CSY/reowolf Changeset - 07b6378685f2 · Centrum Wiskunde & Informatica (CWI)

Changeset - 07b6378685f2

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MH - 4 years ago 2021-11-12 20:02:26
contact@maxhenger.nl

Add forking to the AST walker

4 files changed with 48 insertions and 1 deletions:

src/protocol/ast.rs

src/protocol/eval/executor.rs

src/protocol/mod.rs

src/protocol/parser/pass_validation_linking.rs

0 comments (0 inline, 0 general)

src/protocol/ast.rs

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Show inline comments

@@ @@ -1256,97 +1256,97 @@ pub struct EndWhileStatement { @@
 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,
     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 ForkStatement {
     pub this: ForkStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "fork" keyword
     pub left_body: BlockStatementId,
     pub right_body: Option<BlockStatementId>,
     pub end_fork: EndForkStatementId,
+}
 #[derive(Debug, Clone)]
 pub struct EndForkStatement {
-    pub this: EndForKStatementId,
+    pub this: EndForkStatementId,
     pub start_fork: ForkStatementId,
     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),

src/protocol/eval/executor.rs

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Show inline comments

@@ @@ -155,96 +155,97 @@ impl Frame { @@
                                     _num_pushed += 1;
                                     self.expr_stack.push_back(ExprInstruction::PushValToFront);
                                     self.serialize_expression(heap, field.value);
+                                }
+                            }
+                        }
                         debug_assert_eq!(_num_pushed, literal.fields.len())
                     },
                     Literal::Union(literal) => {
                         for value_expr_id in &literal.values {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
                     },
                     Literal::Array(value_expr_ids) => {
                         for value_expr_id in value_expr_ids {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
+                    }
+                }
             },
             Expression::Cast(expr) => {
                 self.serialize_expression(heap, expr.subject);
+            }
             Expression::Call(expr) => {
                 for arg_expr_id in &expr.arguments {
                     self.expr_stack.push_back(ExprInstruction::PushValToFront);
                     self.serialize_expression(heap, *arg_expr_id);
+                }
             },
             Expression::Variable(_expr) => {
                 // No subexpressions
+            }
+        }
+    }
+}
 type EvalResult = Result<EvalContinuation, EvalError>;
 pub enum EvalContinuation {
     Stepping,
     Inconsistent,
     Terminal,
     SyncBlockStart,
     SyncBlockEnd,
     NewComponent(DefinitionId, i32, ValueGroup),
     NewChannel,
     NewFork,
     BlockFires(PortId),
     BlockGet(PortId),
     Put(PortId, Value),
+}
 // Note: cloning is fine, methinks. cloning all values and the heap regions then
 // we end up with valid "pointers" to heap regions.
 #[derive(Debug, Clone)]
 pub struct Prompt {
     pub(crate) frames: Vec<Frame>,
     pub(crate) store: Store,
+}
 impl Prompt {
     pub fn new(_types: &TypeTable, heap: &Heap, def: DefinitionId, monomorph_idx: i32, args: ValueGroup) -> Self {
         let mut prompt = Self{
             frames: Vec::new(),
             store: Store::new(),
         };
         // Maybe do typechecking in the future?
         debug_assert!((monomorph_idx as usize) < _types.get_base_definition(&def).unwrap().definition.procedure_monomorphs().len());
         let new_frame = Frame::new(heap, def, monomorph_idx);
         let max_stack_size = new_frame.max_stack_size;
         prompt.frames.push(new_frame);
         args.into_store(&mut prompt.store);
         prompt.store.reserve_stack(max_stack_size);
         prompt
+    }
     /// Big 'ol function right here. Didn't want to break it up unnecessarily.
     /// It consists of, in sequence: executing any expressions that should be
     /// executed before the next statement can be evaluated, then a section that
     /// performs debug printing, and finally a section that takes the next
     /// statement and executes it. If the statement requires any expressions to
     /// be evaluated, then they will be added such that the next time `step` is
     /// called, all of these expressions are indeed evaluated.
     pub(crate) fn step(&mut self, types: &TypeTable, heap: &Heap, modules: &[Module], ctx: &mut impl RunContext) -> EvalResult {
         // Helper function to transfer multiple values from the expression value
