[cfe] Pass return type as part of callee type for invocation inference

Change-Id: I3b2f54fe73cc7f7c427e51e20cb60b25fc45f6bc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/156885
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

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

@@ -433,14 +433,12 @@ class InferenceVisitor
     inferrer.inferConstructorParameterTypes(node.target);
     bool hasExplicitTypeArguments =
         getExplicitTypeArguments(node.arguments) != null;
-    InvocationInferenceResult result = inferrer.inferInvocation(
-        typeContext,
-        node.fileOffset,
+    FunctionType functionType = replaceReturnType(
         node.target.function
             .computeThisFunctionType(inferrer.library.nonNullable),
-        node.arguments,
-        returnType:
-            computeConstructorReturnType(node.target, inferrer.coreTypes),
+        computeConstructorReturnType(node.target, inferrer.coreTypes));
+    InvocationInferenceResult result = inferrer.inferInvocation(
+        typeContext, node.fileOffset, functionType, node.arguments,
         isConst: node.isConst);
     if (!inferrer.isTopLevel) {
       SourceLibraryBuilder library = inferrer.library;
@@ -721,14 +719,14 @@ class InferenceVisitor
       FactoryConstructorInvocationJudgment node, DartType typeContext) {
     bool hadExplicitTypeArguments =
         getExplicitTypeArguments(node.arguments) != null;
-    InvocationInferenceResult result = inferrer.inferInvocation(
-        typeContext,
-        node.fileOffset,
+
+    FunctionType functionType = replaceReturnType(
         node.target.function
             .computeThisFunctionType(inferrer.library.nonNullable),
-        node.arguments,
-        returnType:
-            computeConstructorReturnType(node.target, inferrer.coreTypes),
+        computeConstructorReturnType(node.target, inferrer.coreTypes));
+
+    InvocationInferenceResult result = inferrer.inferInvocation(
+        typeContext, node.fileOffset, functionType, node.arguments,
         isConst: node.isConst);
     node.hasBeenInferred = true;
     Expression resultNode = node;
@@ -757,9 +755,10 @@ class InferenceVisitor
     FunctionType calleeType = node.target.function
         .computeAliasedConstructorFunctionType(
             typedef, inferrer.library.library);
+    calleeType = replaceReturnType(calleeType, calleeType.returnType.unalias);
     InvocationInferenceResult result = inferrer.inferInvocation(
         typeContext, node.fileOffset, calleeType, node.arguments,
-        returnType: calleeType.returnType.unalias, isConst: node.isConst);
+        isConst: node.isConst);
     node.hasBeenInferred = true;
     Expression resultNode = node;
     if (!inferrer.isTopLevel) {
@@ -784,9 +783,10 @@ class InferenceVisitor
     Typedef typedef = node.typeAliasBuilder.typedef;
     FunctionType calleeType = node.target.function
         .computeAliasedFactoryFunctionType(typedef, inferrer.library.library);
+    calleeType = replaceReturnType(calleeType, calleeType.returnType.unalias);
     InvocationInferenceResult result = inferrer.inferInvocation(
         typeContext, node.fileOffset, calleeType, node.arguments,
-        returnType: calleeType.returnType.unalias, isConst: node.isConst);
+        isConst: node.isConst);
     node.hasBeenInferred = true;
     Expression resultNode = node;
     if (!inferrer.isTopLevel) {
@@ -1133,14 +1133,13 @@ class InferenceVisitor
     Substitution substitution = Substitution.fromSupertype(
         inferrer.classHierarchy.getClassAsInstanceOf(
             inferrer.thisType.classNode, node.target.enclosingClass));
-    inferrer.inferInvocation(
-        null,
-        node.fileOffset,
+    FunctionType functionType = replaceReturnType(
         substitution.substituteType(node.target.function
             .computeThisFunctionType(inferrer.library.nonNullable)
             .withoutTypeParameters),
-        node.argumentsJudgment,
-        returnType: inferrer.thisType,
+        inferrer.thisType);
+    inferrer.inferInvocation(
+        null, node.fileOffset, functionType, node.argumentsJudgment,
         skipTypeArgumentInference: true);
   }
 
