remove retired experimental flags from kernel

Change-Id: Id0f5e64ad7431e42a10c09fdaf1fae70b73a6d68
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104900
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Commit-Queue: Dan Rubel <danrubel@google.com>

Author: danrubel

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

@@ -182,7 +182,7 @@ class IsExpired {
   static const bool constant_update_2018 = false;
 
   /// Expiration status of the experiment "control-flow-collections"
-  static const bool control_flow_collections = true;
+  static const bool control_flow_collections = false;
 
   /// Expiration status of the experiment "extension-methods"
   static const bool extension_methods = false;
@@ -194,7 +194,7 @@ class IsExpired {
   static const bool set_literals = true;
 
   /// Expiration status of the experiment "spread-collections"
-  static const bool spread_collections = true;
+  static const bool spread_collections = false;
 
   /// Expiration status of the experiment "triple-shift"
   static const bool triple_shift = false;

pkg/dev_compiler/lib/src/kernel/command.dart

@@ -217,7 +217,9 @@ Future<CompilerResult> _compile(List<String> args,
   var experiments = <fe.ExperimentalFlag, bool>{};
   for (var name in options.experiments.keys) {
     var flag = fe.parseExperimentalFlag(name);
-    if (flag != null) {
+    if (flag == fe.ExperimentalFlag.expiredFlag) {
+      stderr.writeln("Flag '$name' is no longer required.");
+    } else if (flag != null) {
       experiments[flag] = options.experiments[name];
     } else {
       stderr.writeln("Unknown experiment flag '$name'.");

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

@@ -244,6 +244,7 @@ Map<ExperimentalFlag, bool> parseExperimentalFlags(
     }
   }
   for (ExperimentalFlag flag in ExperimentalFlag.values) {
+    if (flag == ExperimentalFlag.expiredFlag) continue;
     assert(defaultExperimentalFlags.containsKey(flag),
         "No default value for $flag.");
     flags[flag] ??= defaultExperimentalFlags[flag];

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

@@ -12,9 +12,13 @@ enum ExperimentalFlag {
   controlFlowCollections,
   extensionMethods,
   nonNullable,
-  setLiterals,
   spreadCollections,
   tripleShift,
+
+  // A placeholder representing an "expired" flag which has been removed
+  // from the codebase but still needs to be gracefully ignored
+  // when specified on the command line.
+  expiredFlag,
 }
 
 ExperimentalFlag parseExperimentalFlag(String flag) {
@@ -27,12 +31,14 @@ ExperimentalFlag parseExperimentalFlag(String flag) {
       return ExperimentalFlag.extensionMethods;
     case "non-nullable":
       return ExperimentalFlag.nonNullable;
-    case "set-literals":
-      return ExperimentalFlag.setLiterals;
     case "spread-collections":
       return ExperimentalFlag.spreadCollections;
     case "triple-shift":
       return ExperimentalFlag.tripleShift;
+
+    // Expired flags
+    case "set-literals":
+      return ExperimentalFlag.expiredFlag;
   }
   return null;
 }
@@ -42,7 +48,6 @@ const Map<ExperimentalFlag, bool> defaultExperimentalFlags = {
   ExperimentalFlag.controlFlowCollections: true,
   ExperimentalFlag.extensionMethods: false,
   ExperimentalFlag.nonNullable: false,
-  ExperimentalFlag.setLiterals: true,
   ExperimentalFlag.spreadCollections: true,
   ExperimentalFlag.tripleShift: false,
 };

pkg/front_end/tool/_fasta/generate_experimental_flags.dart

@@ -51,33 +51,53 @@ Future<String> generateMessagesFile() async {
 enum ExperimentalFlag {
 ''');
   for (var key in keys) {
+    var expired = (yaml[key] as YamlMap)['expired'];
+    if (expired == true) continue;
     sb.writeln('  ${keyToIdentifier(key)},');
   }
-  sb.writeln('}');
-
   sb.write('''
 
+  // A placeholder representing an "expired" flag which has been removed
+  // from the codebase but still needs to be gracefully ignored
+  // when specified on the command line.
+  expiredFlag,
+}
+
 ExperimentalFlag parseExperimentalFlag(String flag) {
   switch (flag) {
 ''');
+  var expiredKeys = <String>[];
   for (var key in keys) {
+    var expired = (yaml[key] as YamlMap)['expired'];
+    if (expired == true) {
+      expiredKeys.add(key);
+      continue;
+    }
     sb.writeln('    case "$key":');
     sb.writeln('     return ExperimentalFlag.${keyToIdentifier(key)};');
   }
+  if (expiredKeys.isNotEmpty) {
+    sb.write('''
+
+    // Expired flags
+''');
+    for (var key in expiredKeys) {
+      sb.writeln('    case "$key":');
+      sb.writeln('     return ExperimentalFlag.expiredFlag;');
+    }
+  }
   sb.write('''  }
   return null;
 }
-''');
-
-  sb.write('''
 
 const Map<ExperimentalFlag, bool> defaultExperimentalFlags = {
 ''');
   for (var key in keys) {
+    var expired = (yaml[key] as YamlMap)['expired'];
+    if (expired == true) continue;
     bool shipped = (yaml[key] as YamlMap)['enabledIn'] != null;
     sb.writeln('  ExperimentalFlag.${keyToIdentifier(key)}: ${shipped},');
     if (shipped) {
-      var expired = (yaml[key] as YamlMap)['expired'];
       if (expired == false) {
         throw 'Cannot mark shipped feature as "expired: false"';
       }

tools/experimental_features.yaml

@@ -83,14 +83,13 @@ triple-shift:
   help: "Triple-shift operator"
 
 #
-# Flags below this line are either retired or rejected, cannot be specified
+# Flags below this line are shipped, retired, or rejected, cannot be specified
 # on the command line, and will eventually be removed.
 #
 
 control-flow-collections:
   help: "Control Flow Collections"
   enabledIn: '2.2.2'
-  expired: true
 
 set-literals:
   help: "Set Literals"
@@ -100,4 +99,3 @@ set-literals:
 spread-collections:
   help: "Spread Collections"
   enabledIn: '2.2.2'
-  expired: true