         // array into a heap region (e.g. constructing arrays or structs).
         fn transfer_expression_values_front_into_heap(cur_frame: &mut Frame, store: &mut Store, num_values: usize) -> HeapPos {
             let heap_pos = store.alloc_heap();
             // Do the transformation first (because Rust...)
             for val_idx in 0..num_values {
                 cur_frame.expr_values[val_idx] = store.read_take_ownership(cur_frame.expr_values[val_idx].clone());
+            }
@@ @@ -841,96 +842,123 @@ impl Prompt { @@
                 } else {
                     // Not true, and no false body
                     cur_frame.position = stmt.end_if.upcast();
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndIf(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::While(stmt) => {
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for while 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.body.upcast();
                 } else {
                     cur_frame.position = stmt.end_while.upcast();
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndWhile(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Break(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Continue(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Synchronous(stmt) => {
                 cur_frame.position = stmt.body.upcast();
                 Ok(EvalContinuation::SyncBlockStart)
             },
             Statement::EndSynchronous(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::SyncBlockEnd)
             },
             Statement::Fork(stmt) => {
                 if stmt.right_body.is_none() {
                     // No reason to fork
                     cur_frame.position = stmt.left_body.upcast();
                 } else {
                     // Need to fork
                     if let Some(go_left) = ctx.get_fork() {
                         // Runtime has created a fork
                         if go_left {
                             cur_frame.position = stmt.left_body.upcast();
                         } else {
                             cur_frame.position = stmt.right_body.unwrap().upcast();
+                        }
                     } else {
                         // Request the runtime to create a fork of the current
                         // branch
                         return Ok(EvalContinuation::NewFork);
+                    }
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndFork(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
+            }
             Statement::Return(_stmt) => {
                 debug_assert!(heap[cur_frame.definition].is_function());
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for return statement");
                 // The preceding frame has executed a call, so is expecting the
                 // return expression on its expression value stack. Note that
                 // we may be returning a reference to something on our stack,
                 // so we need to read that value and clone it.
                 let return_value = cur_frame.expr_values.pop_back().unwrap();
                 let return_value = match return_value {
                     Value::Ref(value_id) => self.store.read_copy(value_id),
                     _ => return_value,
                 };
                 // Pre-emptively pop our stack frame
                 self.frames.pop();
                 // Clean up our section of the stack
                 self.store.clear_stack(0);
                 self.store.stack.truncate(self.store.cur_stack_boundary + 1);
                 let prev_stack_idx = self.store.stack.pop().unwrap().as_stack_boundary();
                 // TODO: Temporary hack for testing, remove at some point
                 if self.frames.is_empty() {
                     debug_assert!(prev_stack_idx == -1);
                     debug_assert!(self.store.stack.len() == 0);
                     self.store.stack.push(return_value);
                     return Ok(EvalContinuation::Terminal);
+                }
                 debug_assert!(prev_stack_idx >= 0);
                 // Return to original state of stack frame
                 self.store.cur_stack_boundary = prev_stack_idx as usize;
                 let cur_frame = self.frames.last_mut().unwrap();
                 cur_frame.expr_values.push_back(return_value);
                 // We just returned to the previous frame, which might be in
                 // the middle of evaluating expressions for a particular
                 // statement. So we don't want to enter the code below.
                 return Ok(EvalContinuation::Stepping);
             },
             Statement::Goto(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::New(stmt) => {
                 let call_expr = &heap[stmt.expression];

