[DAS] Fixes void completion on for in iterable position

Bug: #61134
Change-Id: I5ce02226f705e5bce5148494d81435c9eb96aad4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/443631
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Auto-Submit: Felipe Morschel <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: FMorschel

pkg/analysis_server/lib/src/services/completion/dart/in_scope_completion_pass.dart

@@ -4153,6 +4153,7 @@ class InScopeCompletionPass extends SimpleAstVisitor<void> {
       keywordHelper.addKeyword(Keyword.AWAIT);
       declarationHelper(
         mustBeStatic: node.inStaticContext,
+        mustBeNonVoid: true,
       ).addLexicalDeclarations(node);
     }
   }

pkg/analysis_server/test/services/completion/dart/location/for_statement_test.dart

@@ -46,8 +46,8 @@ suggestions
 
   Future<void> test_afterIn() async {
     await computeSuggestions('''
-void f(List<(int, int)> x01) {
-  for (final (a, b) in ^)
+void f(List<int> x01) {
+  for (final a in ^)
 }
 ''');
     assertResponse(r'''
@@ -59,6 +59,23 @@ suggestions
 ''');
   }
 
+  Future<void> test_afterIn_notVoid() async {
+    await computeSuggestions('''
+void f(List<int> x01) {
+  for (final a in ^)
+}
+
+void f01() {}
+''');
+    assertResponse(r'''
+suggestions
+  x01
+    kind: parameter
+  await
+    kind: keyword
+''');
+  }
+
   Future<void> test_afterPattern() async {
     await computeSuggestions('''
 void f(Object x) {