[VM] Implement isExtensionMember in MethodMirror and VariableMirror

Added ability to recognize a MethodMirror to be a mirror of an extension member
Added ability to recognize a VariableMirror to be a mirror of a static
extension field.

Change-Id: I56715a491bba0d8cafb2796ebb755bd339e147c6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/120760
Reviewed-by: Siva Annamalai <asiva@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>

Author: a-siva

runtime/lib/mirrors.cc

@@ -274,6 +274,8 @@ static RawInstance* CreateMethodMirror(const Function& func,
       (static_cast<intptr_t>(func.is_external()) << Mirrors::kExternal);
   bool is_synthetic = func.is_no_such_method_forwarder();
   kind_flags |= (static_cast<intptr_t>(is_synthetic) << Mirrors::kSynthetic);
+  kind_flags |= (static_cast<intptr_t>(func.is_extension_member())
+                 << Mirrors::kExtensionMember);
   args.SetAt(5, Smi::Handle(Smi::New(kind_flags)));
 
   return CreateMirror(Symbols::_MethodMirror(), args);
@@ -286,14 +288,15 @@ static RawInstance* CreateVariableMirror(const Field& field,
 
   const String& name = String::Handle(field.name());
 
-  const Array& args = Array::Handle(Array::New(7));
+  const Array& args = Array::Handle(Array::New(8));
   args.SetAt(0, field_ref);
   args.SetAt(1, name);
   args.SetAt(2, owner_mirror);
   args.SetAt(3, Object::null_instance());  // Null for type.
   args.SetAt(4, Bool::Get(field.is_static()));
   args.SetAt(5, Bool::Get(field.is_final()));
   args.SetAt(6, Bool::Get(field.is_const()));
+  args.SetAt(7, Bool::Get(field.is_extension_member()));
 
   return CreateMirror(Symbols::_VariableMirror(), args);
 }
@@ -1320,12 +1323,16 @@ DEFINE_NATIVE_ENTRY(ClosureMirror_function, 0, 1) {
   Function& function = Function::Handle();
   bool callable = closure.IsCallable(&function);
   if (callable) {
-    if (function.IsImplicitClosureFunction()) {
+    const Function& parent = Function::Handle(function.parent_function());
+    if (function.IsImplicitClosureFunction() || parent.is_extension_member()) {
       // The VM uses separate Functions for tear-offs, but the mirrors consider
       // the tear-offs to be the same as the torn-off methods. Avoid handing out
       // a reference to the tear-off here to avoid a special case in the
       // the equality test.
-      function = function.parent_function();
+      // In the case of extension methods also we avoid handing out a reference
+      // to the tear-off and instead get the parent function of the
+      // anonymous closure.
+      function = parent.raw();
     }
 
     Type& instantiator = Type::Handle();

runtime/lib/mirrors.h

@@ -21,7 +21,8 @@ class Mirrors : public AllStatic {
   V(kRedirectingCtor)                                                          \
   V(kFactoryCtor)                                                              \
   V(kExternal)                                                                 \
-  V(kSynthetic)
+  V(kSynthetic)                                                                \
+  V(kExtensionMember)
 
   // These offsets much be kept in sync with those in mirrors_impl.dart.
   enum KindShifts {

sdk/lib/_internal/vm/lib/mirrors_impl.dart

@@ -157,6 +157,7 @@ class _SyntheticAccessor implements MethodMirror {
   bool get isExternal => false;
   bool get isRedirectingConstructor => false;
   bool get isAbstract => false;
+  bool get isExtensionMember => false;
 
   bool get isSetter => !isGetter;
   bool get isPrivate => _n(simpleName).startsWith('_');
@@ -193,6 +194,7 @@ class _SyntheticSetterParameter implements ParameterMirror {
   bool get isConst => false;
   bool get isFinal => true;
   bool get isPrivate => false;
+  bool get isExtensionMember => false;
   bool get hasDefaultValue => false;
   InstanceMirror get defaultValue => null;
   SourceLocation get location => null;
@@ -1168,6 +1170,7 @@ class _MethodMirror extends _DeclarationMirror implements MethodMirror {
   static const kFactoryCtor = 7;
   static const kExternal = 8;
   static const kSynthetic = 9;
+  static const kExtensionMember = 10;
 
