[cfe] Generate TypedefTearOff nodes on the output

Change-Id: I4b4a25137bffb0fa284a94908b05fef9b9e5c5da
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206370
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: Dmitry Stefantsov

pkg/front_end/lib/src/fasta/kernel/expression_generator.dart

@@ -11,6 +11,7 @@ import 'package:_fe_analyzer_shared/src/parser/parser.dart'
 import 'package:_fe_analyzer_shared/src/scanner/token.dart' show Token;
 
 import 'package:kernel/ast.dart';
+import 'package:kernel/type_algebra.dart';
 
 import '../builder/builder.dart';
 import '../builder/class_builder.dart';
@@ -24,6 +25,7 @@ import '../builder/prefix_builder.dart';
 import '../builder/type_alias_builder.dart';
 import '../builder/type_builder.dart';
 import '../builder/type_declaration_builder.dart';
+import '../builder/type_variable_builder.dart';
 import '../builder/unresolved_type.dart';
 
 import '../constant_context.dart' show ConstantContext;
@@ -3099,6 +3101,7 @@ class TypeUseGenerator extends AbstractReadOnlyAccessGenerator {
     TypeDeclarationBuilder? declarationBuilder = declaration;
     TypeAliasBuilder? aliasBuilder;
     List<TypeBuilder>? unaliasedTypeArguments;
+    bool isGenericTypedefTearOff = false;
     if (declarationBuilder is TypeAliasBuilder) {
       aliasBuilder = declarationBuilder;
       declarationBuilder = aliasBuilder.unaliasDeclaration(null,
@@ -3129,6 +3132,19 @@ class TypeUseGenerator extends AbstractReadOnlyAccessGenerator {
                   ..fileUri = _uri
                   ..offset = fileOffset);
           }
+          if (aliasedTypeArguments == null &&
+              aliasBuilder.typeVariablesCount != 0) {
+            isGenericTypedefTearOff = true;
+            aliasedTypeArguments = <TypeBuilder>[];
+            for (TypeVariableBuilder typeVariable
+                in aliasBuilder.typeVariables!) {
+              aliasedTypeArguments.add(new NamedTypeBuilder(typeVariable.name,
+                  const NullabilityBuilder.omitted(), null, _uri, fileOffset)
+                ..bind(typeVariable));
+            }
+          }
+          unaliasedTypeArguments =
+              aliasBuilder.unaliasTypeArguments(aliasedTypeArguments);
         }
       }
     }
@@ -3177,10 +3193,31 @@ class TypeUseGenerator extends AbstractReadOnlyAccessGenerator {
                 builtTypeArguments =
                     _helper.buildDartTypeArguments(typeArguments);
               }
-              return builtTypeArguments != null && builtTypeArguments.isNotEmpty
-                  ? _helper.forest.createInstantiation(
-                      token.charOffset, tearOffExpression, builtTypeArguments)
-                  : tearOffExpression;
+              if (isGenericTypedefTearOff) {
+                FreshTypeParameters freshTypeParameters =
+                    getFreshTypeParameters(
+                        aliasBuilder!.typedef.typeParameters);
+                List<DartType>? substitutedTypeArguments;
+                if (builtTypeArguments != null) {
+                  substitutedTypeArguments = <DartType>[];
+                  for (DartType builtTypeArgument in builtTypeArguments) {
+                    substitutedTypeArguments
+                        .add(freshTypeParameters.substitute(builtTypeArgument));
+                  }
+                }
+                tearOffExpression = _helper.forest.createTypedefTearOff(
+                    token.charOffset,
+                    freshTypeParameters.freshTypeParameters,
+                    tearOffExpression,
+                    substitutedTypeArguments ?? const <DartType>[]);
+              } else {
+                if (builtTypeArguments != null &&
+                    builtTypeArguments.isNotEmpty) {
+                  tearOffExpression = _helper.forest.createInstantiation(
+                      token.charOffset, tearOffExpression, builtTypeArguments);
+                }
+              }
+              return tearOffExpression;
             }
           }
           generator = new UnresolvedNameGenerator(_helper, send.token, name);

pkg/front_end/lib/src/fasta/kernel/forest.dart

@@ -846,6 +846,17 @@ class Forest {
     return new Instantiation(expression, typeArguments)
       ..fileOffset = fileOffset;
   }
+
+  TypedefTearOff createTypedefTearOff(
+      int fileOffset,
+      List<TypeParameter> typeParameters,
+      Expression expression,
+      List<DartType> typeArguments) {
+    // ignore: unnecessary_null_comparison
+    assert(fileOffset != null);
+    return new TypedefTearOff(typeParameters, expression, typeArguments)
+      ..fileOffset = fileOffset;
+  }
 }
 
 class _VariablesDeclaration extends Statement {

pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart

@@ -7,7 +7,7 @@ import 'package:_fe_analyzer_shared/src/util/link.dart';
 import 'package:front_end/src/api_prototype/lowering_predicates.dart';
 import 'package:kernel/ast.dart';
 import 'package:kernel/src/legacy_erasure.dart';
-import 'package:kernel/type_algebra.dart' show Substitution;
+import 'package:kernel/type_algebra.dart';
 import 'package:kernel/type_environment.dart';
 
