create,
 
    Length,
 
    Assert,
 
    UserFunction,
 
    UserComponent,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct MethodSymbolic {
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) definition: DefinitionId
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralExpression {
 
    pub this: LiteralExpressionId,
 
    // Parsing
 
    pub span: InputSpan,
 
    pub value: Literal,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum Literal {
 
    Null, // message
 
    True,
 
    False,
 
    Character(char),
 
    String(StringRef<'static>),
 
    Integer(LiteralInteger),
 
    Struct(LiteralStruct),
 
    Enum(LiteralEnum),
 
    Union(LiteralUnion),
 
    Array(Vec<ExpressionId>),
 
}
 

	
 
impl Literal {
 
    pub(crate) fn as_struct(&self) -> &LiteralStruct {
 
        if let Literal::Struct(literal) = self{
 
            literal
 
        } else {
 
            unreachable!("Attempted to obtain {:?} as Literal::Struct", self)
 
        }
 
    }
 

	
 
    pub(crate) fn as_enum(&self) -> &LiteralEnum {
 
        if let Literal::Enum(literal) = self {
 
            literal
 
        } else {
 
            unreachable!("Attempted to obtain {:?} as Literal::Enum", self)
 
        }
 
    }
 

	
 
    pub(crate) fn as_union(&self) -> &LiteralUnion {
 
        if let Literal::Union(literal) = self {
 
            literal
 
        } else {
 
            unreachable!("Attempted to obtain {:?} as Literal::Union", self)
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralInteger {
 
    pub(crate) unsigned_value: u64,
 
    pub(crate) negated: bool, // for constant expression evaluation, TODO: @Int
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralStructField {
 
    // Phase 1: parser
 
    pub(crate) identifier: Identifier,
 
    pub(crate) value: ExpressionId,
 
    // Phase 2: linker
 
    pub(crate) field_idx: usize, // in struct definition
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralStruct {
 
    // Phase 1: parser
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) fields: Vec<LiteralStructField>,
 
    pub(crate) definition: DefinitionId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralEnum {
 
    // Phase 1: parser
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) variant: Identifier,
 
    pub(crate) definition: DefinitionId,
 
    // Phase 2: linker
 
    pub(crate) variant_idx: usize, // as present in the type table
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralUnion {
 
    // Phase 1: parser
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) variant: Identifier,
 
    pub(crate) values: Vec<ExpressionId>,
 
    pub(crate) definition: DefinitionId,
 
    // Phase 2: linker
 
    pub(crate) variant_idx: usize, // as present in type table
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct VariableExpression {
 
    pub this: VariableExpressionId,
 
    // Parsing
 
    pub identifier: Identifier,
 
    // Validator/Linker
 
    pub declaration: Option<VariableId>,
 
    pub used_as_binding_target: bool,
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 
\ No newline at end of file
src/protocol/eval/error.rs
Show inline comments
 
use std::fmt;
 

	
 
use crate::protocol::{
 
    ast::*,
 
    Module,
 
    input_source::{ErrorStatement, StatementKind}
 
};
 
use super::executor::*;
 

	
 
/// Represents a stack frame recorded in an error
 
#[derive(Debug)]
 
pub struct EvalFrame {
 
    pub line: u32,
 
    pub module_name: String,
 
    pub procedure: String, // function or component
 
    pub is_func: bool,
 
}
 

	
 
impl fmt::Display for EvalFrame {
 
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 
        let func_or_comp = if self.is_func {
 
            "function "
 
        } else {
 
            "component"
 
        };
 

	
 
        if self.module_name.is_empty() {
 
            write!(f, "{} {}:{}", func_or_comp, &self.procedure, self.line)
 
        } else {
 
            write!(f, "{} {}:{}:{}", func_or_comp, &self.module_name, &self.procedure, self.line)
 
        }
 
    }
 
}
 

	
 
/// Represents an error that ocurred during evaluation. Contains error
 
/// statements just like in parsing errors. Additionally may display the current
 
/// execution state.
 
#[derive(Debug)]
 
pub struct EvalError {
 
    pub(crate) statements: Vec<ErrorStatement>,
 
    pub(crate) frames: Vec<EvalFrame>,
 
}
 

	
 
impl EvalError {
 
    pub(crate) fn new_error_at_expr(prompt: &Prompt, modules: &[Module], heap: &Heap, expr_id: ExpressionId, msg: String) -> EvalError {
 
        // Create frames
 
        debug_assert!(!prompt.frames.is_empty());
 
        let mut frames = Vec::with_capacity(prompt.frames.len());
 
        let mut last_module_source = &modules[0].source;
 
        for frame in prompt.frames.iter() {
 
            let definition = &heap[frame.definition];
 
            let statement = &heap[frame.position];
 
            let statement_span = statement.span();
 

	
 
            let (root_id, procedure, is_func) = match definition {
 
                Definition::Function(def) => {
 
                    (def.defined_in, def.identifier.value.as_str().to_string(), true)
 
                },
 
                Definition::Component(def) => {
 
                    (def.defined_in, def.identifier.value.as_str().to_string(), false)
 
                },
 
                _ => unreachable!("construct stack frame with definition pointing to data type")
 
            };
 

	
 
            // Lookup module name, if it has one
 
            let module = modules.iter().find(|m| m.root_id == root_id).unwrap();
 
            let module_name = if let Some(name) = &module.name {
 
                name.as_str().to_string()
 
            } else {
 
                String::new()
 
            };
 

	
 
            last_module_source = &module.source;
 
            frames.push(EvalFrame{
 
                line: statement_span.begin.line,
 
                module_name,
 
                procedure,
 
                is_func
 
            });
 
        }
 

	
 
        let expr = &heap[expr_id];
 
        let statements = vec![
 
            ErrorStatement::from_source_at_span(StatementKind::Error, last_module_source, expr.span(), msg)
 
            ErrorStatement::from_source_at_span(StatementKind::Error, last_module_source, expr.full_span(), msg)
 
        ];
 

	
 
        EvalError{ statements, frames }
 
    }
 
}
 

	
 
impl fmt::Display for EvalError {
 
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 
        // Display error statement(s)
 
        self.statements[0].fmt(f)?;
 
        for statement in self.statements.iter().skip(1) {
 
            writeln!(f)?;
 
            statement.fmt(f)?;
 
        }
 

	
 
        // Display stack trace
 
        writeln!(f)?;
 
        writeln!(f, " +-  Stack trace:")?;
 
        for frame in self.frames.iter().rev() {
 
            write!(f, " | ")?;
 
            frame.fmt(f)?;
 
            writeln!(f)?;
 
        }
 

	
 
        Ok(())
 
    }
 
}
 
\ No newline at end of file
src/protocol/eval/executor.rs
Show inline comments
 
@@ -398,384 +398,394 @@ impl Prompt {
 
                            // Evaluate indices
 
                            let from_index = cur_frame.expr_values.pop_back().unwrap();
 
                            let from_index = self.store.maybe_read_ref(&from_index);
 
                            let to_index = cur_frame.expr_values.pop_back().unwrap();
 
                            let to_index = self.store.maybe_read_ref(&to_index);
 

	
 
                            debug_assert!(from_index.is_integer() && to_index.is_integer());
 
                            let from_index = if from_index.is_signed_integer() {
 
                                from_index.as_signed_integer()
 
                            } else {
 
                                from_index.as_unsigned_integer() as i64
 
                            };
 
                            let to_index = if to_index.is_signed_integer() {
 
                                to_index.as_signed_integer()
 
                            } else {
 
                                to_index.as_unsigned_integer() as i64
 
                            };
 

	
 
                            // Dereference subject if needed
 
                            let subject = cur_frame.expr_values.pop_back().unwrap();
 
                            let deref_subject = self.store.maybe_read_ref(&subject);
 

	
 
                            // Slicing needs to produce a copy anyway (with the
 
                            // current evaluator implementation)
 
                            enum ValueKind{ Array, String, Message }
 
                            let (value_kind, array_heap_pos) = match deref_subject {
 
                                Value::Array(v) => (ValueKind::Array, *v),
 
                                Value::String(v) => (ValueKind::String, *v),
 
                                Value::Message(v) => (ValueKind::Message, *v),
 
                                _ => unreachable!()
 
                            };
 

	
 
                            if array_inclusive_index_is_invalid(&self.store, array_heap_pos, from_index) {
 
                                return Err(construct_array_error(self, modules, heap, expr.from_index, array_heap_pos, from_index));
 
                            }
 
                            if array_exclusive_index_is_invalid(&self.store, array_heap_pos, to_index) {
 
                                return Err(construct_array_error(self, modules, heap, expr.to_index, array_heap_pos, to_index));
 
                            }
 

	
 
                            // Again: would love to push directly, but rust...
 
                            let new_heap_pos = self.store.alloc_heap();
 
                            debug_assert!(self.store.heap_regions[new_heap_pos as usize].values.is_empty());
 
                            if to_index > from_index {
 
                                let from_index = from_index as usize;
 
                                let to_index = to_index as usize;
 
                                let mut values = Vec::with_capacity(to_index - from_index);
 
                                for idx in from_index..to_index {
 
                                    let value = self.store.heap_regions[array_heap_pos as usize].values[idx].clone();
 
                                    values.push(self.store.clone_value(value));
 
                                }
 

	
 
                                self.store.heap_regions[new_heap_pos as usize].values = values;
 

	
 
                            } // else: empty range
 

	
 
                            cur_frame.expr_values.push_back(match value_kind {
 
                                ValueKind::Array => Value::Array(new_heap_pos),
 
                                ValueKind::String => Value::String(new_heap_pos),
 
                                ValueKind::Message => Value::Message(new_heap_pos),
 
                            });
 

	
 
                            // Dropping the original subject, because we don't
 
                            // want to drop something on the stack
 
                            self.store.drop_value(subject.get_heap_pos());
 
                        },
 
                        Expression::Select(expr) => {
 
                            let subject= cur_frame.expr_values.pop_back().unwrap();
 
                            let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
 
                            let field_idx = mono_data.expr_data[expr.unique_id_in_definition as usize].field_or_monomorph_idx as u32;
 

	
 
                            // Note: same as above: clone if value lives on expr stack, simply
 
                            // refer to it if it already lives on the stack/heap.
 
                            let (deallocate_heap_pos, value_to_push) = match subject {
 
                                Value::Ref(value_ref) => {
 
                                    let subject = self.store.read_ref(value_ref);
 
                                    let subject_heap_pos = subject.as_struct();
 

	
 
                                    (None, Value::Ref(ValueId::Heap(subject_heap_pos, field_idx)))
 
                                },
 
                                _ => {
 
                                    let subject_heap_pos = subject.as_struct();
 
                                    let subject_indexed = Value::Ref(ValueId::Heap(subject_heap_pos, field_idx));
 
                                    (Some(subject_heap_pos), self.store.clone_value(subject_indexed))
 
                                },
 
                            };
 

	
 
                            cur_frame.expr_values.push_back(value_to_push);
 
                            self.store.drop_value(deallocate_heap_pos);
 
                        },
 
                        Expression::Literal(expr) => {
 
                            let value = match &expr.value {
 
                                Literal::Null => Value::Null,
 
                                Literal::True => Value::Bool(true),
 
                                Literal::False => Value::Bool(false),
 
                                Literal::Character(lit_value) => Value::Char(*lit_value),
 
                                Literal::String(lit_value) => {
 
                                    let heap_pos = self.store.alloc_heap();
 
                                    let values = &mut self.store.heap_regions[heap_pos as usize].values;
 
                                    let value = lit_value.as_str();
 
                                    debug_assert!(values.is_empty());
 
                                    values.reserve(value.len());
 
                                    for character in value.as_bytes() {
 
                                        debug_assert!(character.is_ascii());
 
                                        values.push(Value::Char(*character as char));
 
                                    }
 
                                    Value::String(heap_pos)
 
                                }
 
                                Literal::Integer(lit_value) => {
 
                                    use ConcreteTypePart as CTP;
 
                                    let def_types = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
 
                                    let concrete_type = &def_types.expr_data[expr.unique_id_in_definition as usize].expr_type;
 

	
 
                                    debug_assert_eq!(concrete_type.parts.len(), 1);
 
                                    match concrete_type.parts[0] {
 
                                        CTP::UInt8  => Value::UInt8(lit_value.unsigned_value as u8),
 
                                        CTP::UInt16 => Value::UInt16(lit_value.unsigned_value as u16),
 
                                        CTP::UInt32 => Value::UInt32(lit_value.unsigned_value as u32),
 
                                        CTP::UInt64 => Value::UInt64(lit_value.unsigned_value as u64),
 
                                        CTP::SInt8  => Value::SInt8(lit_value.unsigned_value as i8),
 
                                        CTP::SInt16 => Value::SInt16(lit_value.unsigned_value as i16),
 
                                        CTP::SInt32 => Value::SInt32(lit_value.unsigned_value as i32),
 
                                        CTP::SInt64 => Value::SInt64(lit_value.unsigned_value as i64),
 
                                        _ => unreachable!("got concrete type {:?} for integer literal at expr {:?}", concrete_type, expr_id),
 
                                    }
 
                                }
 
                                Literal::Struct(lit_value) => {
 
                                    let heap_pos = transfer_expression_values_front_into_heap(
 
                                        cur_frame, &mut self.store, lit_value.fields.len()
 
                                    );
 
                                    Value::Struct(heap_pos)
 
                                }
 
                                Literal::Enum(lit_value) => {
 
                                    Value::Enum(lit_value.variant_idx as i64)
 
                                }
 
                                Literal::Union(lit_value) => {
 
                                    let heap_pos = transfer_expression_values_front_into_heap(
 
                                        cur_frame, &mut self.store, lit_value.values.len()
 
                                    );
 
                                    Value::Union(lit_value.variant_idx as i64, heap_pos)
 
                                }
 
                                Literal::Array(lit_value) => {
 
                                    let heap_pos = transfer_expression_values_front_into_heap(
 
                                        cur_frame, &mut self.store, lit_value.len()
 
                                    );
 
                                    Value::Array(heap_pos)
 
                                }
 
                            };
 

	
 
                            cur_frame.expr_values.push_back(value);
 
                        },
 
                        Expression::Cast(expr) => {
 
                            let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
 
                            let output_type = &mono_data.expr_data[expr.unique_id_in_definition as usize].expr_type;
 

	
 
                            // Typechecking reduced this to two cases: either we
 
                            // have casting noop (same types), or we're casting
 
                            // between integer/bool/char types.
 
                            let subject = cur_frame.expr_values.pop_back().unwrap();
 
                            match apply_casting(&mut self.store, output_type, &subject) {
 
                                Ok(value) => cur_frame.expr_values.push_back(value),
 
                                Err(msg) => {
 
                                    return Err(EvalError::new_error_at_expr(self, modules, heap, expr.this.upcast(), msg));
 
                                }
 
                            }
 

	
 
                            self.store.drop_value(subject.get_heap_pos());
 
                        }
 
                        Expression::Call(expr) => {
 
                            // If we're dealing with a builtin we don't do any
 
                            // fancy shenanigans at all, just push the result.
 
                            match expr.method {
 
                                Method::Get => {
 
                                    let value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let value = self.store.maybe_read_ref(&value).clone();
 

	
 
                                    match ctx.get(value.clone(), &mut self.store) {
 
                                        Some(result) => {
 
                                            cur_frame.expr_values.push_back(result)
 
                                        },
 
                                        None => {
 
                                            cur_frame.expr_values.push_front(value.clone());
 
                                            cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
 
                                            return Ok(EvalContinuation::BlockGet(value));
 
                                        }
 
                                    }
 
                                },
 
                                Method::Put => {
 
                                    let port_value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let deref_port_value = self.store.maybe_read_ref(&port_value).clone();
 
                                    let msg_value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let deref_msg_value = self.store.maybe_read_ref(&msg_value).clone();
 

	
 
                                    match deref_msg_value {
 
                                        Value::Message(_) => {},
 
                                        _ => {
 
                                            return Err(EvalError::new_error_at_expr(
 
                                                self, modules, heap, expr_id,
 
                                                String::from("Calls to `put` are currently restricted to only send instances of `msg` types. This will change in the future")
 
                                            ));
 
                                        }
 
                                    }
 

	
 
                                    if ctx.did_put(deref_port_value.clone()) {
 
                                        // We're fine, deallocate in case the expression value stack
 
                                        // held an owned value
 
                                        self.store.drop_value(msg_value.get_heap_pos());
 
                                    } else {
 
                                        cur_frame.expr_values.push_front(msg_value);
 
                                        cur_frame.expr_values.push_front(port_value);
 
                                        cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
 
                                        return Ok(EvalContinuation::Put(deref_port_value, deref_msg_value));
 
                                    }
 
                                },
 
                                Method::Fires => {
 
                                    let port_value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let port_value_deref = self.store.maybe_read_ref(&port_value).clone();
 
                                    match ctx.fires(port_value_deref.clone()) {
 
                                        None => {
 
                                            cur_frame.expr_values.push_front(port_value);
 
                                            cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
 
                                            return Ok(EvalContinuation::BlockFires(port_value_deref));
 
                                        },
 
                                        Some(value) => {
 
                                            cur_frame.expr_values.push_back(value);
 
                                        }
 
                                    }
 
                                },
 
                                Method::Create => {
 
                                    let length_value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let length_value = self.store.maybe_read_ref(&length_value);
 
                                    let length = if length_value.is_signed_integer() {
 
                                        let length_value = length_value.as_signed_integer();
 
                                        if length_value < 0 {
 
                                            return Err(EvalError::new_error_at_expr(
 
                                                self, modules, heap, expr_id,
 
                                                format!("got length '{}', can only create a message with a non-negative length", length_value)
 
                                            ));
 
                                        }
 

	
 
                                        length_value as u64
 
                                    } else {
 
                                        debug_assert!(length_value.is_unsigned_integer());
 
                                        length_value.as_unsigned_integer()
 
                                    };
 

	
 
                                    let heap_pos = self.store.alloc_heap();
 
                                    let values = &mut self.store.heap_regions[heap_pos as usize].values;
 
                                    debug_assert!(values.is_empty());
 
                                    values.resize(length as usize, Value::UInt8(0));
 
                                    cur_frame.expr_values.push_back(Value::Message(heap_pos));
 
                                },
 
                                Method::Length => {
 
                                    let value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let value_heap_pos = value.get_heap_pos();
 
                                    let value = self.store.maybe_read_ref(&value);
 

	
 
                                    let heap_pos = match value {
 
                                        Value::Array(pos) => *pos,
 
                                        Value::String(pos) => *pos,
 
                                        _ => unreachable!("length(...) on {:?}", value),
 
                                    };
 

	
 
                                    let len = self.store.heap_regions[heap_pos as usize].values.len();
 

	
 
                                    // TODO: @PtrInt
 
                                    cur_frame.expr_values.push_back(Value::UInt32(len as u32));
 
                                    self.store.drop_value(value_heap_pos);
 
                                },
 
                                Method::Assert => {
 
                                    let value = cur_frame.expr_values.pop_front().unwrap();
 
                                    let value = self.store.maybe_read_ref(&value).clone();
 
                                    if !value.as_bool() {
 
                                        return Ok(EvalContinuation::Inconsistent)
 
                                    }
 
                                },
 
                                Method::UserComponent => {
 
                                    // This is actually handled by the evaluation
 
                                    // of the statement.
 
                                    debug_assert_eq!(heap[expr.definition].parameters().len(), cur_frame.expr_values.len());
 
                                    debug_assert_eq!(heap[cur_frame.position].as_new().expression, expr.this)
 
                                },
 
                                Method::UserFunction => {
 
                                    // Push a new frame. Note that all expressions have
 
                                    // been pushed to the front, so they're in the order
 
                                    // of the definition.
 
