Repository navigation
No high order generics binding #51947
Description
Bug Report
type GenericBinding<
F extends <T1>(value: T1) => any, // take a generic fn with T1 parameter
T2, // also accept a T2 parameter
> = F<T2>; // bind the generic of F to T2This does not work, although #47607 claims to have solved #40542 which is essentially this.
Test:
function myfn<T1>(value: T1) {};
const assert1a: typeof myfn extends (<T>(value: T) => void) ? true : false = true;
const assert1b: (<T>(value: T) => void) extends typeof myfn ? true : false = true;
type Test = GenericBinding<typeof myfn, string>; // bind `T1` at `myfn` to `string`, should get `(value: string) => void`
const assert2a: Test extends ((value: string) => void) ? true : false = true;
const assert2b: ((value: string) => void) extends Test ? true : false = true;
const assert2c: Test extends (<T>(value: T) => void) ? true : false = false;
const assert2d: (<T>(value: T) => void) extends Test ? true : false = false; // broken🔎 Search Terms
High order generics.
#40542
#47607
#37181
🕗 Version & Regression Information
4.6 till 4.9.
⏯ Playground Link
Playground link with relevant code
💻 Code
See above.
🙁 Actual behavior
Compiler error Type 'F' is not generic.ts(2315).
🙂 Expected behavior
Actual evaluation of generics.
Activity
andrewbranch commentedon Dec 20, 2022
Fis a type, while #47607 and #40542 are about values.typescript-bot commentedon Dec 22, 2022
This issue has been marked 'Working as Intended' and has seen no recent activity. It has been automatically closed for house-keeping purposes.
MOZGIII commentedon Dec 23, 2022
#40542 is clearly about types, #47607 only partially solves the issue described. If you follow what's going on at the code that is mentioned at #40542, the devs there were unable to meaningfully use the limited solution provided by #47607. I'd say that issue has to be reopened, as well as this one, which poses the same issue but in an explicitly broader sense.
This issue is marked with
Working as intended, is it because it was submitted as a bug?