Simplify generic function call error reporting

src/compiler/types.ts

@@ -3404,8 +3404,6 @@ namespace ts {
         signature: Signature;               // Generic signature for which inferences are made
         inferences: InferenceInfo[];        // Inferences made for each type parameter
         flags: InferenceFlags;              // Inference flags
-        failedTypeParameterIndex?: number;  // Index of type parameter for which inference failed
-        // It is optional because in contextual signature instantiation, nothing fails
     }
 
     /* @internal */

tests/baselines/reference/decoratorCallGeneric.errors.txt

@@ -1,6 +1,7 @@
-tests/cases/conformance/decorators/decoratorCallGeneric.ts(7,2): error TS1238: Unable to resolve signature of class decorator when called as an expression.
-  The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-    Type argument candidate 'C' is not a valid type argument because it is not a supertype of candidate 'void'.
+tests/cases/conformance/decorators/decoratorCallGeneric.ts(7,2): error TS2345: Argument of type 'typeof C' is not assignable to parameter of type 'I<C>'.
+  Types of property 'm' are incompatible.
+    Type '() => void' is not assignable to type '() => C'.
+      Type 'void' is not assignable to type 'C'.
 
 
 ==== tests/cases/conformance/decorators/decoratorCallGeneric.ts (1 errors) ====
@@ -12,9 +13,10 @@ tests/cases/conformance/decorators/decoratorCallGeneric.ts(7,2): error TS1238: U
 
     @dec
      ~~~
-!!! error TS1238: Unable to resolve signature of class decorator when called as an expression.
-!!! error TS1238:   The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS1238:     Type argument candidate 'C' is not a valid type argument because it is not a supertype of candidate 'void'.
+!!! error TS2345: Argument of type 'typeof C' is not assignable to parameter of type 'I<C>'.
+!!! error TS2345:   Types of property 'm' are incompatible.
+!!! error TS2345:     Type '() => void' is not assignable to type '() => C'.
+!!! error TS2345:       Type 'void' is not assignable to type 'C'.
     class C {
         _brand: any;
         static m() {}

tests/baselines/reference/defaultBestCommonTypesHaveDecls.errors.txt

@@ -1,7 +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 TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate '""'.
+tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(8,24): error TS2345: Argument of type '""' is not assignable to parameter of type '1'.
 
 
 ==== tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts (3 errors) ====
@@ -17,9 +16,8 @@ tests/cases/compiler/defaultBestCommonTypesHaveDecls.ts(8,14): error TS2453: The
 
     function concat<T>(x: T, y: T): T { return null; }
     var result = concat(1, ""); // error
-                 ~~~~~~
-!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate '""'.
+                           ~~
+!!! error TS2345: Argument of type '""' is not assignable to parameter of type '1'.
     var elementCount = result.length; 
 
     function concat2<T, U>(x: T, y: U) { return null; }

tests/baselines/reference/fixTypeParameterInSignatureWithRestParameters.errors.txt

@@ -1,10 +1,8 @@
-tests/cases/compiler/fixTypeParameterInSignatureWithRestParameters.ts(2,1): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate '""'.
+tests/cases/compiler/fixTypeParameterInSignatureWithRestParameters.ts(2,8): error TS2345: Argument of type '""' is not assignable to parameter of type 'number'.
 
 
 ==== tests/cases/compiler/fixTypeParameterInSignatureWithRestParameters.ts (1 errors) ====
     function bar<T>(item1: T, item2: T) { }
     bar(1, ""); // Should be ok
-    ~~~
-!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate '""'.
+           ~~
+!!! error TS2345: Argument of type '""' is not assignable to parameter of type 'number'.