   // These offsets much be kept in sync with those in mirrors.h.
   bool get isAbstract => 0 != (_kindFlags & (1 << kAbstract));
@@ -1182,6 +1185,7 @@ class _MethodMirror extends _DeclarationMirror implements MethodMirror {
   bool get isFactoryConstructor => 0 != (_kindFlags & (1 << kFactoryCtor));
   bool get isExternal => 0 != (_kindFlags & (1 << kExternal));
   bool get isSynthetic => 0 != (_kindFlags & (1 << kSynthetic));
+  bool get isExtensionMember => 0 != (_kindFlags & (1 << kExtensionMember));
 
   static const _operators = const [
     "%", "&", "*", "+", "-", "/", "<", "<<", //
@@ -1281,9 +1285,10 @@ class _VariableMirror extends _DeclarationMirror implements VariableMirror {
   final bool isStatic;
   final bool isFinal;
   final bool isConst;
+  final bool isExtensionMember;
 
   _VariableMirror._(reflectee, String simpleName, this.owner, this._type,
-      this.isStatic, this.isFinal, this.isConst)
+      this.isStatic, this.isFinal, this.isConst, this.isExtensionMember)
       : super._(reflectee, _s(simpleName));
 
   bool get isTopLevel => owner is LibraryMirror;
@@ -1339,7 +1344,8 @@ class _ParameterMirror extends _VariableMirror implements ParameterMirror {
             null, // We override the type.
             false, // isStatic does not apply.
             isFinal,
-            false // Not const.
+            false, // Not const.
+            false // Not extension member.
             );
 
   Object _defaultValueReflectee;

sdk/lib/mirrors/mirrors.dart

@@ -1070,6 +1070,11 @@ abstract class MethodMirror implements DeclarationMirror {
    */
   bool get isFactoryConstructor;
 
+  /**
+   * Is the reflectee an extension method?
+   */
+  bool get isExtensionMember;
+
   /**
    * Whether this mirror is equal to [other].
    *
@@ -1111,6 +1116,11 @@ abstract class VariableMirror implements DeclarationMirror {
    */
   bool get isConst;
 
+  /**
+   * Is the reflectee an extension member?
+   */
+  bool get isExtensionMember;
+
   /**
    * Whether this mirror is equal to [other].
    *

sdk_nnbd/lib/_internal/vm/lib/mirrors_impl.dart

@@ -159,6 +159,7 @@ class _SyntheticAccessor implements MethodMirror {
   bool get isExternal => false;
   bool get isRedirectingConstructor => false;
   bool get isAbstract => false;
+  bool get isExtensionMember => false;
 
   bool get isSetter => !isGetter;
   bool get isPrivate => _n(simpleName).startsWith('_');
@@ -195,6 +196,7 @@ class _SyntheticSetterParameter implements ParameterMirror {
   bool get isConst => false;
   bool get isFinal => true;
   bool get isPrivate => false;
+  bool get isExtensionMember => false;
   bool get hasDefaultValue => false;
   InstanceMirror get defaultValue => null;
   SourceLocation get location => null;
@@ -1170,6 +1172,7 @@ class _MethodMirror extends _DeclarationMirror implements MethodMirror {
   static const kFactoryCtor = 7;
   static const kExternal = 8;
   static const kSynthetic = 9;
+  static const kExtensionMember = 10;
 
   // These offsets much be kept in sync with those in mirrors.h.
   bool get isAbstract => 0 != (_kindFlags & (1 << kAbstract));
@@ -1184,6 +1187,7 @@ class _MethodMirror extends _DeclarationMirror implements MethodMirror {
   bool get isFactoryConstructor => 0 != (_kindFlags & (1 << kFactoryCtor));
   bool get isExternal => 0 != (_kindFlags & (1 << kExternal));
   bool get isSynthetic => 0 != (_kindFlags & (1 << kSynthetic));
+  bool get isExtensionMember => 0 != (_kindFlags & (1 << kExtensionMember));
 
   static const _operators = const [
     "%", "&", "*", "+", "-", "/", "<", "<<", //
@@ -1283,9 +1287,10 @@ class _VariableMirror extends _DeclarationMirror implements VariableMirror {
   final bool isStatic;
   final bool isFinal;
   final bool isConst;
+  final bool isExtensionMember;
 
