Stricter generic signature checks

src/compiler/commandLineParser.ts

@@ -620,6 +620,12 @@ namespace ts {
             category: Diagnostics.Advanced_Options,
             description: Diagnostics.The_maximum_dependency_depth_to_search_under_node_modules_and_load_JavaScript_files
         },
+        {
+            name: "noStrictGenericChecks",
+            type: "boolean",
+            category: Diagnostics.Advanced_Options,
+            description: Diagnostics.Disable_strict_checking_of_generic_signatures_in_function_types,
+        },
         {
             // A list of plugins to load in the language service
             name: "plugins",

src/compiler/diagnosticMessages.json

@@ -3278,6 +3278,10 @@
         "category": "Message",
         "code": 6184
     },
+    "Disable strict checking of generic signatures in function types.": {
+        "category": "Message",
+        "code": 6185
+    },
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005

src/compiler/types.ts

@@ -3522,6 +3522,7 @@ namespace ts {
         noImplicitAny?: boolean;  // Always combine with strict property
         noImplicitReturns?: boolean;
         noImplicitThis?: boolean;  // Always combine with strict property
+        noStrictGenericChecks?: boolean;
         noUnusedLocals?: boolean;
         noUnusedParameters?: boolean;
         noImplicitUseStrict?: boolean;

tests/baselines/reference/assignmentCompatWithCallSignatures3.errors.txt

@@ -1,11 +1,58 @@
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(47,1): error TS2322: Type '(x: number) => number[]' is not assignable to type '<T>(x: T) => T[]'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Type 'T' is not assignable to type 'number'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(50,1): error TS2322: Type '(x: number) => string[]' is not assignable to type '<T>(x: T) => string[]'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Type 'T' is not assignable to type 'number'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(53,1): error TS2322: Type '(x: number) => void' is not assignable to type '<T>(x: T) => T'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Type 'T' is not assignable to type 'number'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(56,1): error TS2322: Type '(x: string, y: number) => string' is not assignable to type '<T, U>(x: T, y: U) => T'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Type 'T' is not assignable to type 'string'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(59,1): error TS2322: Type '(x: (arg: string) => number) => string' is not assignable to type '<T, U>(x: (arg: T) => U) => T'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Types of parameters 'arg' and 'arg' are incompatible.
+      Type 'string' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(62,1): error TS2322: Type '(x: (arg: Base) => Derived) => Base' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U) => T'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Types of parameters 'arg' and 'arg' are incompatible.
+      Type 'Base' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(65,1): error TS2322: Type '(x: (arg: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U) => (r: T) => U'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Types of parameters 'arg' and 'arg' are incompatible.
+      Type 'Base' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(68,1): error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: T) => U) => (r: T) => U'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Types of parameters 'arg' and 'arg' are incompatible.
+      Type 'Base' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(71,1): error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: string; bing: number; }) => U) => (r: T) => U'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Types of parameters 'arg' and 'arg' are incompatible.
+      Type 'Base' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(74,1): error TS2322: Type '(...x: Derived[]) => Derived' is not assignable to type '<T extends Derived>(...x: T[]) => T'.
+  Type 'Derived' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(77,1): error TS2322: Type '(x: { foo: string; }, y: { foo: string; bar: string; }) => Base' is not assignable to type '<T extends Base>(x: T, y: T) => T'.
   Types of parameters 'y' and 'y' are incompatible.
-    Types of parameters 'arg2' and 'arg2' are incompatible.
-      Type 'Base' is not assignable to type '{ foo: string; bing: number; }'.
-        Property 'bing' is missing in type 'Base'.
+    Type 'T' is not assignable to type '{ foo: string; bar: string; }'.
+      Type 'Base' is not assignable to type '{ foo: string; bar: string; }'.
+        Property 'bar' is missing in type 'Base'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(80,1): error TS2322: Type '(x: Base[], y: Derived2[]) => Derived[]' is not assignable to type '<T extends Base[]>(x: Base[], y: T) => Derived[]'.
+  Types of parameters 'y' and 'y' are incompatible.
+    Type 'T' is not assignable to type 'Derived2[]'.
+      Type 'Base[]' is not assignable to type 'Derived2[]'.
+        Type 'Base' is not assignable to type 'Derived2'.
+          Property 'baz' is missing in type 'Base'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(83,1): error TS2322: Type '(x: Base[], y: Derived[]) => Derived[]' is not assignable to type '<T extends Derived[]>(x: Base[], y: T) => T'.
+  Type 'Derived[]' is not assignable to type 'T'.
+tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts(86,1): error TS2322: Type '(x: { a: string; b: number; }) => Object' is not assignable to type '<T>(x: { a: T; b: T; }) => T'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Type '{ a: T; b: T; }' is not assignable to type '{ a: string; b: number; }'.
+      Types of property 'a' are incompatible.
+        Type 'T' is not assignable to type 'string'.
 
