Update the way to get feature set and language version.

#42274
#42321

Change-Id: I5551ecd2803f9d26e720e5cf5671b3be8236bce9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/151423
Reviewed-by: Brian Wilkerson <[email protected]>

Author: scheglov

pkg/analyzer/lib/error/error.dart

@@ -390,6 +390,7 @@ const List<ErrorCode> errorCodeValues = [
   HintCode.INVALID_IMMUTABLE_ANNOTATION,
   HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_AT_SIGN,
   HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_EQUALS,
+  HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_GREATER,
   HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_LOCATION,
   HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_LOWER_CASE,
   HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_NUMBER,

pkg/analyzer/lib/src/dart/analysis/feature_set_provider.dart

@@ -31,7 +31,7 @@ class FeatureSetProvider {
         _packageDefaultFeatureSet = packageDefaultFeatureSet,
         _nonPackageDefaultFeatureSet = nonPackageDefaultFeatureSet;
 
-  /// Return the [FeatureSet] for the Dart file with the given [uri].
+  /// Return the [FeatureSet] for the package that contains the file.
   FeatureSet getFeatureSet(String path, Uri uri) {
     if (uri.isScheme('dart')) {
       var pathSegments = uri.pathSegments;
@@ -57,15 +57,16 @@ class FeatureSetProvider {
 
     var package = _packages.packageForPath(path);
     if (package != null) {
-      var languageVersion = package.languageVersion;
-      languageVersion ??= ExperimentStatus.currentVersion;
-      return _packageDefaultFeatureSet.restrictToVersion(languageVersion);
+      return _packageDefaultFeatureSet;
     }
 
     return _nonPackageDefaultFeatureSet;
   }
 
-  /// Return the language version configured for the file.
+  /// Return the language version for the package that contains the file.
+  ///
+  /// Each individual file might use `// @dart` to override this version, to
+  /// be either lower, or higher than the package language version.
   Version getLanguageVersion(String path, Uri uri) {
     var package = _packages.packageForPath(path);
     if (package != null) {

pkg/analyzer/lib/src/dart/analysis/file_state.dart

@@ -12,10 +12,12 @@ import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
 import 'package:analyzer/dart/ast/token.dart';
+import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/byte_store.dart';
 import 'package:analyzer/src/dart/analysis/defined_names.dart';
+import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/dart/analysis/feature_set_provider.dart';
 import 'package:analyzer/src/dart/analysis/library_graph.dart';
 import 'package:analyzer/src/dart/analysis/performance_logger.dart';
@@ -24,6 +26,7 @@ import 'package:analyzer/src/dart/analysis/unlinked_api_signature.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/source.dart';
@@ -37,6 +40,7 @@ import 'package:analyzer/src/summary2/informative_data.dart';
 import 'package:convert/convert.dart';
 import 'package:crypto/crypto.dart';
 import 'package:meta/meta.dart';
+import 'package:pub_semver/pub_semver.dart';
 
 var counterFileStateRefresh = 0;
 var counterUnlinkedLinkedBytes = 0;
@@ -567,6 +571,36 @@ class FileState {
     return _fsState.getFileForUri(absoluteUri);
   }
 
+  /// Return the language version specified in the [versionToken], or the
+  /// language version from the [FeatureSetProvider].
+  Version _getLanguageVersion(
+    LanguageVersionToken versionToken,
+    AnalysisErrorListener errorListener,
+  ) {
+    if (versionToken != null) {
+      var latestVersion = ExperimentStatus.currentVersion;
+      if (versionToken.major > latestVersion.major ||
+          versionToken.major == latestVersion.major &&
+              versionToken.minor > latestVersion.minor) {
+        errorListener.onError(
+          AnalysisError(
+            source,
+            versionToken.offset,
+            versionToken.length,
+            HintCode.INVALID_LANGUAGE_VERSION_OVERRIDE_GREATER,
+            [latestVersion.major, latestVersion.minor],
+          ),
+        );
+        // Fall-through, use the package language version.
+      } else {
+        return Version(versionToken.major, versionToken.minor, 0);
+      }
+    }
+
+    var featureSetProvider = _fsState.featureSetProvider;
+    return featureSetProvider.getLanguageVersion(path, uri);
+  }
+
   /**
    * Invalidate any data that depends on the current unlinked data of the file,
    * because [refresh] is going to recompute the unlinked data.
@@ -599,14 +633,17 @@ class FileState {
     });
     LineInfo lineInfo = LineInfo(scanner.lineStarts);
 