 import '../../base/instrumentation.dart'
@@ -225,7 +225,37 @@ class InferenceVisitor
   @override
   ExpressionInferenceResult visitTypedefTearOff(
       TypedefTearOff node, DartType typeContext) {
-    return _unhandledExpression(node, typeContext);
+    ExpressionInferenceResult expressionResult = inferrer.inferExpression(
+        node.expression, const UnknownType(), true,
+        isVoidAllowed: true);
+    node.expression = expressionResult.expression..parent = node;
+
+    assert(
+        expressionResult.inferredType is FunctionType,
+        "Expected a FunctionType from tearing off a constructor from "
+        "a typedef, but got '${expressionResult.inferredType.runtimeType}'.");
+    FunctionType expressionType = expressionResult.inferredType as FunctionType;
+
+    assert(expressionType.typeParameters.length == node.typeArguments.length);
+    Substitution substitution = Substitution.fromPairs(
+        expressionType.typeParameters, node.typeArguments);
+    FunctionType resultType = substitution
+        .substituteType(expressionType.withoutTypeParameters) as FunctionType;
+    FreshTypeParameters freshTypeParameters =
+        getFreshTypeParameters(node.typeParameters);
+    resultType = freshTypeParameters.substitute(resultType) as FunctionType;
+    resultType = new FunctionType(resultType.positionalParameters,
+        resultType.returnType, resultType.declaredNullability,
+        namedParameters: resultType.namedParameters,
+        typeParameters: freshTypeParameters.freshTypeParameters,
+        requiredParameterCount: resultType.requiredParameterCount,
+        typedefType: null);
+    ExpressionInferenceResult inferredResult =
+        inferrer.instantiateTearOff(resultType, typeContext, node);
+    Expression ensuredResultExpression =
+        inferrer.ensureAssignableResult(typeContext, inferredResult);
+    return new ExpressionInferenceResult(
+        inferredResult.inferredType, ensuredResultExpression);
   }
 
   @override

pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart

@@ -45,7 +45,9 @@ B<num> Function() test18() => DB3<num, String>.new; // Ok.
 B<num> Function() test19() => DB3<num, String>.foo; // Ok.
 B<num> Function() test20() => DB3<num, String>.bar; // Ok.
 B<num> Function() test21() => DB3.new; // Ok.
-B<Y> Function<Y extends num, Z extends String>() test22() => DB2.new; // Ok.
-B<Y> Function<Y, Z>() test23() => DB2.new; // Error.
+B<Y> Function<Y extends num, Z extends String>() test22() => DB3.new; // Ok.
+B<Y> Function<Y, Z>() test23() => DB3.new; // Error.
+
+B<String> Function() test24() => DB2.new; // Ok.
 