                                    let num_args = expr.arguments.len();
 

	
 
                                    // Determine stack boundaries
 
                                    let cur_stack_boundary = self.store.cur_stack_boundary;
 
                                    let new_stack_boundary = self.store.stack.len();
 

	
 
                                    // Push new boundary and function arguments for new frame
 
                                    self.store.stack.push(Value::PrevStackBoundary(cur_stack_boundary as isize));
 
                                    for _ in 0..num_args {
 
                                        let argument = self.store.read_take_ownership(cur_frame.expr_values.pop_front().unwrap());
 
                                        self.store.stack.push(argument);
 
                                    }
 

	
 
                                    // Determine the monomorph index of the function we're calling
 
                                    let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
 
                                    let call_data = &mono_data.expr_data[expr.unique_id_in_definition as usize];
 

	
 
                                    // Push the new frame and reserve its stack size
 
                                    let new_frame = Frame::new(heap, expr.definition, call_data.field_or_monomorph_idx);
 
                                    let new_stack_size = new_frame.max_stack_size;
 
                                    self.frames.push(new_frame);
 
                                    self.store.cur_stack_boundary = new_stack_boundary;
 
                                    self.store.reserve_stack(new_stack_size);
 

	
 
                                    // To simplify the logic a little bit we will now
 
                                    // return and ask our caller to call us again
 
                                    return Ok(EvalContinuation::Stepping);
 
                                },
 
                            }
 
                        },
 
                        Expression::Variable(expr) => {
 
                            let variable = &heap[expr.declaration.unwrap()];
 
                            let ref_value = if expr.used_as_binding_target {
 
                                Value::Binding(variable.unique_id_in_scope as StackPos)
 
                            } else {
 
                                Value::Ref(ValueId::Stack(variable.unique_id_in_scope as StackPos))
 
                            };
 
                            cur_frame.expr_values.push_back(ref_value);
 
                        }
 
                    }
 
                }
 
            }
 
        }
 

	
 
        debug_log!("Frame [{:?}] at {:?}", cur_frame.definition, cur_frame.position);
 
        if debug_enabled!() {
 
            debug_log!("Expression value stack (size = {}):", cur_frame.expr_values.len());
 
            for (_stack_idx, _stack_val) in cur_frame.expr_values.iter().enumerate() {
 
                debug_log!("  [{:03}] {:?}", _stack_idx, _stack_val);
 
            }
 

	
 
            debug_log!("Stack (size = {}):", self.store.stack.len());
 
            for (_stack_idx, _stack_val) in self.store.stack.iter().enumerate() {
 
                debug_log!("  [{:03}] {:?}", _stack_idx, _stack_val);
 
            }
 

	
 
            debug_log!("Heap:");
 
            for (_heap_idx, _heap_region) in self.store.heap_regions.iter().enumerate() {
 
                let _is_free = self.store.free_regions.iter().any(|idx| *idx as usize == _heap_idx);
 
                debug_log!("  [{:03}] in_use: {}, len: {}, vals: {:?}", _heap_idx, !_is_free, _heap_region.values.len(), &_heap_region.values);
 
            }
 
        }
 
        // No (more) expressions to evaluate. So evaluate statement (that may
 
        // depend on the result on the last evaluated expression(s))
 
        let stmt = &heap[cur_frame.position];
 
        let return_value = match stmt {
 
            Statement::Block(stmt) => {
 
                debug_assert!(stmt.statements.is_empty() || stmt.next == stmt.statements[0]);
 
                cur_frame.position = stmt.next;
 
                Ok(EvalContinuation::Stepping)
 
            },
 
            Statement::EndBlock(stmt) => {
 
                let block = &heap[stmt.start_block];
 
                self.store.clear_stack(block.first_unique_id_in_scope as usize);
 
                cur_frame.position = stmt.next;
 

	
 
                Ok(EvalContinuation::Stepping)
 
            },
 
            Statement::Local(stmt) => {
 
                match stmt {
 
                    LocalStatement::Memory(stmt) => {
 
                        let variable = &heap[stmt.variable];
 
                        self.store.write(ValueId::Stack(variable.unique_id_in_scope as u32), Value::Unassigned);
 

	
 
                        cur_frame.position = stmt.next;
 
                    },
 
                    LocalStatement::Channel(stmt) => {
 
                        let [from_value, to_value] = ctx.new_channel();
 
                        self.store.write(ValueId::Stack(heap[stmt.from].unique_id_in_scope as u32), from_value);
 
                        self.store.write(ValueId::Stack(heap[stmt.to].unique_id_in_scope as u32), to_value);
 

	
 
                        cur_frame.position = stmt.next;
 
                    }
 
                }
 

	
 
                Ok(EvalContinuation::Stepping)
 
            },
 
            Statement::Labeled(stmt) => {
 
                cur_frame.position = stmt.body;
 

	
 
                Ok(EvalContinuation::Stepping)
 
            },
 
            Statement::If(stmt) => {
 
                debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for if statement");
 
                let test_value = cur_frame.expr_values.pop_back().unwrap();
 
                let test_value = self.store.maybe_read_ref(&test_value).as_bool();
 
                if test_value {
 
                    cur_frame.position = stmt.true_body.upcast();
 
                } else if let Some(false_body) = stmt.false_body {
src/protocol/parser/pass_definitions.rs
Show inline comments
 
@@ -672,1121 +672,1155 @@ impl PassDefinitions {
 
                valid = true;
 
            }
 
        }
 

	
 
        if !valid {
 
            return Err(ParseError::new_error_str_at_span(
 
                &module.source, InputSpan::from_positions(start_pos, iter.last_valid_pos()), "expected a call expression"
 
            ));
 
        }
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
        debug_assert!(!call_id.is_invalid());
 
        Ok(ctx.heap.alloc_new_statement(|this| NewStatement{
 
            this,
 
            span: new_span,
 
            expression: call_id,
 
            next: StatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_channel_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ChannelStatementId, ParseError> {
 
        // Consume channel specification
 
        let channel_span = consume_exact_ident(&module.source, iter, KW_STMT_CHANNEL)?;
 
        let (inner_port_type, end_pos) = if Some(TokenKind::OpenAngle) == iter.next() {
 
            // Retrieve the type of the channel, we're cheating a bit here by
 
            // consuming the first '<' and setting the initial angle depth to 1
 
            // such that our final '>' will be consumed as well.
 
            iter.consume();
 
            let definition_id = self.cur_definition;
 
            let poly_vars = ctx.heap[definition_id].poly_vars();
 
            let parser_type = consume_parser_type(
 
                &module.source, iter, &ctx.symbols, &ctx.heap,
 
                poly_vars, SymbolScope::Module(module.root_id), definition_id,
 
                true, 1
 
            )?;
 

	
 
            (parser_type.elements, parser_type.full_span.end)
 
        } else {
 
            // Assume inferred
 
            (
 
                vec![ParserTypeElement{
 
                    element_span: channel_span,
 
                    variant: ParserTypeVariant::Inferred
 
                }],
 
                channel_span.end
 
            )
 
        };
 

	
 
        let from_identifier = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::ArrowRight)?;
 
        let to_identifier = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
        // Construct ports
 
        let port_type_span = InputSpan::from_positions(channel_span.begin, end_pos);
 
        let port_type_len = inner_port_type.len() + 1;
 
        let mut from_port_type = ParserType{ elements: Vec::with_capacity(port_type_len), full_span: port_type_span };
 
        from_port_type.elements.push(ParserTypeElement{
 
            element_span: channel_span,
 
            variant: ParserTypeVariant::Output,
 
        });
 
        from_port_type.elements.extend_from_slice(&inner_port_type);
 
        let from = ctx.heap.alloc_variable(|this| Variable{
 
            this,
 
            kind: VariableKind::Local,
 
            identifier: from_identifier,
 
            parser_type: from_port_type,
 
            relative_pos_in_block: 0,
 
            unique_id_in_scope: -1,
 
        });
 

	
 
        let mut to_port_type = ParserType{ elements: Vec::with_capacity(port_type_len), full_span: port_type_span };
 
        to_port_type.elements.push(ParserTypeElement{
 
            element_span: channel_span,
 
            variant: ParserTypeVariant::Input
 
        });
 
        to_port_type.elements.extend_from_slice(&inner_port_type);
 
        let to = ctx.heap.alloc_variable(|this|Variable{
 
            this,
 
            kind: VariableKind::Local,
 
            identifier: to_identifier,
 
            parser_type: to_port_type,
 
            relative_pos_in_block: 0,
 
            unique_id_in_scope: -1,
 
        });
 

	
 
        // Construct the channel
 
        Ok(ctx.heap.alloc_channel_statement(|this| ChannelStatement{
 
            this,
 
            span: channel_span,
 
            from, to,
 
            relative_pos_in_block: 0,
 
            next: StatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_labeled_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, section: &mut ScopedSection<StatementId>
 
    ) -> Result<(), ParseError> {
 
        let label = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::Colon)?;
 

	
 
        // Not pretty: consume_statement may produce more than one statement.
 
        // The values in the section need to be in the correct order if some
 
        // kind of outer block is consumed, so we take another section, push
 
        // the expressions in that one, and then allocate the labeled statement.
 
        let mut inner_section = self.statements.start_section();
 
        self.consume_statement(module, iter, ctx, &mut inner_section)?;
 
        debug_assert!(inner_section.len() >= 1);
 

	
 
        let stmt_id = ctx.heap.alloc_labeled_statement(|this| LabeledStatement {
 
            this,
 
            label,
 
            body: inner_section[0],
 
            relative_pos_in_block: 0,
 
            in_sync: SynchronousStatementId::new_invalid(),
 
        });
 

	
 
        if inner_section.len() == 1 {
 
            // Produce the labeled statement pointing to the first statement.
 
            // This is by far the most common case.
 
            inner_section.forget();
 
            section.push(stmt_id.upcast());
 
        } else {
 
            // Produce the labeled statement using the first statement, and push
 
            // the remaining ones at the end.
 
            let inner_statements = inner_section.into_vec();
 
            section.push(stmt_id.upcast());
 
            for idx in 1..inner_statements.len() {
 
                section.push(inner_statements[idx])
 
            }
 
        }
 

	
 
        Ok(())
 
    }
 

	
 
    fn maybe_consume_memory_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<Option<(MemoryStatementId, ExpressionStatementId)>, ParseError> {
 
        // This is a bit ugly. It would be nicer if we could somehow
 
        // consume the expression with a type hint if we do get a valid
 
        // type, but we don't get an identifier following it
 
        let iter_state = iter.save();
 
        let definition_id = self.cur_definition;
 
        let poly_vars = ctx.heap[definition_id].poly_vars();
 

	
 
        let parser_type = consume_parser_type(
 
            &module.source, iter, &ctx.symbols, &ctx.heap, poly_vars,
 
            SymbolScope::Definition(definition_id), definition_id, true, 0
 
        );
 

	
 
        if let Ok(parser_type) = parser_type {
 
            if Some(TokenKind::Ident) == iter.next() {
 
                // Assume this is a proper memory statement
 
                let identifier = consume_ident_interned(&module.source, iter, ctx)?;
 
                let memory_span = InputSpan::from_positions(parser_type.full_span.begin, identifier.span.end);
 
                let assign_span = consume_token(&module.source, iter, TokenKind::Equal)?;
 

	
 
                let initial_expr_begin_pos = iter.last_valid_pos();
 
                let initial_expr_id = self.consume_expression(module, iter, ctx)?;
 
                let initial_expr_end_pos = iter.last_valid_pos();
 
                consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
                // Allocate the memory statement with the variable
 
                let local_id = ctx.heap.alloc_variable(|this| Variable{
 
                    this,
 
                    kind: VariableKind::Local,
 
                    identifier: identifier.clone(),
 
                    parser_type,
 
                    relative_pos_in_block: 0,
 
                    unique_id_in_scope: -1,
 
                });
 
                let memory_stmt_id = ctx.heap.alloc_memory_statement(|this| MemoryStatement{
 
                    this,
 
                    span: memory_span,
 
                    variable: local_id,
 
                    next: StatementId::new_invalid()
 
                });
 

	
 
                // Allocate the initial assignment
 
                let variable_expr_id = ctx.heap.alloc_variable_expression(|this| VariableExpression{
 
                    this,
 
                    identifier,
 
                    declaration: None,
 
                    used_as_binding_target: false,
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                });
 
                let assignment_expr_id = ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
 
                    this,
 
                    span: assign_span,
 
                    operator_span: assign_span,
 
                    full_span: InputSpan::from_positions(memory_span.begin, initial_expr_end_pos),
 
                    left: variable_expr_id.upcast(),
 
                    operation: AssignmentOperator::Set,
 
                    right: initial_expr_id,
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                });
 
                let assignment_stmt_id = ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
 
                    this,
 
                    span: InputSpan::from_positions(initial_expr_begin_pos, initial_expr_end_pos),
 
                    expression: assignment_expr_id.upcast(),
 
                    next: StatementId::new_invalid(),
 
                });
 

	
 
                return Ok(Some((memory_stmt_id, assignment_stmt_id)))
 
            }
 
        }
 

	
 
        // If here then one of the preconditions for a memory statement was not
 
        // met. So recover the iterator and return
 
        iter.load(iter_state);
 
        Ok(None)
 
    }
 

	
 
    fn consume_expression_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionStatementId, ParseError> {
 
        let start_pos = iter.last_valid_pos();
 
        let expression = self.consume_expression(module, iter, ctx)?;
 
        let end_pos = iter.last_valid_pos();
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
        Ok(ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
 
            this,
 
            span: InputSpan::from_positions(start_pos, end_pos),
 
            expression,
 
            next: StatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    //--------------------------------------------------------------------------
 
    // Expression Parsing
 
    //--------------------------------------------------------------------------
 

	
 
    // TODO: @Cleanup This is fine for now. But I prefer my stacktraces not to
 
    //  look like enterprise Java code...
 
    fn consume_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_assignment_expression(module, iter, ctx)
 
    }
 

	
 
    fn consume_assignment_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        // Utility to convert token into assignment operator
 
        fn parse_assignment_operator(token: Option<TokenKind>) -> Option<AssignmentOperator> {
 
            use TokenKind as TK;
 
            use AssignmentOperator as AO;
 

	
 
            if token.is_none() {
 
                return None
 
            }
 

	
 
            match token.unwrap() {
 
                TK::Equal               => Some(AO::Set),
 
                TK::AtEquals            => Some(AO::Concatenated),
 
                TK::StarEquals          => Some(AO::Multiplied),
 
                TK::SlashEquals         => Some(AO::Divided),
 
                TK::PercentEquals       => Some(AO::Remained),
 
                TK::PlusEquals          => Some(AO::Added),
 
                TK::MinusEquals         => Some(AO::Subtracted),
 
                TK::ShiftLeftEquals     => Some(AO::ShiftedLeft),
 
                TK::ShiftRightEquals    => Some(AO::ShiftedRight),
 
                TK::AndEquals           => Some(AO::BitwiseAnded),
 
                TK::CaretEquals         => Some(AO::BitwiseXored),
 
                TK::OrEquals            => Some(AO::BitwiseOred),
 
                _                       => None
 
            }
 
        }
 

	
 
        let expr = self.consume_conditional_expression(module, iter, ctx)?;
 
        if let Some(operation) = parse_assignment_operator(iter.next()) {
 
            let span = iter.next_span();
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let left = expr;
 
            let right = self.consume_expression(module, iter, ctx)?;
 

	
 
            let full_span = InputSpan::from_positions(
 
                ctx.heap[left].full_span().begin,
 
                ctx.heap[right].full_span().end,
 
            );
 

	
 
            Ok(ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
 
                this, span, left, operation, right,
 
                this, operator_span, full_span, left, operation, right,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast())
 
        } else {
 
            Ok(expr)
 
        }
 
    }
 

	
 
    fn consume_conditional_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        let result = self.consume_concat_expression(module, iter, ctx)?;
 
        if let Some(TokenKind::Question) = iter.next() {
 
            let span = iter.next_span();
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let test = result;
 
            let true_expression = self.consume_expression(module, iter, ctx)?;
 
            consume_token(&module.source, iter, TokenKind::Colon)?;
 
            let false_expression = self.consume_expression(module, iter, ctx)?;
 

	
 
            let full_span = InputSpan::from_positions(
 
                ctx.heap[test].full_span().begin,
 
                ctx.heap[false_expression].full_span().end,
 
            );
 

	
 
            Ok(ctx.heap.alloc_conditional_expression(|this| ConditionalExpression{
 
                this, span, test, true_expression, false_expression,
 
                this, operator_span, full_span, test, true_expression, false_expression,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast())
 
        } else {
 
            Ok(result)
 
        }
 
    }
 

	
 
    fn consume_concat_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::At) => Some(BinaryOperator::Concatenate),
 
                _ => None
 
            },
 
            Self::consume_logical_or_expression
 
        )
 
    }
 

	
 
    fn consume_logical_or_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::OrOr) => Some(BinaryOperator::LogicalOr),
 
                _ => None
 
            },
 
            Self::consume_logical_and_expression
 
        )
 
    }
 

	
 
    fn consume_logical_and_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::AndAnd) => Some(BinaryOperator::LogicalAnd),
 
                _ => None
 
            },
 
            Self::consume_bitwise_or_expression
 
        )
 
    }
 

	
 
    fn consume_bitwise_or_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Or) => Some(BinaryOperator::BitwiseOr),
 
                _ => None
 
            },
 
            Self::consume_bitwise_xor_expression
 
        )
 
    }
 

	
 
    fn consume_bitwise_xor_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Caret) => Some(BinaryOperator::BitwiseXor),
 
                _ => None
 
            },
 
            Self::consume_bitwise_and_expression
 
        )
 
    }
 

	
 
    fn consume_bitwise_and_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::And) => Some(BinaryOperator::BitwiseAnd),
 
                _ => None
 
            },
 
            Self::consume_equality_expression
 
        )
 
    }
 

	
 
    fn consume_equality_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::EqualEqual) => Some(BinaryOperator::Equality),
 
                Some(TokenKind::NotEqual) => Some(BinaryOperator::Inequality),
 
                _ => None
 
            },
 
            Self::consume_relational_expression
 
        )
 
    }
 

	
 
    fn consume_relational_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::OpenAngle) => Some(BinaryOperator::LessThan),
 
                Some(TokenKind::CloseAngle) => Some(BinaryOperator::GreaterThan),
 
                Some(TokenKind::LessEquals) => Some(BinaryOperator::LessThanEqual),
 
                Some(TokenKind::GreaterEquals) => Some(BinaryOperator::GreaterThanEqual),
 
                _ => None
 
            },
 
            Self::consume_shift_expression
 
        )
 
    }
 

	
 
    fn consume_shift_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::ShiftLeft) => Some(BinaryOperator::ShiftLeft),
 
                Some(TokenKind::ShiftRight) => Some(BinaryOperator::ShiftRight),
 
                _ => None
 
            },
 
            Self::consume_add_or_subtract_expression
 
        )
 
    }
 

	
 
    fn consume_add_or_subtract_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Plus) => Some(BinaryOperator::Add),
 
                Some(TokenKind::Minus) => Some(BinaryOperator::Subtract),
 
                _ => None,
 
            },
 
            Self::consume_multiply_divide_or_modulus_expression
 
        )
 
    }
 

	
 
    fn consume_multiply_divide_or_modulus_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Star) => Some(BinaryOperator::Multiply),
 
                Some(TokenKind::Slash) => Some(BinaryOperator::Divide),
 
                Some(TokenKind::Percent) => Some(BinaryOperator::Remainder),
 
                _ => None
 
            },
 
            Self::consume_prefix_expression
 
        )
 
    }
 

	
 
    fn consume_prefix_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        fn parse_prefix_token(token: Option<TokenKind>) -> Option<UnaryOperator> {
 
            use TokenKind as TK;
 
            use UnaryOperator as UO;
 
            match token {
 
                Some(TK::Plus) => Some(UO::Positive),
 
                Some(TK::Minus) => Some(UO::Negative),
 
                Some(TK::Tilde) => Some(UO::BitwiseNot),
 
                Some(TK::Exclamation) => Some(UO::LogicalNot),
 
                _ => None
 
            }
 
        }
 

	
 
        let next = iter.next();
 
        if let Some(operation) = parse_prefix_token(next) {
 
            let span = iter.next_span();
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let expression = self.consume_prefix_expression(module, iter, ctx)?;
 
            let full_span = InputSpan::from_positions(
 
                operator_span.begin, ctx.heap[expression].full_span().end,
 
            );
 
            Ok(ctx.heap.alloc_unary_expression(|this| UnaryExpression {
 
                this,
 
                span,
 
                operation,
 
                expression,
 
                this, operator_span, full_span, operation, expression,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast())
 
        } else if next == Some(TokenKind::PlusPlus) {
 
            return Err(ParseError::new_error_str_at_span(
 
                &module.source, iter.next_span(), "prefix increment is not supported in the language"
 
            ));
 
        } else if next == Some(TokenKind::MinusMinus) {
 
            return Err(ParseError::new_error_str_at_span(
 
                &module.source, iter.next_span(), "prefix decrement is not supported in this language"
 
            ));
 
        } else {
 
            self.consume_postfix_expression(module, iter, ctx)
 
        }
 
    }
 

	
 
    fn consume_postfix_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        fn has_matching_postfix_token(token: Option<TokenKind>) -> bool {
 
            use TokenKind as TK;
 

	
 
            if token.is_none() { return false; }
 
            match token.unwrap() {
 
                TK::PlusPlus | TK::MinusMinus | TK::OpenSquare | TK::Dot => true,
 
                _ => false
 
            }
 
        }
 

	
 
        let mut result = self.consume_primary_expression(module, iter, ctx)?;
 
        let mut next = iter.next();
 
        while has_matching_postfix_token(next) {
 
            let token = next.unwrap();
 
            let mut span = iter.next_span();
 
            let mut operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            if token == TokenKind::PlusPlus {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &module.source, span, "postfix increment is not supported in this language"
 
                    &module.source, operator_span, "postfix increment is not supported in this language"
 
                ));
 
            } else if token == TokenKind::MinusMinus {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &module.source, span, "prefix increment is not supported in this language"
 
                    &module.source, operator_span, "prefix increment is not supported in this language"
 
                ));
 
            } else if token == TokenKind::OpenSquare {
 
                let subject = result;
 
                let from_index = self.consume_expression(module, iter, ctx)?;
 

	
 
                // Check if we have an indexing or slicing operation
 
                next = iter.next();
 
                if Some(TokenKind::DotDot) == next {
 
                    iter.consume();
 

	
 
                    let to_index = self.consume_expression(module, iter, ctx)?;
 
                    let end_span = consume_token(&module.source, iter, TokenKind::CloseSquare)?;
 
                    span.end = end_span.end;
 
                    operator_span.end = end_span.end;
 
                    let full_span = InputSpan::from_positions(
 
                        ctx.heap[subject].full_span().begin, operator_span.end
 
                    );
 

	
 
                    result = ctx.heap.alloc_slicing_expression(|this| SlicingExpression{
 
                        this, span, subject, from_index, to_index,
 
                        this,
 
                        slicing_span: operator_span,
 
                        full_span, subject, from_index, to_index,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast();
 
                } else if Some(TokenKind::CloseSquare) == next {
 
                    let end_span = consume_token(&module.source, iter, TokenKind::CloseSquare)?;
 
                    span.end = end_span.end;
 
                    operator_span.end = end_span.end;
 

	
 
                    let full_span = InputSpan::from_positions(
 
                        ctx.heap[subject].full_span().begin, operator_span.end
 
                    );
 

	
 
                    result = ctx.heap.alloc_indexing_expression(|this| IndexingExpression{
 
                        this, span, subject,
 
                        this, operator_span, full_span, subject,
 
                        index: from_index,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast();
 
                } else {
 
                    return Err(ParseError::new_error_str_at_pos(
 
                        &module.source, iter.last_valid_pos(), "unexpected token: expected ']' or '..'"
 
