[cfe] Build extension methods as toplevel members

+ add an 'isExtensionMethod' property to Procedure.

Change-Id: I8fb1af1802570c827bf3ccbbb9d710eb2a6981ab
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/112081
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

Author: johnniwinther

pkg/front_end/lib/src/fasta/builder/procedure_builder.dart

@@ -488,6 +488,15 @@ class ProcedureBuilder extends FunctionBuilder {
     return false;
   }
 
+  /// Returns `true` if this procedure is declared in an extension declaration.
+  bool get isExtensionMethod {
+    if (parent is ClassBuilder) {
+      ClassBuilder cls = parent;
+      return cls.isExtension;
+    }
+    return false;
+  }
+
   Procedure build(SourceLibraryBuilder library) {
     // TODO(ahe): I think we may call this twice on parts. Investigate.
     if (procedure.name == null) {
@@ -496,10 +505,18 @@ class ProcedureBuilder extends FunctionBuilder {
       procedure.function.fileOffset = charOpenParenOffset;
       procedure.function.fileEndOffset = procedure.fileEndOffset;
       procedure.isAbstract = isAbstract;
-      procedure.isStatic = isStatic;
       procedure.isExternal = isExternal;
       procedure.isConst = isConst;
-      procedure.name = new Name(name, library.target);
+      if (isExtensionMethod) {
+        ClassBuilder extension = parent;
+        procedure.isStatic = false;
+        procedure.isExtensionMethod = true;
+        procedure.kind = ProcedureKind.Method;
+        procedure.name = new Name('${extension.name}|${name}', library.target);
+      } else {
+        procedure.isStatic = isStatic;
+        procedure.name = new Name(name, library.target);
+      }
     }
     return procedure;
   }

pkg/front_end/lib/src/fasta/source/source_class_builder.dart

@@ -130,9 +130,13 @@ class SourceClassBuilder extends ClassBuilder
           }
         } else if (declaration is FunctionBuilder) {
           Member function = declaration.build(library);
-          function.parent = cls;
-          if (!declaration.isPatch && declaration.next == null) {
-            cls.addMember(function);
+          if (isExtension) {
+            library.target.addMember(function);
+          } else {
+            function.parent = cls;
+            if (!declaration.isPatch && declaration.next == null) {
+              cls.addMember(function);
+            }
           }
         } else {
           unhandled("${declaration.runtimeType}", "buildBuilders",

pkg/front_end/lib/src/testing/id_testing_utils.dart

@@ -104,22 +104,36 @@ ClassBuilder lookupClassBuilder(CompilerResult compilerResult, Class cls,
   return clsBuilder;
 }
 
+/// Look up the [MemberBuilder] for [member] through the [ClassBuilder] for
+/// [cls] using [memberName] as its name.
+MemberBuilder lookupClassMemberBuilder(
+    CompilerResult compilerResult, Class cls, Member member, String memberName,
+    {bool required: true}) {
+  ClassBuilder classBuilder =
+      lookupClassBuilder(compilerResult, cls, required: required);
+  MemberBuilder memberBuilder;
+  if (classBuilder != null) {
+    if (member is Constructor) {
+      memberBuilder = classBuilder.constructors.local[memberName];
+    } else if (member is Procedure && member.isSetter) {
+      memberBuilder = classBuilder.scope.setters[memberName];
+    } else {
+      memberBuilder = classBuilder.scope.local[memberName];
+    }
+  }
+  if (memberBuilder == null && required) {
+    throw new ArgumentError("MemberBuilder for $member not found.");
+  }
+  return memberBuilder;
+}
+
 MemberBuilder lookupMemberBuilder(CompilerResult compilerResult, Member member,
     {bool required: true}) {
   MemberBuilder memberBuilder;
   if (member.enclosingClass != null) {
-    ClassBuilder classBuilder = lookupClassBuilder(
-        compilerResult, member.enclosingClass,
+    memberBuilder = lookupClassMemberBuilder(
+        compilerResult, member.enclosingClass, member, member.name.name,
         required: required);
-    if (classBuilder != null) {
-      if (member is Constructor) {
-        memberBuilder = classBuilder.constructors.local[member.name.name];
-      } else if (member is Procedure && member.isSetter) {
-        memberBuilder = classBuilder.scope.setters[member.name.name];
-      } else {
-        memberBuilder = classBuilder.scope.local[member.name.name];
-      }
-    }
   } else {
     DeclarationBuilder libraryBuilder = lookupLibraryDeclarationBuilder(
         compilerResult, member.enclosingLibrary);

