Test that ! on void is a compile time error

Change-Id: Ia2a43dca23df6d332bd5baa63af7cb68c94ac612
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108762
Auto-Submit: Mike Fairhurst <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Mike Fairhurst <[email protected]>

Author: MichaelRFairhurst

pkg/analyzer/lib/src/generated/error_verifier.dart

@@ -1146,6 +1146,8 @@ class ErrorVerifier extends RecursiveAstVisitor<void> {
       _checkForAssignmentToFinal(node.operand);
       _checkForIntNotAssignable(node.operand);
       _checkForNullableDereference(node.operand);
+    } else {
+      _checkForUseOfVoidResult(node);
     }
     super.visitPostfixExpression(node);
   }

pkg/analyzer/test/src/diagnostics/use_of_void_result_test.dart

@@ -2,13 +2,18 @@
 // 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.
 
+import 'package:analyzer/src/dart/analysis/experiments.dart';
+import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/generated/engine.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
+import '../../generated/test_support.dart';
 import '../dart/resolution/driver_resolution.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseOfVoidResultTest);
+    defineReflectiveTests(UseOfVoidResultTest_NonNullable);
   });
 }
 
@@ -34,3 +39,28 @@ g() {
 ''');
   }
 }
+
+@reflectiveTest
+class UseOfVoidResultTest_NonNullable extends DriverResolutionTest {
+  @override
+  AnalysisOptionsImpl get analysisOptions =>
+      AnalysisOptionsImpl()..enabledExperiments = [EnableString.non_nullable];
+
+  test_bang_nonVoid() async {
+    await assertNoErrorsInCode(r'''
+int? f() => 1;
+g() {
+  f()!;
+}
+''');
+  }
+
+  test_bang_void() async {
+    await assertErrorsInCode(r'''
+void f() => 1;
+g() {
+  f()!;
+}
+''', [ExpectedError(StaticWarningCode.USE_OF_VOID_RESULT, 23, 4)]);
+  }
+}

tests/language_2/nnbd/static_errors/bang_test.dart

@@ -0,0 +1,9 @@
+// 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.
+
+// SharedOptions=--enable-experiment=non-nullable
+void main() {
+  void x;
+  x!; //# 00: compile-time error
+}