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Instantiate conditional types within contextual type instantiation when inference candidates are available - #48838
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Mateusz Burzyński (Andarist) wants to merge 14 commits into
Closed
Instantiate conditional types within contextual type instantiation when inference candidates are available#48838Mateusz Burzyński (Andarist) wants to merge 14 commits into
Mateusz Burzyński (Andarist) wants to merge 14 commits into
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Nathan Shively-Sanders (sandersn)
requested a review
from Wesley Wigham (weswigham)May 4, 2022 15:11
Nathan Shively-Sanders (sandersn)
requested a review
from Gabriela Araujo Britto (gabritto)May 4, 2022 15:12
# Conflicts: # src/compiler/checker.ts
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Mateusz Burzyński (Andarist)
commented
Sep 30, 2022
ContributorAuthor
Anders Hejlsberg (@ahejlsberg) this fix tries to fix the weird inconsistency where the position of the conditional type in the second parameter to a function call changes what is inferred for types without callable signatures (see the seemingly harmless position change in the diff presented at the top of this thread here, or play with this TS playground). The problem is that the |
# Conflicts: # src/compiler/checker.ts
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Ryan Cavanaugh (RyanCavanaugh)
requested a review
from Anders Hejlsberg (ahejlsberg)September 30, 2022 17:30
Simplifiable types within contextual type instantiation when inference candidates are availableWesley Wigham (weswigham)
previously approved these changes
Mar 15, 2023
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Honestly, every time I come across contextual type instantiation I get more and more wishy-washy about when and why we do it. I'm pretty sure, in theory, we should always do it. But only if it'll be useful. But also not when it'll only produce "useless" constraint values. Except we also try to not do it when we don't think it'll be useful to avoid instantiation work. It's just so... eck.
In any case, this looks fine to me, actually, though in this case I somewhat want to defer to Anders Hejlsberg (@ahejlsberg) who may have stronger opinions on why/why not we should be instantiating contextual types with the active inference context. So I'm going to mark this as approved, but refrain from merging it until either Ryan Cavanaugh (@RyanCavanaugh) steps in and says "sure, we'll take this for this release" or Anders Hejlsberg (@ahejlsberg) weighs in one way or another.
Mateusz Burzyński (Andarist)
commented
Jun 7, 2023
ContributorAuthor
Ryan Cavanaugh (@RyanCavanaugh)Anders Hejlsberg (@ahejlsberg) any thoughts on this approved PR? |
Mateusz Burzyński (Andarist)
commented
Jun 17, 2023
ContributorAuthor
Jake Bailey (@jakebailey) would you be so kind to create a playground for this PR? 😉 |
Jake Bailey (jakebailey)
commented
Jun 17, 2023
Member
TypeScript Bot (@typescript-bot) pack this |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the tarball bundle task on this PR at be61797. You can monitor the build here. |
Contributor
Hey Jake Bailey (@jakebailey), I've packed this into an installable tgz. You can install it for testing by referencing it in your and then running There is also a playground for this build and an npm module you can use via |
Mateusz Burzyński (Andarist)
commented
Jun 17, 2023
ContributorAuthor
thank you ❤️ |
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are some more interesting changes from running the top-repos suite Details
|
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are the results of running the top-repos suite comparing Something interesting changed - please have a look. DetailsServer exited prematurely with code unknown and signal SIGABRTAffected reposcalcom/cal.comRaw error text:RepoResults7/calcom.cal.com.rawError.txt in the artifact folderLast few requests{"seq":856,"type":"request","command":"updateOpen","arguments":{"changedFiles":[],"closedFiles":[],"openFiles":[{"file":"@PROJECT_ROOT@/apps/swagger/next-env.d.ts","projectRootPath":"@PROJECT_ROOT@"}]}}
{"seq":857,"type":"request","command":"getOutliningSpans","arguments":{"file":"@PROJECT_ROOT@/apps/swagger/next-env.d.ts"}}
{"seq":858,"type":"request","command":"updateOpen","arguments":{"changedFiles":[],"closedFiles":["@PROJECT_ROOT@/apps/api/test/lib/middleware/verifyApiKey.test.ts"],"openFiles":[]}}
{"seq":859,"type":"request","command":"updateOpen","arguments":{"changedFiles":[],"closedFiles":[],"openFiles":[{"file":"@PROJECT_ROOT@/apps/web/app/_trpc/client.ts","projectRootPath":"@PROJECT_ROOT@"}]}}
Repro steps
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Jake Bailey (jakebailey)
commented
Jan 11, 2024
Member
Seems like it wasn't a fluke, and this is very breaky? |
Simplifiable types within contextual type instantiation when inference candidates are availableMateusz Burzyński (Andarist)
commented
Jan 11, 2024
ContributorAuthor
Yeah, it seems like it. I reviewed a couple of those and started work on extracting new test cases. I think that all of those might be related to instantiating indexed access types. This is something that wasn't originally in this PR - I only added it because it felt like maybe they would fall into the same category as conditional types. I removed this now and it would be cool to rerun all of those tests. I will also take another look at the core issue. I created this PR almost 2 years ago and I learned a lot about the codebase in the meantime 😉 Maybe I will be able to figure out some alternative solution to the original issue (but maybe not). |
Jake Bailey (jakebailey)
commented
Jan 11, 2024
Member