src/protocol/mod.rs

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Show inline comments

@@ @@ -242,333 +242,344 @@ impl ProtocolDescription { @@
             CTP::UInt64 => if let Value::UInt64(_) = argument { true } else { false },
             CTP::SInt8 => if let Value::SInt8(_) = argument { true } else { false },
             CTP::SInt16 => if let Value::SInt16(_) = argument { true } else { false },
             CTP::SInt32 => if let Value::SInt32(_) = argument { true } else { false },
             CTP::SInt64 => if let Value::SInt64(_) = argument { true } else { false },
             CTP::Character => if let Value::Char(_) = argument { true } else { false },
             CTP::String => {
                 // Match outer string type and embedded character types
                 if let Value::String(heap_pos) = argument {
                     for element in &arguments.regions[*heap_pos as usize] {
                         if let Value::Char(_) = element {} else {
                             return false;
+                        }
+                    }
                 } else {
                     return false;
+                }
                 return true;
             },
             CTP::Array => {
                 if let Value::Array(heap_pos) = argument {
                     let heap_pos = *heap_pos;
                     for element in &arguments.regions[heap_pos as usize] {
                         if !self.verify_same_type(expected, expected_idx + 1, arguments, element) {
                             return false;
+                        }
+                    }
                     return true;
                 } else {
                     return false;
+                }
             },
             CTP::Input => if let Value::Input(_) = argument { true } else { false },
             CTP::Output => if let Value::Output(_) = argument { true } else { false },
             CTP::Instance(_definition_id, _num_embedded) => {
                 todo!("implement full type checking on user-supplied arguments");
                 return false;
             },
+        }
+    }
+}
 // TODO: @temp Should just become a concrete thing that is passed in
 pub trait RunContext {
     fn did_put(&mut self, port: PortId) -> bool;
     fn get(&mut self, port: PortId) -> Option<ValueGroup>; // None if still waiting on message
     fn fires(&mut self, port: PortId) -> Option<Value>; // None if not yet branched
     fn get_fork(&mut self) -> Option<bool>; // None if not yet forked
     fn get_channel(&mut self) -> Option<(Value, Value)>; // None if not yet prepared
+}
 #[derive(Debug)]
 pub enum RunResult {
     // Can only occur outside sync blocks
     ComponentTerminated, // component has exited its procedure
     ComponentAtSyncStart,
     NewComponent(DefinitionId, i32, ValueGroup), // should also be possible inside sync
     NewChannel, // should also be possible inside sync
     // Can only occur inside sync blocks
     BranchInconsistent, // branch has inconsistent behaviour
     BranchMissingPortState(PortId), // branch doesn't know about port firing
     BranchMissingPortValue(PortId), // branch hasn't received message on input port yet
     BranchAtSyncEnd,
     BranchFork,
     BranchPut(PortId, ValueGroup),
+}
 impl ComponentState {
     pub(crate) fn run(&mut self, ctx: &mut impl RunContext, pd: &ProtocolDescription) -> RunResult {
         use EvalContinuation as EC;
         use RunResult as RR;
         loop {
             let step_result = self.prompt.step(&pd.types, &pd.heap, &pd.modules, ctx);
             match step_result {
                 Err(reason) => {
                     // TODO: @temp
                     println!("Evaluation error:\n{}", reason);
                     todo!("proper error handling/bubbling up");
                 },
                 Ok(continuation) => match continuation {
                     // TODO: Probably want to remove this translation
                     EC::Stepping => continue,
                     EC::Inconsistent => return RR::BranchInconsistent,
                     EC::Terminal => return RR::ComponentTerminated,
                     EC::SyncBlockStart => return RR::ComponentAtSyncStart,
                     EC::SyncBlockEnd => return RR::BranchAtSyncEnd,
                     EC::NewComponent(definition_id, monomorph_idx, args) =>
                         return RR::NewComponent(definition_id, monomorph_idx, args),
                     EC::NewChannel =>
                         return RR::NewChannel,
                     EC::NewFork =>
                         return RR::BranchFork,
                     EC::BlockFires(port_id) => return RR::BranchMissingPortState(port_id),
                     EC::BlockGet(port_id) => return RR::BranchMissingPortValue(port_id),
                     EC::Put(port_id, value) => {
                         let value_group = ValueGroup::from_store(&self.prompt.store, &[value]);
                         return RR::BranchPut(port_id, value_group);
                     },
+                }
+            }
+        }
+    }
+}
 // TODO: @remove the old stuff
 impl ComponentState {
     pub(crate) fn nonsync_run<'a: 'b, 'b>(
         &'a mut self,
         context: &'b mut NonsyncProtoContext<'b>,
         pd: &'a ProtocolDescription,
     ) -> NonsyncBlocker {
         let mut context = EvalContext::Nonsync(context);
         loop {
             let result = self.prompt.step(&pd.types, &pd.heap, &pd.modules, &mut context);
             match result {
                 Err(err) => {