@@ -5013,14 +5012,13 @@ class InferenceVisitor
           classTypeParameters[i], inferrer.library.library);
     }
     ArgumentsImpl.setNonInferrableArgumentTypes(node.arguments, typeArguments);
-    inferrer.inferInvocation(
-        null,
-        node.fileOffset,
+    FunctionType functionType = replaceReturnType(
         node.target.function
             .computeThisFunctionType(inferrer.library.nonNullable),
-        node.arguments,
-        returnType: inferrer.coreTypes.thisInterfaceType(
-            node.target.enclosingClass, inferrer.library.nonNullable),
+        inferrer.coreTypes.thisInterfaceType(
+            node.target.enclosingClass, inferrer.library.nonNullable));
+    inferrer.inferInvocation(
+        null, node.fileOffset, functionType, node.arguments,
         skipTypeArgumentInference: true);
     ArgumentsImpl.removeNonInferrableArgumentTypes(node.arguments);
   }
@@ -5225,14 +5223,13 @@ class InferenceVisitor
     Substitution substitution = Substitution.fromSupertype(
         inferrer.classHierarchy.getClassAsInstanceOf(
             inferrer.thisType.classNode, node.target.enclosingClass));
-    inferrer.inferInvocation(
-        null,
-        node.fileOffset,
+    FunctionType functionType = replaceReturnType(
         substitution.substituteType(node.target.function
             .computeThisFunctionType(inferrer.library.nonNullable)
             .withoutTypeParameters),
-        node.arguments,
-        returnType: inferrer.thisType,
+        inferrer.thisType);
+    inferrer.inferInvocation(
+        null, node.fileOffset, functionType, node.arguments,
         skipTypeArgumentInference: true);
   }
 

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

@@ -218,14 +218,6 @@ class TypeInferrerImpl implements TypeInferrer {
   /// inside a closure.
   ClosureContext closureContext;
 