   _VariableMirror._(reflectee, String simpleName, this.owner, this._type,
-      this.isStatic, this.isFinal, this.isConst)
+      this.isStatic, this.isFinal, this.isConst, this.isExtensionMember)
       : super._(reflectee, _s(simpleName));
 
   bool get isTopLevel => owner is LibraryMirror;
@@ -1341,7 +1346,8 @@ class _ParameterMirror extends _VariableMirror implements ParameterMirror {
             null, // We override the type.
             false, // isStatic does not apply.
             isFinal,
-            false // Not const.
+            false, // Not const.
+            false // Not extension member.
             );
 
   Object _defaultValueReflectee;

sdk_nnbd/lib/mirrors/mirrors.dart

@@ -1072,6 +1072,11 @@ abstract class MethodMirror implements DeclarationMirror {
    */
   bool get isFactoryConstructor;
 
+  /**
+   * Is the reflectee an extension method?
+   */
+  bool get isExtensionMember;
+
   /**
    * Whether this mirror is equal to [other].
    *
@@ -1113,6 +1118,11 @@ abstract class VariableMirror implements DeclarationMirror {
    */
   bool get isConst;
 
+  /**
+   * Is the reflectee an extension member?
+   */
+  bool get isExtensionMember;
+
   /**
    * Whether this mirror is equal to [other].
    *

tests/lib_2/mirrors/method_mirror_extension_test.dart

@@ -0,0 +1,124 @@
+// Copyright (c) 2019, 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.
+
+// SharedOptions=--enable-experiment=extension-methods
+
+library lib;
+
+import "dart:mirrors";
+
+import "package:expect/expect.dart";
+
+class C<T> {
+  static int tracefunc() {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+    return 10;
+  }
+}
+
+extension ext<T> on C<T> {
+  func() {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  get prop {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  set prop(value) {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  operator +(val) {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  operator -(val) {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  static int sfld = C.tracefunc();
+  static sfunc() {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  static get sprop {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+
+  static set sprop(value) {
+    try {
+      throw "producing a stack trace";
+    } catch (e, s) {
+      print(s);
+    }
+  }
+}
+
+checkExtensionKind(closure, kind) {
+  var closureMirror = reflect(closure) as ClosureMirror;
+  var methodMirror = closureMirror.function;
+  Expect.equals(kind, methodMirror.isExtensionMember, "isExtension");
+}
+
+void testExtension(sym, mirror) {
+  if (mirror is MethodMirror) {
+    var methodMirror = mirror as MethodMirror;
+    if (MirrorSystem.getName(sym).startsWith('ext', 0)) {
+      Expect.equals(true, methodMirror.isExtensionMember, "isExtension");
+    } else {
+      Expect.equals(false, methodMirror.isExtensionMember, "isExtension");
+    }
+  } else if (mirror is VariableMirror) {
+    var variableMirror = mirror as VariableMirror;
+    if (MirrorSystem.getName(sym).startsWith('ext', 0)) {
+      Expect.equals(true, variableMirror.isExtensionMember, "isExtension");
+    } else {
+      Expect.equals(false, variableMirror.isExtensionMember, "isExtension");
+    }
+  }
+}
+
+main() {
+  checkExtensionKind(C.tracefunc, false);
+
+  C c = new C();
+  checkExtensionKind(c.func, true);
+  checkExtensionKind(ext.sfunc, true);
+
+  var libraryMirror = reflectClass(C).owner as LibraryMirror;
+  libraryMirror.declarations.forEach(testExtension);
+}

tests/lib_2/mirrors/method_mirror_properties_test.dart

@@ -43,6 +43,7 @@ checkKinds(method, kinds) {
   Expect.equals(kinds[2], method.isGetter, "isGetter");
   Expect.equals(kinds[3], method.isSetter, "isSetter");
   Expect.equals(kinds[4], method.isConstructor, "isConstructor");
+  Expect.equals(false, method.isExtensionMember, "isExtension");
 }
 
 main() {