pkg/front_end/test/extensions/data/explicit_this.dart

@@ -15,26 +15,26 @@ class A1 {
  cls-supertype=Object
 */
 extension A2 on A1 {
-  /*member: A2.method2:
+  /*member: A2|method2:
     builder-name=method2,
     builder-params=[#this],
-    member-name=method2,
+    member-name=A2|method2,
     member-params=[#this]
   */
   void method2() => this.method1();
 
-  /*member: A2.method3:
+  /*member: A2|method3:
    builder-name=method3,
    builder-params=[#this],
-   member-name=method3,
+   member-name=A2|method3,
    member-params=[#this]
  */
   Object method3() => this.field;
 
-  /*member: A2.method4:
+  /*member: A2|method4:
      builder-name=method4,
      builder-params=[#this,o],
-     member-name=method4,
+     member-name=A2|method4,
      member-params=[#this,o]
     */
   void method4(Object o) {

pkg/front_end/test/extensions/data/extension_on_type_variable.dart

@@ -12,11 +12,11 @@
  cls-type-params=[T]
 */
 extension GeneralGeneric<T> on T {
-  /*member: GeneralGeneric.method:
+  /*member: GeneralGeneric|method:
    builder-name=method,
    builder-params=[#this],
    builder-type-params=[T],
-   member-name=method,
+   member-name=GeneralGeneric|method,
    member-params=[#this],
    member-type-params=[#T]
   */

pkg/front_end/test/extensions/data/implicit_this.dart

@@ -15,26 +15,26 @@ class A1 {
  cls-supertype=Object
 */
 extension A2 on A1 {
-  /*member: A2.method2:
+  /*member: A2|method2:
    builder-name=method2,
    builder-params=[#this],
-   member-name=method2,
+   member-name=A2|method2,
    member-params=[#this]
   */
   void method2() => method1();
 
-  /*member: A2.method3:
+  /*member: A2|method3:
    builder-name=method3,
    builder-params=[#this],
-   member-name=method3,
+   member-name=A2|method3,
    member-params=[#this]
   */
   Object method3() => field;
 
-  /*member: A2.method4:
+  /*member: A2|method4:
    builder-name=method4,
    builder-params=[#this,o],
-   member-name=method4,
+   member-name=A2|method4,
    member-params=[#this,o]
   */
   void method4(Object o) {

pkg/front_end/test/extensions/data/instance_members.dart

@@ -12,21 +12,21 @@ class A1 {}
  cls-supertype=Object
 */
 extension A2 on A1 {
-  /*member: A2.method1:
+  /*member: A2|method1:
      builder-name=method1,
      builder-params=[#this],
-     member-name=method1,
+     member-name=A2|method1,
      member-params=[#this]
   */
   A1 method1() {
     return this;
   }
 
-  /*member: A2.method2:
+  /*member: A2|method2:
      builder-name=method2,
      builder-params=[#this,o],
      builder-type-params=[T],
-     member-name=method2,
+     member-name=A2|method2,
      member-params=[#this,o],
      member-type-params=[T]
   */
@@ -35,12 +35,12 @@ extension A2 on A1 {
     return this;
   }
 
