Specify error message for type argument inference failing

Author: JsonFreeman

src/compiler/checker.ts

@@ -129,6 +129,7 @@ module ts {
         var emptyObjectType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
         var anyFunctionType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
         var noConstraintType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
+        var typeArgumentInferenceFailureType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
 
         var anySignature = createSignature(undefined, undefined, emptyArray, anyType, 0, false, false);
         var unknownSignature = createSignature(undefined, undefined, emptyArray, unknownType, 0, false, false);
@@ -3993,23 +3994,26 @@ module ts {
         }
 
         function getInferredType(context: InferenceContext, index: number): Type {
-            var result = context.inferredTypes[index];
-            if (!result) {
+            var inferredType = context.inferredTypes[index];
+            if (!inferredType) {
                 var inferences = context.inferences[index];
                 if (inferences.length) {
                     // Infer widened union or supertype, or the undefined type for no common supertype
                     var unionOrSuperType = context.inferUnionTypes ? getUnionType(inferences) : getCommonSupertype(inferences);
-                    var inferredType = unionOrSuperType ? getWidenedType(unionOrSuperType) : undefinedType;
+                    inferredType = unionOrSuperType ? getWidenedType(unionOrSuperType) : typeArgumentInferenceFailureType;
                 }
                 else {
                     // Infer the empty object type when no inferences were made
                     inferredType = emptyObjectType;
                 }
-                var constraint = getConstraintOfTypeParameter(context.typeParameters[index]);
-                var result = constraint && !isTypeAssignableTo(inferredType, constraint) ? constraint : inferredType;
-                context.inferredTypes[index] = result;
+
+                if (inferredType !== typeArgumentInferenceFailureType) {
+                    var constraint = getConstraintOfTypeParameter(context.typeParameters[index]);
+                    inferredType = constraint && !isTypeAssignableTo(inferredType, constraint) ? constraint : inferredType;
+                }
+                context.inferredTypes[index] = inferredType;
             }
-            return result;
+            return inferredType;
         }
 
         function getInferredTypes(context: InferenceContext): Type[] {
@@ -5094,7 +5098,7 @@ module ts {
             }
             var inferredTypes = getInferredTypes(context);
             // Inference has failed if the undefined type is in list of inferences
-            return !contains(inferredTypes, undefinedType);
+            return !contains(inferredTypes, typeArgumentInferenceFailureType);
         }
 
         function checkTypeArguments(signature: Signature, typeArguments: TypeNode[], typeArgumentResultTypes: Type[], reportErrors: boolean): boolean {
@@ -5161,6 +5165,7 @@ module ts {
 
             var candidateForArgumentError: Signature;
             var candidateForTypeArgumentError: Signature;
+            var indexOfUninferredTypeParameter: number;
             var result: Signature;
             if (candidates.length > 1) {
                 result = chooseOverload(candidates, subtypeRelation, excludeArgument);
@@ -5169,6 +5174,7 @@ module ts {
                 // Reinitialize these pointers for round two
                 candidateForArgumentError = undefined;
                 candidateForTypeArgumentError = undefined;
+                indexOfUninferredTypeParameter = undefined;
                 result = chooseOverload(candidates, assignableRelation, excludeArgument);
             }
             if (result) {
@@ -5187,7 +5193,8 @@ module ts {
                     checkTypeArguments(candidateForTypeArgumentError, node.typeArguments, [], /*reportErrors*/ true)
                 }
                 else {
-                    error(node.func, Diagnostics.The_type_arguments_cannot_be_inferred_from_the_usage_Try_specifying_the_type_arguments_explicitly);
+                    error(node.func, Diagnostics.The_type_argument_for_type_parameter_0_cannot_be_inferred_from_the_usage_Try_specifying_the_type_arguments_explicitly,
+                        typeToString(candidateForTypeArgumentError.typeParameters[indexOfUninferredTypeParameter]));
                 }
             }
             else {
@@ -5251,6 +5258,9 @@ module ts {
                         }
                         else {
                             candidateForTypeArgumentError = originalCandidate;
+                            if (!node.typeArguments) {
+                                indexOfUninferredTypeParameter = typeArgumentTypes.indexOf(typeArgumentInferenceFailureType);
+                            }
                         }
                     }
                     else {

src/compiler/diagnosticInformationMap.generated.ts

@@ -261,7 +261,7 @@ module ts {
         Property_0_is_protected_and_only_accessible_within_class_1_and_its_subclasses: { code: 2445, category: DiagnosticCategory.Error, key: "Property '{0}' is protected and only accessible within class '{1}' and its subclasses." },
         Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1: { code: 2446, category: DiagnosticCategory.Error, key: "Property '{0}' is protected and only accessible through an instance of class '{1}'." },
         The_0_operator_is_not_allowed_for_boolean_types_Consider_using_1_instead: { code: 2447, category: DiagnosticCategory.Error, key: "The '{0}' operator is not allowed for boolean types. Consider using '{1}' instead." },
-        The_type_arguments_cannot_be_inferred_from_the_usage_Try_specifying_the_type_arguments_explicitly: { code: 2448, category: DiagnosticCategory.Error, key: "The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly." },
+        The_type_argument_for_type_parameter_0_cannot_be_inferred_from_the_usage_Try_specifying_the_type_arguments_explicitly: { code: 2448, category: DiagnosticCategory.Error, key: "The type argument for type parameter '{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly." },
         Import_declaration_0_is_using_private_name_1: { code: 4000, category: DiagnosticCategory.Error, key: "Import declaration '{0}' is using private name '{1}'." },
         Type_parameter_0_of_exported_class_has_or_is_using_name_1_from_private_module_2: { code: 4001, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported class has or is using name '{1}' from private module '{2}'." },
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: { code: 4002, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported class has or is using private name '{1}'." },

