Fix ThisParameterType<T> type (#36013)

* Simplify ThisParameterType<T> type

* Add tests

Author: ahejlsberg

src/lib/es5.d.ts

@@ -298,7 +298,7 @@ declare var Function: FunctionConstructor;
 /**
  * Extracts the type of the 'this' parameter of a function type, or 'unknown' if the function type has no 'this' parameter.
  */
-type ThisParameterType<T> = T extends (this: unknown, ...args: any[]) => any ? unknown : T extends (this: infer U, ...args: any[]) => any ? U : unknown;
+type ThisParameterType<T> = T extends (this: infer U, ...args: any[]) => any ? U : unknown;
 
 /**
  * Removes the 'this' parameter from a function type.

tests/baselines/reference/strictBindCallApply2.js

@@ -0,0 +1,16 @@
+//// [strictBindCallApply2.ts]
+// Repro from #32964
+
+interface Foo { blub: string };
+function fn(this: Foo) {}
+
+type Test = ThisParameterType<typeof fn>; 
+
+const fb = fn.bind({ blub: "blub" });
+
+
+//// [strictBindCallApply2.js]
+// Repro from #32964
+;
+function fn() { }
+var fb = fn.bind({ blub: "blub" });

tests/baselines/reference/strictBindCallApply2.symbols

@@ -0,0 +1,24 @@
+=== tests/cases/conformance/functions/strictBindCallApply2.ts ===
+// Repro from #32964
+
+interface Foo { blub: string };
+>Foo : Symbol(Foo, Decl(strictBindCallApply2.ts, 0, 0))
+>blub : Symbol(Foo.blub, Decl(strictBindCallApply2.ts, 2, 15))
+
+function fn(this: Foo) {}
+>fn : Symbol(fn, Decl(strictBindCallApply2.ts, 2, 31))
+>this : Symbol(this, Decl(strictBindCallApply2.ts, 3, 12))
+>Foo : Symbol(Foo, Decl(strictBindCallApply2.ts, 0, 0))
+
+type Test = ThisParameterType<typeof fn>; 
+>Test : Symbol(Test, Decl(strictBindCallApply2.ts, 3, 25))
+>ThisParameterType : Symbol(ThisParameterType, Decl(lib.es5.d.ts, --, --))
+>fn : Symbol(fn, Decl(strictBindCallApply2.ts, 2, 31))
+
+const fb = fn.bind({ blub: "blub" });
+>fb : Symbol(fb, Decl(strictBindCallApply2.ts, 7, 5))
+>fn.bind : Symbol(CallableFunction.bind, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 1 more)
+>fn : Symbol(fn, Decl(strictBindCallApply2.ts, 2, 31))
+>bind : Symbol(CallableFunction.bind, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 1 more)
+>blub : Symbol(blub, Decl(strictBindCallApply2.ts, 7, 20))
+

tests/baselines/reference/strictBindCallApply2.types

@@ -0,0 +1,24 @@
+=== tests/cases/conformance/functions/strictBindCallApply2.ts ===
+// Repro from #32964
+
+interface Foo { blub: string };
+>blub : string
+
+function fn(this: Foo) {}
+>fn : (this: Foo) => void
+>this : Foo
+
+type Test = ThisParameterType<typeof fn>; 
+>Test : Foo
+>fn : (this: Foo) => void
+
+const fb = fn.bind({ blub: "blub" });
+>fb : () => void
+>fn.bind({ blub: "blub" }) : () => void
+>fn.bind : { <T>(this: T, thisArg: ThisParameterType<T>): OmitThisParameter<T>; <T, A0, A extends any[], R>(this: (this: T, arg0: A0, ...args: A) => R, thisArg: T, arg0: A0): (...args: A) => R; <T, A0, A1, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1): (...args: A) => R; <T, A0, A1, A2, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, arg2: A2, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, arg2: A2): (...args: A) => R; <T, A0, A1, A2, A3, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, arg2: A2, arg3: A3, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, arg2: A2, arg3: A3): (...args: A) => R; <T, AX, R>(this: (this: T, ...args: AX[]) => R, thisArg: T, ...args: AX[]): (...args: AX[]) => R; }
+>fn : (this: Foo) => void
+>bind : { <T>(this: T, thisArg: ThisParameterType<T>): OmitThisParameter<T>; <T, A0, A extends any[], R>(this: (this: T, arg0: A0, ...args: A) => R, thisArg: T, arg0: A0): (...args: A) => R; <T, A0, A1, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1): (...args: A) => R; <T, A0, A1, A2, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, arg2: A2, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, arg2: A2): (...args: A) => R; <T, A0, A1, A2, A3, A extends any[], R>(this: (this: T, arg0: A0, arg1: A1, arg2: A2, arg3: A3, ...args: A) => R, thisArg: T, arg0: A0, arg1: A1, arg2: A2, arg3: A3): (...args: A) => R; <T, AX, R>(this: (this: T, ...args: AX[]) => R, thisArg: T, ...args: AX[]): (...args: AX[]) => R; }
+>{ blub: "blub" } : { blub: string; }
+>blub : string
+>"blub" : "blub"
+

tests/cases/conformance/functions/strictBindCallApply2.ts

@@ -0,0 +1,11 @@
+// @strictFunctionTypes: false
+// @strictBindCallApply: true
+
+// Repro from #32964
+
+interface Foo { blub: string };
+function fn(this: Foo) {}
+
+type Test = ThisParameterType<typeof fn>; 
+
+const fb = fn.bind({ blub: "blub" });