                    ));
 
                }
 
            } else {
 
                debug_assert_eq!(token, TokenKind::Dot);
 
                let subject = result;
 
                let field_name = consume_ident_interned(&module.source, iter, ctx)?;
 

	
 
                let full_span = InputSpan::from_positions(
 
                    ctx.heap[subject].full_span().begin, field_name.span.end
 
                );
 
                result = ctx.heap.alloc_select_expression(|this| SelectExpression{
 
                    this, span, subject, field_name,
 
                    this, operator_span, full_span, subject, field_name,
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                }).upcast();
 
            }
 

	
 
            next = iter.next();
 
        }
 

	
 
        Ok(result)
 
    }
 

	
 
    fn consume_primary_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        let next = iter.next();
 

	
 
        let result = if next == Some(TokenKind::OpenParen) {
 
            // Expression between parentheses
 
            iter.consume();
 
            let result = self.consume_expression(module, iter, ctx)?;
 
            consume_token(&module.source, iter, TokenKind::CloseParen)?;
 

	
 
            result
 
        } else if next == Some(TokenKind::OpenCurly) {
 
            // Array literal
 
            let (start_pos, mut end_pos) = iter.next_positions();
 
            let mut scoped_section = self.expressions.start_section();
 
            consume_comma_separated(
 
                TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
 
                |_source, iter, ctx| self.consume_expression(module, iter, ctx),
 
                &mut scoped_section, "an expression", "a list of expressions", Some(&mut end_pos)
 
            )?;
 

	
 
            ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                this,
 
                span: InputSpan::from_positions(start_pos, end_pos),
 
                value: Literal::Array(scoped_section.into_vec()),
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast()
 
        } else if next == Some(TokenKind::Integer) {
 
            let (literal, span) = consume_integer_literal(&module.source, iter, &mut self.buffer)?;
 

	
 
            ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                this, span,
 
                value: Literal::Integer(LiteralInteger{ unsigned_value: literal, negated: false }),
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast()
 
        } else if next == Some(TokenKind::String) {
 
            let span = consume_string_literal(&module.source, iter, &mut self.buffer)?;
 
            let interned = ctx.pool.intern(self.buffer.as_bytes());
 

	
 
            ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                this, span,
 
                value: Literal::String(interned),
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast()
 
        } else if next == Some(TokenKind::Character) {
 
            let (character, span) = consume_character_literal(&module.source, iter)?;
 

	
 
            ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                this, span,
 
                value: Literal::Character(character),
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast()
 
        } else if next == Some(TokenKind::Ident) {
 
            // May be a variable, a type instantiation or a function call. If we
 
            // have a single identifier that we cannot find in the type table
 
            // then we're going to assume that we're dealing with a variable.
 
            let ident_span = iter.next_span();
 
            let ident_text = module.source.section_at_span(ident_span);
 
            let symbol = ctx.symbols.get_symbol_by_name(SymbolScope::Module(module.root_id), ident_text);
 

	
 
            if symbol.is_some() {
 
                // The first bit looked like a symbol, so we're going to follow
 
                // that all the way through, assume we arrive at some kind of
 
                // function call or type instantiation
 
                use ParserTypeVariant as PTV;
 

	
 
                let symbol_scope = SymbolScope::Definition(self.cur_definition);
 
                let poly_vars = ctx.heap[self.cur_definition].poly_vars();
 
                let parser_type = consume_parser_type(
 
                    &module.source, iter, &ctx.symbols, &ctx.heap, poly_vars, symbol_scope,
 
                    self.cur_definition, true, 0
 
                )?;
 
                debug_assert!(!parser_type.elements.is_empty());
 
                match parser_type.elements[0].variant {
 
                    PTV::Definition(target_definition_id, _) => {
 
                        let definition = &ctx.heap[target_definition_id];
 
                        match definition {
 
                            Definition::Struct(_) => {
 
                                // Struct literal
 
                                let mut last_token = iter.last_valid_pos();
 
                                let mut struct_fields = Vec::new();
 
                                consume_comma_separated(
 
                                    TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
 
                                    |source, iter, ctx| {
 
                                        let identifier = consume_ident_interned(source, iter, ctx)?;
 
                                        consume_token(source, iter, TokenKind::Colon)?;
 
                                        let value = self.consume_expression(module, iter, ctx)?;
 
                                        Ok(LiteralStructField{ identifier, value, field_idx: 0 })
 
                                    },
 
                                    &mut struct_fields, "a struct field", "a list of struct fields", Some(&mut last_token)
 
                                )?;
 

	
 
                                ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                                    this,
 
                                    span: InputSpan::from_positions(ident_span.begin, last_token),
 
                                    value: Literal::Struct(LiteralStruct{
 
                                        parser_type,
 
                                        fields: struct_fields,
 
                                        definition: target_definition_id,
 
                                    }),
 
                                    parent: ExpressionParent::None,
 
                                    unique_id_in_definition: -1,
 
                                }).upcast()
 
                            },
 
                            Definition::Enum(_) => {
 
                                // Enum literal: consume the variant
 
                                consume_token(&module.source, iter, TokenKind::ColonColon)?;
 
                                let variant = consume_ident_interned(&module.source, iter, ctx)?;
 

	
 
                                ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                                    this,
 
                                    span: InputSpan::from_positions(ident_span.begin, variant.span.end),
 
                                    value: Literal::Enum(LiteralEnum{
 
                                        parser_type,
 
                                        variant,
 
                                        definition: target_definition_id,
 
                                        variant_idx: 0
 
                                    }),
 
                                    parent: ExpressionParent::None,
 
                                    unique_id_in_definition: -1,
 
                                }).upcast()
 
                            },
 
                            Definition::Union(_) => {
 
                                // Union literal: consume the variant
 
                                consume_token(&module.source, iter, TokenKind::ColonColon)?;
 
                                let variant = consume_ident_interned(&module.source, iter, ctx)?;
 

	
 
                                // Consume any possible embedded values
 
                                let mut end_pos = variant.span.end;
 
                                let values = if Some(TokenKind::OpenParen) == iter.next() {
 
                                    self.consume_expression_list(module, iter, ctx, Some(&mut end_pos))?
 
                                } else {
 
                                    Vec::new()
 
                                };
 

	
 
                                ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                                    this,
 
                                    span: InputSpan::from_positions(ident_span.begin, end_pos),
 
                                    value: Literal::Union(LiteralUnion{
 
                                        parser_type, variant, values,
 
                                        definition: target_definition_id,
 
                                        variant_idx: 0,
 
                                    }),
 
                                    parent: ExpressionParent::None,
 
                                    unique_id_in_definition: -1,
 
                                }).upcast()
 
                            },
 
                            Definition::Component(_) => {
 
                                // Component instantiation
 
                                let arguments = self.consume_expression_list(module, iter, ctx, None)?;
 
                                let func_span = parser_type.full_span;
 
                                let mut full_span = func_span;
 
                                let arguments = self.consume_expression_list(
 
                                    module, iter, ctx, Some(&mut full_span.end)
 
                                )?;
 

	
 
                                ctx.heap.alloc_call_expression(|this| CallExpression{
 
                                    this,
 
                                    span: parser_type.full_span,
 
                                    this, func_span, full_span,
 
                                    parser_type,
 
                                    method: Method::UserComponent,
 
                                    arguments,
 
                                    definition: target_definition_id,
 
                                    parent: ExpressionParent::None,
 
                                    unique_id_in_definition: -1,
 
                                }).upcast()
 
                            },
 
                            Definition::Function(function_definition) => {
 
                                // Check whether it is a builtin function
 
                                let method = if function_definition.builtin {
 
                                    match function_definition.identifier.value.as_str() {
 
                                        "get" => Method::Get,
 
                                        "put" => Method::Put,
 
                                        "fires" => Method::Fires,
 
                                        "create" => Method::Create,
 
                                        "length" => Method::Length,
 
                                        "assert" => Method::Assert,
 
                                        _ => unreachable!(),
 
                                    }
 
                                } else {
 
                                    Method::UserFunction
 
                                };
 

	
 
                                // Function call: consume the arguments
 
                                let arguments = self.consume_expression_list(module, iter, ctx, None)?;
 
                                let func_span = parser_type.full_span;
 
                                let mut full_span = func_span;
 
                                let arguments = self.consume_expression_list(
 
                                    module, iter, ctx, Some(&mut full_span.end)
 
                                )?;
 

	
 
                                ctx.heap.alloc_call_expression(|this| CallExpression{
 
                                    this,
 
                                    span: parser_type.full_span,
 
                                    parser_type,
 
                                    method,
 
                                    arguments,
 
                                    this, func_span, full_span, parser_type, method, arguments,
 
                                    definition: target_definition_id,
 
                                    parent: ExpressionParent::None,
 
                                    unique_id_in_definition: -1,
 
                                }).upcast()
 
                            }
 
                        }
 
                    },
 
                    _ => {
 
                        return Err(ParseError::new_error_str_at_span(
 
                            &module.source, parser_type.full_span, "unexpected type in expression"
 
                        ))
 
                    }
 
                }
 
            } else {
 
                // Check for builtin keywords or builtin functions
 
                if ident_text == KW_LIT_NULL || ident_text == KW_LIT_TRUE || ident_text == KW_LIT_FALSE {
 
                    iter.consume();
 

	
 
                    // Parse builtin literal
 
                    let value = match ident_text {
 
                        KW_LIT_NULL => Literal::Null,
 
                        KW_LIT_TRUE => Literal::True,
 
                        KW_LIT_FALSE => Literal::False,
 
                        _ => unreachable!(),
 
                    };
 

	
 
                    ctx.heap.alloc_literal_expression(|this| LiteralExpression {
 
                        this,
 
                        span: ident_span,
 
                        value,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast()
 
                } else if ident_text == KW_LET {
 
                    // Binding expression
 
                    let keyword_span = iter.next_span();
 
                    let operator_span = iter.next_span();
 
                    iter.consume();
 

	
 
                    let bound_to = self.consume_prefix_expression(module, iter, ctx)?;
 
                    consume_token(&module.source, iter, TokenKind::Equal)?;
 
                    let bound_from = self.consume_prefix_expression(module, iter, ctx)?;
 

	
 
                    let full_span = InputSpan::from_positions(
 
                        operator_span.begin, ctx.heap[bound_from].full_span().end,
 
                    );
 

	
 
                    ctx.heap.alloc_binding_expression(|this| BindingExpression{
 
                        this,
 
                        span: keyword_span,
 
                        bound_to,
 
                        bound_from,
 
                        this, operator_span, full_span, bound_to, bound_from,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast()
 
                } else if ident_text == KW_CAST {
 
                    // Casting expression
 
                    iter.consume();
 
                    let to_type = if Some(TokenKind::OpenAngle) == iter.next() {
 
                        iter.consume();
 
                        let definition_id = self.cur_definition;
 
                        let poly_vars = ctx.heap[definition_id].poly_vars();
 
                        consume_parser_type(
 
                            &module.source, iter, &ctx.symbols, &ctx.heap,
 
                            poly_vars, SymbolScope::Module(module.root_id), definition_id,
 
                            true, 1
 
                        )?
 
                    } else {
 
                        // Automatic casting with inferred target type
 
                        ParserType{
 
                            elements: vec![ParserTypeElement{
 
                                element_span: ident_span,
 
                                variant: ParserTypeVariant::Inferred,
 
                            }],
 
                            full_span: ident_span
 
                        }
 
                    };
 

	
 
                    consume_token(&module.source, iter, TokenKind::OpenParen)?;
 
                    let subject = self.consume_expression(module, iter, ctx)?;
 
                    let mut full_span = iter.next_span();
 
                    full_span.begin = to_type.full_span.begin;
 
                    consume_token(&module.source, iter, TokenKind::CloseParen)?;
 

	
 
                    ctx.heap.alloc_cast_expression(|this| CastExpression{
 
                        this,
 
                        span: ident_span,
 
                        to_type,
 
                        subject,
 
                        cast_span: to_type.full_span,
 
                        full_span, to_type, subject,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast()
 
                } else {
 
                    // Not a builtin literal, but also not a known type. So we
 
                    // assume it is a variable expression. Although if we do,
 
                    // then if a programmer mistyped a struct/function name the
 
                    // error messages will be rather cryptic. For polymorphic
 
                    // arguments we can't really do anything at all (because it
 
                    // uses the '<' token). In the other cases we try to provide
 
                    // a better error message.
 
                    iter.consume();
 
                    let next = iter.next();
 
                    if Some(TokenKind::ColonColon) == next {
 
                        return Err(ParseError::new_error_str_at_span(&module.source, ident_span, "unknown identifier"));
 
                    } else if Some(TokenKind::OpenParen) == next {
 
                        return Err(ParseError::new_error_str_at_span(
 
                            &module.source, ident_span,
 
                            "unknown identifier, did you mistype a union variant's, component's, or function's name?"
 
                        ));
 
                    } else if Some(TokenKind::OpenCurly) == next {
 
                        return Err(ParseError::new_error_str_at_span(
 
                            &module.source, ident_span,
 
                            "unknown identifier, did you mistype a struct type's name?"
 
                        ))
 
                    }
 

	
 
                    let ident_text = ctx.pool.intern(ident_text);
 
                    let identifier = Identifier { span: ident_span, value: ident_text };
 

	
 
                    ctx.heap.alloc_variable_expression(|this| VariableExpression {
 
                        this,
 
                        identifier,
 
                        declaration: None,
 
                        used_as_binding_target: false,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast()
 
                }
 
            }
 
        } else {
 
            return Err(ParseError::new_error_str_at_pos(
 
                &module.source, iter.last_valid_pos(), "expected an expression"
 
            ));
 
        };
 

	
 
        Ok(result)
 
    }
 

	
 
    //--------------------------------------------------------------------------
 
    // Expression Utilities
 
    //--------------------------------------------------------------------------
 

	
 
    #[inline]
 
    fn consume_generic_binary_expression<
 
        M: Fn(Option<TokenKind>) -> Option<BinaryOperator>,
 
        F: Fn(&mut PassDefinitions, &Module, &mut TokenIter, &mut PassCtx) -> Result<ExpressionId, ParseError>
 
    >(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, match_fn: M, higher_precedence_fn: F
 
    ) -> Result<ExpressionId, ParseError> {
 
        let mut result = higher_precedence_fn(self, module, iter, ctx)?;
 
        while let Some(operation) = match_fn(iter.next()) {
 
            let span = iter.next_span();
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let left = result;
 
            let right = higher_precedence_fn(self, module, iter, ctx)?;
 

	
 
            let full_span = InputSpan::from_positions(
 
                ctx.heap[left].full_span().begin,
 
                ctx.heap[right].full_span().end,
 
            );
 

	
 
            result = ctx.heap.alloc_binary_expression(|this| BinaryExpression{
 
                this, span, left, operation, right,
 
                this, operator_span, full_span, left, operation, right,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast();
 
        }
 

	
 
        Ok(result)
 
    }
 

	
 
    #[inline]
 
    fn consume_expression_list(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, end_pos: Option<&mut InputPosition>
 
    ) -> Result<Vec<ExpressionId>, ParseError> {
 
        let mut section = self.expressions.start_section();
 
        consume_comma_separated(
 
            TokenKind::OpenParen, TokenKind::CloseParen, &module.source, iter, ctx,
 
            |_source, iter, ctx| self.consume_expression(module, iter, ctx),
 
            &mut section, "an expression", "a list of expressions", end_pos
 
        )?;
 
        Ok(section.into_vec())
 
    }
 
}
 

	
 
/// Consumes a type. A type always starts with an identifier which may indicate
 
/// a builtin type or a user-defined type. The fact that it may contain
 
/// polymorphic arguments makes it a tree-like structure. Because we cannot rely
 
/// on knowing the exact number of polymorphic arguments we do not check for
 
/// these.
 
///
 
/// Note that the first depth index is used as a hack.
 
// TODO: @Optimize, @Cleanup
 
fn consume_parser_type(
 
    source: &InputSource, iter: &mut TokenIter, symbols: &SymbolTable, heap: &Heap, poly_vars: &[Identifier],
 
    cur_scope: SymbolScope, wrapping_definition: DefinitionId, allow_inference: bool, first_angle_depth: i32,
 
) -> Result<ParserType, ParseError> {
 
    struct Entry{
 
        element: ParserTypeElement,
 
        depth: i32,
 
    }
 

	
 
    // After parsing the array modified "[]", we need to insert an array type
 
    // before the most recently parsed type.
 
    fn insert_array_before(elements: &mut Vec<Entry>, depth: i32, span: InputSpan) {
 
        let index = elements.iter().rposition(|e| e.depth == depth).unwrap();
 
        let num_embedded = elements[index].element.variant.num_embedded();
 
        elements.insert(index, Entry{
 
            element: ParserTypeElement{ element_span: span, variant: ParserTypeVariant::Array },
 
            depth,
 
        });
 

	
 
        // Now the original element, and all of its children, should have their
 
        // depth incremented by 1
 
        elements[index + 1].depth += 1;
 
        if num_embedded != 0 {
 
            for idx in index + 2..elements.len() {
 
                let element = &mut elements[idx];
 
                if element.depth >= depth + 1 {
 
                    element.depth += 1;
 
                } else {
 
                    break;
 
                }
 
            }
 
        }
 
    }
 

	
 
    // Most common case we just have one type, perhaps with some array
 
    // annotations. This is both the hot-path, and simplifies the state machine
 
    // that follows and is responsible for parsing more complicated types.
 
    let element = consume_parser_type_ident(
 
        source, iter, symbols, heap, poly_vars, cur_scope,
 
        wrapping_definition, allow_inference
 
    )?;
 

	
 
    if iter.next() != Some(TokenKind::OpenAngle) {
 
        let num_embedded = element.variant.num_embedded();
 
        let first_pos = element.element_span.begin;
 
        let mut last_pos = element.element_span.end;
 
        let mut elements = Vec::with_capacity(num_embedded + 2); // type itself + embedded + 1 (maybe) array type
 

	
 
        // Consume any potential array elements
 
        while iter.next() == Some(TokenKind::OpenSquare) {
 
            let mut array_span = iter.next_span();
 
            iter.consume();
 

	
 
            let end_span = iter.next_span();
 
            array_span.end = end_span.end;
 
            consume_token(source, iter, TokenKind::CloseSquare)?;
 

	
 
            last_pos = end_span.end;
 
            elements.push(ParserTypeElement{ element_span: array_span, variant: ParserTypeVariant::Array });
 
        }
 

	
 
        // Push the element itself
 
        let element_span = element.element_span;
 
        elements.push(element);
 

	
 
        // Check if polymorphic arguments are expected
 
        if num_embedded != 0 {
 
            if !allow_inference {
 
                return Err(ParseError::new_error_str_at_span(source, element_span, "type inference is not allowed here"));
 
            }
 

	
 
            for _ in 0..num_embedded {
 
                elements.push(ParserTypeElement { element_span, variant: ParserTypeVariant::Inferred });
 
            }
 
        }
 

	
 
        // When we have applied the initial-open-angle hack (e.g. consuming an
 
        // explicit type on a channel), then we consume the closing angles as
 
        // well.
 
        for _ in 0..first_angle_depth {
 
            let (_, angle_end_pos) = iter.next_positions();
 
            last_pos = angle_end_pos;
 
            consume_token(source, iter, TokenKind::CloseAngle)?;
 
        }
 

	
 
        return Ok(ParserType{
 
            elements,
 
            full_span: InputSpan::from_positions(first_pos, last_pos)
 
        });
 
    };
 

	
 
    // We have a polymorphic specification. So we start by pushing the item onto
 
    // our stack, then start adding entries together with the angle-brace depth
 
    // at which they're found.
 
    let mut elements = Vec::new();
 
    let first_pos = element.element_span.begin;
 
    let mut last_pos = element.element_span.end;
 
    elements.push(Entry{ element, depth: 0 });
 

	
 
    // Start out with the first '<' consumed.
 
    iter.consume();
 
    enum State { Ident, Open, Close, Comma }
 
    let mut state = State::Open;
 
    let mut angle_depth = first_angle_depth + 1;
 

	
 
    loop {
 
        let next = iter.next();
 

	
 
        match state {
 
            State::Ident => {
 
                // Just parsed an identifier, may expect comma, angled braces,
 
                // or the tokens indicating an array
 
                if Some(TokenKind::OpenAngle) == next {
 
                    angle_depth += 1;
 
                    state = State::Open;
 
                } else if Some(TokenKind::CloseAngle) == next {
 
                    let (_, end_angle_pos) = iter.next_positions();
 
                    last_pos = end_angle_pos;
 
                    angle_depth -= 1;
 
                    state = State::Close;
 
                } else if Some(TokenKind::ShiftRight) == next {
 
                    let (_, end_angle_pos) = iter.next_positions();
 
                    last_pos = end_angle_pos;
 
                    angle_depth -= 2;
 
                    state = State::Close;
 
                } else if Some(TokenKind::Comma) == next {
 
                    state = State::Comma;
 
                } else if Some(TokenKind::OpenSquare) == next {
 
                    let (start_pos, _) = iter.next_positions();
 
                    iter.consume(); // consume opening square
 
                    if iter.next() != Some(TokenKind::CloseSquare) {
 
                        return Err(ParseError::new_error_str_at_pos(
 
                            source, iter.last_valid_pos(),
 
                            "unexpected token: expected ']'"
 
                        ));
 
                    }
 
                    let (_, end_pos) = iter.next_positions();
 
                    let array_span = InputSpan::from_positions(start_pos, end_pos);
 
                    insert_array_before(&mut elements, angle_depth, array_span);
 
                } else {
 
                    return Err(ParseError::new_error_str_at_pos(
 
                        source, iter.last_valid_pos(),
 
                        "unexpected token: expected '<', '>', ',' or '['")
 
                    );
 
                }
 

	
 
                iter.consume();
 
            },
 
            State::Open => {
 
                // Just parsed an opening angle bracket, expecting an identifier
 
                let element = consume_parser_type_ident(source, iter, symbols, heap, poly_vars, cur_scope, wrapping_definition, allow_inference)?;
 
                elements.push(Entry{ element, depth: angle_depth });
 
                state = State::Ident;
 
            },
 
            State::Close => {
 
                // Just parsed 1 or 2 closing angle brackets, expecting comma,
 
                // more closing brackets or the tokens indicating an array
 
                if Some(TokenKind::Comma) == next {
 
                    state = State::Comma;
 
                } else if Some(TokenKind::CloseAngle) == next {
 
                    let (_, end_angle_pos) = iter.next_positions();
 
                    last_pos = end_angle_pos;
src/protocol/parser/pass_typing.rs
Show inline comments
 
@@ -1240,412 +1240,412 @@ impl Visitor for PassTyping {
 
    }
 

	
 
    fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 

	
 
        let indexing_expr = &ctx.heap[id];
 
        let subject_expr_id = indexing_expr.subject;
 
        let index_expr_id = indexing_expr.index;
 

	
 
        self.visit_expr(ctx, subject_expr_id)?;
 
        self.visit_expr(ctx, index_expr_id)?;
 

	
 
        self.progress_indexing_expr(ctx, id)
 
    }
 

	
 
    fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 

	
 
        let slicing_expr = &ctx.heap[id];
 
        let subject_expr_id = slicing_expr.subject;
 
        let from_expr_id = slicing_expr.from_index;
 
        let to_expr_id = slicing_expr.to_index;
 

	
 
        self.visit_expr(ctx, subject_expr_id)?;
 
        self.visit_expr(ctx, from_expr_id)?;
 
        self.visit_expr(ctx, to_expr_id)?;
 

	
 
        self.progress_slicing_expr(ctx, id)
 
    }
 

	
 
    fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 

	
 
        let select_expr = &ctx.heap[id];
 
        let subject_expr_id = select_expr.subject;
 

	
 
        self.visit_expr(ctx, subject_expr_id)?;
 

	
 
        self.progress_select_expr(ctx, id)
 
    }
 

	
 
    fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 

	
 
        let literal_expr = &ctx.heap[id];
 
        match &literal_expr.value {
 
            Literal::Null | Literal::False | Literal::True |
 
            Literal::Integer(_) | Literal::Character(_) | Literal::String(_) => {
 
                // No subexpressions
 
            },
 
            Literal::Struct(literal) => {
 
                // TODO: @performance
 
                let expr_ids: Vec<_> = literal.fields
 
                    .iter()
 
                    .map(|f| f.value)
 
                    .collect();
 

	
 
                self.insert_initial_struct_polymorph_data(ctx, id);
 

	
 
                for expr_id in expr_ids {
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 
            },
 
            Literal::Enum(_) => {
 
                // Enumerations do not carry any subexpressions, but may still
 
                // have a user-defined polymorphic marker variable. For this 
 
                // reason we may still have to apply inference to this 
 
                // polymorphic variable
 
                self.insert_initial_enum_polymorph_data(ctx, id);
 
            },
 
            Literal::Union(literal) => {
 
                // May carry subexpressions and polymorphic arguments
 
                // TODO: @performance
 
                let expr_ids = literal.values.clone();
 
                self.insert_initial_union_polymorph_data(ctx, id);
 

	
 
                for expr_id in expr_ids {
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 
            },
 
