a9ad94ab3c
* Introduce simpliciations for extract/exclude-like conditional types and fix restrictive instantiations * Add test for the common simplifications * unify true branch constraint generation logic and true branch simplification * Use identical check on instantiated types * Add late-instantiate conditionals to test * Globally cache conditional type instantiations ala indexed access types * Handle `any` simplifications * Factor empty intersection check into function * Modifify conditional type constraints to better handle single-branch `any` and restrictive type parameters * Add test case motivating prior commit * Fix lint * Factor logic into worker vs cacheing function * Remove now unneeded casts
66 lines
1.7 KiB
TypeScript
66 lines
1.7 KiB
TypeScript
// @strict: true
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const fn1 = <Params>(
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params: Pick<Params, Exclude<keyof Params, never>>,
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): Params => params;
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function fn2<T>(x: Exclude<T, never>) {
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var y: T = x;
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x = y;
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}
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const fn3 = <Params>(
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params: Pick<Params, Extract<keyof Params, keyof Params>>,
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): Params => params;
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function fn4<T>(x: Extract<T, T>) {
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var y: T = x;
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x = y;
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}
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declare var x: Extract<number | string, any>; // Should be `numebr | string` and not `any`
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type ExtractWithDefault<T, U, D = never> = T extends U ? T : D;
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type ExcludeWithDefault<T, U, D = never> = T extends U ? D : T;
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const fn5 = <Params>(
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params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,
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): Params => params;
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function fn6<T>(x: ExcludeWithDefault<T, never>) {
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var y: T = x;
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x = y;
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}
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const fn7 = <Params>(
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params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,
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): Params => params;
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function fn8<T>(x: ExtractWithDefault<T, T>) {
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var y: T = x;
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x = y;
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}
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type TemplatedConditional<TCheck, TExtends, TTrue, TFalse> = TCheck extends TExtends ? TTrue : TFalse;
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const fn9 = <Params>(
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params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,
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): Params => params;
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function fn10<T>(x: TemplatedConditional<T, never, never, T>) {
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var y: T = x;
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x = y;
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}
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const fn11 = <Params>(
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params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,
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): Params => params;
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function fn12<T>(x: TemplatedConditional<T, T, T, never>) {
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var y: T = x;
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x = y;
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}
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declare var z: any;
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const zee = z!!!; // since x is `any`, `x extends null | undefined` should be both true and false - and thus yield `any`
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