Remove support for --emit-metadata in DDC

This flag is unused and the behavior it enables was only useful along with
`dart:mirrors`.

- Remove the flag and the field on the options object.
- Prune code branches that are no longer reachable.
- Remove or inline some functions that became either empty or trivially small.
- Remove the manual check for a `dart:mirrors` import since this is handled by
  the CFE now.
- Remove references to the flag in tests.
- Remove test files which only existed to enable the flag for other tests.

Change-Id: I21bf594271fb4eeb5b73fcbf07da736e9e8d1f33
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138018
Reviewed-by: Nicholas Shahan <[email protected]>
Commit-Queue: Nate Bosch <[email protected]>
Auto-Submit: Nate Bosch <[email protected]>

Author: natebosch

pkg/dev_compiler/lib/src/compiler/shared_command.dart

@@ -66,9 +66,6 @@ class SharedCompilerOptions {
   /// This is required for a modular build process.
   final bool summarizeApi;
 
-  /// Whether to preserve metdata only accessible via mirrors.
-  final bool emitMetadata;
-
   // Whether to enable assertions.
   final bool enableAsserts;
 
@@ -98,7 +95,6 @@ class SharedCompilerOptions {
       {this.sourceMap = true,
       this.inlineSourceMap = false,
       this.summarizeApi = true,
-      this.emitMetadata = false,
       this.enableAsserts = true,
       this.replCompile = false,
       this.summaryModules = const {},
@@ -112,7 +108,6 @@ class SharedCompilerOptions {
             sourceMap: args['source-map'] as bool,
             inlineSourceMap: args['inline-source-map'] as bool,
             summarizeApi: args['summarize'] as bool,
-            emitMetadata: args['emit-metadata'] as bool,
             enableAsserts: args['enable-asserts'] as bool,
             experiments: parseExperimentalArguments(
                 args['enable-experiment'] as List<String>),
@@ -139,8 +134,6 @@ class SharedCompilerOptions {
           help: 'emit source mapping', defaultsTo: true, hide: hide)
       ..addFlag('inline-source-map',
           help: 'emit source mapping inline', defaultsTo: false, hide: hide)
-      ..addFlag('emit-metadata',
-          help: 'emit metadata annotations queriable via mirrors', hide: hide)
       ..addFlag('enable-asserts',
           help: 'enable assertions', defaultsTo: true, hide: hide)
       ..addOption('module-name',

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

@@ -348,10 +348,6 @@ Future<CompilerResult> _compile(List<String> args,
     if (!librariesFromDill.contains(lib)) compiledLibraries.libraries.add(lib);
   }
 
-  if (!options.emitMetadata && _checkForDartMirrorsImport(compiledLibraries)) {
-    return CompilerResult(1, kernelState: compilerState);
-  }
-
   // Output files can be written in parallel, so collect the futures.
   var outFiles = <Future>[];
   if (argResults['summarize'] as bool) {
@@ -631,21 +627,6 @@ final defaultSdkSummaryPath =
 
 final defaultLibrarySpecPath = p.join(getSdkPath(), 'lib', 'libraries.json');
 
-bool _checkForDartMirrorsImport(Component component) {
-  for (var library in component.libraries) {
-    if (library.importUri.scheme == 'dart') continue;
-    for (var dep in library.dependencies) {
-      var uri = dep.targetLibrary.importUri;
-      if (uri.scheme == 'dart' && uri.path == 'mirrors') {
-        print('${library.importUri}: Error: Cannot import "dart:mirrors" '
-            'in web applications (https://goo.gl/R1anEs).');
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
 /// Returns the absolute path to the default `.packages` file, or `null` if one
 /// could not be found.
 ///

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

@@ -600,7 +600,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     if (!c.isMixinDeclaration) {
       _defineExtensionMembers(className, body);
     }
-    _emitClassMetadata(c.annotations, className, body);
 
     var classDef = js_ast.Statement.from(body);
     var typeFormals = c.typeParameters;
@@ -1162,19 +1161,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     }
   }
 
-  void _emitClassMetadata(List<Expression> metadata,
-      js_ast.Expression className, List<js_ast.Statement> body) {
-    // Metadata
-    if (_options.emitMetadata && metadata.isNotEmpty) {
-      body.add(js.statement('#[#.metadata] = #;', [
-        className,
-        runtimeModule,
-        _arrowFunctionWithLetScope(() => js_ast.ArrayInitializer(
-            metadata.map(_instantiateAnnotation).toList()))
-      ]));
-    }
-  }
-
   /// Ensure `dartx.` symbols we will use are present.
   void _initExtensionSymbols(Class c) {
     if (_extensionTypes.hasNativeSubtype(c) || c == _coreTypes.objectClass) {
@@ -1272,7 +1258,7 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     for (var member in classProcedures) {
       // Static getters/setters/methods cannot be called with dynamic dispatch,
       // nor can they be torn off.
-      if (!_options.emitMetadata && member.isStatic) continue;
+      if (member.isStatic) continue;
 
