Issue 39059. Check for minor / major version overflow.

Bug: https://github.com/dart-lang/sdk/issues/39059
Change-Id: I78a5598b2433d772409a41f7c6e87b32f859c6be
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/131705
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/dart/scanner/scanner.dart

@@ -4,9 +4,9 @@
 
 import 'package:_fe_analyzer_shared/src/scanner/errors.dart'
     show translateErrorToken;
+import 'package:_fe_analyzer_shared/src/scanner/scanner.dart' as fasta;
 import 'package:_fe_analyzer_shared/src/scanner/token.dart'
     show Token, TokenType;
-import 'package:_fe_analyzer_shared/src/scanner/scanner.dart' as fasta;
 import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
@@ -190,9 +190,11 @@ class Scanner {
   void _languageVersionChanged(
       fasta.Scanner scanner, fasta.LanguageVersionToken languageVersion) {
     if (_featureSet != null) {
-      _featureSet = _featureSet.restrictToVersion(
-          Version(languageVersion.major, languageVersion.minor, 0));
-      scanner.configuration = buildConfig(_featureSet);
+      if (languageVersion.major >= 0 && languageVersion.minor >= 0) {
+        _featureSet = _featureSet.restrictToVersion(
+            Version(languageVersion.major, languageVersion.minor, 0));
+        scanner.configuration = buildConfig(_featureSet);
+      }
     }
   }
 

pkg/analyzer/test/generated/scanner_test.dart

@@ -5,11 +5,14 @@
 import 'package:_fe_analyzer_shared/src/scanner/error_token.dart';
 import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/token.dart';
+import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/dart/ast/token.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/string_source.dart';
+import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -18,6 +21,7 @@ import 'test_support.dart';
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LineInfoTest);
+    defineReflectiveTests(ScannerTest);
   });
 }
 
@@ -183,6 +187,49 @@ class LineInfoTest {
   }
 }
 
+@reflectiveTest
+class ScannerTest with ResourceProviderMixin {
+  test_featureSet() {
+    var scanner = _createScanner(r'''
+// @dart = 2.0
+''');
+    var defaultFeatureSet = FeatureSet.fromEnableFlags([]);
+    expect(defaultFeatureSet.isEnabled(Feature.extension_methods), isTrue);
+
+    scanner.configureFeatures(FeatureSet.forTesting());
+    scanner.tokenize();
+
+    var featureSet = scanner.featureSet;
+    expect(featureSet.isEnabled(Feature.extension_methods), isFalse);
+  }
+
+  test_featureSet_majorOverflow() {
+    var scanner = _createScanner(r'''
+// @dart = 99999999999999999999999999999999.0
+''');
+    scanner.configureFeatures(FeatureSet.forTesting());
+    scanner.tokenize();
+    // Don't check features, but should not crash.
+  }
+
+  test_featureSet_minorOverflow() {
+    var scanner = _createScanner(r'''
+// @dart = 2.99999999999999999999999999999999
+''');
+    scanner.configureFeatures(FeatureSet.forTesting());
+    scanner.tokenize();
+    // Don't check features, but should not crash.
+  }
+
+  Scanner _createScanner(String content) {
+    var path = convertPath('/test/lib/a.dart');
+    var source = StringSource(content, path);
+    var reader = CharSequenceReader(content);
+    var errorCollector = RecordingErrorListener();
+    return Scanner(source, reader, errorCollector);
+  }
+}
+
 /**
  * An `ExpectedLocation` encodes information about the expected location of a
  * given offset in source code.