            Literal::Array(expressions) => {
 
                // TODO: @performance
 
                let expr_ids = expressions.clone();
 
                for expr_id in expr_ids {
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 
            }
 
        }
 

	
 
        self.progress_literal_expr(ctx, id)
 
    }
 

	
 
    fn visit_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 

	
 
        let cast_expr = &ctx.heap[id];
 
        let subject_expr_id = cast_expr.subject;
 

	
 
        self.visit_expr(ctx, subject_expr_id)?;
 

	
 
        self.progress_cast_expr(ctx, id)
 
    }
 

	
 
    fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 
        self.insert_initial_call_polymorph_data(ctx, id);
 

	
 
        // By default we set the polymorph idx for calls to 0. If the call ends
 
        // up not being a polymorphic one, then we will select the default
 
        // expression types in the type table
 
        let call_expr = &ctx.heap[id];
 
        self.expr_types[call_expr.unique_id_in_definition as usize].field_or_monomorph_idx = 0;
 

	
 
        // Visit all arguments
 
        for arg_expr_id in call_expr.arguments.clone() { // TODO: @Performance
 
            self.visit_expr(ctx, arg_expr_id)?;
 
        }
 

	
 
        self.progress_call_expr(ctx, id)
 
    }
 

	
 
    fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        self.insert_initial_expr_inference_type(ctx, upcast_id)?;
 

	
 
        let var_expr = &ctx.heap[id];
 
        debug_assert!(var_expr.declaration.is_some());
 

	
 
        // Not pretty: if a binding expression, then this is the first time we
 
        // encounter the variable, so we still need to insert the variable data.
 
        let declaration = &ctx.heap[var_expr.declaration.unwrap()];
 
        if !self.var_types.contains_key(&declaration.this)  {
 
            debug_assert!(declaration.kind == VariableKind::Binding);
 
            let var_type = self.determine_inference_type_from_parser_type_elements(
 
                &declaration.parser_type.elements, true
 
            );
 
            self.var_types.insert(declaration.this, VarData{
 
                var_type,
 
                used_at: vec![upcast_id],
 
                linked_var: None
 
            });
 
        } else {
 
            let var_data = self.var_types.get_mut(&declaration.this).unwrap();
 
            var_data.used_at.push(upcast_id);
 
        }
 

	
 
        self.progress_variable_expr(ctx, id)
 
    }
 
}
 

	
 
impl PassTyping {
 
    #[allow(dead_code)] // used when debug flag at the top of this file is true.
 
    fn debug_get_display_name(&self, ctx: &Ctx, expr_id: ExpressionId) -> String {
 
        let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
 
        let expr_type = &self.expr_types[expr_idx as usize].expr_type;
 
        expr_type.display_name(&ctx.heap)
 
    }
 

	
 
    fn resolve_types(&mut self, ctx: &mut Ctx, queue: &mut ResolveQueue) -> Result<(), ParseError> {
 
        // Keep inferring until we can no longer make any progress
 
        while !self.expr_queued.is_empty() {
 
            let next_expr_idx = self.expr_queued.pop_front().unwrap();
 
            self.progress_expr(ctx, next_expr_idx)?;
 
        }
 

	
 
        // Helper for transferring polymorphic variables to concrete types and
 
        // checking if they're completely specified
 
        fn poly_inference_to_concrete_type(
 
            ctx: &Ctx, expr_id: ExpressionId, inference: &Vec<InferenceType>
 
        ) -> Result<Vec<ConcreteType>, ParseError> {
 
            let mut concrete = Vec::with_capacity(inference.len());
 
            for (poly_idx, poly_type) in inference.iter().enumerate() {
 
                if !poly_type.is_done {
 
                    let expr = &ctx.heap[expr_id];
 
                    let definition = match expr {
 
                        Expression::Call(expr) => expr.definition,
 
                        Expression::Literal(expr) => match &expr.value {
 
                            Literal::Enum(lit) => lit.definition,
 
                            Literal::Union(lit) => lit.definition,
 
                            Literal::Struct(lit) => lit.definition,
 
                            _ => unreachable!()
 
                        },
 
                        _ => unreachable!(),
 
                    };
 
                    let poly_vars = ctx.heap[definition].poly_vars();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module.source, expr.span(), format!(
 
                        &ctx.module.source, expr.operation_span(), format!(
 
                            "could not fully infer the type of polymorphic variable '{}' of this expression (got '{}')",
 
                            poly_vars[poly_idx].value.as_str(), poly_type.display_name(&ctx.heap)
 
                        )
 
                    ));
 
                }
 

	
 
                let mut concrete_type = ConcreteType::default();
 
                poly_type.write_concrete_type(&mut concrete_type);
 
                concrete.push(concrete_type);
 
            }
 

	
 
            Ok(concrete)
 
        }
 

	
 
        // Inference is now done. But we may still have uninferred types. So we
 
        // check for these.
 
        for (infer_expr_idx, infer_expr) in self.expr_types.iter_mut().enumerate() {
 
            let expr_type = &mut infer_expr.expr_type;
 
            if !expr_type.is_done {
 
                // Auto-infer numberlike/integerlike types to a regular int
 
                if expr_type.parts.len() == 1 && expr_type.parts[0] == InferenceTypePart::IntegerLike {
 
                    expr_type.parts[0] = InferenceTypePart::SInt32;
 
                    self.expr_queued.push_back(infer_expr_idx as i32);
 
                } else {
 
                    let expr = &ctx.heap[infer_expr.expr_id];
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module.source, expr.span(), format!(
 
                        &ctx.module.source, expr.full_span(), format!(
 
                            "could not fully infer the type of this expression (got '{}')",
 
                            expr_type.display_name(&ctx.heap)
 
                        )
 
                    ));
 
                }
 
            }
 

	
 
            // Expression is fine, check if any extra data is attached
 
            if infer_expr.extra_data_idx < 0 { continue; }
 

	
 
            // Extra data is attached, perform typechecking and transfer
 
            // resolved information to the expression
 
            let extra_data = &self.extra_data[infer_expr.extra_data_idx as usize];
 
            if extra_data.poly_vars.is_empty() { continue; }
 

	
 
            // Note that only call and literal expressions need full inference.
 
            // Select expressions also use `extra_data`, but only for temporary
 
            // storage of the struct type whose field it is selecting.
 
            match &ctx.heap[extra_data.expr_id] {
 
                Expression::Call(expr) => {
 
                    if expr.method != Method::UserFunction && expr.method != Method::UserComponent {
 
                        // Builtin function
 
                        continue;
 
                    }
 

	
 
                    let definition_id = expr.definition;
 
                    let poly_types = poly_inference_to_concrete_type(ctx, extra_data.expr_id, &extra_data.poly_vars)?;
 

	
 
                    match ctx.types.get_procedure_monomorph_index(&definition_id, &poly_types) {
 
                        Some(reserved_idx) => {
 
                            // Already typechecked, or already put into the resolve queue
 
                            infer_expr.field_or_monomorph_idx = reserved_idx;
 
                        },
 
                        None => {
 
                            // Not typechecked yet, so add an entry in the queue
 
                            let reserved_idx = ctx.types.reserve_procedure_monomorph_index(&definition_id, Some(poly_types.clone()));
 
                            infer_expr.field_or_monomorph_idx = reserved_idx;
 
                            queue.push(ResolveQueueElement{
 
                                root_id: ctx.heap[definition_id].defined_in(),
 
                                definition_id,
 
                                monomorph_types: poly_types,
 
                                reserved_monomorph_idx: reserved_idx,
 
                            });
 
                        }
 
                    }
 
                },
 
                Expression::Literal(expr) => {
 
                    let definition_id = match &expr.value {
 
                        Literal::Enum(lit) => lit.definition,
 
                        Literal::Union(lit) => lit.definition,
 
                        Literal::Struct(lit) => lit.definition,
 
                        _ => unreachable!(),
 
                    };
 

	
 
                    let poly_types = poly_inference_to_concrete_type(ctx, extra_data.expr_id, &extra_data.poly_vars)?;
 
                    let mono_index = ctx.types.add_data_monomorph(&definition_id, poly_types);
 
                    infer_expr.field_or_monomorph_idx = mono_index;
 
                },
 
                Expression::Select(_) => {
 
                    debug_assert!(infer_expr.field_or_monomorph_idx >= 0);
 
                },
 
                _ => {
 
                    unreachable!("handling extra data for expression {:?}", &ctx.heap[extra_data.expr_id]);
 
                }
 
            }
 
        }
 

	
 
        // If we did any implicit type forcing, then our queue isn't empty
 
        // anymore
 
        while !self.expr_queued.is_empty() {
 
            let expr_idx = self.expr_queued.pop_back().unwrap();
 
            self.progress_expr(ctx, expr_idx)?;
 
        }
 

	
 
        // Every expression checked, and new monomorphs are queued. Transfer the
 
        // expression information to the type table.
 
        let definition_id = match &self.definition_type {
 
            DefinitionType::Component(id) => id.upcast(),
 
            DefinitionType::Function(id) => id.upcast(),
 
        };
 

	
 
        let target = ctx.types.get_procedure_expression_data_mut(&definition_id, self.reserved_idx);
 
        debug_assert!(target.poly_args == self.poly_vars);
 
        debug_assert!(target.expr_data.is_empty()); // makes sure we never queue something twice
 

	
 
        target.expr_data.reserve(self.expr_types.len());
 
        for infer_expr in self.expr_types.iter() {
 
            let mut concrete = ConcreteType::default();
 
            infer_expr.expr_type.write_concrete_type(&mut concrete);
 
            target.expr_data.push(MonomorphExpression{
 
                expr_type: concrete,
 
                field_or_monomorph_idx: infer_expr.field_or_monomorph_idx
 
            });
 
        }
 

	
 
        Ok(())
 
    }
 

	
 
    fn progress_expr(&mut self, ctx: &mut Ctx, idx: i32) -> Result<(), ParseError> {
 
        let id = self.expr_types[idx as usize].expr_id; // TODO: @Temp
 
        match &ctx.heap[id] {
 
            Expression::Assignment(expr) => {
 
                let id = expr.this;
 
                self.progress_assignment_expr(ctx, id)
 
            },
 
            Expression::Binding(expr) => {
 
                let id = expr.this;
 
                self.progress_binding_expr(ctx, id)
 
            },
 
            Expression::Conditional(expr) => {
 
                let id = expr.this;
 
                self.progress_conditional_expr(ctx, id)
 
            },
 
            Expression::Binary(expr) => {
 
                let id = expr.this;
 
                self.progress_binary_expr(ctx, id)
 
            },
 
            Expression::Unary(expr) => {
 
                let id = expr.this;
 
                self.progress_unary_expr(ctx, id)
 
            },
 
            Expression::Indexing(expr) => {
 
                let id = expr.this;
 
                self.progress_indexing_expr(ctx, id)
 
            },
 
            Expression::Slicing(expr) => {
 
                let id = expr.this;
 
                self.progress_slicing_expr(ctx, id)
 
            },
 
            Expression::Select(expr) => {
 
                let id = expr.this;
 
                self.progress_select_expr(ctx, id)
 
            },
 
            Expression::Literal(expr) => {
 
                let id = expr.this;
 
                self.progress_literal_expr(ctx, id)
 
            },
 
            Expression::Cast(expr) => {
 
                let id = expr.this;
 
                self.progress_cast_expr(ctx, id)
 
            },
 
            Expression::Call(expr) => {
 
                let id = expr.this;
 
                self.progress_call_expr(ctx, id)
 
            },
 
            Expression::Variable(expr) => {
 
                let id = expr.this;
 
                self.progress_variable_expr(ctx, id)
 
            }
 
        }
 
    }
 

	
 
    fn progress_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> Result<(), ParseError> {
 
        use AssignmentOperator as AO;
 

	
 
        let upcast_id = id.upcast();
 

	
 
        let expr = &ctx.heap[id];
 
        let arg1_expr_id = expr.left;
 
        let arg2_expr_id = expr.right;
 

	
 
        debug_log!("Assignment expr '{:?}': {}", expr.operation, upcast_id.index);
 
        debug_log!(" * Before:");
 
        debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
 
        debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
 
        debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
 

	
 
        // Assignment does not return anything (it operates like a statement)
 
        let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &VOID_TEMPLATE)?;
 

	
 
        // Apply forced constraint to LHS value
 
        let progress_forced = match expr.operation {
 
            AO::Set =>
 
                false,
 
            AO::Concatenated =>
 
                self.apply_template_constraint(ctx, arg1_expr_id, &ARRAYLIKE_TEMPLATE)?,
 
            AO::Multiplied | AO::Divided | AO::Added | AO::Subtracted =>
 
                self.apply_template_constraint(ctx, arg1_expr_id, &NUMBERLIKE_TEMPLATE)?,
 
            AO::Remained | AO::ShiftedLeft | AO::ShiftedRight |
 
            AO::BitwiseAnded | AO::BitwiseXored | AO::BitwiseOred =>
 
                self.apply_template_constraint(ctx, arg1_expr_id, &INTEGERLIKE_TEMPLATE)?,
 
        };
 

	
 
        let (progress_arg1, progress_arg2) = self.apply_equal2_constraint(
 
            ctx, upcast_id, arg1_expr_id, 0, arg2_expr_id, 0
 
        )?;
 

	
 
        debug_log!(" * After:");
 
        debug_log!("   - Arg1 type [{}]: {}", progress_forced || progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
 
        debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
 
        debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
 

	
 
@@ -2250,729 +2250,729 @@ impl PassTyping {
 
                let mut poly_progress = HashSet::new();
 
                debug_assert_eq!(extra.embedded.len(), data.values.len());
 

	
 
                debug_log!(" * During (inferring types from variant values and union type):");
 

	
 
                // Mutually infer union variant values
 
                for (value_idx, value_expr_id) in data.values.iter().enumerate() {
 
                    let value_expr_id = *value_expr_id;
 
                    let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
 
                    let signature_type: *mut _ = &mut extra.embedded[value_idx];
 
                    let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
 
                    let (_, progress_arg) = Self::apply_equal2_signature_constraint(
 
                        ctx, upcast_id, Some(value_expr_id), extra, &mut poly_progress,
 
                        signature_type, 0, value_type, 0 
 
                    )?;
 

	
 
                    debug_log!(
 
                        "   - Value {} type | sig: {}, field: {}", value_idx,
 
                        unsafe{&*signature_type}.display_name(&ctx.heap),
 
                        unsafe{&*value_type}.display_name(&ctx.heap)
 
                    );
 

	
 
                    if progress_arg {
 
                        self.expr_queued.push_back(value_expr_idx);
 
                    }
 
                }
 

	
 
                debug_log!("   - Field poly progress | {:?}", poly_progress);
 

	
 
                // Infer type of union itself
 
                let signature_type: *mut _ = &mut extra.returned;
 
                let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
 
                let (_, progress_expr) = Self::apply_equal2_signature_constraint(
 
                    ctx, upcast_id, None, extra, &mut poly_progress,
 
                    signature_type, 0, expr_type, 0
 
                )?;
 

	
 
                debug_log!(
 
                    "   - Ret type | sig: {}, expr: {}",
 
                    unsafe{&*signature_type}.display_name(&ctx.heap),
 
                    unsafe{&*expr_type}.display_name(&ctx.heap)
 
                );
 
                debug_log!("   - Ret poly progress | {:?}", poly_progress);
 

	
 
                if progress_expr {
 
                    // TODO: @cleanup, borrowing rules
 
                    if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
 
                        let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
 
                        self.expr_queued.push_back(parent_idx);
 
                    }
 
                }
 

	
 
                debug_log!(" * During (reinferring from progress polyvars):");
 
            
 
                // For all embedded values of the union variant
 
                for value_idx in 0..extra.embedded.len() {
 
                    let signature_type: *mut _ = &mut extra.embedded[value_idx];
 
                    let value_expr_id = data.values[value_idx];
 
                    let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
 
                    let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
 
                    
 
                    let progress_arg = Self::apply_equal2_polyvar_constraint(
 
                        extra, &poly_progress, signature_type, value_type
 
                    );
 

	
 
                    debug_log!(
 
                        "   - Value {} type | sig: {}, value: {}", value_idx,
 
                        unsafe{&*signature_type}.display_name(&ctx.heap),
 
                        unsafe{&*value_type}.display_name(&ctx.heap)
 
                    );
 
                    if progress_arg {
 
                        self.expr_queued.push_back(value_expr_idx);
 
                    }
 
                }
 

	
 
                // And for the union type itself
 
                let signature_type: *mut _ = &mut extra.returned;
 
                let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
 

	
 
                let progress_expr = Self::apply_equal2_polyvar_constraint(
 
                    extra, &poly_progress, signature_type, expr_type
 
                );
 

	
 
                progress_expr
 
            },
 
            Literal::Array(data) => {
 
                let expr_elements = data.clone(); // TODO: @performance
 
                debug_log!("Array expr ({} elements): {}", expr_elements.len(), upcast_id.index);
 
                debug_log!(" * Before:");
 
                debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
 

	
 
                // All elements should have an equal type
 
                let progress = self.apply_equal_n_constraint(ctx, upcast_id, &expr_elements)?;
 
                for (progress_arg, arg_id) in progress.iter().zip(expr_elements.iter()) {
 
                    if *progress_arg {
 
                        self.queue_expr(ctx, *arg_id);
 
                    }
 
                }
 

	
 
                // And the output should be an array of the element types
 
                let mut progress_expr = self.apply_template_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?;
 
                if !expr_elements.is_empty() {
 
                    let first_arg_id = expr_elements[0];
 
                    let (inner_expr_progress, arg_progress) = self.apply_equal2_constraint(
 
                        ctx, upcast_id, upcast_id, 1, first_arg_id, 0
 
                    )?;
 

	
 
                    progress_expr = progress_expr || inner_expr_progress;
 

	
 
                    // Note that if the array type progressed the type of the arguments,
 
                    // then we should enqueue this progression function again
 
                    // TODO: @fix Make apply_equal_n accept a start idx as well
 
                    if arg_progress { self.queue_expr(ctx, upcast_id); }
 
                }
 

	
 
                debug_log!(" * After:");
 
                debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
 

	
 
                progress_expr
 
            },
 
        };
 

	
 
        debug_log!(" * After:");
 
        debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
 

	
 
        if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
 

	
 
        Ok(())
 
    }
 

	
 
    fn progress_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> Result<(), ParseError> {
 
        let upcast_id = id.upcast();
 
        let expr = &ctx.heap[id];
 
        let expr_idx = expr.unique_id_in_definition;
 

	
 
        debug_log!("Casting expr: {}", upcast_id.index);
 
        debug_log!(" * Before:");
 
        debug_log!("   - Expr type:    {}", self.debug_get_display_name(ctx, upcast_id));
 
        debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, expr.subject));
 

	
 
        // The cast expression might have its output type fixed by the
 
        // programmer, so apply that type to the output. Apart from that casting
 
        // acts like a blocker for two-way inference. So we'll just have to wait
 
        // until we know if the cast is valid.
 
        // TODO: Another thing that has to be updated the moment the type
 
        //  inferencer is fully index/job-based
 
        let infer_type = self.determine_inference_type_from_parser_type_elements(&expr.to_type.elements, true);
 
        let expr_progress = self.apply_template_constraint(ctx, upcast_id, &infer_type.parts)?;
 

	
 
        if expr_progress {
 
            self.queue_expr_parent(ctx, upcast_id);
 
        }
 

	
 
        // Check if the two types are compatible
 
        debug_log!(" * After:");
 
        debug_log!("   - Expr type [{}]: {}", expr_progress, self.debug_get_display_name(ctx, upcast_id));
 
        debug_log!("   - Note that the subject type can never be inferred");
 
        debug_log!(" * Decision:");
 

	
 
        let subject_idx = ctx.heap[expr.subject].get_unique_id_in_definition();
 
        let expr_type = &self.expr_types[expr_idx as usize].expr_type;
 
        let subject_type = &self.expr_types[subject_idx as usize].expr_type;
 
        if !expr_type.is_done || !subject_type.is_done {
 
            // Not yet done
 
            debug_log!("   - Casting is valid: unknown as the types are not yet complete");
 
            return Ok(())
 
        }
 

	
 
        // Valid casts: (bool, integer, character) can always be cast to one
 
        // another. A cast from a type to itself is also valid.
 
        fn is_bool_int_or_char(parts: &[InferenceTypePart]) -> bool {
 
            return parts.len() == 1 && (
 
                parts[0] == InferenceTypePart::Bool ||
 
                parts[0] == InferenceTypePart::Character ||
 
                parts[0].is_concrete_integer()
 
            );
 
        }
 

	
 
        let is_valid = if is_bool_int_or_char(&expr_type.parts) && is_bool_int_or_char(&subject_type.parts) {
 
            true
 
        } else if expr_type.parts == subject_type.parts {
 
            true
 
        } else {
 
            false
 
        };
 

	
 
        debug_log!("   - Casting is valid: {}", is_valid);
 

	
 
        if !is_valid {
 
            let cast_expr = &ctx.heap[id];
 
            let subject_expr = &ctx.heap[cast_expr.subject];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, cast_expr.span, "invalid casting operation"
 
                &ctx.module.source, cast_expr.full_span, "invalid casting operation"
 
            ).with_info_at_span(
 
                &ctx.module.source, subject_expr.span(), format!(
 
                    "cannot cast this type '{}' to the cast type '{}'",
 
                &ctx.module.source, subject_expr.full_span(), format!(
 
                    "cannot cast the argument type '{}' to the cast type '{}'",
 
                    subject_type.display_name(&ctx.heap),
 
                    expr_type.display_name(&ctx.heap)
 
                )
 
            ));
 
        }
 

	
 
        Ok(())
 
    }
 

	
 
    // TODO: @cleanup, see how this can be cleaned up once I implement
 
    //  polymorphic struct/enum/union literals. These likely follow the same
 
    //  pattern as here.
 
    fn progress_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> Result<(), ParseError> {
 
        let upcast_id = id.upcast();
 
        let expr = &ctx.heap[id];
 
        let expr_idx = expr.unique_id_in_definition;
 
        let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
 

	
 
        debug_log!("Call expr '{}': {}", ctx.heap[expr.definition].identifier().value.as_str(), upcast_id.index);
 
        debug_log!(" * Before:");
 
        debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
 
        debug_log!(" * During (inferring types from arguments and return type):");
 

	
 
        let extra = &mut self.extra_data[extra_idx as usize];
 

	
 
        // Check if we can make progress using the arguments and/or return types
 
        // while keeping track of the polyvars we've extended
 
        let mut poly_progress = HashSet::new();
 
        debug_assert_eq!(extra.embedded.len(), expr.arguments.len());
 

	
 
        for (call_arg_idx, arg_id) in expr.arguments.clone().into_iter().enumerate() {
 
            let arg_expr_idx = ctx.heap[arg_id].get_unique_id_in_definition();
 
            let signature_type: *mut _ = &mut extra.embedded[call_arg_idx];
 
            let argument_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
 
            let (_, progress_arg) = Self::apply_equal2_signature_constraint(
 
                ctx, upcast_id, Some(arg_id), extra, &mut poly_progress,
 
                signature_type, 0, argument_type, 0
 
            )?;
 

