[cfe] Allow local const variables as annotations.

Fixes dart-lang/sdk#37065

Change-Id: If902bd22fc6e0925c361a31e22b32d046ea4754e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103628
Commit-Queue: Aske Simon Christensen <[email protected]>
Reviewed-by: Lasse R.H. Nielsen <[email protected]>

Author: askeksa

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -509,7 +509,8 @@ abstract class BodyBuilder extends ScopeListener<JumpTarget>
       }
 
       ConstantContext savedConstantContext = pop();
-      if (expression is! StaticAccessGenerator) {
+      if (expression is! StaticAccessGenerator &&
+          expression is! VariableUseGenerator) {
         push(wrapInProblem(
             toValue(expression), fasta.messageExpressionNotMetadata, noLength));
       } else {

tests/language_2/local_var_in_annotation_test.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test for https://github.com/dart-lang/sdk/issues/37065
+
+const x = 0;
+main(@x args) {
+  const z = 0;
+  foo(@z args) {}
+  bar(@x args) {}
+}