+    var languageVersion = _getLanguageVersion(
+      scanner.languageVersion,
+      errorListener,
+    );
+    var featureSet = _featureSet.restrictToVersion(languageVersion);
+
     bool useFasta = analysisOptions.useFastaParser;
-    // Pass the feature set from the scanner to the parser
-    // because the scanner may have detected a language version comment
-    // and downgraded the feature set it holds.
     Parser parser = Parser(
       source,
       errorListener,
-      featureSet: scanner.featureSet,
+      featureSet: featureSet,
       useFasta: useFasta,
     );
     parser.enableOptionalNewAndConst = true;
@@ -616,7 +653,10 @@ class FileState {
     try {
       unit = parser.parseCompilationUnit(token);
       unit.lineInfo = lineInfo;
-      _setLanguageVersion(unit, scanner.languageVersion);
+
+      var unitImpl = unit as CompilationUnitImpl;
+      unitImpl.languageVersionMajor = languageVersion.major;
+      unitImpl.languageVersionMinor = languageVersion.minor;
     } catch (e) {
       throw StateError('''
 Parser error.
@@ -647,22 +687,6 @@ $content
     return directive.uri;
   }
 
-  /// Set the language version into the [unit], from the [languageVersionToken]
-  /// override, or the configured from the [FeatureSetProvider].
-  void _setLanguageVersion(
-    CompilationUnitImpl unit,
-    LanguageVersionToken languageVersionToken,
-  ) {
-    if (languageVersionToken != null) {
-      unit.languageVersionMajor = languageVersionToken.major;
-      unit.languageVersionMinor = languageVersionToken.minor;
-    } else {
-      var version = _fsState.featureSetProvider.getLanguageVersion(path, uri);
-      unit.languageVersionMajor = version.major;
-      unit.languageVersionMinor = version.minor;
-    }
-  }
-
   static UnlinkedUnit2Builder serializeAstUnlinked2(CompilationUnit unit) {
     var exports = <UnlinkedNamespaceDirectiveBuilder>[];
     var imports = <UnlinkedNamespaceDirectiveBuilder>[];

pkg/analyzer/lib/src/dart/error/hint_codes.dart

@@ -742,6 +742,15 @@ class HintCode extends AnalyzerErrorCode {
           correction: "Specify a Dart language version override with a comment "
               "like '// @dart = 2.0'.");
 
+  static const HintCode INVALID_LANGUAGE_VERSION_OVERRIDE_GREATER =
+      HintCodeWithUniqueName(
+    'INVALID_LANGUAGE_VERSION_OVERRIDE',
+    'INVALID_LANGUAGE_VERSION_OVERRIDE_GREATER',
+    "The language version override can't specify a version greater than the "
+        "latest known language version: {0}.{1}",
+    correction: "Try removing the language version override.",
+  );
+
   static const HintCode INVALID_LANGUAGE_VERSION_OVERRIDE_LOCATION =
       HintCodeWithUniqueName(
     'INVALID_LANGUAGE_VERSION_OVERRIDE',

pkg/analyzer/test/src/dart/analysis/feature_set_provider_test.dart

@@ -196,18 +196,6 @@ class FeatureSetProviderTest with ResourceProviderMixin {
           libFolder: newFolder('/packages/aaa/lib'),
           languageVersion: null,
         ),
-        'bbb': Package(
-          name: 'bbb',
-          rootFolder: newFolder('/packages/bbb'),
-          libFolder: newFolder('/packages/bbb/lib'),
-          languageVersion: Version(2, 7, 0),
-        ),
-        'ccc': Package(
-          name: 'ccc',
-          rootFolder: newFolder('/packages/ccc'),
-          libFolder: newFolder('/packages/ccc/lib'),
-          languageVersion: Version(2, 9, 0),
-        ),
       },
     );
 
@@ -226,14 +214,6 @@ class FeatureSetProviderTest with ResourceProviderMixin {
     _assertNonNullableForPath('/packages/aaa/lib/b.dart', true);
     _assertNonNullableForPath('/packages/aaa/test/c.dart', true);
 
-    _assertNonNullableForPath('/packages/bbb/a.dart', false);
-    _assertNonNullableForPath('/packages/bbb/lib/b.dart', false);
-    _assertNonNullableForPath('/packages/bbb/test/c.dart', false);
-
-    _assertNonNullableForPath('/packages/ccc/a.dart', true);
-    _assertNonNullableForPath('/packages/ccc/lib/b.dart', true);
-    _assertNonNullableForPath('/packages/ccc/test/c.dart', true);
-
     _assertNonNullableForPath('/other/file.dart', false);
   }
 

pkg/analyzer/test/src/dart/resolution/language_version_test.dart

@@ -6,18 +6,20 @@ import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/src/context/packages.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/test_utilities/mock_sdk.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'driver_resolution.dart';
 
 main() {
   defineReflectiveSuite(() {
-    defineReflectiveTests(DefaultNonNullableTest);
+    defineReflectiveTests(NullSafetyUsingAllowedExperimentsTest);
+    defineReflectiveTests(NullSafetyExperimentGlobalTest);
   });
 }
 