	
 
            debug_log!(
 
                "   - Arg {} type | sig: {}, arg: {}", call_arg_idx,
 
                unsafe{&*signature_type}.display_name(&ctx.heap), 
 
                unsafe{&*argument_type}.display_name(&ctx.heap));
 

	
 
            if progress_arg {
 
                // Progressed argument expression
 
                self.expr_queued.push_back(arg_expr_idx);
 
            }
 
        }
 

	
 
        // Do the same for the return type
 
        let signature_type: *mut _ = &mut extra.returned;
 
        let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
 
        let (_, progress_expr) = Self::apply_equal2_signature_constraint(
 
            ctx, upcast_id, None, extra, &mut poly_progress,
 
            signature_type, 0, expr_type, 0
 
        )?;
 

	
 
        debug_log!(
 
            "   - Ret type | sig: {}, expr: {}", 
 
            unsafe{&*signature_type}.display_name(&ctx.heap), 
 
            unsafe{&*expr_type}.display_name(&ctx.heap)
 
        );
 

	
 
        if progress_expr {
 
            // TODO: @cleanup, cannot call utility self.queue_parent thingo
 
            if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
 
                let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
 
                self.expr_queued.push_back(parent_idx);
 
            }
 
        }
 

	
 
        // If we did not have an error in the polymorph inference above, then
 
        // reapplying the polymorph type to each argument type and the return
 
        // type should always succeed.
 
        debug_log!(" * During (reinferring from progressed polyvars):");
 
        for (_poly_idx, _poly_var) in extra.poly_vars.iter().enumerate() {
 
            debug_log!("   - Poly {} | sig: {}", _poly_idx, _poly_var.display_name(&ctx.heap));
 
        }
 
        // TODO: @performance If the algorithm is changed to be more "on demand
 
        //  argument re-evaluation", instead of "all-argument re-evaluation",
 
        //  then this is no longer true
 
        for arg_idx in 0..extra.embedded.len() {
 
            let signature_type: *mut _ = &mut extra.embedded[arg_idx];
 
            let arg_expr_id = expr.arguments[arg_idx];
 
            let arg_expr_idx = ctx.heap[arg_expr_id].get_unique_id_in_definition();
 
            let arg_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
 
            
 
            let progress_arg = Self::apply_equal2_polyvar_constraint(
 
                extra, &poly_progress,
 
                signature_type, arg_type
 
            );
 
            
 
            debug_log!(
 
                "   - Arg {} type | sig: {}, arg: {}", arg_idx, 
 
                unsafe{&*signature_type}.display_name(&ctx.heap), 
 
                unsafe{&*arg_type}.display_name(&ctx.heap)
 
            );
 
            if progress_arg {
 
                self.expr_queued.push_back(arg_expr_idx);
 
            }
 
        }
 

	
 
        // Once more for the return type
 
        let signature_type: *mut _ = &mut extra.returned;
 
        let ret_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
 

	
 
        let progress_ret = Self::apply_equal2_polyvar_constraint(
 
            extra, &poly_progress, signature_type, ret_type
 
        );
 
        debug_log!(
 
            "   - Ret type | sig: {}, arg: {}", 
 
            unsafe{&*signature_type}.display_name(&ctx.heap), 
 
            unsafe{&*ret_type}.display_name(&ctx.heap)
 
        );
 
        if progress_ret {
 
            self.queue_expr_parent(ctx, upcast_id);
 
        }
 

	
 
        debug_log!(" * After:");
 
        debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
 

	
 
        Ok(())
 
    }
 

	
 
    fn progress_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> Result<(), ParseError> {
 
        let upcast_id = id.upcast();
 
        let var_expr = &ctx.heap[id];
 
        let var_expr_idx = var_expr.unique_id_in_definition;
 
        let var_id = var_expr.declaration.unwrap();
 

	
 
        debug_log!("Variable expr '{}': {}", ctx.heap[var_id].identifier.value.as_str(), upcast_id.index);
 
        debug_log!(" * Before:");
 
        debug_log!("   - Var  type: {}", self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
 
        debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
 

	
 
        // Retrieve shared variable type and expression type and apply inference
 
        let var_data = self.var_types.get_mut(&var_id).unwrap();
 
        let expr_type = &mut self.expr_types[var_expr_idx as usize].expr_type;
 

	
 
        let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
 
            &mut var_data.var_type as *mut _, 0, expr_type, 0
 
        ) };
 
        if infer_res == DualInferenceResult::Incompatible {
 
            let var_decl = &ctx.heap[var_id];
 
            return Err(ParseError::new_error_at_span(
 
                &ctx.module.source, var_decl.identifier.span, format!(
 
                    "Conflicting types for this variable, previously assigned the type '{}'",
 
                    var_data.var_type.display_name(&ctx.heap)
 
                )
 
            ).with_info_at_span(
 
                &ctx.module.source, var_expr.identifier.span, format!(
 
                    "But inferred to have incompatible type '{}' here",
 
                    expr_type.display_name(&ctx.heap)
 
                )
 
            ))
 
        }
 

	
 
        let progress_var = infer_res.modified_lhs();
 
        let progress_expr = infer_res.modified_rhs();
 

	
 
        if progress_var {
 
            // Let other variable expressions using this type progress as well
 
            for other_expr in var_data.used_at.iter() {
 
                if *other_expr != upcast_id {
 
                    let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
 
                    self.expr_queued.push_back(other_expr_idx);
 
                }
 
            }
 

	
 
            // Let a linked port know that our type has updated
 
            if let Some(linked_id) = var_data.linked_var {
 
                // Only perform one-way inference to prevent updating our type,
 
                // this would lead to an inconsistency in the type inference
 
                // algorithm otherwise.
 
                let var_type: *mut _ = &mut var_data.var_type;
 
                let link_data = self.var_types.get_mut(&linked_id).unwrap();
 

	
 
                debug_assert!(
 
                    unsafe{&*var_type}.parts[0] == InferenceTypePart::Input ||
 
                    unsafe{&*var_type}.parts[0] == InferenceTypePart::Output
 
                );
 
                debug_assert!(
 
                    link_data.var_type.parts[0] == InferenceTypePart::Input ||
 
                    link_data.var_type.parts[0] == InferenceTypePart::Output
 
                );
 
                match InferenceType::infer_subtree_for_single_type(&mut link_data.var_type, 1, &unsafe{&*var_type}.parts, 1, false) {
 
                    SingleInferenceResult::Modified => {
 
                        for other_expr in &link_data.used_at {
 
                            let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
 
                            self.expr_queued.push_back(other_expr_idx);
 
                        }
 
                    },
 
                    SingleInferenceResult::Unmodified => {},
 
                    SingleInferenceResult::Incompatible => {
 
                        let var_data = self.var_types.get(&var_id).unwrap();
 
                        let link_data = self.var_types.get(&linked_id).unwrap();
 
                        let var_decl = &ctx.heap[var_id];
 
                        let link_decl = &ctx.heap[linked_id];
 

	
 
                        return Err(ParseError::new_error_at_span(
 
                            &ctx.module.source, var_decl.identifier.span, format!(
 
                                "Conflicting types for this variable, assigned the type '{}'",
 
                                var_data.var_type.display_name(&ctx.heap)
 
                            )
 
                        ).with_info_at_span(
 
                            &ctx.module.source, link_decl.identifier.span, format!(
 
                                "Because it is incompatible with this variable, assigned the type '{}'",
 
                                link_data.var_type.display_name(&ctx.heap)
 
                            )
 
                        ));
 
                    }
 
                }
 
            }
 
        }
 
        if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
 

	
 
        debug_log!(" * After:");
 
        debug_log!("   - Var  type [{}]: {}", progress_var, self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
 
        debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
 

	
 

	
 
        Ok(())
 
    }
 

	
 
    fn queue_expr_parent(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
 
        if let ExpressionParent::Expression(parent_expr_id, _) = &ctx.heap[expr_id].parent() {
 
            let expr_idx = ctx.heap[*parent_expr_id].get_unique_id_in_definition();
 
            self.expr_queued.push_back(expr_idx);
 
        }
 
    }
 

	
 
    fn queue_expr(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
 
        let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
 
        self.expr_queued.push_back(expr_idx);
 
    }
 

	
 
    /// Applies a template type constraint: the type associated with the
 
    /// supplied expression will be molded into the provided `template`. But
 
    /// will be considered valid if the template could've been molded into the
 
    /// expression type as well. Hence the template may be fully specified (e.g.
 
    /// a bool) or contain "inference" variables (e.g. an array of T)
 
    fn apply_template_constraint(
 
        &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
 
    ) -> Result<bool, ParseError> {
 
        let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
 
        let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
 
        match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, false) {
 
            SingleInferenceResult::Modified => Ok(true),
 
            SingleInferenceResult::Unmodified => Ok(false),
 
            SingleInferenceResult::Incompatible => Err(
 
                self.construct_template_type_error(ctx, expr_id, template)
 
            )
 
        }
 
    }
 

	
 
    fn apply_template_constraint_to_types(
 
        to_infer: *mut InferenceType, to_infer_start_idx: usize,
 
        template: &[InferenceTypePart], template_start_idx: usize
 
    ) -> Result<bool, ()> {
 
        match InferenceType::infer_subtree_for_single_type(
 
            unsafe{ &mut *to_infer }, to_infer_start_idx,
 
            template, template_start_idx, false
 
        ) {
 
            SingleInferenceResult::Modified => Ok(true),
 
            SingleInferenceResult::Unmodified => Ok(false),
 
            SingleInferenceResult::Incompatible => Err(()),
 
        }
 
    }
 

	
 
    /// Applies a forced constraint: the supplied expression's type MUST be
 
    /// inferred from the template, the other way around is considered invalid.
 
    fn apply_forced_constraint(
 
        &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
 
    ) -> Result<bool, ParseError> {
 
        let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
 
        let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
 
        match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, true) {
 
            SingleInferenceResult::Modified => Ok(true),
 
            SingleInferenceResult::Unmodified => Ok(false),
 
            SingleInferenceResult::Incompatible => Err(
 
                self.construct_template_type_error(ctx, expr_id, template)
 
            )
 
        }
 
    }
 

	
 
    /// Applies a type constraint that expects the two provided types to be
 
    /// equal. We attempt to make progress in inferring the types. If the call
 
    /// is successful then the composition of all types are made equal.
 
    /// The "parent" `expr_id` is provided to construct errors.
 
    fn apply_equal2_constraint(
 
        &mut self, ctx: &Ctx, expr_id: ExpressionId,
 
        arg1_id: ExpressionId, arg1_start_idx: usize,
 
        arg2_id: ExpressionId, arg2_start_idx: usize
 
    ) -> Result<(bool, bool), ParseError> {
 
        let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition(); // TODO: @Temp
 
        let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
 
        let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
 
        let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
 

	
 
        let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
 
            arg1_type, arg1_start_idx,
 
            arg2_type, arg2_start_idx
 
        ) };
 
        if infer_res == DualInferenceResult::Incompatible {
 
            return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
 
        }
 

	
 
        Ok((infer_res.modified_lhs(), infer_res.modified_rhs()))
 
    }
 

	
 
    /// Applies an equal2 constraint between a signature type (e.g. a function
 
    /// argument or struct field) and an expression whose type should match that
 
    /// expression. If we make progress on the signature, then we try to see if
 
    /// any of the embedded polymorphic types can be progressed.
 
    ///
 
    /// `outer_expr_id` is the main expression we're progressing (e.g. a 
 
    /// function call), while `expr_id` is the embedded expression we're 
 
    /// matching against the signature. `expression_type` and 
 
    /// `expression_start_idx` belong to `expr_id`.
 
    fn apply_equal2_signature_constraint(
 
        ctx: &Ctx, outer_expr_id: ExpressionId, expr_id: Option<ExpressionId>,
 
        polymorph_data: &mut ExtraData, polymorph_progress: &mut HashSet<u32>,
 
        signature_type: *mut InferenceType, signature_start_idx: usize,
 
        expression_type: *mut InferenceType, expression_start_idx: usize
 
    ) -> Result<(bool, bool), ParseError> {
 
        // Safety: all pointers distinct
 

	
 
        // Infer the signature and expression type
 
        let infer_res = unsafe { 
 
            InferenceType::infer_subtrees_for_both_types(
 
                signature_type, signature_start_idx,
 
                expression_type, expression_start_idx
 
            ) 
 
        };
 

	
 
        if infer_res == DualInferenceResult::Incompatible {
 
            // TODO: Check if I still need to use this
 
            let outer_span = ctx.heap[outer_expr_id].span();
 
            let outer_span = ctx.heap[outer_expr_id].full_span();
 
            let (span_name, span) = match expr_id {
 
                Some(expr_id) => ("argument's", ctx.heap[expr_id].span()),
 
                Some(expr_id) => ("argument's", ctx.heap[expr_id].full_span()),
 
                None => ("type's", outer_span)
 
            };
 
            let (signature_display_type, expression_display_type) = unsafe { (
 
                (&*signature_type).display_name(&ctx.heap),
 
                (&*expression_type).display_name(&ctx.heap)
 
            ) };
 

	
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, outer_span,
 
                "failed to fully resolve the types of this expression"
 
            ).with_info_at_span(
 
                &ctx.module.source, span, format!(
 
                    "because the {} signature has been resolved to '{}', but the expression has been resolved to '{}'",
 
                    span_name, signature_display_type, expression_display_type
 
                )
 
            ));
 
        }
 

	
 
        // Try to see if we can progress any of the polymorphic variables
 
        let progress_sig = infer_res.modified_lhs();
 
        let progress_expr = infer_res.modified_rhs();
 

	
 
        if progress_sig {
 
            let signature_type = unsafe{&mut *signature_type};
 
            debug_assert!(
 
                signature_type.has_marker,
 
                "made progress on signature type, but it doesn't have a marker"
 
            );
 
            for (poly_idx, poly_section) in signature_type.marker_iter() {
 
                let polymorph_type = &mut polymorph_data.poly_vars[poly_idx as usize];
 
                match Self::apply_template_constraint_to_types(
 
                    polymorph_type, 0, poly_section, 0
 
                ) {
 
                    Ok(true) => { polymorph_progress.insert(poly_idx); },
 
                    Ok(false) => {},
 
                    Err(()) => { return Err(Self::construct_poly_arg_error(ctx, polymorph_data, outer_expr_id))}
 
                }
 
            }
 
        }
 
        Ok((progress_sig, progress_expr))
 
    }
 

	
 
    /// Applies equal2 constraints on the signature type for each of the 
 
    /// polymorphic variables. If the signature type is progressed then we 
 
    /// progress the expression type as well.
 
    ///
 
    /// This function assumes that the polymorphic variables have already been
 
    /// progressed as far as possible by calling 
 
    /// `apply_equal2_signature_constraint`. As such, we expect to not encounter
 
    /// any errors.
 
    ///
 
    /// This function returns true if the expression's type has been progressed
 
    fn apply_equal2_polyvar_constraint(
 
        polymorph_data: &ExtraData, _polymorph_progress: &HashSet<u32>,
 
        signature_type: *mut InferenceType, expr_type: *mut InferenceType
 
    ) -> bool {
 
        // Safety: all pointers should be distinct
 
        //         polymorph_data containers may not be modified
 
        let signature_type = unsafe{&mut *signature_type};
 
        let expr_type = unsafe{&mut *expr_type};
 

	
 
        // Iterate through markers in signature type to try and make progress
 
        // on the polymorphic variable        
 
        let mut seek_idx = 0;
 
        let mut modified_sig = false;
 
        
 
        while let Some((poly_idx, start_idx)) = signature_type.find_marker(seek_idx) {
 
            let end_idx = InferenceType::find_subtree_end_idx(&signature_type.parts, start_idx);
 
            // if polymorph_progress.contains(&poly_idx) {
 
                // Need to match subtrees
 
                let polymorph_type = &polymorph_data.poly_vars[poly_idx as usize];
 
                let modified_at_marker = Self::apply_template_constraint_to_types(
 
                    signature_type, start_idx, 
 
                    &polymorph_type.parts, 0
 
                ).expect("no failure when applying polyvar constraints");
 

	
 
                modified_sig = modified_sig || modified_at_marker;
 
            // }
 

	
 
            seek_idx = end_idx;
 
        }
 

	
 
        // If we made any progress on the signature's type, then we also need to
 
        // apply it to the expression that is supposed to match the signature.
 
        if modified_sig {
 
            match InferenceType::infer_subtree_for_single_type(
 
                expr_type, 0, &signature_type.parts, 0, true
 
            ) {
 
                SingleInferenceResult::Modified => true,
 
                SingleInferenceResult::Unmodified => false,
 
                SingleInferenceResult::Incompatible =>
 
                    unreachable!("encountered failure while reapplying modified signature to expression after polyvar inference")
 
            }
 
        } else {
 
            false
 
        }
 
    }
 

	
 
    /// Applies a type constraint that expects all three provided types to be
 
    /// equal. In case we can make progress in inferring the types then we
 
    /// attempt to do so. If the call is successful then the composition of all
 
    /// types is made equal.
 
    fn apply_equal3_constraint(
 
        &mut self, ctx: &Ctx, expr_id: ExpressionId,
 
        arg1_id: ExpressionId, arg2_id: ExpressionId,
 
        start_idx: usize
 
    ) -> Result<(bool, bool, bool), ParseError> {
 
        // Safety: all points are unique
 
        //         containers may not be modified
 
        let expr_expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
 
        let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition();
 
        let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
 

	
 
        let expr_type: *mut _ = &mut self.expr_types[expr_expr_idx as usize].expr_type;
 
        let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
 
        let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
 

	
 
        let expr_res = unsafe{
 
            InferenceType::infer_subtrees_for_both_types(expr_type, start_idx, arg1_type, start_idx)
 
        };
 
        if expr_res == DualInferenceResult::Incompatible {
 
            return Err(self.construct_expr_type_error(ctx, expr_id, arg1_id));
 
        }
 

	
 
        let args_res = unsafe{
 
            InferenceType::infer_subtrees_for_both_types(arg1_type, start_idx, arg2_type, start_idx) };
 
        if args_res == DualInferenceResult::Incompatible {
 
            return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
 
        }
 

	
 
        // If all types are compatible, but the second call caused the arg1_type
 
        // to be expanded, then we must also assign this to expr_type.
 
        let mut progress_expr = expr_res.modified_lhs();
 
        let mut progress_arg1 = expr_res.modified_rhs();
 
        let progress_arg2 = args_res.modified_rhs();
 

	
 
        if args_res.modified_lhs() { 
 
            unsafe {
 
                let end_idx = InferenceType::find_subtree_end_idx(&(*arg2_type).parts, start_idx);
 
                let subtree = &((*arg2_type).parts[start_idx..end_idx]);
 
                (*expr_type).replace_subtree(start_idx, subtree);
 
            }
 
            progress_expr = true;
 
            progress_arg1 = true;
 
        }
 

	
 
        Ok((progress_expr, progress_arg1, progress_arg2))
 
    }
 

	
 
    // TODO: @optimize Since we only deal with a single type this might be done
 
    //  a lot more efficiently, methinks (disregarding the allocations here)
 
    fn apply_equal_n_constraint(
 
        &mut self, ctx: &Ctx, expr_id: ExpressionId, args: &[ExpressionId],
 
    ) -> Result<Vec<bool>, ParseError> {
 
        // Early exit
 
        match args.len() {
 
            0 => return Ok(vec!()),         // nothing to progress
 
            1 => return Ok(vec![false]),    // only one type, so nothing to infer
 
            _ => {}
 
        }
 

	
 
        let mut progress = Vec::new();
 
        progress.resize(args.len(), false);
 

	
 
        // Do pairwise inference, keep track of the last entry we made progress
 
        // on. Once done we need to update everything to the most-inferred type.
 
        let mut arg_iter = args.iter();
 
        let mut last_arg_id = *arg_iter.next().unwrap();
 
        let mut last_lhs_progressed = 0;
 
        let mut lhs_arg_idx = 0;
 

	
 
        while let Some(next_arg_id) = arg_iter.next() {
 
            let last_expr_idx = ctx.heap[last_arg_id].get_unique_id_in_definition(); // TODO: @Temp
 
            let next_expr_idx = ctx.heap[*next_arg_id].get_unique_id_in_definition();
 
            let last_type: *mut _ = &mut self.expr_types[last_expr_idx as usize].expr_type;
 
            let next_type: *mut _ = &mut self.expr_types[next_expr_idx as usize].expr_type;
 

	
 
            let res = unsafe {
 
                InferenceType::infer_subtrees_for_both_types(last_type, 0, next_type, 0)
 
            };
 

	
 
            if res == DualInferenceResult::Incompatible {
 
                return Err(self.construct_arg_type_error(ctx, expr_id, last_arg_id, *next_arg_id));
 
            }
 

	
 
            if res.modified_lhs() {
 
                // We re-inferred something on the left hand side, so everything
 
                // up until now should be re-inferred.
 
                progress[lhs_arg_idx] = true;
 
                last_lhs_progressed = lhs_arg_idx;
 
            }
 
            progress[lhs_arg_idx + 1] = res.modified_rhs();
 
@@ -3279,548 +3279,548 @@ impl PassTyping {
 

	
 
        for embedded_elements in literal.parser_type.iter_embedded(0) {
 
            let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
 
            total_num_poly_parts += poly_type.parts.len();
 
            poly_args.push(poly_type);
 
        }
 

	
 
        // Handle any of the embedded values in the variant, if specified
 
        let definition_id = literal.definition;
 
        let type_definition = ctx.types.get_base_definition(&definition_id).unwrap();
 
        let union_definition = type_definition.definition.as_union();
 
        debug_assert_eq!(poly_args.len(), type_definition.poly_vars.len());
 

	
 
        let variant_definition = &union_definition.variants[literal.variant_idx];
 
        debug_assert_eq!(variant_definition.embedded.len(), literal.values.len());
 

	
 
        let mut embedded = Vec::with_capacity(variant_definition.embedded.len());
 
        for embedded_parser_type in &variant_definition.embedded {
 
            let inference_type = self.determine_inference_type_from_parser_type_elements(&embedded_parser_type.elements, false);
 
            embedded.push(inference_type);
 
        }
 

	
 
        // Handle the type of the union itself
 
        let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
 
        let mut parts = Vec::with_capacity(parts_reserved);
 
        parts.push(ITP::Instance(definition_id, poly_args.len() as u32));
 
        let mut union_type_done = true;
 
        for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
 
            if !poly_var.is_done { union_type_done = false; }
 

	
 
            parts.push(ITP::Marker(poly_var_idx as u32));
 
            parts.extend(poly_var.parts.iter().cloned());
 
        }
 

	
 
        debug_assert_eq!(parts_reserved, parts.len());
 
        let union_type = InferenceType::new(!poly_args.is_empty(), union_type_done, parts);
 

	
 
        self.extra_data[extra_data_idx as usize] = ExtraData{
 
            expr_id: lit_id.upcast(),
 
            definition_id: literal.definition,
 
            poly_vars: poly_args,
 
            embedded,
 
            returned: union_type
 
        };
 
    }
 

	
 
    /// Inserts the extra polymorphic data struct. Assumes that the select
 
    /// expression's referenced (definition_id, field_idx) has been resolved.
 
    fn insert_initial_select_polymorph_data(
 
        &mut self, ctx: &Ctx, select_id: SelectExpressionId, struct_def_id: DefinitionId
 
    ) {
 
        use InferenceTypePart as ITP;
 

	
 
        // Retrieve relevant data
 
        let expr = &ctx.heap[select_id];
 
        let expr_type = &self.expr_types[expr.unique_id_in_definition as usize];
 
        let field_idx = expr_type.field_or_monomorph_idx as usize;
 
        let extra_data_idx = expr_type.extra_data_idx; // TODO: @Temp
 
        debug_assert!(extra_data_idx != -1, "initial select polymorph data, but no preallocated ExtraData");
 

	
 
        let definition = ctx.heap[struct_def_id].as_struct();
 

	
 
        // Generate initial polyvar types and struct type
 
        // TODO: @Performance: we can immediately set the polyvars of the subject's struct type
 
        let num_poly_vars = definition.poly_vars.len();
 
        let mut poly_vars = Vec::with_capacity(num_poly_vars);
 
        let struct_parts_reserved = 1 + 2 * num_poly_vars;
 
        let mut struct_parts = Vec::with_capacity(struct_parts_reserved);
 
        struct_parts.push(ITP::Instance(struct_def_id, num_poly_vars as u32));
 

	
 
        for poly_idx in 0..num_poly_vars {
 
            poly_vars.push(InferenceType::new(true, false, vec![
 
                ITP::Marker(poly_idx as u32), ITP::Unknown,
 
            ]));
 
            struct_parts.push(ITP::Marker(poly_idx as u32));
 
            struct_parts.push(ITP::Unknown);
 
        }
 
        debug_assert_eq!(struct_parts.len(), struct_parts_reserved);
 

	
 
        // Generate initial field type
 
        let field_type = self.determine_inference_type_from_parser_type_elements(&definition.fields[field_idx].parser_type.elements, false);
 
        self.extra_data[extra_data_idx as usize] = ExtraData{
 
            expr_id: select_id.upcast(),
 
            definition_id: struct_def_id,
 
            poly_vars,
 
            embedded: vec![InferenceType::new(num_poly_vars != 0, num_poly_vars == 0, struct_parts)],
 
            returned: field_type
 
        };
 
    }
 

	
 
    /// Determines the initial InferenceType from the provided ParserType. This
 
    /// may be called with two kinds of intentions:
 
    /// 1. To resolve a ParserType within the body of a function, or on
 
    ///     polymorphic arguments to calls/instantiations within that body. This
 
    ///     means that the polymorphic variables are known and can be replaced
 
    ///     with the monomorph we're instantiating.
 