tests/baselines/reference/for-of39.errors.txt

@@ -1,12 +1,28 @@
-tests/cases/conformance/es6/for-ofStatements/for-of39.ts(1,15): error TS2453: The type argument for type parameter 'V' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate 'boolean' is not a valid type argument because it is not a supertype of candidate 'number'.
+tests/cases/conformance/es6/for-ofStatements/for-of39.ts(1,19): error TS2345: Argument of type '([string, true] | [string, 0])[]' is not assignable to parameter of type 'Iterable<[string, boolean]>'.
+  Types of property '[Symbol.iterator]' are incompatible.
+    Type '() => IterableIterator<[string, true] | [string, 0]>' is not assignable to type '() => Iterator<[string, boolean]>'.
+      Type 'IterableIterator<[string, true] | [string, 0]>' is not assignable to type 'Iterator<[string, boolean]>'.
+        Types of property 'next' are incompatible.
+          Type '(value?: any) => IteratorResult<[string, true] | [string, 0]>' is not assignable to type '(value?: any) => IteratorResult<[string, boolean]>'.
+            Type 'IteratorResult<[string, true] | [string, 0]>' is not assignable to type 'IteratorResult<[string, boolean]>'.
+              Type '[string, true] | [string, 0]' is not assignable to type '[string, boolean]'.
+                Type '[string, 0]' is not assignable to type '[string, boolean]'.
+                  Type '0' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/conformance/es6/for-ofStatements/for-of39.ts (1 errors) ====
     var map = new Map([["", true], ["", 0]]);
-                  ~~~
-!!! error TS2453: The type argument for type parameter 'V' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate 'boolean' is not a valid type argument because it is not a supertype of candidate 'number'.
+                      ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2345: Argument of type '([string, true] | [string, 0])[]' is not assignable to parameter of type 'Iterable<[string, boolean]>'.
+!!! error TS2345:   Types of property '[Symbol.iterator]' are incompatible.
+!!! error TS2345:     Type '() => IterableIterator<[string, true] | [string, 0]>' is not assignable to type '() => Iterator<[string, boolean]>'.
+!!! error TS2345:       Type 'IterableIterator<[string, true] | [string, 0]>' is not assignable to type 'Iterator<[string, boolean]>'.
+!!! error TS2345:         Types of property 'next' are incompatible.
+!!! error TS2345:           Type '(value?: any) => IteratorResult<[string, true] | [string, 0]>' is not assignable to type '(value?: any) => IteratorResult<[string, boolean]>'.
+!!! error TS2345:             Type 'IteratorResult<[string, true] | [string, 0]>' is not assignable to type 'IteratorResult<[string, boolean]>'.
+!!! error TS2345:               Type '[string, true] | [string, 0]' is not assignable to type '[string, boolean]'.
+!!! error TS2345:                 Type '[string, 0]' is not assignable to type '[string, boolean]'.
+!!! error TS2345:                   Type '0' is not assignable to type 'boolean'.
     for (var [k, v] of map) {
         k;
         v;

tests/baselines/reference/generatorTypeCheck63.errors.txt

@@ -3,8 +3,9 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(24,61): err
     Type 'State | 1' is not assignable to type 'StrategicState'.
       Type '1' has no properties in common with type 'StrategicState'.
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(29,70): error TS7025: Generator implicitly has type 'IterableIterator<any>' because it does not yield any values. Consider supplying a return type.
-tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(32,42): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate 'State' is not a valid type argument because it is not a supertype of candidate '1'.
+tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(32,62): error TS2345: Argument of type '(state: State) => IterableIterator<1>' is not assignable to parameter of type '(a: State) => IterableIterator<State>'.
+  Type 'IterableIterator<1>' is not assignable to type 'IterableIterator<State>'.
+    Type '1' is not assignable to type 'State'.
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(36,62): error TS2345: Argument of type '(state: State) => IterableIterator<State | 1>' is not assignable to parameter of type '(a: StrategicState) => IterableIterator<StrategicState>'.
   Type 'IterableIterator<State | 1>' is not assignable to type 'IterableIterator<StrategicState>'.
 
@@ -49,9 +50,10 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(36,62): err
     });
 
     export const Nothing2: Strategy<State> = strategy("Nothing", function* (state: State) {
-                                             ~~~~~~~~
-!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate 'State' is not a valid type argument because it is not a supertype of candidate '1'.
