[cfe] Dot Shorthands: Handle constructor tearoffs.

This CL adds support for constructor tearoffs in dot shorthands. If there's any type parameters on the tearoff and it's a constructor, we produce an error.

I also updated the expectations of existing tests due to an early return of `InvalidExpression`s and added language + cfe tests for the new behavior.

This CL fixes the following co19 tests and is a follow up to dart-lang/co19#3122
co19/LanguageFeatures/Static-access-shorthand/constant_expression_A03_t01
co19/LanguageFeatures/Static-access-shorthand/constant_expression_A04_t01
co19/LanguageFeatures/Static-access-shorthand/semantics_A05_t01
co19/LanguageFeatures/Static-access-shorthand/constant_expression_A03_t02

Bug: #59758, dart-lang/co19#3122
Change-Id: I1ea837342ad818cd3b1de9e422065f42e8a61d6b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/419782
Commit-Queue: Kallen Tu <[email protected]>
Reviewed-by: Chloe Stefantsova <[email protected]>

Author: kallentu

pkg/front_end/lib/src/kernel/body_builder.dart

@@ -9323,6 +9323,9 @@ class BodyBuilder extends StackListenerImpl
         pop() as List<TypeBuilder>?; // typeArguments
     if (libraryFeatures.constructorTearoffs.isEnabled) {
       Object? operand = pop();
+      if (operand is DotShorthandPropertyGet && typeArguments != null) {
+        operand.hasTypeParameters = true;
+      }
       if (operand is Generator) {
         push(operand.applyTypeArguments(
             openAngleBracket.charOffset, typeArguments));

pkg/front_end/lib/src/kernel/internal_ast.dart

@@ -3293,7 +3293,14 @@ class DotShorthandPropertyGet extends InternalExpression {
   final Name name;
   final int nameOffset;
 
-  DotShorthandPropertyGet(this.name, {required this.nameOffset});
+  /// Whether this dot shorthand has type parameters.
+  ///
+  /// Used for error checking for constructors with type parameters in the
+  /// [InferenceVisitor].
+  bool hasTypeParameters;
+
+  DotShorthandPropertyGet(this.name,
+      {required this.nameOffset, this.hasTypeParameters = false});
 
   @override
   ExpressionInferenceResult acceptInference(

pkg/front_end/lib/src/type_inference/inference_visitor.dart

@@ -697,6 +697,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
     ExpressionInferenceResult operandResult = inferExpression(
         node.expression, const UnknownType(),
         isVoidAllowed: true);
+    if (operandResult.expression is InvalidExpression) return operandResult;
     Expression operand = operandResult.expression;
     DartType operandType = operandResult.inferredType;
     if (operandType is! FunctionType) {
@@ -12289,12 +12290,42 @@ class InferenceVisitorImpl extends InferenceVisitorBase
           expressionInferenceResult =
               inferExpression(new StaticGet(member), cachedContext);
         } else {
-          // Tearoff like `Object.new`;
-          expressionInferenceResult =
-              inferExpression(new StaticTearOff(member), cachedContext);
+          // Method tearoffs.
+          DartType type =
+              member.function.computeFunctionType(Nullability.nonNullable);
+          return instantiateTearOff(
+              type, typeContext, new StaticTearOff(member));
         }
       case Constructor():
       case null:
+        // Handle constructor tearoffs.
+        if (cachedContext is TypeDeclarationType) {
+          Member? constructor = findConstructor(
+              cachedContext, node.name, node.fileOffset,
+              isTearoff: true);
+          // Dot shorthand constructor invocations with type parameters
+          // `.id<type>()` are not allowed.
+          if (constructor != null && node.hasTypeParameters) {
+            return new ExpressionInferenceResult(
+                const DynamicType(),
+                helper.buildProblem(
+                    messageDotShorthandsConstructorInvocationWithTypeArguments,
+                    node.nameOffset,
+                    node.name.text.length));
+          }
+          if (constructor is Constructor) {
+            DartType type = constructor.function
+                .computeFunctionType(Nullability.nonNullable);
+            return instantiateTearOff(
+                type, typeContext, new ConstructorTearOff(constructor));
+          } else if (constructor is Procedure) {
+            DartType type = constructor.function
+                .computeFunctionType(Nullability.nonNullable);
+            return instantiateTearOff(
+                type, typeContext, new StaticTearOff(constructor));
+          }
+        }
+
         if (isKnown(cachedContext)) {
           // Error when we can't find the static getter or field [node.name] in
           // the declaration of [cachedContext].

pkg/front_end/lib/src/type_inference/inference_visitor_base.dart

@@ -1148,7 +1148,8 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
   }
 
   /// Finds a constructor of [type] called [name].
-  Member? findConstructor(TypeDeclarationType type, Name name, int fileOffset) {
+  Member? findConstructor(TypeDeclarationType type, Name name, int fileOffset,
+      {bool isTearoff = false}) {
     // TODO(Dart Model team): Seems like an abstraction level issue to require
     // going from `Class` objects back to builders to find a `Member`.
     DeclarationBuilder builder;
@@ -1164,7 +1165,9 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
 