    /// 2. To resolve a ParserType on a called function's definition or on
 
    ///     an instantiated datatype's members. This means that the polymorphic
 
    ///     arguments inside those ParserTypes refer to the polymorphic
 
    ///     variables in the called/instantiated type's definition.
 
    /// In the second case we place InferenceTypePart::Marker instances such
 
    /// that we can perform type inference on the polymorphic variables.
 
    fn determine_inference_type_from_parser_type_elements(
 
        &mut self, elements: &[ParserTypeElement],
 
        use_definitions_known_poly_args: bool
 
    ) -> InferenceType {
 
        use ParserTypeVariant as PTV;
 
        use InferenceTypePart as ITP;
 

	
 
        let mut infer_type = Vec::with_capacity(elements.len());
 
        let mut has_inferred = false;
 
        let mut has_markers = false;
 

	
 
        for element in elements {
 
            match &element.variant {
 
                // Compiler-only types
 
                PTV::Void => { infer_type.push(ITP::Void); },
 
                PTV::InputOrOutput => { infer_type.push(ITP::PortLike); has_inferred = true },
 
                PTV::ArrayLike => { infer_type.push(ITP::ArrayLike); has_inferred = true },
 
                PTV::IntegerLike => { infer_type.push(ITP::IntegerLike); has_inferred = true },
 
                // Builtins
 
                PTV::Message => {
 
                    // TODO: @types Remove the Message -> Byte hack at some point...
 
                    infer_type.push(ITP::Message);
 
                    infer_type.push(ITP::UInt8);
 
                },
 
                PTV::Bool => { infer_type.push(ITP::Bool); },
 
                PTV::UInt8 => { infer_type.push(ITP::UInt8); },
 
                PTV::UInt16 => { infer_type.push(ITP::UInt16); },
 
                PTV::UInt32 => { infer_type.push(ITP::UInt32); },
 
                PTV::UInt64 => { infer_type.push(ITP::UInt64); },
 
                PTV::SInt8 => { infer_type.push(ITP::SInt8); },
 
                PTV::SInt16 => { infer_type.push(ITP::SInt16); },
 
                PTV::SInt32 => { infer_type.push(ITP::SInt32); },
 
                PTV::SInt64 => { infer_type.push(ITP::SInt64); },
 
                PTV::Character => { infer_type.push(ITP::Character); },
 
                PTV::String => { infer_type.push(ITP::String); },
 
                // Special markers
 
                PTV::IntegerLiteral => { unreachable!("integer literal type on variable type"); },
 
                PTV::Inferred => {
 
                    infer_type.push(ITP::Unknown);
 
                    has_inferred = true;
 
                },
 
                // With nested types
 
                PTV::Array => { infer_type.push(ITP::Array); },
 
                PTV::Input => { infer_type.push(ITP::Input); },
 
                PTV::Output => { infer_type.push(ITP::Output); },
 
                PTV::PolymorphicArgument(belongs_to_definition, poly_arg_idx) => {
 
                    let poly_arg_idx = *poly_arg_idx;
 
                    if use_definitions_known_poly_args {
 
                        // Refers to polymorphic argument on procedure we're currently processing.
 
                        // This argument is already known.
 
                        debug_assert_eq!(*belongs_to_definition, self.definition_type.definition_id());
 
                        debug_assert!((poly_arg_idx as usize) < self.poly_vars.len());
 

	
 
                        for concrete_part in &self.poly_vars[poly_arg_idx as usize].parts {
 
                            infer_type.push(ITP::from(*concrete_part));
 
                        }
 
                    } else {
 
                        // Polymorphic argument has to be inferred
 
                        has_markers = true;
 
                        has_inferred = true;
 
                        infer_type.push(ITP::Marker(poly_arg_idx));
 
                        infer_type.push(ITP::Unknown)
 
                    }
 
                },
 
                PTV::Definition(definition_id, num_embedded) => {
 
                    infer_type.push(ITP::Instance(*definition_id, *num_embedded));
 
                }
 
            }
 
        }
 

	
 
        InferenceType::new(has_markers, !has_inferred, infer_type)
 
    }
 

	
 
    /// Construct an error when an expression's type does not match. This
 
    /// happens if we infer the expression type from its arguments (e.g. the
 
    /// expression type of an addition operator is the type of the arguments)
 
    /// But the expression type was already set due to our parent (e.g. an
 
    /// "if statement" or a "logical not" always expecting a boolean)
 
    fn construct_expr_type_error(
 
        &self, ctx: &Ctx, expr_id: ExpressionId, arg_id: ExpressionId
 
    ) -> ParseError {
 
        // TODO: Expand and provide more meaningful information for humans
 
        let expr = &ctx.heap[expr_id];
 
        let arg_expr = &ctx.heap[arg_id];
 
        let expr_idx = expr.get_unique_id_in_definition();
 
        let arg_expr_idx = arg_expr.get_unique_id_in_definition();
 
        let expr_type = &self.expr_types[expr_idx as usize].expr_type;
 
        let arg_type = &self.expr_types[arg_expr_idx as usize].expr_type;
 

	
 
        return ParseError::new_error_at_span(
 
            &ctx.module.source, expr.span(), format!(
 
            &ctx.module.source, expr.operation_span(), format!(
 
                "incompatible types: this expression expected a '{}'",
 
                expr_type.display_name(&ctx.heap)
 
            )
 
        ).with_info_at_span(
 
            &ctx.module.source, arg_expr.span(), format!(
 
            &ctx.module.source, arg_expr.full_span(), format!(
 
                "but this expression yields a '{}'",
 
                arg_type.display_name(&ctx.heap)
 
            )
 
        )
 
    }
 

	
 
    fn construct_arg_type_error(
 
        &self, ctx: &Ctx, expr_id: ExpressionId,
 
        arg1_id: ExpressionId, arg2_id: ExpressionId
 
    ) -> ParseError {
 
        let expr = &ctx.heap[expr_id];
 
        let arg1 = &ctx.heap[arg1_id];
 
        let arg2 = &ctx.heap[arg2_id];
 

	
 
        let arg1_idx = arg1.get_unique_id_in_definition();
 
        let arg1_type = &self.expr_types[arg1_idx as usize].expr_type;
 
        let arg2_idx = arg2.get_unique_id_in_definition();
 
        let arg2_type = &self.expr_types[arg2_idx as usize].expr_type;
 

	
 
        return ParseError::new_error_str_at_span(
 
            &ctx.module.source, expr.span(),
 
            &ctx.module.source, expr.operation_span(),
 
            "incompatible types: cannot apply this expression"
 
        ).with_info_at_span(
 
            &ctx.module.source, arg1.span(), format!(
 
            &ctx.module.source, arg1.full_span(), format!(
 
                "Because this expression has type '{}'",
 
                arg1_type.display_name(&ctx.heap)
 
            )
 
        ).with_info_at_span(
 
            &ctx.module.source, arg2.span(), format!(
 
            &ctx.module.source, arg2.full_span(), format!(
 
                "But this expression has type '{}'",
 
                arg2_type.display_name(&ctx.heap)
 
            )
 
        )
 
    }
 

	
 
    fn construct_template_type_error(
 
        &self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
 
    ) -> ParseError {
 
        let expr = &ctx.heap[expr_id];
 
        let expr_idx = expr.get_unique_id_in_definition();
 
        let expr_type = &self.expr_types[expr_idx as usize].expr_type;
 

	
 
        return ParseError::new_error_at_span(
 
            &ctx.module.source, expr.span(), format!(
 
            &ctx.module.source, expr.full_span(), format!(
 
                "incompatible types: got a '{}' but expected a '{}'",
 
                expr_type.display_name(&ctx.heap), 
 
                InferenceType::partial_display_name(&ctx.heap, template)
 
            )
 
        )
 
    }
 

	
 
    /// Constructs a human interpretable error in the case that type inference
 
    /// on a polymorphic variable to a function call or literal construction 
 
    /// failed. This may only be caused by a pair of inference types (which may 
 
    /// come from arguments or the return type) having two different inferred 
 
    /// values for that polymorphic variable.
 
    ///
 
    /// So we find this pair and construct the error using it.
 
    ///
 
    /// We assume that the expression is a function call or a struct literal,
 
    /// and that an actual error has occurred.
 
    fn construct_poly_arg_error(
 
        ctx: &Ctx, poly_data: &ExtraData, expr_id: ExpressionId
 
    ) -> ParseError {
 
        // Helper function to check for polymorph mismatch between two inference
 
        // types.
 
        fn has_poly_mismatch<'a>(type_a: &'a InferenceType, type_b: &'a InferenceType) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
 
            if !type_a.has_marker || !type_b.has_marker {
 
                return None
 
            }
 

	
 
            for (marker_a, section_a) in type_a.marker_iter() {
 
                for (marker_b, section_b) in type_b.marker_iter() {
 
                    if marker_a != marker_b {
 
                        // Not the same polymorphic variable
 
                        continue;
 
                    }
 

	
 
                    if !InferenceType::check_subtrees(section_a, 0, section_b, 0) {
 
                        // Not compatible
 
                        return Some((marker_a, section_a, section_b))
 
                    }
 
                }
 
            }
 

	
 
            None
 
        }
 

	
 
        // Helper function to check for polymorph mismatch between an inference
 
        // type and the polymorphic variables in the poly_data struct.
 
        fn has_explicit_poly_mismatch<'a>(
 
            poly_vars: &'a [InferenceType], arg: &'a InferenceType
 
        ) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
 
            for (marker, section) in arg.marker_iter() {
 
                debug_assert!((marker as usize) < poly_vars.len());
 
                let poly_section = &poly_vars[marker as usize].parts;
 
                if !InferenceType::check_subtrees(poly_section, 0, section, 0) {
 
                    return Some((marker, poly_section, section))
 
                }
 
            }
 

	
 
            None
 
        }
 

	
 
        // Helpers function to retrieve polyvar name and definition name
 
        fn get_poly_var_and_definition_name<'a>(ctx: &'a Ctx, poly_var_idx: u32, definition_id: DefinitionId) -> (&'a str, &'a str) {
 
            let definition = &ctx.heap[definition_id];
 
            let poly_var = definition.poly_vars()[poly_var_idx as usize].value.as_str();
 
            let func_name = definition.identifier().value.as_str();
 

	
 
            (poly_var, func_name)
 
        }
 

	
 
        // Helper function to construct initial error
 
        fn construct_main_error(ctx: &Ctx, poly_data: &ExtraData, poly_var_idx: u32, expr: &Expression) -> ParseError {
 
            match expr {
 
                Expression::Call(expr) => {
 
                    let (poly_var, func_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
 
                    return ParseError::new_error_at_span(
 
                        &ctx.module.source, expr.span, format!(
 
                        &ctx.module.source, expr.func_span, format!(
 
                            "Conflicting type for polymorphic variable '{}' of '{}'",
 
                            poly_var, func_name
 
                        )
 
                    )
 
                },
 
                Expression::Literal(expr) => {
 
                    let (poly_var, type_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
 
                    return ParseError::new_error_at_span(
 
                        &ctx.module.source, expr.span, format!(
 
                            "Conflicting type for polymorphic variable '{}' of instantiation of '{}'",
 
                            poly_var, type_name
 
                        )
 
                    );
 
                },
 
                Expression::Select(expr) => {
 
                    let (poly_var, struct_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
 
                    return ParseError::new_error_at_span(
 
                        &ctx.module.source, expr.span, format!(
 
                        &ctx.module.source, expr.full_span, format!(
 
                            "Conflicting type for polymorphic variable '{}' while accessing field '{}' of '{}'",
 
                            poly_var, expr.field_name.value.as_str(), struct_name
 
                        )
 
                    )
 
                }
 
                _ => unreachable!("called construct_poly_arg_error without an expected expression, got: {:?}", expr)
 
            }
 
        }
 

	
 
        // Actual checking
 
        let expr = &ctx.heap[expr_id];
 
        let (expr_args, expr_return_name) = match expr {
 
            Expression::Call(expr) => 
 
                (
 
                    expr.arguments.clone(),
 
                    "return type"
 
                ),
 
            Expression::Literal(expr) => {
 
                let expressions = match &expr.value {
 
                    Literal::Struct(v) => v.fields.iter()
 
                        .map(|f| f.value)
 
                        .collect(),
 
                    Literal::Enum(_) => Vec::new(),
 
                    Literal::Union(v) => v.values.clone(),
 
                    _ => unreachable!()
 
                };
 

	
 
                ( expressions, "literal" )
 
            },
 
            Expression::Select(expr) =>
 
                // Select expression uses the polymorphic variables of the 
 
                // struct it is accessing, so get the subject expression.
 
                (
 
                    vec![expr.subject],
 
                    "selected field"
 
                ),
 
            _ => unreachable!(),
 
        };
 

	
 
        // - check return type with itself
 
        if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(
 
            &poly_data.returned, &poly_data.returned
 
        ) {
 
            return construct_main_error(ctx, poly_data, poly_idx, expr)
 
                .with_info_at_span(
 
                    &ctx.module.source, expr.span(), format!(
 
                    &ctx.module.source, expr.full_span(), format!(
 
                        "The {} inferred the conflicting types '{}' and '{}'",
 
                        expr_return_name,
 
                        InferenceType::partial_display_name(&ctx.heap, section_a),
 
                        InferenceType::partial_display_name(&ctx.heap, section_b)
 
                    )
 
                );
 
        }
 

	
 
        // - check arguments with each other argument and with return type
 
        for (arg_a_idx, arg_a) in poly_data.embedded.iter().enumerate() {
 
            for (arg_b_idx, arg_b) in poly_data.embedded.iter().enumerate() {
 
                if arg_b_idx > arg_a_idx {
 
                    break;
 
                }
 

	
 
                if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(&arg_a, &arg_b) {
 
                    let error = construct_main_error(ctx, poly_data, poly_idx, expr);
 
                    if arg_a_idx == arg_b_idx {
 
                        // Same argument
 
                        let arg = &ctx.heap[expr_args[arg_a_idx]];
 
                        return error.with_info_at_span(
 
                            &ctx.module.source, arg.span(), format!(
 
                            &ctx.module.source, arg.full_span(), format!(
 
                                "This argument inferred the conflicting types '{}' and '{}'",
 
                                InferenceType::partial_display_name(&ctx.heap, section_a),
 
                                InferenceType::partial_display_name(&ctx.heap, section_b)
 
                            )
 
                        );
 
                    } else {
 
                        let arg_a = &ctx.heap[expr_args[arg_a_idx]];
 
                        let arg_b = &ctx.heap[expr_args[arg_b_idx]];
 
                        return error.with_info_at_span(
 
                            &ctx.module.source, arg_a.span(), format!(
 
                            &ctx.module.source, arg_a.full_span(), format!(
 
                                "This argument inferred it to '{}'",
 
                                InferenceType::partial_display_name(&ctx.heap, section_a)
 
                            )
 
                        ).with_info_at_span(
 
                            &ctx.module.source, arg_b.span(), format!(
 
                            &ctx.module.source, arg_b.full_span(), format!(
 
                                "While this argument inferred it to '{}'",
 
                                InferenceType::partial_display_name(&ctx.heap, section_b)
 
                            )
 
                        )
 
                    }
 
                }
 
            }
 

	
 
            // Check with return type
 
            if let Some((poly_idx, section_arg, section_ret)) = has_poly_mismatch(arg_a, &poly_data.returned) {
 
                let arg = &ctx.heap[expr_args[arg_a_idx]];
 
                return construct_main_error(ctx, poly_data, poly_idx, expr)
 
                    .with_info_at_span(
 
                        &ctx.module.source, arg.span(), format!(
 
                        &ctx.module.source, arg.full_span(), format!(
 
                            "This argument inferred it to '{}'",
 
                            InferenceType::partial_display_name(&ctx.heap, section_arg)
 
                        )
 
                    )
 
                    .with_info_at_span(
 
                        &ctx.module.source, expr.span(), format!(
 
                        &ctx.module.source, expr.full_span(), format!(
 
                            "While the {} inferred it to '{}'",
 
                            expr_return_name,
 
                            InferenceType::partial_display_name(&ctx.heap, section_ret)
 
                        )
 
                    );
 
            }
 
        }
 

	
 
        // Now check against the explicitly specified polymorphic variables (if
 
        // any).
 
        for (arg_idx, arg) in poly_data.embedded.iter().enumerate() {
 
            if let Some((poly_idx, poly_section, arg_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, arg) {
 
                let arg = &ctx.heap[expr_args[arg_idx]];
 
                return construct_main_error(ctx, poly_data, poly_idx, expr)
 
                    .with_info_at_span(
 
                        &ctx.module.source, arg.span(), format!(
 
                        &ctx.module.source, arg.full_span(), format!(
 
                            "The polymorphic variable has type '{}' (which might have been partially inferred) while the argument inferred it to '{}'",
 
                            InferenceType::partial_display_name(&ctx.heap, poly_section),
 
                            InferenceType::partial_display_name(&ctx.heap, arg_section)
 
                        )
 
                    );
 
            }
 
        }
 

	
 
        if let Some((poly_idx, poly_section, ret_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, &poly_data.returned) {
 
            return construct_main_error(ctx, poly_data, poly_idx, expr)
 
                .with_info_at_span(
 
                    &ctx.module.source, expr.span(), format!(
 
                    &ctx.module.source, expr.full_span(), format!(
 
                        "The polymorphic variable has type '{}' (which might have been partially inferred) while the {} inferred it to '{}'",
 
                        InferenceType::partial_display_name(&ctx.heap, poly_section),
 
                        expr_return_name,
 
                        InferenceType::partial_display_name(&ctx.heap, ret_section)
 
                    )
 
                )
 
        }
 

	
 
        unreachable!("construct_poly_arg_error without actual error found?")
 