+                                                                 ~~~~~~~~
+!!! error TS2345: Argument of type '(state: State) => IterableIterator<1>' is not assignable to parameter of type '(a: State) => IterableIterator<State>'.
+!!! error TS2345:   Type 'IterableIterator<1>' is not assignable to type 'IterableIterator<State>'.
+!!! error TS2345:     Type '1' is not assignable to type 'State'.
         return 1;
     });
 

tests/baselines/reference/genericCallWithFunctionTypedArguments.errors.txt

@@ -1,13 +1,16 @@
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(26,10): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'string'.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(30,15): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'T'.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(33,15): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'T'.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(34,16): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'T'.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(35,15): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-  Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'string'.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(26,18): error TS2345: Argument of type '(a: number) => string' is not assignable to parameter of type '(a: number) => 1'.
+  Type 'string' is not assignable to type '1'.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(30,23): error TS2345: Argument of type '(x: T) => string' is not assignable to parameter of type '(a: 1) => string'.
+  Types of parameters 'x' and 'a' are incompatible.
+    Type '1' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(33,23): error TS2345: Argument of type '(x: T) => string' is not assignable to parameter of type '(a: 1) => string'.
+  Types of parameters 'x' and 'a' are incompatible.
+    Type '1' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(34,24): error TS2345: Argument of type '(x: T) => string' is not assignable to parameter of type '(a: 1) => string'.
+  Types of parameters 'x' and 'a' are incompatible.
+    Type '1' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts(35,23): error TS2345: Argument of type '(a: number) => string' is not assignable to parameter of type '(a: number) => 1'.
+  Type 'string' is not assignable to type '1'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFunctionTypedArguments.ts (5 errors) ====
@@ -37,28 +40,31 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithFun
     var r7 = foo3(1, <Z>(a: Z) => '', ''); // string
 
     var r8 = foo3(1, function (a) { return '' }, 1); // error
-             ~~~~
-!!! error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'string'.
+                     ~~~~~~~~
+!!! error TS2345: Argument of type '(a: number) => string' is not assignable to parameter of type '(a: number) => 1'.
+!!! error TS2345:   Type 'string' is not assignable to type '1'.
     var r9 = foo3<number, string>(1, (a) => '', ''); // string
 
     function other<T, U>(t: T, u: U) {
         var r10 = foo2(1, (x: T) => ''); // error
-                  ~~~~
-!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'T'.
+                          ~~~~~~~~~~~~
+!!! error TS2345: Argument of type '(x: T) => string' is not assignable to parameter of type '(a: 1) => string'.
+!!! error TS2345:   Types of parameters 'x' and 'a' are incompatible.
+!!! error TS2345:     Type '1' is not assignable to type 'T'.
         var r10 = foo2(1, (x) => ''); // string
 
         var r11 = foo3(1, (x: T) => '', ''); // error
-                  ~~~~
-!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'T'.
+                          ~~~~~~~~~~~~
+!!! error TS2345: Argument of type '(x: T) => string' is not assignable to parameter of type '(a: 1) => string'.
+!!! error TS2345:   Types of parameters 'x' and 'a' are incompatible.
+!!! error TS2345:     Type '1' is not assignable to type 'T'.
         var r11b = foo3(1, (x: T) => '', 1); // error
-                   ~~~~
-!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'T'.
+                           ~~~~~~~~~~~~
+!!! error TS2345: Argument of type '(x: T) => string' is not assignable to parameter of type '(a: 1) => string'.
+!!! error TS2345:   Types of parameters 'x' and 'a' are incompatible.
+!!! error TS2345:     Type '1' is not assignable to type 'T'.
         var r12 = foo3(1, function (a) { return '' }, 1); // error
-                  ~~~~
-!!! error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '1' is not a valid type argument because it is not a supertype of candidate 'string'.
+                          ~~~~~~~~
+!!! error TS2345: Argument of type '(a: number) => string' is not assignable to parameter of type '(a: number) => 1'.
+!!! error TS2345:   Type 'string' is not assignable to type '1'.
     }