Defer generic awaited type#35064
Defer generic awaited type #35064
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jablkoforce-pushed the patch-22 branch 3 times, most recently from 4855cc2 to f8e58ecCompare
orta commented Nov 18, 2019
@typescript-bot test this |
typescript-bot commented Nov 18, 2019
The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master. |
jablkoforce-pushed the patch-22 branch 5 times, most recently from 1c8c527 to 7f71fcdComparejablkoforce-pushed the patch-22 branch 3 times, most recently from ad41b21 to 62a1d57Compareorta commented Jan 22, 2020
@typescript-bot test this |
typescript-bot commented Jan 22, 2020
The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master. |
orta commented Jan 23, 2020
Looks like most of that diff is just file number changing There is a few errors though at this location - which I think could be correct. Does that feel right? |
orta commented Jan 23, 2020
Relates to #35998 |
ExE-Boss left a comment
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The then method only needs to be assignable to Function.
src/lib/es5.d.ts Outdated
| // The undefined case is for strictNullChecks false, in which case | ||
| // undefined extends PromiseLike<infer U> is true, which would otherwise | ||
| // make Awaited<undefined> -> unknown. | ||
| typeAwaited<T>=Textendsundefined ? T : TextendsPromiseLike<infer U> ? U : Textends{then(...args: any[]): any} ? unknown : T; |
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| typeAwaited<T>=Textendsundefined ? T : TextendsPromiseLike<infer U> ? U : Textends{then(...args: any[]): any} ? unknown : T; | |
| typeAwaited<T>=Textendsundefined ? T : TextendsPromiseLike<infer U> ? U : Textends{then: Function} ? unknown : T; |
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👍 Works, thanks for your help! Done. ✔️
jablkoforce-pushed the patch-22 branch 2 times, most recently from 3e6abf1 to b48a356Comparetypescript-bot commented Jan 25, 2020
The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master. |
orta commented Jan 27, 2020
These baselines look alright to me - jablko#7 |
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I do not believe this is the correct solution to this problem.
| return typeAsAwaitable.awaitedTypeOfType = type; | ||
| } | ||
| const promisedType = getPromisedTypeOfPromise(type); |
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I don't agree with this change. This completely removes support for recursively unwrapping a non-native promise, which is a core capability of await and our type-system support for it which has existed since the feature was added.
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Can a non-native promise resolve to another promise? If not, then await isn't recursive and I think this change is safe?
If it can, then I concede that implies a recursive awaited solution.
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Well, non‑native promises can resolve to an object with a .then function property, which await will resolve recursively.
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@jablko: non-native promise-like implementations aren't all guaranteed to be Promise/A+. In the past, JQuery's defer created something promise-like (i.e. it has a callable then that accepted fulfill/reject callbacks), but it did not recursively unwrap. This is why native await and native Promise both recursively unwrap (to defend against non-Promise/A+-compliant promise-likes)
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awaitis recursive for non-native promises. In https://tc39.es/ecma262/#await, the value is passed to PromiseResolve which adopts the foreign promise and performs recursive unwrapping.
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Thanks! I concede that await is recursive for non-compliant promises. Does supporting non-compliant promises justify introducing a new kind of type?
There's only ever been incomplete support for non-compliant promises in TypeScript. TypeScript's native promise type hasn't recursively unwrapped non-compliant promises until now. For native and A+-compliant promises, await isn't recursive because they can't be nested.
Is a non-compliant promise more likely actually an error? Supporting non-compliant promises can be error prone, masking what are otherwise errors.
jablkoforce-pushed the patch-22 branch 4 times, most recently from 7da42e8 to 034a6fcCompare
sandersn left a comment
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It looks like there are outstanding comments on this PR, so I'm going to request changes to help me track our PR backlog.
jablkoforce-pushed the patch-22 branch 4 times, most recently from 340aaa9 to d802893Comparejablkoforce-pushed the patch-22 branch 4 times, most recently from 5cb7c3f to 49ad9c9CompareYou can include es2015.promise.d.ts without es2015.iterable.d.ts. It was moved to es2015.promise.d.ts in microsoft#31117
sandersn commented Feb 27, 2020
This PR hasn't seen any activity for quite a while, so I'm going to close it to keep the number of open PRs manageable. Feel free to open a fresh PR or continue the discussion here. |
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Roll up
#33062, #33074,#33103,#33105, #33707 and #35284Fixes
#27711Fixes#22469
Fixes#28427
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#30390Fixes#31722
Fixes#33559
Fixes#33562
Fixes#33752
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#34924Fixes#34937
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#35136Fixes
#35258@typescript-bot test this
@typescript-bot run dt
@typescript-bot user test this