    }
 
}
 

	
 
#[cfg(test)]
 
mod tests {
 
    use super::*;
 
    use crate::protocol::arena::Id;
 
    use InferenceTypePart as ITP;
 
    use InferenceType as IT;
 

	
 
    #[test]
 
    fn test_single_part_inference() {
 
        // lhs argument inferred from rhs
 
        let pairs = [
 
            (ITP::NumberLike, ITP::UInt8),
 
            (ITP::IntegerLike, ITP::SInt32),
 
            (ITP::Unknown, ITP::UInt64),
 
            (ITP::Unknown, ITP::String)
 
        ];
 
        for (lhs, rhs) in pairs.iter() {
 
            // Using infer-both
 
            let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
 
            let mut rhs_type = IT::new(false, true, vec![rhs.clone()]);
 
            let result = unsafe{ IT::infer_subtrees_for_both_types(
 
                &mut lhs_type, 0, &mut rhs_type, 0
 
            ) };
 
            assert_eq!(DualInferenceResult::First, result);
 
            assert_eq!(lhs_type.parts, rhs_type.parts);
 

	
 
            // Using infer-single
 
            let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
 
            let rhs_type = IT::new(false, true, vec![rhs.clone()]);
 
            let result = IT::infer_subtree_for_single_type(
 
                &mut lhs_type, 0, &rhs_type.parts, 0, false
 
            );
 
            assert_eq!(SingleInferenceResult::Modified, result);
 
            assert_eq!(lhs_type.parts, rhs_type.parts);
 
        }
 
    }
 

	
 
    #[test]
 
    fn test_multi_part_inference() {
 
        let pairs = [
 
            (vec![ITP::ArrayLike, ITP::NumberLike], vec![ITP::Slice, ITP::SInt8]),
 
            (vec![ITP::Unknown], vec![ITP::Input, ITP::Array, ITP::String]),
 
            (vec![ITP::PortLike, ITP::SInt32], vec![ITP::Input, ITP::SInt32]),
 
            (vec![ITP::Unknown], vec![ITP::Output, ITP::SInt32]),
 
            (
 
                vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Unknown, ITP::Output, ITP::Unknown],
 
                vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Array, ITP::SInt32, ITP::Output, ITP::SInt32]
 
            )
 
        ];
 

	
 
        for (lhs, rhs) in pairs.iter() {
 
            let mut lhs_type = IT::new(false, false, lhs.clone());
 
            let mut rhs_type = IT::new(false, true, rhs.clone());
 
            let result = unsafe{ IT::infer_subtrees_for_both_types(
 
                &mut lhs_type, 0, &mut rhs_type, 0
 
            ) };
 
            assert_eq!(DualInferenceResult::First, result);
 
            assert_eq!(lhs_type.parts, rhs_type.parts);
 

	
 
            let mut lhs_type = IT::new(false, false, lhs.clone());
 
            let rhs_type = IT::new(false, true, rhs.clone());
 
            let result = IT::infer_subtree_for_single_type(
 
                &mut lhs_type, 0, &rhs_type.parts, 0, false
 
            );
 
            assert_eq!(SingleInferenceResult::Modified, result);
 
            assert_eq!(lhs_type.parts, rhs_type.parts)
 
        }
 
    }
 
}
 
\ No newline at end of file
src/protocol/parser/pass_validation_linking.rs
Show inline comments
 
@@ -274,505 +274,506 @@ impl Visitor for PassValidationLinking {
 
        let end_while_id = stmt.end_while;
 
        let test_expr_id = stmt.test;
 
        let body_stmt_id = stmt.body;
 

	
 
        let old_while = self.in_while;
 
        self.in_while = id;
 

	
 
        // Visit test expression
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        debug_assert!(self.in_test_expr.is_invalid());
 
        self.in_test_expr = id.upcast();
 
        self.expr_parent = ExpressionParent::While(id);
 
        self.visit_expr(ctx, test_expr_id)?;
 
        self.in_test_expr = StatementId::new_invalid();
 

	
 
        // Link up to body statement
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        self.expr_parent = ExpressionParent::None;
 
        self.visit_block_stmt(ctx, body_stmt_id)?;
 
        self.in_while = old_while;
 

	
 
        // Link final entry in while's block statement back to the while. The
 
        // executor will go to the end-while statement if the test expression
 
        // is false, so put that in as the new previous stmt
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        self.prev_stmt = end_while_id.upcast();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_break_stmt(&mut self, ctx: &mut Ctx, id: BreakStatementId) -> VisitorResult {
 
        // Resolve break target
 
        let target_end_while = {
 
            let stmt = &ctx.heap[id];
 
            let target_while_id = self.resolve_break_or_continue_target(ctx, stmt.span, &stmt.label)?;
 
            let target_while = &ctx.heap[target_while_id];
 
            debug_assert!(!target_while.end_while.is_invalid());
 

	
 
            target_while.end_while
 
        };
 

	
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        let stmt = &mut ctx.heap[id];
 
        stmt.target = Some(target_end_while);
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_continue_stmt(&mut self, ctx: &mut Ctx, id: ContinueStatementId) -> VisitorResult {
 
        // Resolve continue target
 
        let target_while_id = {
 
            let stmt = &ctx.heap[id];
 
            self.resolve_break_or_continue_target(ctx, stmt.span, &stmt.label)?
 
        };
 

	
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        let stmt = &mut ctx.heap[id];
 
        stmt.target = Some(target_while_id);
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
 
        // Check for validity of synchronous statement
 
        let sync_stmt = &ctx.heap[id];
 
        let end_sync_id = sync_stmt.end_sync;
 
        let cur_sync_span = sync_stmt.span;
 
        if !self.in_sync.is_invalid() {
 
            // Nested synchronous statement
 
            let old_sync_span = ctx.heap[self.in_sync].span;
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, cur_sync_span, "Illegal nested synchronous statement"
 
            ).with_info_str_at_span(
 
                &ctx.module.source, old_sync_span, "It is nested in this synchronous statement"
 
            ));
 
        }
 

	
 
        if !self.def_type.is_primitive() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, cur_sync_span,
 
                "synchronous statements may only be used in primitive components"
 
            ));
 
        }
 

	
 
        // Synchronous statement implicitly moves to its block
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        let sync_body = ctx.heap[id].body;
 
        debug_assert!(self.in_sync.is_invalid());
 
        self.in_sync = id;
 
        self.visit_block_stmt_with_hint(ctx, sync_body, Some(id))?;
 
        assign_and_replace_next_stmt!(self, ctx, end_sync_id.upcast());
 

	
 
        self.in_sync = SynchronousStatementId::new_invalid();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_return_stmt(&mut self, ctx: &mut Ctx, id: ReturnStatementId) -> VisitorResult {
 
        // Check if "return" occurs within a function
 
        let stmt = &ctx.heap[id];
 
        if !self.def_type.is_function() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, stmt.span,
 
                "return statements may only appear in function bodies"
 
            ));
 
        }
 

	
 
        // If here then we are within a function
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        debug_assert_eq!(ctx.heap[id].expressions.len(), 1);
 
        self.expr_parent = ExpressionParent::Return(id);
 
        self.visit_expr(ctx, ctx.heap[id].expressions[0])?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_goto_stmt(&mut self, ctx: &mut Ctx, id: GotoStatementId) -> VisitorResult {
 
        let target_id = self.find_label(ctx, &ctx.heap[id].label)?;
 
        ctx.heap[id].target = Some(target_id);
 

	
 
        let target = &ctx.heap[target_id];
 
        if self.in_sync != target.in_sync {
 
            // We can only goto the current scope or outer scopes. Because
 
            // nested sync statements are not allowed we must be inside a sync
 
            // statement.
 
            debug_assert!(!self.in_sync.is_invalid());
 
            let goto_stmt = &ctx.heap[id];
 
            let sync_stmt = &ctx.heap[self.in_sync];
 
            return Err(
 
                ParseError::new_error_str_at_span(&ctx.module.source, goto_stmt.span, "goto may not escape the surrounding synchronous block")
 
                .with_info_str_at_span(&ctx.module.source, target.label.span, "this is the target of the goto statement")
 
                .with_info_str_at_span(&ctx.module.source, sync_stmt.span, "which will jump past this statement")
 
            );
 
        }
 

	
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_new_stmt(&mut self, ctx: &mut Ctx, id: NewStatementId) -> VisitorResult {
 
        // Make sure the new statement occurs inside a composite component
 
        if !self.def_type.is_composite() {
 
            let new_stmt = &ctx.heap[id];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, new_stmt.span,
 
                "instantiating components may only be done in composite components"
 
            ));
 
        }
 

	
 
        // Recurse into call expression (which will check the expression parent
 
        // to ensure that the "new" statment instantiates a component)
 
        let call_expr_id = ctx.heap[id].expression;
 

	
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        self.expr_parent = ExpressionParent::New(id);
 
        self.visit_call_expr(ctx, call_expr_id)?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
 
        let expr_id = ctx.heap[id].expression;
 

	
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        self.expr_parent = ExpressionParent::ExpressionStmt(id);
 
        self.visit_expr(ctx, expr_id)?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 

	
 
    //--------------------------------------------------------------------------
 
    // Expression visitors
 
    //--------------------------------------------------------------------------
 

	
 
    fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 

	
 
        let assignment_expr = &mut ctx.heap[id];
 

	
 
        // Although we call assignment an expression to simplify the compiler's
 
        // code (mainly typechecking), we disallow nested use in expressions
 
        match self.expr_parent {
 
            // Look at us: lying through our teeth while providing error messages.
 
            ExpressionParent::ExpressionStmt(_) => {},
 
            _ => return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, assignment_expr.span,
 
                "assignments may only appear at the statement level"
 
                &ctx.module.source, assignment_expr.full_span,
 
                "assignments are statements, and cannot be used in expressions"
 
            )),
 
        }
 

	
 
        let left_expr_id = assignment_expr.left;
 
        let right_expr_id = assignment_expr.right;
 
        let old_expr_parent = self.expr_parent;
 
        assignment_expr.parent = old_expr_parent;
 
        assignment_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.must_be_assignable = Some(assignment_expr.span);
 
        self.must_be_assignable = Some(assignment_expr.operator_span);
 
        self.visit_expr(ctx, left_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.must_be_assignable = None;
 
        self.visit_expr(ctx, right_expr_id)?;
 
        self.expr_parent = old_expr_parent;
 
        Ok(())
 
    }
 

	
 
    fn visit_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 

	
 
        // Check for valid context of binding expression
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to the result from a binding expression"
 
            ));
 
        }
 

	
 
        if self.in_test_expr.is_invalid() {
 
            let binding_expr = &ctx.heap[id];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, binding_expr.span,
 
                &ctx.module.source, binding_expr.full_span,
 
                "binding expressions can only be used inside the testing expression of 'if' and 'while' statements"
 
            ));
 
        }
 

	
 
        if !self.in_binding_expr.is_invalid() {
 
            let binding_expr = &ctx.heap[id];
 
            let previous_expr = &ctx.heap[self.in_binding_expr];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, binding_expr.span,
 
                &ctx.module.source, binding_expr.full_span,
 
                "nested binding expressions are not allowed"
 
            ).with_info_str_at_span(
 
                &ctx.module.source, previous_expr.span,
 
                &ctx.module.source, previous_expr.operator_span,
 
                "the outer binding expression is found here"
 
            ));
 
        }
 

	
 
        let mut seeking_parent = self.expr_parent;
 
        loop {
 
            // Perform upward search to make sure only LogicalAnd is applied to
 
            // the binding expression
 
            let valid = match seeking_parent {
 
                ExpressionParent::If(_) | ExpressionParent::While(_) => {
 
                    // Every parent expression (if any) were LogicalAnd.
 
                    break;
 
                }
 
                ExpressionParent::Expression(parent_id, _) => {
 
                    let parent_expr = &ctx.heap[parent_id];
 
                    match parent_expr {
 
                        Expression::Binary(parent_expr) => {
 
                            // Set new parent to continue the search. Otherwise
 
                            // halt and provide an error using the current
 
                            // parent.
 
                            if parent_expr.operation == BinaryOperator::LogicalAnd {
 
                                seeking_parent = parent_expr.parent;
 
                                true
 
                            } else {
 
                                false
 
                            }
 
                        },
 
                        _ => false,
 
                    }
 
                },
 
                _ => unreachable!(), // nested under if/while, so always expressions as parents
 
            };
 

	
 
            if !valid {
 
                let binding_expr = &ctx.heap[id];
 
                let parent_expr = &ctx.heap[seeking_parent.as_expression()];
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module.source, binding_expr.span,
 
                    &ctx.module.source, binding_expr.full_span,
 
                    "only the logical-and operator (&&) may be applied to binding expressions"
 
                ).with_info_str_at_span(
 
                    &ctx.module.source, parent_expr.span(),
 
                    &ctx.module.source, parent_expr.operation_span(),
 
                    "this was the disallowed operation applied to the result from a binding expression"
 
                ));
 
            }
 
        }
 

	
 
        // Perform all of the index/parent assignment magic
 
        let binding_expr = &mut ctx.heap[id];
 

	
 
        let old_expr_parent = self.expr_parent;
 
        binding_expr.parent = old_expr_parent;
 
        binding_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 
        self.in_binding_expr = id;
 

	
 
        // Perform preliminary check on children: binding expressions only make
 
        // sense if the left hand side is just a variable expression, or if it
 
        // is a literal of some sort. The typechecker will take care of the rest
 
        let bound_to_id = binding_expr.bound_to;
 
        let bound_from_id = binding_expr.bound_from;
 

	
 
        match &ctx.heap[bound_to_id] {
 
            // Variables may not be binding variables, and literals may
 
            // actually not contain binding variables. But in that case we just
 
            // perform an equality check.
 
            Expression::Variable(_) => {}
 
            Expression::Literal(_) => {},
 
            _ => {
 
                let binding_expr = &ctx.heap[id];
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module.source, binding_expr.span,
 
                    &ctx.module.source, binding_expr.operator_span,
 
                    "the left hand side of a binding expression may only be a variable or a literal expression"
 
                ));
 
            },
 
        }
 

	
 
        // Visit the children themselves
 
        self.in_binding_expr_lhs = true;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, bound_to_id)?;
 
        self.in_binding_expr_lhs = false;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, bound_from_id)?;
 

	
 
        self.expr_parent = old_expr_parent;
 
        self.in_binding_expr = BindingExpressionId::new_invalid();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let conditional_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to the result from a conditional expression"
 
            ))
 
        }
 

	
 
        let test_expr_id = conditional_expr.test;
 
        let true_expr_id = conditional_expr.true_expression;
 
        let false_expr_id = conditional_expr.false_expression;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        conditional_expr.parent = old_expr_parent;
 
        conditional_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, test_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, true_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
 
        self.visit_expr(ctx, false_expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let binary_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to the result from a binary expression"
 
            ))
 
        }
 

	
 
        let left_expr_id = binary_expr.left;
 
        let right_expr_id = binary_expr.right;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        binary_expr.parent = old_expr_parent;
 
        binary_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, left_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, right_expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
 
        let unary_expr = &mut ctx.heap[id];
 
        let expr_id = unary_expr.expression;
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to the result from a unary expression"
 
            ))
 
        }
 

	
 
        let old_expr_parent = self.expr_parent;
 
        unary_expr.parent = old_expr_parent;
 
        unary_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
 
        self.visit_expr(ctx, expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let indexing_expr = &mut ctx.heap[id];
 

	
 
        let subject_expr_id = indexing_expr.subject;
 
        let index_expr_id = indexing_expr.index;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        indexing_expr.parent = old_expr_parent;
 
        indexing_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, subject_expr_id)?;
 

	
 
        let old_assignable = self.must_be_assignable.take();
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, index_expr_id)?;
 

	
 
        self.must_be_assignable = old_assignable;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let slicing_expr = &mut ctx.heap[id];
 

	
 
        let subject_expr_id = slicing_expr.subject;
 
        let from_expr_id = slicing_expr.from_index;
 
        let to_expr_id = slicing_expr.to_index;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        slicing_expr.parent = old_expr_parent;
 
        slicing_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, subject_expr_id)?;
 

	
 
        let old_assignable = self.must_be_assignable.take();
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, from_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
 
        self.visit_expr(ctx, to_expr_id)?;
 

	
 
        self.must_be_assignable = old_assignable;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
 
        let select_expr = &mut ctx.heap[id];
 
        let expr_id = select_expr.subject;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        select_expr.parent = old_expr_parent;
 
        select_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
 
        self.visit_expr(ctx, expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
 
        let literal_expr = &mut ctx.heap[id];
 
        let old_expr_parent = self.expr_parent;
 
        literal_expr.parent = old_expr_parent;
 
        literal_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to a literal expression"
 
            ))
 
        }
 

	
 
        match &mut literal_expr.value {
 
            Literal::Null | Literal::True | Literal::False |
 
            Literal::Character(_) | Literal::String(_) | Literal::Integer(_) => {
 
                // Just the parent has to be set, done above
 
            },
 
            Literal::Struct(literal) => {
 
                let upcast_id = id.upcast();
 
                // Retrieve type definition
 
                let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
 
                let struct_definition = type_definition.definition.as_struct();
 

	
 
                // Make sure all fields are specified, none are specified twice
 
@@ -791,558 +792,558 @@ impl Visitor for PassValidationLinking {
 
                            &ctx.module.source, field_span, format!(
 
                                "This field does not exist on the struct '{}'",
 
                                ast_definition.identifier().value.as_str()
 
                            )
 
                        ));
 
                    }
 
                    field.field_idx = field_idx.unwrap();
 

	
 
                    // Check if specified more than once
 
                    if specified[field.field_idx] {
 
                        return Err(ParseError::new_error_str_at_span(
 
                            &ctx.module.source, field.identifier.span,
 
                            "This field is specified more than once"
 
                        ));
 
                    }
 

	
 
                    specified[field.field_idx] = true;
 
                }
 

	
 
                if !specified.iter().all(|v| *v) {
 
                    // Some fields were not specified
 
                    let mut not_specified = String::new();
 
                    let mut num_not_specified = 0;
 
                    for (def_field_idx, is_specified) in specified.iter().enumerate() {
 
                        if !is_specified {
 
                            if !not_specified.is_empty() { not_specified.push_str(", ") }
 
                            let field_ident = &struct_definition.fields[def_field_idx].identifier;
 
                            not_specified.push_str(field_ident.value.as_str());
 
                            num_not_specified += 1;
 
                        }
 
                    }
 

	
 
                    debug_assert!(num_not_specified > 0);
 
                    let msg = if num_not_specified == 1 {
 
                        format!("not all fields are specified, '{}' is missing", not_specified)
 
                    } else {
 
                        format!("not all fields are specified, [{}] are missing", not_specified)
 
                    };
 

	
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module.source, literal.parser_type.full_span, msg
 
                    ));
 
                }
 

	
 
                // Need to traverse fields expressions in struct and evaluate
 
                // the poly args
 
                let mut expr_section = self.expression_buffer.start_section();
 
                for field in &literal.fields {
 
                    expr_section.push(field.value);
 
                }
 

	
 
                for expr_idx in 0..expr_section.len() {
 
                    let expr_id = expr_section[expr_idx];
 
                    self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 

	
 
                expr_section.forget();
 
            },
 
            Literal::Enum(literal) => {
 
                // Make sure the variant exists
 
                let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
 
                let enum_definition = type_definition.definition.as_enum();
 

	
 
                let variant_idx = enum_definition.variants.iter().position(|v| {
 
                    v.identifier == literal.variant
 
                });
 

	
 
                if variant_idx.is_none() {
 
                    let literal = ctx.heap[id].value.as_enum();
 
                    let ast_definition = ctx.heap[literal.definition].as_enum();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module.source, literal.parser_type.full_span, format!(
 
                            "the variant '{}' does not exist on the enum '{}'",
 
                            literal.variant.value.as_str(), ast_definition.identifier.value.as_str()
 
                        )
 
                    ));
 
                }
 

	
 
                literal.variant_idx = variant_idx.unwrap();
 
            },
 
            Literal::Union(literal) => {
 
                // Make sure the variant exists
 
                let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
 
                let union_definition = type_definition.definition.as_union();
 

	
 
                let variant_idx = union_definition.variants.iter().position(|v| {
 
                    v.identifier == literal.variant
 
                });
 
                if variant_idx.is_none() {
 
                    let literal = ctx.heap[id].value.as_union();
 
                    let ast_definition = ctx.heap[literal.definition].as_union();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module.source, literal.parser_type.full_span, format!(
 
                            "the variant '{}' does not exist on the union '{}'",
 
                            literal.variant.value.as_str(), ast_definition.identifier.value.as_str()
 
                        )
 
                    ));
 
                }
 

	
 
                literal.variant_idx = variant_idx.unwrap();
 

	
 
                // Make sure the number of specified values matches the expected
 
                // number of embedded values in the union variant.
 
                let union_variant = &union_definition.variants[literal.variant_idx];
 
                if union_variant.embedded.len() != literal.values.len() {
 
                    let literal = ctx.heap[id].value.as_union();
 
                    let ast_definition = ctx.heap[literal.definition].as_union();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module.source, literal.parser_type.full_span, format!(
 
                            "The variant '{}' of union '{}' expects {} embedded values, but {} were specified",
 
                            literal.variant.value.as_str(), ast_definition.identifier.value.as_str(),
 
                            union_variant.embedded.len(), literal.values.len()
 
                        ),
 
                    ))
 
                }
 

	
 
                // Traverse embedded values of union (if any) and evaluate the
 
                // polymorphic arguments
 
                let upcast_id = id.upcast();
 
                let mut expr_section = self.expression_buffer.start_section();
 
                for value in &literal.values {
 
                    expr_section.push(*value);
 
                }
 

	
 
                for expr_idx in 0..expr_section.len() {
 
                    let expr_id = expr_section[expr_idx];
 
                    self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 

	
 
                expr_section.forget();
 
            },
 
            Literal::Array(literal) => {
 
                // Visit all expressions in the array
 
                let upcast_id = id.upcast();
 
                let expr_section = self.expression_buffer.start_section_initialized(literal);
 
                for expr_idx in 0..expr_section.len() {
 
                    let expr_id = expr_section[expr_idx];
 
                    self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 

	
 
                expr_section.forget();
 
            }
 
        }
 

	
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> VisitorResult {
 
        let cast_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to the result from a cast expression"
 
            ))
 
        }
 

	
 
        let upcast_id = id.upcast();
 
        let old_expr_parent = self.expr_parent;
 
        cast_expr.parent = old_expr_parent;
 
        cast_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        // Recurse into the thing that we're casting
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        let subject_id = cast_expr.subject;
 
        self.visit_expr(ctx, subject_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
 
        let call_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module.source, span, "cannot assign to the result from a call expression"
 
            ))
 
        }
 

	
 
        // Check whether the method is allowed to be called within the code's
 
        // context (in sync, definition type, etc.)
 
        let mut expected_wrapping_new_stmt = false;
 
        match &mut call_expr.method {
 
            Method::Get => {
 
                if !self.def_type.is_primitive() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "a call to 'get' may only occur in primitive component definitions"
 
                    ));
 
                }
 
                if self.in_sync.is_invalid() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "a call to 'get' may only occur inside synchronous blocks"
 
                    ));
 
                }
 
            },
 
            Method::Put => {
 
                if !self.def_type.is_primitive() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "a call to 'put' may only occur in primitive component definitions"
 
                    ));
 
                }
 
                if self.in_sync.is_invalid() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "a call to 'put' may only occur inside synchronous blocks"
 
                    ));
 
                }
 
            },
 
            Method::Fires => {
 
                if !self.def_type.is_primitive() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "a call to 'fires' may only occur in primitive component definitions"
 
                    ));
 
                }
 
                if self.in_sync.is_invalid() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "a call to 'fires' may only occur inside synchronous blocks"
 
                    ));
 
                }
 
            },
 
            Method::Create => {},
 
            Method::Length => {},
 
            Method::Assert => {
 
                if self.def_type.is_function() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "assert statement may only occur in components"
 
                    ));
 
                }
 
                if self.in_sync.is_invalid() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, call_expr.span,
 
                        &ctx.module.source, call_expr.func_span,
 
                        "assert statements may only occur inside synchronous blocks"
 
                    ));
 
                }
 
            },
 
            Method::UserFunction => {},
 
            Method::UserComponent => {
 
                expected_wrapping_new_stmt = true;
 
            },
 
        }
 

	
 
        if expected_wrapping_new_stmt {
 
            if !self.expr_parent.is_new() {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module.source, call_expr.span,
 
                    &ctx.module.source, call_expr.func_span,
 
                    "cannot call a component, it can only be instantiated by using 'new'"
 
                ));
 
            }
 
        } else {
 
            if self.expr_parent.is_new() {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module.source, call_expr.span,
 
                    &ctx.module.source, call_expr.func_span,
 
                    "only components can be instantiated, this is a function"
 
                ));
 
            }
 
        }
 

	
 
        // Check the number of arguments
 
        let call_definition = ctx.types.get_base_definition(&call_expr.definition).unwrap();
 
        let num_expected_args = match &call_definition.definition {
 
            DefinedTypeVariant::Function(definition) => definition.arguments.len(),
 
            DefinedTypeVariant::Component(definition) => definition.arguments.len(),
 
            v => unreachable!("encountered {} type in call expression", v.type_class()),
 
        };
 

