From e16722f0d0acc77d8aaa9a59339056b63ff84c03 2020-02-10 15:48:57
From: Hans-Dieter Hiep <hdh@cwi.nl>
Date: 2020-02-10 15:48:57
Subject: [PATCH] Lift parser restriction on assignable expressions

---

diff --git a/src/protocol/parser.rs b/src/protocol/parser.rs
index da7f78c16934df9f13e2bce24528a3e1459a8502..ab1611acf6699235c4208c300f26d606283ddeb7 100644
--- a/src/protocol/parser.rs
+++ b/src/protocol/parser.rs
@@ -1575,9 +1575,7 @@ struct IndexableExpressions {
 }
 
 impl IndexableExpressions {
-    fn new() -> Self {
-        IndexableExpressions { indexable: false }
-    }
+    fn new() -> Self {  IndexableExpressions { indexable: false }  }
     fn error(&self, position: InputPosition) -> VisitorResult {
         Err(ParseError::new(position, "Unindexable expression"))
     }
@@ -1627,10 +1625,12 @@ impl Visitor for IndexableExpressions {
         expr: IndexingExpressionId,
     ) -> VisitorResult {
         let old = self.indexable;
-        self.indexable = false;
+        self.indexable = true;
         self.visit_expression(h, h[expr].subject)?;
+        self.indexable = false;
+        self.visit_expression(h, h[expr].index)?;
         self.indexable = old;
-        self.visit_expression(h, h[expr].index)
+        Ok(())
     }
     fn visit_slicing_expression(
         &mut self,
diff --git a/testdata/parser/negative/20.txt b/testdata/parser/negative/20.txt
deleted file mode 100644
index 41f6d4d1d7e99f9f2719619dab57624c85068f43..0000000000000000000000000000000000000000
--- a/testdata/parser/negative/20.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-Parse error at 20.pdl:6:10: Unindexable expression
-	x[1] = x[1][0:1];
-	        ^
diff --git a/testdata/parser/negative/20.pdl b/testdata/parser/positive/20.pdl
similarity index 100%
rename from testdata/parser/negative/20.pdl
rename to testdata/parser/positive/20.pdl