 main() {}

pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart.strong.expect

@@ -15,24 +15,24 @@ library /*isNonNullableByDefault*/;
 // B<num> Function() test9() => DB1.new; // Error.
 //                              ^
 //
-// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:41:44: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y extends num>()'.
+// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:42:32: Error: A value of type 'B<X> Function<X extends num>()' can't be assigned to a variable of type 'B<Y> Function<Y>()'.
 //  - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
-// B<Y> Function<Y extends num>() test16() => DB2.new; // Ok.
-//                                            ^
+// B<Y> Function<Y>() test17() => DB2.new; // Error.
+//                                ^
 //
-// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:42:32: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y>()'.
+// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:42:32: Error: A value of type 'B<X> Function<X extends num>()' can't be returned from a function with return type 'B<Y> Function<Y>()'.
 //  - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
 // B<Y> Function<Y>() test17() => DB2.new; // Error.
 //                                ^
 //
-// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:48:62: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y extends num, Z extends String>()'.
+// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:49:35: Error: A value of type 'B<X> Function<X extends num, Y extends String>()' can't be assigned to a variable of type 'B<Y> Function<Y, Z>()'.
 //  - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
-// B<Y> Function<Y extends num, Z extends String>() test22() => DB2.new; // Ok.
-//                                                              ^
+// B<Y> Function<Y, Z>() test23() => DB3.new; // Error.
+//                                   ^
 //
-// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:49:35: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y, Z>()'.
+// pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:49:35: Error: A value of type 'B<X> Function<X extends num, Y extends String>()' can't be returned from a function with return type 'B<Y> Function<Y, Z>()'.
 //  - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
-// B<Y> Function<Y, Z>() test23() => DB2.new; // Error.
+// B<Y> Function<Y, Z>() test23() => DB3.new; // Error.
 //                                   ^
 //
 import self as self;
@@ -63,9 +63,9 @@ static method test1() → () → self::A
 static method test2() → () → self::A
   return self::A::•;
 static method test3() → () → self::A
-  return self::A::•;
+  return <unrelated X extends core::num>.(self::A::•)<core::num>;
 static method test4() → () → self::A
-  return self::A::•;
+  return <unrelated X extends core::num>.(self::A::•)<core::num>;
 static method test5() → () → self::A
   return self::A::•;
 static method test6() → () → self::A
@@ -90,33 +90,35 @@ static method test13() → () → self::B<core::num>
 static method test14() → () → self::B<core::num>
   return self::B::bar<core::num>;
 static method test15() → () → self::B<core::num>
-  return self::B::•<core::num>;
+  return <X extends core::num>.(self::B::•<X>)<core::num>;
 static method test16() → <Y extends core::num = dynamic>() → self::B<Y>
-  return let final Never #t2 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:41:44: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y extends num>()'.
- - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
-B<Y> Function<Y extends num>() test16() => DB2.new; // Ok.
-                                           ^" in (self::B::•<core::num>) as{TypeError,ForNonNullableByDefault} <Y extends core::num = dynamic>() → self::B<Y>;
+  return <X extends core::num>.(self::B::•<X>);
 static method test17() → <Y extends core::Object? = dynamic>() → self::B<Y%>
-  return let final Never #t3 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:42:32: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y>()'.
+  return let final Never #t2 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:42:32: Error: A value of type 'B<X> Function<X extends num>()' can't be returned from a function with return type 'B<Y> Function<Y>()'.
+ - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
+B<Y> Function<Y>() test17() => DB2.new; // Error.
+                               ^" in (let final Never #t3 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:42:32: Error: A value of type 'B<X> Function<X extends num>()' can't be assigned to a variable of type 'B<Y> Function<Y>()'.
  - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
 B<Y> Function<Y>() test17() => DB2.new; // Error.
-                               ^" in (self::B::•<core::num>) as{TypeError,ForNonNullableByDefault} <Y extends core::Object? = dynamic>() → self::B<Y%>;
+                               ^" in (<X extends core::num>.(self::B::•<X>)) as{TypeError,ForNonNullableByDefault} <Y extends core::Object? = dynamic>() → self::B<Y%>) as{TypeError,ForNonNullableByDefault} <Y extends core::Object? = dynamic>() → self::B<Y%>;
 static method test18() → () → self::B<core::num>
   return self::B::•<core::num>;
 static method test19() → () → self::B<core::num>
   return self::B::foo<core::num>;
 static method test20() → () → self::B<core::num>
   return self::B::bar<core::num>;
 static method test21() → () → self::B<core::num>
-  return self::B::•<core::num>;
+  return <X extends core::num, unrelated Y extends core::String>.(self::B::•<X>)<core::num, core::String>;
 static method test22() → <Y extends core::num = dynamic, Z extends core::String = dynamic>() → self::B<Y>
-  return let final Never #t4 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:48:62: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y extends num, Z extends String>()'.
- - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
-B<Y> Function<Y extends num, Z extends String>() test22() => DB2.new; // Ok.
-                                                             ^" in (self::B::•<core::num>) as{TypeError,ForNonNullableByDefault} <Y extends core::num = dynamic, Z extends core::String = dynamic>() → self::B<Y>;
+  return <X extends core::num, unrelated Y extends core::String>.(self::B::•<X>);
 static method test23() → <Y extends core::Object? = dynamic, Z extends core::Object? = dynamic>() → self::B<Y%>
-  return let final Never #t5 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:49:35: Error: A value of type 'B<num> Function()' can't be returned from a function with return type 'B<Y> Function<Y, Z>()'.
+  return let final Never #t4 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:49:35: Error: A value of type 'B<X> Function<X extends num, Y extends String>()' can't be returned from a function with return type 'B<Y> Function<Y, Z>()'.
+ - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
+B<Y> Function<Y, Z>() test23() => DB3.new; // Error.
+                                  ^" in (let final Never #t5 = invalid-expression "pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart:49:35: Error: A value of type 'B<X> Function<X extends num, Y extends String>()' can't be assigned to a variable of type 'B<Y> Function<Y, Z>()'.
  - 'B' is from 'pkg/front_end/testcases/constructor_tearoffs/typedef_tearoffs.dart'.
-B<Y> Function<Y, Z>() test23() => DB2.new; // Error.
-                                  ^" in (self::B::•<core::num>) as{TypeError,ForNonNullableByDefault} <Y extends core::Object? = dynamic, Z extends core::Object? = dynamic>() → self::B<Y%>;
+B<Y> Function<Y, Z>() test23() => DB3.new; // Error.
+                                  ^" in (<X extends core::num, unrelated Y extends core::String>.(self::B::•<X>)) as{TypeError,ForNonNullableByDefault} <Y extends core::Object? = dynamic, Z extends core::Object? = dynamic>() → self::B<Y%>) as{TypeError,ForNonNullableByDefault} <Y extends core::Object? = dynamic, Z extends core::Object? = dynamic>() → self::B<Y%>;
+static method test24() → () → self::B<core::String>
+  return <X extends core::num>.(self::B::•<X>)<Never>;
 static method main() → dynamic {}