 
-==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts (1 errors) ====
+==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts (14 errors) ====
     // these are all permitted with the current rules, since we do not do contextual signature instantiation
 
     class Base { foo: string; }
@@ -53,51 +100,111 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
     var b: <T>(x: T) => T[]; 
     a = b; // ok
     b = a; // ok
+    ~
+!!! error TS2322: Type '(x: number) => number[]' is not assignable to type '<T>(x: T) => T[]'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Type 'T' is not assignable to type 'number'.
     var b2: <T>(x: T) => string[]; 
     a2 = b2; // ok 
     b2 = a2; // ok
+    ~~
+!!! error TS2322: Type '(x: number) => string[]' is not assignable to type '<T>(x: T) => string[]'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Type 'T' is not assignable to type 'number'.
     var b3: <T>(x: T) => T; 
     a3 = b3; // ok
     b3 = a3; // ok
+    ~~
+!!! error TS2322: Type '(x: number) => void' is not assignable to type '<T>(x: T) => T'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Type 'T' is not assignable to type 'number'.
     var b4: <T, U>(x: T, y: U) => T; 
     a4 = b4; // ok
     b4 = a4; // ok
+    ~~
+!!! error TS2322: Type '(x: string, y: number) => string' is not assignable to type '<T, U>(x: T, y: U) => T'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Type 'T' is not assignable to type 'string'.
     var b5: <T, U>(x: (arg: T) => U) => T; 
     a5 = b5; // ok
     b5 = a5; // ok
+    ~~
+!!! error TS2322: Type '(x: (arg: string) => number) => string' is not assignable to type '<T, U>(x: (arg: T) => U) => T'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Types of parameters 'arg' and 'arg' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'T'.
     var b6: <T extends Base, U extends Derived>(x: (arg: T) => U) => T; 
     a6 = b6; // ok
     b6 = a6; // ok
+    ~~
+!!! error TS2322: Type '(x: (arg: Base) => Derived) => Base' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U) => T'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Types of parameters 'arg' and 'arg' are incompatible.
+!!! error TS2322:       Type 'Base' is not assignable to type 'T'.
     var b7: <T extends Base, U extends Derived>(x: (arg: T) => U) => (r: T) => U; 
     a7 = b7; // ok
     b7 = a7; // ok
+    ~~
+!!! error TS2322: Type '(x: (arg: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U) => (r: T) => U'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Types of parameters 'arg' and 'arg' are incompatible.
+!!! error TS2322:       Type 'Base' is not assignable to type 'T'.
     var b8: <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: T) => U) => (r: T) => U;
     a8 = b8; // ok
     b8 = a8; // ok
+    ~~
+!!! error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: T) => U) => (r: T) => U'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Types of parameters 'arg' and 'arg' are incompatible.
+!!! error TS2322:       Type 'Base' is not assignable to type 'T'.
     var b9: <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: string; bing: number }) => U) => (r: T) => U; 
     a9 = b9; // ok
     b9 = a9; // ok
     ~~
 !!! error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: string; bing: number; }) => U) => (r: T) => U'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Types of parameters 'arg2' and 'arg2' are incompatible.
-!!! error TS2322:       Type 'Base' is not assignable to type '{ foo: string; bing: number; }'.
-!!! error TS2322:         Property 'bing' is missing in type 'Base'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Types of parameters 'arg' and 'arg' are incompatible.
+!!! error TS2322:       Type 'Base' is not assignable to type 'T'.
     var b10: <T extends Derived>(...x: T[]) => T; 
     a10 = b10; // ok
     b10 = a10; // ok
+    ~~~
+!!! error TS2322: Type '(...x: Derived[]) => Derived' is not assignable to type '<T extends Derived>(...x: T[]) => T'.
+!!! error TS2322:   Type 'Derived' is not assignable to type 'T'.
     var b11: <T extends Base>(x: T, y: T) => T; 
     a11 = b11; // ok
     b11 = a11; // ok
+    ~~~
+!!! error TS2322: Type '(x: { foo: string; }, y: { foo: string; bar: string; }) => Base' is not assignable to type '<T extends Base>(x: T, y: T) => T'.
+!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:     Type 'T' is not assignable to type '{ foo: string; bar: string; }'.
+!!! error TS2322:       Type 'Base' is not assignable to type '{ foo: string; bar: string; }'.
+!!! error TS2322:         Property 'bar' is missing in type 'Base'.
     var b12: <T extends Array<Base>>(x: Array<Base>, y: T) => Array<Derived>; 
     a12 = b12; // ok
     b12 = a12; // ok
+    ~~~
+!!! error TS2322: Type '(x: Base[], y: Derived2[]) => Derived[]' is not assignable to type '<T extends Base[]>(x: Base[], y: T) => Derived[]'.
+!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:     Type 'T' is not assignable to type 'Derived2[]'.
+!!! error TS2322:       Type 'Base[]' is not assignable to type 'Derived2[]'.
+!!! error TS2322:         Type 'Base' is not assignable to type 'Derived2'.
+!!! error TS2322:           Property 'baz' is missing in type 'Base'.
     var b13: <T extends Array<Derived>>(x: Array<Base>, y: T) => T; 
     a13 = b13; // ok
     b13 = a13; // ok
+    ~~~
+!!! error TS2322: Type '(x: Base[], y: Derived[]) => Derived[]' is not assignable to type '<T extends Derived[]>(x: Base[], y: T) => T'.
+!!! error TS2322:   Type 'Derived[]' is not assignable to type 'T'.
     var b14: <T>(x: { a: T; b: T }) => T; 
     a14 = b14; // ok
     b14 = a14; // ok
+    ~~~
+!!! error TS2322: Type '(x: { a: string; b: number; }) => Object' is not assignable to type '<T>(x: { a: T; b: T; }) => T'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Type '{ a: T; b: T; }' is not assignable to type '{ a: string; b: number; }'.
+!!! error TS2322:       Types of property 'a' are incompatible.
+!!! error TS2322:         Type 'T' is not assignable to type 'string'.
     var b15: <T>(x: T) => T[]; 
     a15 = b15; // ok
     b15 = a15; // ok