Report ILLEGAL_LANGUAGE_VERSION_OVERRIDE even when the package language version causes it.

Change-Id: I617d67ba06758e3f57d9ff0048a080d0a699fc96
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/232126
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -2745,21 +2745,26 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
       return;
     }
 
-    var languageVersionToken = node.languageVersionToken;
-    if (languageVersionToken == null) {
-      return;
-    }
-
     var languageVersion = _currentLibrary.languageVersion.effective;
     if (sourceLanguageConstraint.allows(languageVersion)) {
       return;
     }
 
-    errorReporter.reportErrorForToken(
-      CompileTimeErrorCode.ILLEGAL_LANGUAGE_VERSION_OVERRIDE,
-      languageVersionToken,
-      ['$sourceLanguageConstraint'],
-    );
+    var languageVersionToken = node.languageVersionToken;
+    if (languageVersionToken != null) {
+      errorReporter.reportErrorForToken(
+        CompileTimeErrorCode.ILLEGAL_LANGUAGE_VERSION_OVERRIDE,
+        languageVersionToken,
+        ['$sourceLanguageConstraint'],
+      );
+    } else {
+      errorReporter.reportErrorForOffset(
+        CompileTimeErrorCode.ILLEGAL_LANGUAGE_VERSION_OVERRIDE,
+        0,
+        0,
+        ['$sourceLanguageConstraint'],
+      );
+    }
   }
 
   /// Verify that the given implements [clause] does not implement classes such

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

@@ -40,6 +40,31 @@ int a = null;
     ]);
   }
 
+  test_hasPackageLanguage_less_hasOverride_greater() async {
+    writeTestPackageConfig(
+      PackageConfigFileBuilder(),
+      languageVersion: '2.9',
+    );
+
+    await assertNoErrorsInCode(r'''
+// @dart = 2.12
+void f() {}
+''');
+  }
+
+  test_hasPackageLanguage_less_noOverride_less() async {
+    writeTestPackageConfig(
+      PackageConfigFileBuilder(),
+      languageVersion: '2.9',
+    );
+
+    await assertErrorsInCode(r'''
+void f() {}
+''', [
+      error(CompileTimeErrorCode.ILLEGAL_LANGUAGE_VERSION_OVERRIDE, 0, 0),
+    ]);
+  }
+
   test_noOverride() async {
     await assertNoErrorsInCode(r'''
 void f() {}