TypeScript Bot (@typescript-bot) test top200 TypeScript Bot (@typescript-bot) perf test this TypeScript Bot (@typescript-bot) user test tsserver |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the diff-based user code test suite (tsserver) on this PR at e3f11a8. You can monitor the build here. Update: The results are in! |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the diff-based top-repos suite (tsserver) on this PR at e3f11a8. You can monitor the build here. Update: The results are in! |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the parallelized Definitely Typed test suite on this PR at e3f11a8. You can monitor the build here. Update: The results are in! |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the diff-based user code test suite on this PR at e3f11a8. You can monitor the build here. Update: The results are in! |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the regular perf test suite on this PR at e3f11a8. You can monitor the build here. Update: The results are in! |
Contributor
Heya Jake Bailey (@jakebailey), I've started to run the public perf test suite on this PR at e3f11a8. You can monitor the build here. Update: The results are in! |
Contributor
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are the results of running the user test suite comparing Everything looks good! |
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are the results of running the user test suite comparing There were infrastructure failures potentially unrelated to your change:
Otherwise... Something interesting changed - please have a look. Details
|
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here they are:tscComparison Report - baseline..pr
System info unknown Hosts
Scenarios
Developer Information: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here they are:tscComparison Report - baseline..pr
System info unknown Hosts
Scenarios
tsserverComparison Report - baseline..pr
System info unknown Hosts
Scenarios
startupComparison Report - baseline..pr
System info unknown Hosts
Scenarios
Developer Information: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Hey Jake Bailey (@jakebailey), the results of running the DT tests are ready. |
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are the results of running the top-repos suite comparing Something interesting changed - please have a look. DetailsServer exited prematurely with code unknown and signal SIGABRTAffected reposcalcom/cal.comRaw error text:RepoResults7/calcom.cal.com.rawError.txt in the artifact folderLast few requests{"seq":887,"type":"request","command":"organizeImports","arguments":{"scope":{"type":"file","args":{"file":"@PROJECT_ROOT@/apps/swagger/next-env.d.ts"}},"skipDestructiveCodeActions":false}}
{"seq":888,"type":"request","command":"getOutliningSpans","arguments":{"file":"@PROJECT_ROOT@/apps/swagger/next-env.d.ts"}}
{"seq":889,"type":"request","command":"updateOpen","arguments":{"changedFiles":[],"closedFiles":["@PROJECT_ROOT@/apps/api/test/lib/middleware/verifyApiKey.test.ts"],"openFiles":[]}}
{"seq":890,"type":"request","command":"updateOpen","arguments":{"changedFiles":[],"closedFiles":[],"openFiles":[{"file":"@PROJECT_ROOT@/apps/web/abTest/utils.ts","projectRootPath":"@PROJECT_ROOT@"}]}}
Repro steps
|
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are the results of running the top-repos suite comparing Something interesting changed - please have a look. Details
|
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are some more interesting changes from running the top-repos suite Details
|
TypeScript Bot (typescript-bot)
commented
Jan 11, 2024
Contributor
Jake Bailey (@jakebailey) Here are some more interesting changes from running the top-repos suite Details
|
Mateusz Burzyński (Andarist)
commented
Jan 11, 2024
ContributorAuthor
Oh, that's not great for me 😅 I'll have to extract some test cases out of this to add as tests to the repo, and... gonna get back to the drawing board to figure out a different fix for this. |
Mateusz Burzyński (Andarist)
marked this pull request as draft
January 11, 2024 20:29
Member
Mateusz Burzyński (@Andarist) are you still working on this? Is it worth keeping this PR open? |
TypeScript Bot (typescript-bot)
commented
Mar 24, 2026
Contributor
With 6.0 out as the final release vehicle for this codebase, we're closing all PRs that don't fit the merge criteria for post-6.0 patches. If you think this was a mistake and this PR fits the post-6.0 patch criteria, please post to the 6.0 iteration issue with details (specifically, which PR and which patch criteria it satisfies). Next steps for PRs:
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Fixes#46201
Highly related to #48823
The problem was that in this case, even though there were some inference candidates here, the conditional type was not instantiated "soon enough". It was especially surprising to me, as a user, as changing the position of this conditional type was fixing the issue:
You can checkout the playground with both variants here.
So how both of those cases were different?
The working variant was able to retrieve the
contextualTypewithininferTypeArgumentsas:Where within
getContextualTypeForObjectLiteralElementthegetApparentTypeOfContextualTypewas returning:and from that type a type for the
actionproperty was unpackages bygetTypeOfPropertyOfContextualType. So a conditional type itself, as a type for this property, was returned toinferTypeArgumentsand it was simply instantiated usinginstantiateType(contextualType, outerMapper), so the correct type was computed just fine here.The problem with the broken variant was that the conditional type wasn't instantiated in
getApparentTypeOfContextualType(while thecontextualTypethere was this conditional type) and it was passed tomapType(instantiatedType, getApparentType, true). This converted the conditional type to a union of its branches:This has lost the relation between the condition and those union members.
So my idea is that we could just instantiate conditional types early to avoid such situations because if we can evaluate the condition it should always be better to focus on the resulting branch than to unionize both of them.