Also do contravariant parameter type inferences

Author: andrewbranch

src/compiler/checker.ts

@@ -33856,7 +33856,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         const sourceSignature = mapper ? instantiateSignature(contextualSignature, mapper) : contextualSignature;
         applyToParameterTypes(sourceSignature, signature, (source, target) => {
             // Type parameters from outer context referenced by source type are fixed by instantiation of the source type
-            inferTypes(context.inferences, source, target);
+            inferTypes(context.inferences, source, target, /*priority*/ undefined, /*contravariant*/ strictFunctionTypes);
         });
         if (!inferenceContext) {
             applyToReturnTypes(contextualSignature, signature, (source, target) => {

tests/baselines/reference/callbackAssignabilityErrorMessage.errors.txt

@@ -1,6 +1,6 @@
 callbackAssignabilityErrorMessage.ts(31,1): error TS2322: Type 'Source1' is not assignable to type 'Target'.
-  The types returned by 'map(...)' are incompatible between these types.
-    Type '(T | undefined)[]' is not assignable to type 'T[]'.
+  Types of property 'map' are incompatible.
+    Types of parameters 'callbackfn' and 'callbackfn' are incompatible.
       Type 'T | undefined' is not assignable to type 'T'.
         'T' could be instantiated with an arbitrary type which could be unrelated to 'T | undefined'.
 
@@ -39,7 +39,7 @@ callbackAssignabilityErrorMessage.ts(31,1): error TS2322: Type 'Source1' is not
     t = s1; // Bad:  instantiates `S` with `T | undefined`, fails `map` return type assignability
     ~
 !!! error TS2322: Type 'Source1' is not assignable to type 'Target'.
-!!! error TS2322:   The types returned by 'map(...)' are incompatible between these types.
-!!! error TS2322:     Type '(T | undefined)[]' is not assignable to type 'T[]'.
+!!! error TS2322:   Types of property 'map' are incompatible.
+!!! error TS2322:     Types of parameters 'callbackfn' and 'callbackfn' are incompatible.
 !!! error TS2322:       Type 'T | undefined' is not assignable to type 'T'.
 !!! error TS2322:         'T' could be instantiated with an arbitrary type which could be unrelated to 'T | undefined'.

tests/baselines/reference/mappedTypeInferenceFromApparentType.errors.txt

@@ -1,9 +1,7 @@
 mappedTypeInferenceFromApparentType.ts(10,1): error TS2322: Type 'foo' is not assignable to type 'bar'.
   Types of parameters 'target' and 'source' are incompatible.
-    Type '{ [K in keyof U]: Obj[K]; }' is not assignable to type '{ [K in keyof U]: U[K]; }'.
-      Type 'Obj[K]' is not assignable to type 'U[K]'.
-        Type 'Obj' is not assignable to type 'U'.
-          'U' could be instantiated with an arbitrary type which could be unrelated to 'Obj'.
+    Type '{ [K in keyof U]: Obj[K]; }' is not assignable to type '{ [x: string]: number; }'.
+      Index signature for type 'string' is missing in type 'number[]'.
 
 
 ==== mappedTypeInferenceFromApparentType.ts (1 errors) ====
@@ -20,7 +18,5 @@ mappedTypeInferenceFromApparentType.ts(10,1): error TS2322: Type 'foo' is not as
     ~
 !!! error TS2322: Type 'foo' is not assignable to type 'bar'.
 !!! error TS2322:   Types of parameters 'target' and 'source' are incompatible.
-!!! error TS2322:     Type '{ [K in keyof U]: Obj[K]; }' is not assignable to type '{ [K in keyof U]: U[K]; }'.
-!!! error TS2322:       Type 'Obj[K]' is not assignable to type 'U[K]'.
-!!! error TS2322:         Type 'Obj' is not assignable to type 'U'.
-!!! error TS2322:           'U' could be instantiated with an arbitrary type which could be unrelated to 'Obj'.
+!!! error TS2322:     Type '{ [K in keyof U]: Obj[K]; }' is not assignable to type '{ [x: string]: number; }'.
+!!! error TS2322:       Index signature for type 'string' is missing in type 'number[]'.