                     println!("Evaluation error:\n{}", err);
                     panic!("proper error handling when component fails");
                 },
                 Ok(cont) => match cont {
                     EvalContinuation::Stepping => continue,
                     EvalContinuation::Inconsistent => return NonsyncBlocker::Inconsistent,
                     EvalContinuation::Terminal => return NonsyncBlocker::ComponentExit,
                     EvalContinuation::SyncBlockStart => return NonsyncBlocker::SyncBlockStart,
                     // Not possible to end sync block if never entered one
                     EvalContinuation::SyncBlockEnd => unreachable!(),
                     EvalContinuation::NewComponent(definition_id, monomorph_idx, args) => {
                         // Look up definition (TODO for now, assume it is a definition)
                         let mut moved_ports = HashSet::new();
                         for arg in args.values.iter() {
                             match arg {
                                 Value::Output(port) => {
                                     moved_ports.insert(*port);
+                                }
                                 Value::Input(port) => {
                                     moved_ports.insert(*port);
+                                }
                                 _ => {}
+                            }
+                        }
                         for region in args.regions.iter() {
                             for arg in region {
                                 match arg {
                                     Value::Output(port) => { moved_ports.insert(*port); },
                                     Value::Input(port) => { moved_ports.insert(*port); },
                                     _ => {},
+                                }
+                            }
+                        }
                         let init_state = ComponentState { prompt: Prompt::new(&pd.types, &pd.heap, definition_id, monomorph_idx, args) };
                         context.new_component(moved_ports, init_state);
                         // Continue stepping
                         continue;
                     },
                     EvalContinuation::NewChannel => {
                         // Because of the way we emulate the old context for now, we can safely
                         // assume that this will never happen. The old context thingamajig always
                         // creates a channel, it never bubbles a "need to create a channel" message
                         // to the runtime
                         unreachable!();
                     },
                     EvalContinuation::NewFork => unreachable!(),
                     // Outside synchronous blocks, no fires/get/put happens
                     EvalContinuation::BlockFires(_) => unreachable!(),
                     EvalContinuation::BlockGet(_) => unreachable!(),
                     EvalContinuation::Put(_, _) => unreachable!(),
                 },
+            }
+        }
+    }
     pub(crate) fn sync_run<'a: 'b, 'b>(
         &'a mut self,
         context: &'b mut SyncProtoContext<'b>,
         pd: &'a ProtocolDescription,
     ) -> SyncBlocker {
         let mut context = EvalContext::Sync(context);
         loop {
             let result = self.prompt.step(&pd.types, &pd.heap, &pd.modules, &mut context);
             match result {
                 Err(err) => {
                     println!("Evaluation error:\n{}", err);
                     panic!("proper error handling when component fails");
                 },
                 Ok(cont) => match cont {
                     EvalContinuation::Stepping => continue,
                     EvalContinuation::Inconsistent => return SyncBlocker::Inconsistent,
                     // First need to exit synchronous block before definition may end
                     EvalContinuation::Terminal => unreachable!(),
                     // No nested synchronous blocks
                     EvalContinuation::SyncBlockStart => unreachable!(),
                     EvalContinuation::SyncBlockEnd => return SyncBlocker::SyncBlockEnd,
                     // Not possible to create component in sync block
                     EvalContinuation::NewComponent(_, _, _) => unreachable!(),
                     EvalContinuation::NewChannel => unreachable!(),
                     EvalContinuation::NewFork => unreachable!(),
                     EvalContinuation::BlockFires(port) => {
                         return SyncBlocker::CouldntCheckFiring(port);
                     },
                     EvalContinuation::BlockGet(port) => {
                         return SyncBlocker::CouldntReadMsg(port);
                     },
                     EvalContinuation::Put(port, message) => {
                         let payload;
                         match message {
                             Value::Null => {
                                 return SyncBlocker::Inconsistent;
                             },
                             Value::Message(heap_pos) => {
                                 // Create a copy of the payload
                                 let values = &self.prompt.store.heap_regions[heap_pos as usize].values;
                                 let mut bytes = Vec::with_capacity(values.len());
                                 for value in values {
                                     bytes.push(value.as_uint8());
+                                }