     MemberBuilder? constructorBuilder = builder.findConstructorOrFactory(
         name.text, fileOffset, helper.uri, libraryBuilder);
-    return constructorBuilder?.invokeTarget;
+    return isTearoff
+        ? constructorBuilder?.readTarget
+        : constructorBuilder?.invokeTarget;
   }
 
   /// Finds a member of [receiverType] called [name], and if it is found,

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

@@ -179,11 +179,6 @@ library;
 //   Class<int><int>.named<int>;
 //                   ^^^^^
 //
-// pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:24: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-// Try changing the operand or remove the type arguments.
-//   Class<int><int>.named<int>;
-//                        ^
-//
 // pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:22:8: Error: The operator '<' isn't defined for the class 'Type'.
 //  - 'Type' is from 'dart:core'.
 // Try correcting the operator to an existing operator, or defining a '<' operator.
@@ -276,10 +271,11 @@ Try correcting the name to the name of an existing method, or defining a method
  - 'Type' is from 'dart:core'.
 Try correcting the operator to an existing operator, or defining a '<' operator.
   Class<int><int>.named<int>;
-       ^" in #C2{<unresolved>}.<(#C3){dynamic}.>(invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:24: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-Try changing the operand or remove the type arguments.
+       ^" in #C2{<unresolved>}.<(#C3){dynamic}.>(invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:19: Error: The getter 'named' isn't defined for the class 'List<int>'.
+ - 'List' is from 'dart:core'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'named'.
   Class<int><int>.named<int>;
-                       ^");
+                  ^^^^^" in <core::int>[]{<unresolved>}.named);
   invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:22:8: Error: The operator '<' isn't defined for the class 'Type'.
  - 'Type' is from 'dart:core'.
 Try correcting the operator to an existing operator, or defining a '<' operator.

pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart.strong.modular.expect

@@ -179,11 +179,6 @@ library;
 //   Class<int><int>.named<int>;
 //                   ^^^^^
 //
-// pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:24: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-// Try changing the operand or remove the type arguments.
-//   Class<int><int>.named<int>;
-//                        ^
-//
 // pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:22:8: Error: The operator '<' isn't defined for the class 'Type'.
 //  - 'Type' is from 'dart:core'.
 // Try correcting the operator to an existing operator, or defining a '<' operator.
@@ -276,10 +271,11 @@ Try correcting the name to the name of an existing method, or defining a method
  - 'Type' is from 'dart:core'.
 Try correcting the operator to an existing operator, or defining a '<' operator.
   Class<int><int>.named<int>;
-       ^" in #C2{<unresolved>}.<(#C3){dynamic}.>(invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:24: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-Try changing the operand or remove the type arguments.
+       ^" in #C2{<unresolved>}.<(#C3){dynamic}.>(invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:19: Error: The getter 'named' isn't defined for the class 'List<int>'.
+ - 'List' is from 'dart:core'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'named'.
   Class<int><int>.named<int>;
-                       ^");
+                  ^^^^^" in <core::int>[]{<unresolved>}.named);
   invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:22:8: Error: The operator '<' isn't defined for the class 'Type'.
  - 'Type' is from 'dart:core'.
 Try correcting the operator to an existing operator, or defining a '<' operator.

pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart.strong.transformed.expect

@@ -179,11 +179,6 @@ library;
 //   Class<int><int>.named<int>;
 //                   ^^^^^
 //
-// pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:24: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-// Try changing the operand or remove the type arguments.
-//   Class<int><int>.named<int>;
-//                        ^
-//
 // pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:22:8: Error: The operator '<' isn't defined for the class 'Type'.
 //  - 'Type' is from 'dart:core'.
 // Try correcting the operator to an existing operator, or defining a '<' operator.
@@ -276,10 +271,11 @@ Try correcting the name to the name of an existing method, or defining a method
  - 'Type' is from 'dart:core'.
 Try correcting the operator to an existing operator, or defining a '<' operator.
   Class<int><int>.named<int>;
-       ^" in #C2{<unresolved>}.<(#C3){dynamic}.>(invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:24: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-Try changing the operand or remove the type arguments.
+       ^" in #C2{<unresolved>}.<(#C3){dynamic}.>(invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:21:19: Error: The getter 'named' isn't defined for the class 'List<int>'.
+ - 'List' is from 'dart:core'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'named'.
   Class<int><int>.named<int>;
-                       ^");
+                  ^^^^^" in core::_GrowableList::•<core::int>(0){<unresolved>}.named);
   invalid-expression "pkg/front_end/testcases/constructor_tearoffs/duplicate_instantiation.dart:22:8: Error: The operator '<' isn't defined for the class 'Type'.
  - 'Type' is from 'dart:core'.
 Try correcting the operator to an existing operator, or defining a '<' operator.

pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart

@@ -7,8 +7,12 @@ class C {
   C.named();
 }
 
+extension type ET<T>(T v) {}
+
 void test() {
   C newConstructor = .new<int>();
   C namedConstructor = .named<int>();
   C newTearoff = .new<int>;
+  C namedTearoff = .new<int>;
+  ET e = .new<int>;
 }

pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart.strong.expect

@@ -2,26 +2,30 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:11:23: Error: A dot shorthand constructor invocation can't have type arguments.
+// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:13:23: Error: A dot shorthand constructor invocation can't have type arguments.
 // Try adding the class name and type arguments explicitly before the constructor name.
 //   C newConstructor = .new<int>();
 //                       ^^^
 //
-// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:12:25: Error: A dot shorthand constructor invocation can't have type arguments.
+// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:14:25: Error: A dot shorthand constructor invocation can't have type arguments.
 // Try adding the class name and type arguments explicitly before the constructor name.
 //   C namedConstructor = .named<int>();
 //                         ^^^^^
 //
-// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:13:19: Error: The static getter or field 'new' isn't defined for the type 'C'.
-//  - 'C' is from 'pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart'.
-// Try correcting the name to the name of an existing static getter or field, or defining a getter or field named 'new'.
+// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:15:19: Error: A dot shorthand constructor invocation can't have type arguments.
+// Try adding the class name and type arguments explicitly before the constructor name.
 //   C newTearoff = .new<int>;
 //                   ^^^
 //
-// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:13:22: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-// Try changing the operand or remove the type arguments.
-//   C newTearoff = .new<int>;
-//                      ^
+// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:16:21: Error: A dot shorthand constructor invocation can't have type arguments.
+// Try adding the class name and type arguments explicitly before the constructor name.
+//   C namedTearoff = .new<int>;
+//                     ^^^
+//
+// pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:17:11: Error: A dot shorthand constructor invocation can't have type arguments.
+// Try adding the class name and type arguments explicitly before the constructor name.
+//   ET e = .new<int>;
+//           ^^^
 //
 import self as self;
 import "dart:core" as core;
@@ -34,17 +38,36 @@ class C extends core::Object {
     : super core::Object::•()
     ;
 }
+extension type ET<T extends core::Object? = dynamic>(T% v) {
+  abstract extension-type-member representation-field get v() → T%;
+  constructor • = self::ET|constructor#;
+  constructor tearoff • = self::ET|constructor#_#new#tearOff;
+}
+static extension-type-member method ET|constructor#<T extends core::Object? = dynamic>(self::ET|constructor#::T% v) → self::ET<self::ET|constructor#::T%>% /* erasure=self::ET|constructor#::T%, declared=! */ {
+  lowered final self::ET<self::ET|constructor#::T%>% /* erasure=self::ET|constructor#::T%, declared=! */ #this = v;
+  return #this;
+}
+static extension-type-member method ET|constructor#_#new#tearOff<T extends core::Object? = dynamic>(self::ET|constructor#_#new#tearOff::T% v) → self::ET<self::ET|constructor#_#new#tearOff::T%>% /* erasure=self::ET|constructor#_#new#tearOff::T%, declared=! */
+  return self::ET|constructor#<self::ET|constructor#_#new#tearOff::T%>(v);
 static method test() → void {
-  self::C newConstructor = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:11:23: Error: A dot shorthand constructor invocation can't have type arguments.
+  self::C newConstructor = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:13:23: Error: A dot shorthand constructor invocation can't have type arguments.
 Try adding the class name and type arguments explicitly before the constructor name.
   C newConstructor = .new<int>();
                       ^^^" as{TypeError,ForDynamic} self::C;
-  self::C namedConstructor = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:12:25: Error: A dot shorthand constructor invocation can't have type arguments.
+  self::C namedConstructor = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:14:25: Error: A dot shorthand constructor invocation can't have type arguments.
 Try adding the class name and type arguments explicitly before the constructor name.
   C namedConstructor = .named<int>();
                         ^^^^^" as{TypeError,ForDynamic} self::C;
-  self::C newTearoff = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:13:22: Error: The static type of the explicit instantiation operand must be a generic function type but is 'dynamic'.
-Try changing the operand or remove the type arguments.
+  self::C newTearoff = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:15:19: Error: A dot shorthand constructor invocation can't have type arguments.
+Try adding the class name and type arguments explicitly before the constructor name.
   C newTearoff = .new<int>;
-                     ^";
+                  ^^^" as{TypeError,ForDynamic} self::C;
+  self::C namedTearoff = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:16:21: Error: A dot shorthand constructor invocation can't have type arguments.
+Try adding the class name and type arguments explicitly before the constructor name.
+  C namedTearoff = .new<int>;
+                    ^^^" as{TypeError,ForDynamic} self::C;
+  self::ET<dynamic>% /* erasure=dynamic, declared=! */ e = invalid-expression "pkg/front_end/testcases/dot_shorthands/constructor_type_parameter_error.dart:17:11: Error: A dot shorthand constructor invocation can't have type arguments.
+Try adding the class name and type arguments explicitly before the constructor name.
+  ET e = .new<int>;
+          ^^^" as{TypeError,ForDynamic} self::ET<dynamic>% /* erasure=dynamic, declared=! */;
 }