 @reflectiveTest
-class DefaultNonNullableTest extends DriverResolutionTest {
+class NullSafetyExperimentGlobalTest extends _FeaturesTest {
   @override
   AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
     ..contextFeatures = FeatureSet.fromEnableFlags(
@@ -46,12 +48,7 @@ class DefaultNonNullableTest extends DriverResolutionTest {
   ]
 }
 ''');
-    driver.configure(
-      packages: findPackagesFrom(
-        resourceProvider,
-        getFolder('/test'),
-      ),
-    );
+    _configureTestWithJsonConfig();
 
     newFile('/aaa/lib/a.dart', content: r'''
 int a = 0;
@@ -89,12 +86,7 @@ var z = PI;
   ]
 }
 ''');
-    driver.configure(
-      packages: findPackagesFrom(
-        resourceProvider,
-        getFolder('/test'),
-      ),
-    );
+    _configureTestWithJsonConfig();
 
     newFile('/aaa/lib/a.dart', content: r'''
 int a = 0;
@@ -113,3 +105,114 @@ var z = PI;
     assertType(findElement.topVar('z').type, 'double');
   }
 }
+
+@reflectiveTest
+class NullSafetyUsingAllowedExperimentsTest extends _FeaturesTest {
+  @override
+  bool get typeToStringWithNullability => true;
+
+  test_jsonConfig_disable() async {
+    _configureAllowedExperimentsTestNullSafety();
+
+    newFile('/test/.dart_tool/package_config.json', content: '''
+{
+  "configVersion": 2,
+  "packages": [
+    {
+      "name": "test",
+      "rootUri": "../",
+      "packageUri": "lib/",
+      "languageVersion": "2.8"
+    }
+  ]
+}
+''');
+    _configureTestWithJsonConfig();
+
+    await assertNoErrorsInCode('''
+var x = 0;
+''');
+    assertType(findElement.topVar('x').type, 'int*');
+
+    // Upgrade the language version to `2.9`, so enabled Null Safety.
+    _changeTestFile();
+    await assertNoErrorsInCode('''
+// @dart = 2.9
+var x = 0;
+''');
+    assertType(findElement.topVar('x').type, 'int');
+  }
+
+  test_jsonConfig_enable() async {
+    _configureAllowedExperimentsTestNullSafety();
+
+    newFile('/test/.dart_tool/package_config.json', content: '''
+{
+  "configVersion": 2,
+  "packages": [
+    {
+      "name": "test",
+      "rootUri": "../",
+      "packageUri": "lib/"
+    }
+  ]
+}
+''');
+    _configureTestWithJsonConfig();
+
+    await assertNoErrorsInCode('''
+var x = 0;
+''');
+    assertType(findElement.topVar('x').type, 'int');
+
+    // Downgrade the version to `2.8`, so disable Null Safety.
+    _changeTestFile();
+    await assertNoErrorsInCode('''
+// @dart = 2.8
+var x = 0;
+''');
+    assertType(findElement.topVar('x').type, 'int*');
+  }
+
+  void _changeTestFile() {
+    var path = convertPath('/test/lib/test.dart');
+    driver.changeFile(path);
+  }
+
+  void _configureAllowedExperimentsTestNullSafety() {
+    _newSdkExperimentsFile(r'''
+{
+  "version": 1,
+  "experimentSets": {
+    "nullSafety": ["non-nullable"]
+  },
+  "sdk": {
+    "default": {
+      "experimentSet": "nullSafety"
+    }
+  },
+  "packages": {
+    "test": {
+      "experimentSet": "nullSafety"
+    }
+  }
+}
+''');
+  }
+
+  void _newSdkExperimentsFile(String content) {
+    newFile('$sdkRoot/lib/_internal/allowed_experiments.json',
+        content: content);
+  }
+}
+
+class _FeaturesTest extends DriverResolutionTest {
+  void _configureTestWithJsonConfig() {
+    driver.configure(
+      packages: findPackagesFrom(
+        resourceProvider,
+        getFolder('/test'),
+      ),
+    );
+  }
+}