src/compiler/diagnosticMessages.json

@@ -1036,7 +1036,7 @@
         "category": "Error",
         "code": 2447
     },
-    "The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.": {
+    "The type argument for type parameter '{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly.": {
         "category": "Error",
         "code": 2448
     },

tests/baselines/reference/contextualTypingWithFixedTypeParameters1.errors.txt

@@ -1,5 +1,5 @@
 tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(2,22): error TS2339: Property 'foo' does not exist on type 'string'.
-tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,10): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,10): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
 
 ==== tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts (2 errors) ====
@@ -9,4 +9,4 @@ tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,10): error TS
 !!! error TS2339: Property 'foo' does not exist on type 'string'.
     var r9 = f10('', () => (a => a.foo), 1); // error
              ~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.

tests/baselines/reference/defaultBestCommonTypesHaveDecls.errors.txt

@@ -1,6 +1,6 @@
 tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(2,6): error TS2339: Property 'length' does not exist on type '{}'.
 tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(5,6): error TS2339: Property 'length' does not exist on type 'Object'.
-tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(8,14): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(8,14): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
 
 ==== tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts (3 errors) ====
@@ -17,7 +17,7 @@ tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(8,14): error TS2448: The
     function concat<T>(x: T, y: T): T { return null; }
     var result = concat(1, ""); // error
                  ~~~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
     var elementCount = result.length; 
 
     function concat2<T, U>(x: T, y: U) { return null; }

tests/baselines/reference/fixTypeParameterInSignatureWithRestParameters.errors.txt

@@ -1,8 +1,8 @@
-tests/cases/compiler/fixTypeParameterInSignatureWithRestParameters.ts(2,1): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/compiler/fixTypeParameterInSignatureWithRestParameters.ts(2,1): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
 
 ==== tests/cases/compiler/fixTypeParameterInSignatureWithRestParameters.ts (1 errors) ====
     function bar<T>(item1: T, item2: T) { }
     bar(1, ""); // Should be ok
     ~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.

tests/baselines/reference/genericCallWithFunctionTypedArguments.errors.txt

@@ -1,8 +1,8 @@
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(26,10): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(30,15): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(33,15): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(34,16): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(35,15): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(26,10): error TS2448: The type argument for type parameter 'U' cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(30,15): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(33,15): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(34,16): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(35,15): error TS2448: The type argument for type parameter 'U' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts (5 errors) ====
@@ -33,22 +33,22 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFun
 
     var r8 = foo3(1, function (a) { return '' }, 1); // error
              ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'U' cannot be inferred from the usage. Try specifying the type arguments explicitly.
     var r9 = foo3<number, string>(1, (a) => '', ''); // string
 
     function other<T, U>(t: T, u: U) {
         var r10 = foo2(1, (x: T) => ''); // error
                   ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
         var r10 = foo2(1, (x) => ''); // string
 
         var r11 = foo3(1, (x: T) => '', ''); // error
                   ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
         var r11b = foo3(1, (x: T) => '', 1); // error
                    ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
         var r12 = foo3(1, function (a) { return '' }, 1); // error
                   ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'U' cannot be inferred from the usage. Try specifying the type arguments explicitly.
     }

tests/baselines/reference/genericCallWithFunctionTypedArguments2.errors.txt

@@ -1,5 +1,5 @@
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments2.ts(29,10): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments2.ts(40,10): error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments2.ts(29,10): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments2.ts(40,10): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments2.ts (2 errors) ====
@@ -33,7 +33,7 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFun
 
     var r4 = foo2(1, i2); // error
              ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
     var r4b = foo2(1, a); // any
     var r5 = foo2(1, i); // any
     var r6 = foo2<string, string>('', i2); // string
@@ -46,5 +46,5 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFun
     var r7b = foo3(null, a, ''); // any
     var r8 = foo3(1, i2, 1); // error
              ~~~~
-!!! error TS2448: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly.
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
     var r9 = foo3<string, string>('', i2, ''); // string

tests/baselines/reference/genericCallWithGenericSignatureArguments.errors.txt

@@ -1,5 +1,5 @@
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments.ts(18,10): error TS2346: Supplied parameters do not match any signature of call target.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments.ts(19,10): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments.ts(18,10): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments.ts(19,10): error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments.ts (2 errors) ====
@@ -21,11 +21,11 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
     var b: { x: number; z?: number; };
 
     var r4 = foo((x: typeof a) => a, (x: typeof b) => b); // typeof a => typeof a
-             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2346: Supplied parameters do not match any signature of call target.
+             ~~~
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
     var r5 = foo((x: typeof b) => b, (x: typeof a) => a); // typeof b => typeof b
-             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2346: Supplied parameters do not match any signature of call target.
+             ~~~
+!!! error TS2448: The type argument for type parameter 'T' cannot be inferred from the usage. Try specifying the type arguments explicitly.
 
     function other<T>(x: T) {
         var r6 = foo((a: T) => a, (b: T) => b); // T => T