-  /// The [Substitution] inferred by the last [inferInvocation], or `null` if
-  /// the last invocation didn't require any inference.
-  Substitution lastInferredSubstitution;
-
-  /// The [FunctionType] of the callee in the last [inferInvocation], or `null`
-  /// if the last invocation didn't require any inference.
-  FunctionType lastCalleeType;
-
   TypeInferrerImpl(this.engine, this.uriForInstrumentation, bool topLevel,
       this.thisType, this.library, this.assignedVariables, this.dataForTesting)
       : assert(library != null),
@@ -1653,20 +1645,13 @@ class TypeInferrerImpl implements TypeInferrer {
       {List<VariableDeclaration> hoistedExpressions,
       bool isSpecialCasedBinaryOperator: false,
       bool isSpecialCasedTernaryOperator: false,
-      DartType returnType,
       DartType receiverType,
       bool skipTypeArgumentInference: false,
       bool isConst: false,
       bool isImplicitExtensionMember: false,
       bool isImplicitCall: false}) {
-    assert(
-        returnType == null || !containsFreeFunctionTypeVariables(returnType),
-        "Return type $returnType contains free variables."
-        "Provided function type: $calleeType.");
     int extensionTypeParameterCount = getExtensionTypeParameterCount(arguments);
     if (extensionTypeParameterCount != 0) {
-      assert(returnType == null,
-          "Unexpected explicit return type for extension method invocation.");
       return _inferGenericExtensionMethodInvocation(extensionTypeParameterCount,
           typeContext, offset, calleeType, arguments, hoistedExpressions,
           isSpecialCasedBinaryOperator: isSpecialCasedBinaryOperator,
@@ -1681,7 +1666,6 @@ class TypeInferrerImpl implements TypeInferrer {
         isSpecialCasedBinaryOperator: isSpecialCasedBinaryOperator,
         isSpecialCasedTernaryOperator: isSpecialCasedTernaryOperator,
         receiverType: receiverType,
-        returnType: returnType,
         skipTypeArgumentInference: skipTypeArgumentInference,
         isConst: isConst,
         isImplicitExtensionMember: isImplicitExtensionMember,
@@ -1770,17 +1754,10 @@ class TypeInferrerImpl implements TypeInferrer {
       {bool isSpecialCasedBinaryOperator: false,
       bool isSpecialCasedTernaryOperator: false,
       DartType receiverType,
-      DartType returnType,
       bool skipTypeArgumentInference: false,
       bool isConst: false,
       bool isImplicitExtensionMember: false,
       bool isImplicitCall}) {
-    assert(
-        returnType == null || !containsFreeFunctionTypeVariables(returnType),
-        "Return type $returnType contains free variables."
-        "Provided function type: $calleeType.");
-    lastInferredSubstitution = null;
-    lastCalleeType = null;
     List<TypeParameter> calleeTypeParameters = calleeType.typeParameters;
     if (calleeTypeParameters.isNotEmpty) {
       // It's possible that one of the callee type parameters might match a type
@@ -1794,9 +1771,6 @@ class TypeInferrerImpl implements TypeInferrer {
       // in which me must do this, to avoid a performance regression?
       FreshTypeParameters fresh = getFreshTypeParameters(calleeTypeParameters);
       calleeType = fresh.applyToFunctionType(calleeType);
-      if (returnType != null) {
-        returnType = fresh.substitute(returnType);
-      }
       calleeTypeParameters = fresh.freshTypeParameters;
     }
     List<DartType> explicitTypeArguments = getExplicitTypeArguments(arguments);
@@ -1825,8 +1799,8 @@ class TypeInferrerImpl implements TypeInferrer {
           calleeTypeParameters.length, const UnknownType());
       typeSchemaEnvironment.inferGenericFunctionOrType(
           isNonNullableByDefault
-              ? returnType ?? calleeType.returnType
-              : legacyErasure(coreTypes, returnType ?? calleeType.returnType),
+              ? calleeType.returnType
+              : legacyErasure(coreTypes, calleeType.returnType),
           calleeTypeParameters,
           null,
           null,
@@ -1893,12 +1867,16 @@ class TypeInferrerImpl implements TypeInferrer {
       }
     }
     if (isSpecialCasedBinaryOperator) {
-      returnType = typeSchemaEnvironment.getTypeOfSpecialCasedBinaryOperator(
-          receiverType, actualTypes[0],
-          isNonNullableByDefault: isNonNullableByDefault);
+      calleeType = replaceReturnType(
+          calleeType,
+          typeSchemaEnvironment.getTypeOfSpecialCasedBinaryOperator(
+              receiverType, actualTypes[0],
+              isNonNullableByDefault: isNonNullableByDefault));
     } else if (isSpecialCasedTernaryOperator) {
-      returnType = typeSchemaEnvironment.getTypeOfSpecialCasedTernaryOperator(
-          receiverType, actualTypes[0], actualTypes[1], library.library);
+      calleeType = replaceReturnType(
+          calleeType,
+          typeSchemaEnvironment.getTypeOfSpecialCasedTernaryOperator(
+              receiverType, actualTypes[0], actualTypes[1], library.library));
     }
     for (NamedExpression namedArgument in arguments.named) {
       DartType formalType =
@@ -1968,7 +1946,7 @@ class TypeInferrerImpl implements TypeInferrer {
 
     if (inferenceNeeded) {
       typeSchemaEnvironment.inferGenericFunctionOrType(
-          returnType ?? calleeType.returnType,
+          calleeType.returnType,
           calleeTypeParameters,
           formalTypes,
           actualTypes,
@@ -2034,19 +2012,11 @@ class TypeInferrerImpl implements TypeInferrer {
       }
     }
     DartType inferredType;
-    lastInferredSubstitution = substitution;
-    lastCalleeType = calleeType;
-    if (returnType != null) {
-      inferredType = substitution == null
-          ? returnType
-          : substitution.substituteType(returnType);
-    } else {
-      if (substitution != null) {
-        calleeType =
-            substitution.substituteType(calleeType.withoutTypeParameters);
-      }
-      inferredType = calleeType.returnType;
+    if (substitution != null) {
+      calleeType =
+          substitution.substituteType(calleeType.withoutTypeParameters);
     }
+    inferredType = calleeType.returnType;
     assert(
         !containsFreeFunctionTypeVariables(inferredType),
         "Inferred return type $inferredType contains free variables."
@@ -4227,3 +4197,11 @@ class TypedTearoff {
 
   TypedTearoff(this.tearoffType, this.tearoff);
 }
+
+FunctionType replaceReturnType(FunctionType functionType, DartType returnType) {
+  return new FunctionType(functionType.positionalParameters, returnType,
+      functionType.declaredNullability,
+      requiredParameterCount: functionType.requiredParameterCount,
+      namedParameters: functionType.namedParameters,
+      typeParameters: functionType.typeParameters);
+}