Add an experiment flag for patterns.

Change-Id: I175e4680a0949e52ae05f46c2051c701b55a99cd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/260500
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Devon Carew <devoncarew@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

pkg/analyzer/lib/dart/analysis/features.dart

@@ -40,6 +40,9 @@ abstract class Feature {
   /// Feature information for macros.
   static final macros = ExperimentalFeatures.macros;
 
+  /// Feature information for patterns.
+  static final patterns = ExperimentalFeatures.patterns;
+
   /// Feature information for records.
   static final records = ExperimentalFeatures.records;
 

pkg/analyzer/lib/src/dart/analysis/experiments.g.dart

@@ -33,6 +33,7 @@ final _knownFeatures = <String, ExperimentalFeature>{
   EnableString.non_nullable: ExperimentalFeatures.non_nullable,
   EnableString.nonfunction_type_aliases:
       ExperimentalFeatures.nonfunction_type_aliases,
+  EnableString.patterns: ExperimentalFeatures.patterns,
   EnableString.records: ExperimentalFeatures.records,
   EnableString.set_literals: ExperimentalFeatures.set_literals,
   EnableString.spread_collections: ExperimentalFeatures.spread_collections,
@@ -88,6 +89,9 @@ class EnableString {
   /// String to enable the experiment "nonfunction-type-aliases"
   static const String nonfunction_type_aliases = 'nonfunction-type-aliases';
 
+  /// String to enable the experiment "patterns"
+  static const String patterns = 'patterns';
+
   /// String to enable the experiment "records"
   static const String records = 'records';
 
@@ -258,8 +262,18 @@ class ExperimentalFeatures {
     releaseVersion: Version.parse('2.13.0'),
   );
 
-  static final records = ExperimentalFeature(
+  static final patterns = ExperimentalFeature(
     index: 14,
+    enableString: EnableString.patterns,
+    isEnabledByDefault: IsEnabledByDefault.patterns,
+    isExpired: IsExpired.patterns,
+    documentation: 'Patterns',
+    experimentalReleaseVersion: null,
+    releaseVersion: null,
+  );
+
+  static final records = ExperimentalFeature(
+    index: 15,
     enableString: EnableString.records,
     isEnabledByDefault: IsEnabledByDefault.records,
     isExpired: IsExpired.records,
@@ -269,7 +283,7 @@ class ExperimentalFeatures {
   );
 
   static final set_literals = ExperimentalFeature(
-    index: 15,
+    index: 16,
     enableString: EnableString.set_literals,
     isEnabledByDefault: IsEnabledByDefault.set_literals,
     isExpired: IsExpired.set_literals,
@@ -279,7 +293,7 @@ class ExperimentalFeatures {
   );
 
   static final spread_collections = ExperimentalFeature(
-    index: 16,
+    index: 17,
     enableString: EnableString.spread_collections,
     isEnabledByDefault: IsEnabledByDefault.spread_collections,
     isExpired: IsExpired.spread_collections,
@@ -289,7 +303,7 @@ class ExperimentalFeatures {
   );
 
   static final super_parameters = ExperimentalFeature(
-    index: 17,
+    index: 18,
     enableString: EnableString.super_parameters,
     isEnabledByDefault: IsEnabledByDefault.super_parameters,
     isExpired: IsExpired.super_parameters,
@@ -299,7 +313,7 @@ class ExperimentalFeatures {
   );
 
   static final test_experiment = ExperimentalFeature(
-    index: 18,
+    index: 19,
     enableString: EnableString.test_experiment,
     isEnabledByDefault: IsEnabledByDefault.test_experiment,
     isExpired: IsExpired.test_experiment,
@@ -310,7 +324,7 @@ class ExperimentalFeatures {
   );
 
   static final triple_shift = ExperimentalFeature(
-    index: 19,
+    index: 20,
     enableString: EnableString.triple_shift,
     isEnabledByDefault: IsEnabledByDefault.triple_shift,
     isExpired: IsExpired.triple_shift,
@@ -320,7 +334,7 @@ class ExperimentalFeatures {
   );
 
   static final value_class = ExperimentalFeature(
-    index: 20,
+    index: 21,
     enableString: EnableString.value_class,
     isEnabledByDefault: IsEnabledByDefault.value_class,
     isExpired: IsExpired.value_class,
@@ -330,7 +344,7 @@ class ExperimentalFeatures {
   );
 
   static final variance = ExperimentalFeature(
-    index: 21,
+    index: 22,
     enableString: EnableString.variance,
     isEnabledByDefault: IsEnabledByDefault.variance,
     isExpired: IsExpired.variance,
@@ -385,6 +399,9 @@ class IsEnabledByDefault {
   /// Default state of the experiment "nonfunction-type-aliases"
   static const bool nonfunction_type_aliases = true;
 