       var name = member.name.name;
       var reifiedType = _memberRuntimeType(member, c) as FunctionType;
@@ -1293,14 +1279,11 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
       if (needsSignature) {
         js_ast.Expression type;
         if (member.isAccessor) {
-          type = _emitAnnotatedResult(
-              _emitType(member.isGetter
-                  ? reifiedType.returnType
-                  : reifiedType.positionalParameters[0]),
-              member.annotations,
-              member);
+          type = _emitType(member.isGetter
+              ? reifiedType.returnType
+              : reifiedType.positionalParameters[0]);
         } else {
-          type = _emitAnnotatedFunctionType(reifiedType, member);
+          type = visitFunctionType(reifiedType, member: member);
         }
         var property = js_ast.Property(_declareMemberName(member), type);
         var signatures = getSignatureList(member);
@@ -1329,7 +1312,7 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     for (var field in classFields) {
       // Only instance fields need to be saved for dynamic dispatch.
       var isStatic = field.isStatic;
-      if (!_options.emitMetadata && isStatic) continue;
+      if (isStatic) continue;
 
       var memberName = _declareMemberName(field);
       var fieldSig = _emitFieldSignature(field, c);
@@ -1339,24 +1322,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     emitSignature('Field', instanceFields);
     emitSignature('StaticField', staticFields);
 
-    if (_options.emitMetadata) {
-      var constructors = <js_ast.Property>[];
-      var allConstructors = [
-        ...c.constructors,
-        ...c.procedures.where((p) => p.isFactory),
-      ];
-      for (var ctor in allConstructors) {
-        var memberName = _constructorName(ctor.name.name);
-        var type = _emitAnnotatedFunctionType(
-            ctor.function
-                .computeThisFunctionType(c.enclosingLibrary.nonNullable)
-                .withoutTypeParameters,
-            ctor);
-        constructors.add(js_ast.Property(memberName, type));
-      }
-      emitSignature('Constructor', constructors);
-    }
-
     // Add static property dart._runtimeType to Object.
     // All other Dart classes will (statically) inherit this property.
     if (c == _coreTypes.objectClass) {
@@ -1370,16 +1335,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   js_ast.Expression _emitFieldSignature(Field field, Class fromClass) {
     var type = _typeFromClass(field.type, field.enclosingClass, fromClass);
     var args = [_emitType(type)];
-    var annotations = field.annotations;
-    if (_options.emitMetadata &&
-        annotations != null &&
-        annotations.isNotEmpty) {
-      var savedUri = _currentUri;
-      _currentUri = field.enclosingClass.fileUri;
-      args.add(js_ast.ArrayInitializer(
-          annotations.map(_instantiateAnnotation).toList()));
-      _currentUri = savedUri;
-    }
     return runtimeCall(
         field.isFinal ? 'finalFieldType(#)' : 'fieldType(#)', [args]);
   }
@@ -2067,9 +2022,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
         ]) as js_ast.Fun);
   }
 
-  js_ast.Expression _instantiateAnnotation(Expression node) =>
-      _visitExpression(node);
-
   void _registerExtensionType(
       Class c, String jsPeerName, List<js_ast.Statement> body) {
     var className = _emitTopLevelName(c);
@@ -2181,19 +2133,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     return body;
   }
 
-  js_ast.ArrowFun _arrowFunctionWithLetScope(
-      js_ast.Expression Function() visitBody) {
-    var savedLetVariables = _letVariables;
-    _letVariables = [];
-
-    var expr = visitBody();
-    var letVars = _initLetVariables();
-
-    _letVariables = savedLetVariables;
-    return js_ast.ArrowFun(
-        [], letVars == null ? expr : js_ast.Block([letVars, expr.toReturn()]));
-  }
-
   js_ast.PropertyAccess _emitTopLevelName(NamedNode n, {String suffix = ''}) {
     return _emitJSInterop(n) ?? _emitTopLevelNameNoInterop(n, suffix: suffix);
   }
@@ -2540,18 +2479,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     var nameExpr = _emitTopLevelName(p);
     body.add(js.statement('# = #',
         [nameExpr, js_ast.NamedFunction(_emitTemporaryId(p.name.name), fn)]));
-    // Function types of top-level/static functions are only needed when
-    // dart:mirrors is enabled.
-    // TODO(jmesserly): do we even need this for mirrors, since statics are not
-    // commonly reflected on?
-    if (_options.emitMetadata && _reifyFunctionType(p.function)) {
-      body.add(_emitFunctionTagged(
-              nameExpr,
-              p.function
-                  .computeThisFunctionType(p.enclosingLibrary.nonNullable),
-              topLevel: true)
-          .toStatement());
-    }
 
     _currentUri = savedUri;
     _staticTypeContext.leaveMember(p);
@@ -2887,24 +2814,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     return _emitNullabilityWrapper(typeRep, type.nullability);
   }
 
