Don't crash on doc comments inside local variable declarations. (#1623)

Fix #1621.

Author: munificent

CHANGELOG.md

@@ -6,6 +6,7 @@
 * Ensure comment formatting is idempotent (#1606).
 * Better indentation of leading comments on property accesses in binary operator
   operands (#1611).
+* Don't crash on doc comments in local variable declarations (#1621).
 
 ## 3.0.0
 

lib/src/ast_extensions.dart

@@ -31,14 +31,18 @@ extension AstNodeExtensions on AstNode {
       AnnotatedNode(metadata: [var annotation, ...]) => annotation.beginToken,
       AnnotatedNode(firstTokenAfterCommentAndMetadata: var token) => token,
 
-      // DefaultFormalParameter is not an AnnotatedNode, but its first child
-      // (parameter) *is* an AnnotatedNode, so we can't just use beginToken.
+      // The inner [NormalFormalParameter] is an [AnnotatedNode].
       DefaultFormalParameter(:var parameter) => parameter.firstNonCommentToken,
 
-      // A pattern variable statement isn't itself an AnnotatedNode, but the
-      // [PatternVariableDeclaration] that it wraps is.
+      // The inner [PatternVariableDeclaration] is an [AnnotatedNode].
       PatternVariableDeclarationStatement(:var declaration) =>
         declaration.firstNonCommentToken,
+
+      // The inner [VariableDeclarationList] is an [AnnotatedNode].
+      VariableDeclarationStatement(:var variables) =>
+        variables.firstNonCommentToken,
+
+      // Otherwise, we don't have to worry about doc comments.
       _ => beginToken
     };
   }

test/tall/regression/1600/1621.unit

@@ -0,0 +1,24 @@
+>>>
+/*member: readLocalInAnonymousClosure:*/
+readLocalInAnonymousClosure(/**/ parameter) {
+  var /**/ local = parameter;
+  return /*fields=[local],free=[local]*/ () => local;
+}
+<<<
+/*member: readLocalInAnonymousClosure:*/
+readLocalInAnonymousClosure(/**/ parameter) {
+  var /**/ local = parameter;
+  return /*fields=[local],free=[local]*/ () => local;
+}
+>>>
+class C {
+  @override
+  // ignore: overridden_fields
+  final FunctionEntity _member;
+}
+<<<
+class C {
+  @override
+  // ignore: overridden_fields
+  final FunctionEntity _member;
+}