	
 
        let num_provided_args = call_expr.arguments.len();
 
        if num_provided_args != num_expected_args {
 
            let argument_text = if num_expected_args == 1 { "argument" } else { "arguments" };
 
            return Err(ParseError::new_error_at_span(
 
                &ctx.module.source, call_expr.span, format!(
 
                &ctx.module.source, call_expr.full_span, format!(
 
                    "expected {} {}, but {} were provided",
 
                    num_expected_args, argument_text, num_provided_args
 
                )
 
            ));
 
        }
 

	
 
        // Recurse into all of the arguments and set the expression's parent
 
        let upcast_id = id.upcast();
 

	
 
        let section = self.expression_buffer.start_section_initialized(&call_expr.arguments);
 
        let old_expr_parent = self.expr_parent;
 
        call_expr.parent = old_expr_parent;
 
        call_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        for arg_expr_idx in 0..section.len() {
 
            let arg_expr_id = section[arg_expr_idx];
 
            self.expr_parent = ExpressionParent::Expression(upcast_id, arg_expr_idx as u32);
 
            self.visit_expr(ctx, arg_expr_id)?;
 
        }
 

	
 
        section.forget();
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
 
        let var_expr = &ctx.heap[id];
 

	
 
        let (variable_id, is_binding_target) = match self.find_variable(ctx, self.relative_pos_in_block, &var_expr.identifier) {
 
            Ok(variable_id) => {
 
                // Regular variable
 
                (variable_id, false)
 
            },
 
            Err(()) => {
 
                // Couldn't find variable, but if we're in a binding expression,
 
                // then this may be the thing we're binding to.
 
                if self.in_binding_expr.is_invalid() || !self.in_binding_expr_lhs {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, var_expr.identifier.span, "unresolved variable"
 
                    ));
 
                }
 

	
 
                // This is a binding variable, but it may only appear in very
 
                // specific locations.
 
                let is_valid_binding = match self.expr_parent {
 
                    ExpressionParent::Expression(expr_id, idx) => {
 
                        match &ctx.heap[expr_id] {
 
                            Expression::Binding(_binding_expr) => {
 
                                // Nested binding is disallowed, and because of
 
                                // the check above we know we're directly at the
 
                                // LHS of the binding expression
 
                                debug_assert_eq!(_binding_expr.this, self.in_binding_expr);
 
                                debug_assert_eq!(idx, 0);
 
                                true
 
                            }
 
                            Expression::Literal(lit_expr) => {
 
                                // Only struct, unions and arrays can have
 
                                // subexpressions, so we're always fine
 
                                if cfg!(debug_assertions) {
 
                                    match lit_expr.value {
 
                                        Literal::Struct(_) | Literal::Union(_) | Literal::Array(_) => {},
 
                                        _ => unreachable!(),
 
                                    }
 
                                }
 

	
 
                                true
 
                            },
 
                            _ => false,
 
                        }
 
                    },
 
                    _ => {
 
                        false
 
                    }
 
                };
 

	
 
                if !is_valid_binding {
 
                    let binding_expr = &ctx.heap[self.in_binding_expr];
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module.source, var_expr.identifier.span,
 
                        "illegal location for binding variable: binding variables may only be nested under a binding expression, or a struct, union or array literal"
 
                    ).with_info_at_span(
 
                        &ctx.module.source, binding_expr.span, format!(
 
                        &ctx.module.source, binding_expr.operator_span, format!(
 
                            "'{}' was interpreted as a binding variable because the variable is not declared and it is nested under this binding expression",
 
                            var_expr.identifier.value.as_str()
 
                        )
 
                    ));
 
                }
 

	
 
                // By now we know that this is a valid binding expression. Given
 
                // that a binding expression must be nested under an if/while
 
                // statement, we now add the variable to the (implicit) block
 
                // statement following the if/while statement.
 
                let bound_identifier = var_expr.identifier.clone();
 
                let bound_variable_id = ctx.heap.alloc_variable(|this| Variable{
 
                    this,
 
                    kind: VariableKind::Binding,
 
                    parser_type: ParserType{
 
                        elements: vec![ParserTypeElement{
 
                            element_span: bound_identifier.span,
 
                            variant: ParserTypeVariant::Inferred
 
                        }],
 
                        full_span: bound_identifier.span
 
                    },
 
                    identifier: bound_identifier,
 
                    relative_pos_in_block: 0,
 
                    unique_id_in_scope: -1,
 
                });
 

	
 
                let body_stmt_id = match &ctx.heap[self.in_test_expr] {
 
                    Statement::If(stmt) => stmt.true_body,
 
                    Statement::While(stmt) => stmt.body,
 
                    _ => unreachable!(),
 
                };
 
                let body_scope = Scope::Regular(body_stmt_id);
 
                self.checked_at_single_scope_add_local(ctx, body_scope, 0, bound_variable_id)?;
 

	
 
                (bound_variable_id, true)
 
            }
 
        };
 

	
 
        let var_expr = &mut ctx.heap[id];
 
        var_expr.declaration = Some(variable_id);
 
        var_expr.used_as_binding_target = is_binding_target;
 
        var_expr.parent = self.expr_parent;
 
        var_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        Ok(())
 
    }
 
}
 

	
 
impl PassValidationLinking {
 
    //--------------------------------------------------------------------------
 
    // Special traversal
 
    //--------------------------------------------------------------------------
 

	
 
    fn visit_block_stmt_with_hint(&mut self, ctx: &mut Ctx, id: BlockStatementId, hint: Option<SynchronousStatementId>) -> VisitorResult {
 
        // Set parent scope and relative position in the parent scope. Remember
 
        // these values to set them back to the old values when we're done with
 
        // the traversal of the block's statements.
 
        let old_scope = self.cur_scope.clone();
 
        let new_scope = match hint {
 
            Some(sync_id) => Scope::Synchronous((sync_id, id)),
 
            None => Scope::Regular(id),
 
        };
 

	
 
        match old_scope {
 
            Scope::Definition(_def_id) => {
 
                // Don't do anything. Block is implicitly a child of a
 
                // definition scope.
 
                if cfg!(debug_assertions) {
 
                    match &ctx.heap[_def_id] {
 
                        Definition::Function(proc_def) => debug_assert_eq!(proc_def.body, id),
 
                        Definition::Component(proc_def) => debug_assert_eq!(proc_def.body, id),
 
                        _ => unreachable!(),
 
                    }
 
                }
 
            },
 
            Scope::Regular(block_id) | Scope::Synchronous((_, block_id)) => {
 
                let parent_block = &mut ctx.heap[block_id];
 
                parent_block.scope_node.nested.push(new_scope);
 
            }
 
        }
 

	
 
        self.cur_scope = new_scope;
 

	
 
        let body = &mut ctx.heap[id];
 
        body.scope_node.parent = old_scope;
 
        body.relative_pos_in_parent = self.relative_pos_in_block;
 
        let end_block_id = body.end_block;
 

	
 
        let old_relative_pos = self.relative_pos_in_block;
 

	
 
        // Copy statement IDs into buffer
 
        let statement_section = self.statement_buffer.start_section_initialized(&body.statements);
 

	
 
        // Perform the breadth-first pass. Its main purpose is to find labeled
 
        // statements such that we can find the `goto`-targets immediately when
 
        // performing the depth pass
 
        for stmt_idx in 0..statement_section.len() {
 
            self.relative_pos_in_block = stmt_idx as u32;
 
            self.visit_statement_for_locals_labels_and_in_sync(ctx, self.relative_pos_in_block, statement_section[stmt_idx])?;
 
        }
 

	
 
        // Perform the depth-first traversal
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast());
 
        for stmt_idx in 0..statement_section.len() {
 
            self.relative_pos_in_block = stmt_idx as u32;
 
            self.visit_stmt(ctx, statement_section[stmt_idx])?;
 
        }
 
        assign_and_replace_next_stmt!(self, ctx, end_block_id.upcast());
 

	
 
        self.cur_scope = old_scope;
 
        self.relative_pos_in_block = old_relative_pos;
 
        statement_section.forget();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_statement_for_locals_labels_and_in_sync(&mut self, ctx: &mut Ctx, relative_pos: u32, id: StatementId) -> VisitorResult {
 
        let statement = &mut ctx.heap[id];
 
        match statement {
 
            Statement::Local(stmt) => {
 
                match stmt {
 
                    LocalStatement::Memory(local) => {
 
                        let variable_id = local.variable;
 
                        self.checked_add_local(ctx, relative_pos, variable_id)?;
 
                    },
 
                    LocalStatement::Channel(local) => {
 
                        let from_id = local.from;
 
                        let to_id = local.to;
 
                        self.checked_add_local(ctx, relative_pos, from_id)?;
 
                        self.checked_add_local(ctx, relative_pos, to_id)?;
 
                    }
 
                }
 
            }
 
            Statement::Labeled(stmt) => {
 
                let stmt_id = stmt.this;
 
                let body_id = stmt.body;
 
                self.checked_add_label(ctx, relative_pos, self.in_sync, stmt_id)?;
 
                self.visit_statement_for_locals_labels_and_in_sync(ctx, relative_pos, body_id)?;
 
            },
 
            Statement::While(stmt) => {
 
                stmt.in_sync = self.in_sync;
 
            },
 
            _ => {},
 
        }
 

	
 
        return Ok(())
 
    }
 

	
 
    fn visit_definition_and_assign_local_ids(&mut self, ctx: &mut Ctx, definition_id: DefinitionId) {
 
        let mut var_counter = 0;
 

	
 
        // Set IDs on parameters
 
        let (param_section, body_id) = match &ctx.heap[definition_id] {
 
            Definition::Function(func_def) => (
 
                self.variable_buffer.start_section_initialized(&func_def.parameters),
 
                func_def.body
 
            ),
 
            Definition::Component(comp_def) => (
 
                self.variable_buffer.start_section_initialized(&comp_def.parameters),
 
                comp_def.body
 
            ),
 
            _ => unreachable!(),
 
        } ;
 

	
 
        for idx in 0..param_section.len() {
 
            let var_id = param_section[idx];
 
            let var = &mut ctx.heap[var_id];
 
            var.unique_id_in_scope = var_counter;
 
            var_counter += 1;
 
        }
 

	
 
        param_section.forget();
 

	
 
        // Recurse into body
 
        self.visit_block_and_assign_local_ids(ctx, body_id, var_counter);
 
    }
 

	
 
    fn visit_block_and_assign_local_ids(&mut self, ctx: &mut Ctx, block_id: BlockStatementId, mut var_counter: i32) {
 
        let block_stmt = &mut ctx.heap[block_id];
 
        block_stmt.first_unique_id_in_scope = var_counter;
 

	
 
        let var_section = self.variable_buffer.start_section_initialized(&block_stmt.locals);
 
        let mut scope_section = self.statement_buffer.start_section();
 
        for child_scope in &block_stmt.scope_node.nested {
 
            debug_assert!(child_scope.is_block(), "found a child scope that is not a block statement");
 
            scope_section.push(child_scope.to_block().upcast());
 
        }
 

	
 
        let mut var_idx = 0;
 
        let mut scope_idx = 0;
 
        while var_idx < var_section.len() || scope_idx < scope_section.len() {
src/protocol/tests/parser_inference.rs
Show inline comments
 
@@ -199,293 +199,293 @@ fn test_struct_inference() {
 
        func construct<T1, T2>(T1 l, T2 r) -> Node<T1, T2> {
 
            return Node{ l: l, r: r };
 
        }
 
        func fix_poly<T>(Node<T, T> a) -> s32 { return 0; }
 
        func test() -> s32 {
 
            s8 assigned = 0;
 
            auto thing = construct(assigned, construct(0, 1));
 
            fix_poly(thing.r);
 
            thing.r.r = assigned;
 
            return 0;
 
        }
 
        ",
 
    ).for_function("test", |f| { f
 
        .for_variable("thing", |v| { v
 
            .assert_parser_type("auto")
 
            .assert_concrete_type("Node<s8,Node<s8,s8>>");
 
        });
 
    });
 
}
 

	
 
#[test]
 
fn test_enum_inference() {
 
    Tester::new_single_source_expect_ok(
 
        "no polymorphic vars",
 
        "
 
        enum Choice { A, B }
 
        func test_instances() -> s32 {
 
            auto foo = Choice::A;
 
            auto bar = Choice::B;
 
            return 0;
 
        }
 
        "
 
    ).for_function("test_instances", |f| { f
 
        .for_variable("foo", |v| { v
 
            .assert_parser_type("auto")
 
            .assert_concrete_type("Choice");
 
        })
 
        .for_variable("bar", |v| { v
 
            .assert_parser_type("auto")
 
            .assert_concrete_type("Choice");
 
        });
 
    });
 

	
 
    Tester::new_single_source_expect_ok(
 
        "one polymorphic var",
 
        "
 
        enum Choice<T>{
 
            A,
 
            B,
 
        }
 
        func fix_as_s8(Choice<s8> arg) -> s32 { return 0; }
 
        func fix_as_s32(Choice<s32> arg) -> s32 { return 0; }
 
        func test_instances() -> s32 {
 
            auto choice_s8 = Choice::A;
 
            auto choice_s32_1 = Choice::B;
 
            Choice<auto> choice_s32_2 = Choice::B;
 
            fix_as_s8(choice_s8);
 
            fix_as_s32(choice_s32_1);
 
            return fix_as_s32(choice_s32_2);
 
        }
 
        "
 
    ).for_function("test_instances", |f| { f
 
        .for_variable("choice_s8", |v| { v
 
            .assert_parser_type("auto")
 
            .assert_concrete_type("Choice<s8>");
 
        })
 
        .for_variable("choice_s32_1", |v| { v
 
            .assert_parser_type("auto")
 
            .assert_concrete_type("Choice<s32>");
 
        })
 
        .for_variable("choice_s32_2", |v| { v
 
            .assert_parser_type("Choice<auto>")
 
            .assert_concrete_type("Choice<s32>");
 
        });
 
    });
 

	
 
    Tester::new_single_source_expect_ok(
 
        "two polymorphic vars",
 
        "
 
        enum Choice<T1, T2>{ A, B, }
 
        func fix_t1<T>(Choice<s8, T> arg) -> s32 { return 0; }
 
        func fix_t2<T>(Choice<T, s32> arg) -> s32 { return 0; }
 
        func test_instances() -> s32 {
 
            Choice<s8, auto> choice1 = Choice::A;
 
            Choice<auto, s32> choice2 = Choice::A;
 
            Choice<auto, auto> choice3 = Choice::B;
 
            auto choice4 = Choice::B;
 
            fix_t1(choice1); fix_t1(choice2); fix_t1(choice3); fix_t1(choice4);
 
            fix_t2(choice1); fix_t2(choice2); fix_t2(choice3); fix_t2(choice4);
 
            return 0;
 
        }
 
        "
 
    ).for_function("test_instances", |f| { f
 
        .for_variable("choice1", |v| { v
 
            .assert_parser_type("Choice<s8,auto>")
 
            .assert_concrete_type("Choice<s8,s32>");
 
        })
 
        .for_variable("choice2", |v| { v
 
            .assert_parser_type("Choice<auto,s32>")
 
            .assert_concrete_type("Choice<s8,s32>");
 
        })
 
        .for_variable("choice3", |v| { v
 
            .assert_parser_type("Choice<auto,auto>")
 
            .assert_concrete_type("Choice<s8,s32>");
 
        })
 
        .for_variable("choice4", |v| { v
 
            .assert_parser_type("auto")
 
            .assert_concrete_type("Choice<s8,s32>");
 
        });
 
    });
 
}
 

	
 
#[test]
 
fn test_failed_variable_inference() {
 
    Tester::new_single_source_expect_err(
 
        "variable assignment mismatch",
 
        "
 
        func call() -> u32 {
 
            u16 val16 = 0;
 
            u32 val32 = 0;
 
            auto a = val16;
 
            a = val32;
 
            return 0;
 
        }
 
        "
 
    ).error(|e| { e
 
        .assert_num(2)
 
        .assert_msg_has(0, "type 'u16'")
 
        .assert_msg_has(1, "type 'u32'");
 
    });
 
}
 

	
 
#[test]
 
fn test_failed_polymorph_inference() {
 
    Tester::new_single_source_expect_err(
 
        "function call inference mismatch",
 
        "
 
        func poly<T>(T a, T b) -> s32 { return 0; }
 
        func call() -> s32 {
 
            s8 first_arg = 5;
 
            s64 second_arg = 2;
 
            return poly(first_arg, second_arg);
 
        }
 
        "
 
    ).error(|e| { e
 
        .assert_num(3)
 
        .assert_ctx_has(0, "poly(first_arg, second_arg)")
 
        .assert_occurs_at(0, "poly")
 
        .assert_msg_has(0, "Conflicting type for polymorphic variable 'T'")
 
        .assert_occurs_at(1, "second_arg")
 
        .assert_msg_has(1, "inferred it to 's64'")
 
        .assert_occurs_at(2, "first_arg")
 
        .assert_msg_has(2, "inferred it to 's8'");
 
    });
 

	
 
    Tester::new_single_source_expect_err(
 
        "struct literal inference mismatch",
 
        "
 
        struct Pair<T>{ T first, T second }
 
        func call() -> s32 {
 
            s8 first_arg = 5;
 
            s64 second_arg = 2;
 
            auto pair = Pair{ first: first_arg, second: second_arg };
 
            return 3;
 
        }
 
        "
 
    ).error(|e| { e
 
        .assert_num(3)
 
        .assert_ctx_has(0, "Pair{ first: first_arg, second: second_arg }")
 
        .assert_occurs_at(0, "Pair{")
 
        .assert_msg_has(0, "Conflicting type for polymorphic variable 'T'")
 
        .assert_occurs_at(1, "second_arg")
 
        .assert_msg_has(1, "inferred it to 's64'")
 
        .assert_occurs_at(2, "first_arg")
 
        .assert_msg_has(2, "inferred it to 's8'");
 
    });
 

	
 
    // Cannot really test literal inference error, but this comes close
 
    Tester::new_single_source_expect_err(
 
        "enum literal inference mismatch",
 
        "
 
        enum Uninteresting<T>{ Variant }
 
        func fix_t<T>(Uninteresting<T> arg) -> s32 { return 0; }
 
        func call() -> s32 {
 
            auto a = Uninteresting::Variant;
 
            fix_t<s8>(a);
 
            fix_t<s32>(a);
 
            return 4;
 
        }
 
        "
 
    ).error(|e| { e
 
        .assert_num(2)
 
        .assert_any_msg_has("type 'Uninteresting<s8>'")
 
        .assert_any_msg_has("type 'Uninteresting<s32>'");
 
        .assert_msg_has(0, "type 'Uninteresting<s8>'")
 
        .assert_msg_has(1, "type 'Uninteresting<s32>'");
 
    });
 

	
 
    Tester::new_single_source_expect_err(
 
        "field access inference mismatch",
 
        "
 
        struct Holder<Shazam>{ Shazam a }
 
        func call() -> s32 {
 
            s8 to_hold = 0;
 
            auto holder = Holder{ a: to_hold };
 
            return holder.a;
 
        }
 
        "
 
    ).error(|e| { e
 
        .assert_num(3)
 
        .assert_ctx_has(0, "holder.a")
 
        .assert_occurs_at(0, ".")
 
        .assert_occurs_at(0, "holder.a")
 
        .assert_msg_has(0, "Conflicting type for polymorphic variable 'Shazam'")
 
        .assert_msg_has(1, "inferred it to 's8'")
 
        .assert_msg_has(2, "inferred it to 's32'");
 
    });
 

	
 
    // Silly regression test
 
    Tester::new_single_source_expect_err(
 
        "nested field access inference mismatch",
 
        "
 
        struct Node<T1, T2>{ T1 l, T2 r }
 
        func construct<T1, T2>(T1 l, T2 r) -> Node<T1, T2> { return Node{ l: l, r: r }; }
 
        func fix_poly<T>(Node<T, T> a) -> s32 { return 0; }
 
        func test() -> s32 {
 
            s8 assigned = 0;
 
            s64 another = 1;
 
            auto thing = construct(assigned, construct(another, 1));
 
            fix_poly(thing.r);
 
            thing.r.r = assigned;
 
            return 0;
 
        }
 
        ",
 
    );
 
}
 

	
 

	
 
#[test]
 
fn test_explicit_polymorph_argument() {
 
    // Failed because array was put at same type depth as u32. So interpreted
 
    // as a function with two polymorphic arguments
 
    Tester::new_single_source_expect_ok("explicit with array", "
 
    func foo<T>(T a, T b) -> T {
 
        return a @ b;
 
    }
 
    func test() -> u32 {
 
        return foo<u32[]>({1}, {2})[1];
 
    }").for_function("test", |f| { f
 
        .call_ok(Some(Value::UInt32(2)));
 
    });
 

	
 
    Tester::new_single_source_expect_err("multi-explicit with array", "
 
    func foo<A, B, C>(A a, B b) -> C {
 
        return (a @ b)[1];
 
    }
 
    func test() -> u32 {
 
        return foo<u32[], u32[], u32, u32>({1}, {2});
 
    }").error(|e| { e
 
        .assert_num(1)
 
        .assert_occurs_at(0, "foo<u32")
 
        .assert_msg_has(0, "expected 3")
 
        .assert_msg_has(0, "4 were provided");
 
    });
 

	
 
    // Failed because type inferencer did not construct polymorph errors by
 
    // considering that argument/return types failed against explicitly
 
    // specified polymorphic arguments
 
    Tester::new_single_source_expect_err("explicit polymorph mismatch", "
 
    func foo<T>(T a, T b) -> T { return a + b; }
 
    struct Bar<A, B>{A a, B b}
 
    func test() -> u32 {
 
        return foo<Bar<u32, u64>[]>(5, 6);
 
    }").error(|e| { e
 
        .assert_num(2)
 
        .assert_occurs_at(0, "foo<Bar")
 
        .assert_msg_has(0, "'T' of 'foo'")
 
        .assert_occurs_at(1, "5, ")
 
        .assert_msg_has(1, "has type 'Bar<u32, u64>[]")
 
        .assert_msg_has(1, "inferred it to 'integerlike'");
 
    });
 

	
 
    // Similar to above, now for return type
 
    Tester::new_single_source_expect_err("explicit polymorph mismatch", "
 
    func foo<T>(T a, T b) -> T { return a + b; }
 
    func test() -> u32 {
 
        return foo<u64>(5, 6);
 
    }").error(|e| { e
 
        .assert_num(2)
 
        .assert_occurs_at(0, "foo<u64")
 
        .assert_msg_has(0, "'T' of 'foo'")
 
        .assert_occurs_at(1, "foo<u64")
 
        .assert_msg_has(1, "has type 'u64'")
 
        .assert_msg_has(1, "return type inferred it to 'u32'");
 
    });
 
}
 
\ No newline at end of file

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