-  js_ast.Expression _emitAnnotatedFunctionType(
-      FunctionType type, Member member) {
-    var result = visitFunctionType(type, member: member);
-
-    var annotations = member.annotations;
-    if (_options.emitMetadata && annotations.isNotEmpty) {
-      // TODO(jmesserly): should we disable source info for annotations?
-      var savedUri = _currentUri;
-      _currentUri = member.enclosingClass.fileUri;
-      result = js_ast.ArrayInitializer([
-        result,
-        for (var annotation in annotations) _instantiateAnnotation(annotation)
-      ]);
-      _currentUri = savedUri;
-    }
-    return result;
-  }
-
   /// Emits an expression that lets you access statics on a [type] from code.
   js_ast.Expression _emitConstructorAccess(InterfaceType type) {
     return _emitJSInterop(type.classNode) ??
@@ -2923,21 +2832,6 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     return _emitTopLevelName(c);
   }
 
-  // Wrap a result - usually a type - with its metadata.  The runtime is
-  // responsible for unpacking this.
-  js_ast.Expression _emitAnnotatedResult(
-      js_ast.Expression result, List<Expression> metadata, Member member) {
-    if (_options.emitMetadata && metadata.isNotEmpty) {
-      // TODO(jmesserly): should we disable source info for annotations?
-      var savedUri = _currentUri;
-      _currentUri = member.enclosingClass.fileUri;
-      result = js_ast.ArrayInitializer(
-          [result, for (var value in metadata) _instantiateAnnotation(value)]);
-      _currentUri = savedUri;
-    }
-    return result;
-  }
-
   /// Emits named parameters in the form '{name: type}'.
   js_ast.ObjectInitializer _emitTypeProperties(Iterable<NamedType> types) {
     return js_ast.ObjectInitializer(types
@@ -2949,17 +2843,8 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   ///
   /// Annotatable contexts include typedefs and method/function declarations.
   js_ast.ArrayInitializer _emitTypeNames(List<DartType> types,
-      List<VariableDeclaration> parameters, Member member) {
-    var result = <js_ast.Expression>[];
-    for (var i = 0; i < types.length; ++i) {
-      var type = _emitType(types[i]);
-      if (parameters != null) {
-        type = _emitAnnotatedResult(type, parameters[i].annotations, member);
-      }
-      result.add(type);
-    }
-    return js_ast.ArrayInitializer(result);
-  }
+          List<VariableDeclaration> parameters, Member member) =>
+      js_ast.ArrayInitializer([for (var type in types) _emitType(type)]);
 
   @override
   js_ast.Expression visitTypeParameterType(TypeParameterType type) =>

sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/classes.dart

@@ -287,11 +287,6 @@ getSetterType(type, name) {
   if (setters != null) {
     var type = JS('', '#[#]', setters, name);
     if (type != null) {
-      if (JS('!', '# instanceof Array', type)) {
-        // The type has metadata attached.  Pull out just the type.
-        // TODO(jmesserly): remove when we remove mirrors
-        return JS('', '#[0]', type);
-      }
       return type;
     }
   }

sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart

@@ -282,10 +282,6 @@ _checkAndCall(f, ftype, obj, typeArgs, args, named, displayName) =>
     return $f.apply($obj, $args);
   }
 
-  // TODO(vsm): Remove when we no longer need mirrors metadata.
-  // An array is used to encode annotations attached to the type.
-  if ($ftype instanceof Array) $ftype = $ftype[0];
-
   // Apply type arguments
   if ($ftype instanceof $GenericFunctionType) {
     let formalCount = $ftype.formalCount;

sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/classes.dart

@@ -301,11 +301,6 @@ getSetterType(type, name) {
   if (setters != null) {
     var type = JS('', '#[#]', setters, name);
     if (type != null) {
-      if (JS('!', '# instanceof Array', type)) {
-        // The type has metadata attached.  Pull out just the type.
-        // TODO(jmesserly): remove when we remove mirrors
-        return JS('', '#[0]', type);
-      }
       return type;
     }
   }

sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart

@@ -300,10 +300,6 @@ _checkAndCall(f, ftype, obj, typeArgs, args, named, displayName) =>
     return $f.apply($obj, $args);
   }
 
-  // TODO(vsm): Remove when we no longer need mirrors metadata.
-  // An array is used to encode annotations attached to the type.
-  if ($ftype instanceof Array) $ftype = $ftype[0];
-
   // Apply type arguments
   if ($ftype instanceof $GenericFunctionType) {
     let formalCount = $ftype.formalCount;

tests/lib/mirrors/field_metadata2_test.dart

@@ -1,4 +1,3 @@
-// compile options: --emit-metadata
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

tests/lib/mirrors/metadata_constructed_constant_test.dart

@@ -1,4 +1,3 @@
-// compile options: --emit-metadata
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.