+  /// Default state of the experiment "patterns"
+  static const bool patterns = false;
+
   /// Default state of the experiment "records"
   static const bool records = false;
 
@@ -456,6 +473,9 @@ class IsExpired {
   /// Expiration status of the experiment "nonfunction-type-aliases"
   static const bool nonfunction_type_aliases = true;
 
+  /// Expiration status of the experiment "patterns"
+  static const bool patterns = false;
+
   /// Expiration status of the experiment "records"
   static const bool records = false;
 
@@ -532,6 +552,9 @@ mixin _CurrentState {
   bool get nonfunction_type_aliases =>
       isEnabled(ExperimentalFeatures.nonfunction_type_aliases);
 
+  /// Current state for the flag "patterns"
+  bool get patterns => isEnabled(ExperimentalFeatures.patterns);
+
   /// Current state for the flag "records"
   bool get records => isEnabled(ExperimentalFeatures.records);
 

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

@@ -347,9 +347,8 @@ class ResolverVisitor extends ThrowingAstVisitor<void>
             definingLibrary.featureSet.isEnabled(Feature.generic_metadata),
         options = TypeAnalyzerOptions(
             nullSafetyEnabled: definingLibrary.isNonNullableByDefault,
-            // TODO(paulberry): set `patternsEnabled` correctly once we have an
-            // experiment flag for patterns.
-            patternsEnabled: false) {
+            patternsEnabled:
+                definingLibrary.featureSet.isEnabled(Feature.patterns)) {
     var analysisOptions =
         definingLibrary.context.analysisOptions as AnalysisOptionsImpl;
 

pkg/front_end/lib/src/api_prototype/experimental_flags_generated.dart

@@ -171,6 +171,14 @@ class ExperimentalFlag {
       experimentEnabledVersion: const Version(2, 13),
       experimentReleasedVersion: const Version(2, 13));
 
+  static const ExperimentalFlag patterns = const ExperimentalFlag(
+      name: 'patterns',
+      isEnabledByDefault: false,
+      isExpired: false,
+      enabledVersion: const Version(2, 19),
+      experimentEnabledVersion: const Version(2, 19),
+      experimentReleasedVersion: const Version(2, 19));
+
   static const ExperimentalFlag records = const ExperimentalFlag(
       name: 'records',
       isEnabledByDefault: false,
@@ -342,6 +350,10 @@ class GlobalFeatures {
   GlobalFeature get nonfunctionTypeAliases => _nonfunctionTypeAliases ??=
       _computeGlobalFeature(ExperimentalFlag.nonfunctionTypeAliases);
 
+  GlobalFeature? _patterns;
+  GlobalFeature get patterns =>
+      _patterns ??= _computeGlobalFeature(ExperimentalFlag.patterns);
+
   GlobalFeature? _records;
   GlobalFeature get records =>
       _records ??= _computeGlobalFeature(ExperimentalFlag.records);
@@ -468,6 +480,11 @@ class LibraryFeatures {
           canonicalUri,
           libraryVersion);
 
+  LibraryFeature? _patterns;
+  LibraryFeature get patterns =>
+      _patterns ??= globalFeatures._computeLibraryFeature(
+          ExperimentalFlag.patterns, canonicalUri, libraryVersion);
+
   LibraryFeature? _records;
   LibraryFeature get records =>
       _records ??= globalFeatures._computeLibraryFeature(
@@ -541,6 +558,8 @@ ExperimentalFlag? parseExperimentalFlag(String flag) {
       return ExperimentalFlag.nonNullable;
     case "nonfunction-type-aliases":
       return ExperimentalFlag.nonfunctionTypeAliases;
+    case "patterns":
+      return ExperimentalFlag.patterns;
     case "records":
       return ExperimentalFlag.records;
     case "set-literals":
@@ -590,6 +609,7 @@ final Map<ExperimentalFlag, bool> defaultExperimentalFlags = {
   ExperimentalFlag.nonNullable: ExperimentalFlag.nonNullable.isEnabledByDefault,
   ExperimentalFlag.nonfunctionTypeAliases:
       ExperimentalFlag.nonfunctionTypeAliases.isEnabledByDefault,
+  ExperimentalFlag.patterns: ExperimentalFlag.patterns.isEnabledByDefault,
   ExperimentalFlag.records: ExperimentalFlag.records.isEnabledByDefault,
   ExperimentalFlag.setLiterals: ExperimentalFlag.setLiterals.isEnabledByDefault,
   ExperimentalFlag.spreadCollections:

tools/experimental_features.yaml

@@ -131,6 +131,9 @@ features:
   records:
     help: "Records"
 
+  patterns:
+    help: "Patterns"
+
 # Experiment flag only used for testing.
   test-experiment:
     help: >-