                                 payload = Payload(Arc::new(bytes));
+                            }
                             _ => unreachable!(),
+                        }
                         return SyncBlocker::PutMsg(port, payload);
+                    }
                 },
+            }
+        }
+    }
+}
 impl RunContext for EvalContext<'_> {
     fn did_put(&mut self, port: PortId) -> bool {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(_) => unreachable!(),
             EvalContext::Sync(ctx) => {
                 ctx.did_put_or_get(port)
+            }
+        }
+    }
     fn get(&mut self, port: PortId) -> Option<ValueGroup> {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(_) => unreachable!(),
             EvalContext::Sync(ctx) => {
                 let payload = ctx.read_msg(port);
                 if payload.is_none() {
                     return None;
+                }
                 let payload = payload.unwrap();
                 let mut transformed = Vec::with_capacity(payload.len());
                 for byte in payload.0.iter() {
                     transformed.push(Value::UInt8(*byte));
+                }
                 let value_group = ValueGroup{
                     values: vec![Value::Message(0)],
                     regions: vec![transformed],
                 };
                 return Some(value_group);
+            }
+        }
+    }
     fn fires(&mut self, port: PortId) -> Option<Value> {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(_) => unreachable!(),
             EvalContext::Sync(context) => {
                 match context.is_firing(port) {
                     Some(did_fire) => Some(Value::Bool(did_fire)),
                     None => None,
+                }
+            }
+        }
+    }
     fn get_channel(&mut self) -> Option<(Value, Value)> {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(context) => {
                 let [from, to] = context.new_port_pair();
                 let from = Value::Output(from);
                 let to = Value::Input(to);
                 return Some((from, to));
             },
             EvalContext::Sync(_) => unreachable!(),
+        }
+    }
     fn get_fork(&mut self) -> Option<bool> {
         // Never actually used in the old runtime
         return None;
+    }
+}
 // TODO: @remove once old runtime has disappeared
 impl EvalContext<'_> {
     // fn random(&mut self) -> LongValue {
     //     match self {
     //         // EvalContext::None => unreachable!(),
     //         EvalContext::Nonsync(_context) => todo!(),
     //         EvalContext::Sync(_) => unreachable!(),
     //     }
     // }
     fn new_component(&mut self, moved_ports: HashSet<PortId>, init_state: ComponentState) -> () {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(context) => {
                 context.new_component(moved_ports, init_state)
+            }
             EvalContext::Sync(_) => unreachable!(),
+        }
+    }
     fn new_channel(&mut self) -> [Value; 2] {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(context) => {
                 let [from, to] = context.new_port_pair();
                 let from = Value::Output(from);
                 let to = Value::Input(to);
                 return [from, to];
+            }
             EvalContext::Sync(_) => unreachable!(),
+        }
+    }
     fn fires(&mut self, port: Value) -> Option<Value> {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(_) => unreachable!(),
             EvalContext::Sync(context) => match port {
                 Value::Output(port) => context.is_firing(port).map(Value::Bool),
                 Value::Input(port) => context.is_firing(port).map(Value::Bool),
                 _ => unreachable!(),
             },
+        }
+    }
     fn get(&mut self, port: Value, store: &mut Store) -> Option<Value> {
         match self {
             EvalContext::None => unreachable!(),
             EvalContext::Nonsync(_) => unreachable!(),
             EvalContext::Sync(context) => match port {

src/protocol/parser/pass_validation_linking.rs

➞

Show inline comments

@@ @@ -369,96 +369,104 @@ impl Visitor for PassValidationLinking { @@
         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_fork_stmt(&mut self, ctx: &mut Ctx, id: ForkStatementId) -> VisitorResult {
         let fork_stmt = &ctx.heap[id];
         let end_fork_id = fork_stmt.end_fork;
         let left_body_id = fork_stmt.left_body;
         let right_body_id = fork_stmt.right_body;
         // Fork statements may only occur inside sync blocks
         if self.in_sync.is_invalid() {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, fork_stmt.span,
                 "Forking may only occur inside sync blocks"
             ));
+        }
         // Visit the respective bodies. Like the if statement, a fork statement
         // does not have a single static subsequent statement. It forks and then
         // each fork has a different next statement.
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         self.visit_block_stmt(ctx, left_body_id)?;
         assign_then_erase_next_stmt!(self, ctx, end_fork_id.upcast());
         if let Some(right_body_id) = right_body_id {
             self.visit_block_stmt(ctx, right_body_id)?;
             assign_then_erase_next_stmt!(self, ctx, end_fork_id.upcast());
+        }
         self.prev_stmt = end_fork_id.upcast();
         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];

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