-  /*member: A2.method3:
+  /*member: A2|method3:
      builder-name=method3,
      builder-params=[#this],
      builder-pos-params=[o],
      builder-type-params=[T],
-     member-name=method3,
+     member-name=A2|method3,
      member-params=[#this],
      member-pos-params=[o],
      member-type-params=[T]
@@ -50,12 +50,12 @@ extension A2 on A1 {
     return this;
   }
 
-  /*member: A2.method4:
+  /*member: A2|method4:
      builder-name=method4,
      builder-params=[#this],
      builder-named-params=[o],
      builder-type-params=[T],
-     member-name=method4,
+     member-name=A2|method4,
      member-params=[#this],
      member-named-params=[o],
      member-type-params=[T]
@@ -78,23 +78,23 @@ class B1<T> {}
  cls-type-params=[T]
 */
 extension B2<T> on B1<T> {
-  /*member: B2.method1:
+  /*member: B2|method1:
      builder-name=method1,
      builder-params=[#this],
      builder-type-params=[T],
-     member-name=method1,
+     member-name=B2|method1,
      member-params=[#this],
      member-type-params=[#T]
   */
   B1<T> method1() {
     return this;
   }
 
-  /*member: B2.method2:
+  /*member: B2|method2:
      builder-name=method2,
      builder-params=[#this,o],
      builder-type-params=[T,S],
-     member-name=method2,
+     member-name=B2|method2,
      member-params=[#this,o],
      member-type-params=[#T,S]
   */

pkg/front_end/test/extensions/data/static_members.dart

@@ -12,19 +12,19 @@ class A1 {}
  cls-supertype=Object
 */
 extension A2 on A1 {
-  /*member: A2.method1:
+  /*member: A2|method1:
      builder-name=method1,
      builder-params=[o],
-     member-name=method1,
+     member-name=A2|method1,
      member-params=[o]
   */
   static A1 method1(A1 o) => o;
 
-  /*member: A2.method2:
+  /*member: A2|method2:
      builder-name=method2,
      builder-params=[o],
      builder-type-params=[T],
-     member-name=method2,
+     member-name=A2|method2,
      member-params=[o],
      member-type-params=[T]
   */
@@ -43,19 +43,19 @@ class B1<T> {}
  cls-type-params=[T]
 */
 extension B2<T> on B1<T> {
-  /*member: B2.method1:
+  /*member: B2|method1:
      builder-name=method1,
      builder-params=[o],
-     member-name=method1,
+     member-name=B2|method1,
      member-params=[o]
   */
   static B1 method1(B1 o) => o;
 
-  /*member: B2.method2:
+  /*member: B2|method2:
      builder-name=method2,
      builder-params=[o],
      builder-type-params=[S],
-     member-name=method2,
+     member-name=B2|method2,
      member-params=[o],
      member-type-params=[S]
   */

pkg/front_end/test/extensions/data/super.dart

@@ -14,10 +14,10 @@ class A1 {
  cls-supertype=Object
 */
 extension A2 on A1 {
-  /*member: A2.method2:
+  /*member: A2|method2:
    builder-name=method2,
    builder-params=[#this],
-   member-name=method2,
+   member-name=A2|method2,
    member-params=[#this]
   */
   method2() {

pkg/front_end/test/extensions/data/type_variables.dart

@@ -14,23 +14,23 @@ class A1<T> {}
  cls-type-params=[T]
 */
 extension A2<T> on A1<T> {
-  /*member: A2.method1:
+  /*member: A2|method1:
      builder-name=method1,
      builder-params=[#this],
      builder-type-params=[T,S extends T],
-     member-name=method1,
+     member-name=A2|method1,
      member-params=[#this],
      member-type-params=[#T,S extends #T]
   */
   A1<T> method1<S extends T>() {
     return this;
   }
 
-  /*member: A2.method2:
+  /*member: A2|method2:
      builder-name=method2,
      builder-params=[#this,o],
      builder-type-params=[T,S extends A1<T>],
-     member-name=method2,
+     member-name=A2|method2,
      member-params=[#this,o],
      member-type-params=[#T,S extends A1<#T>]
   */