Uh oh!
There was an error while loading. Please reload this page.
Bail on 0- and 1-length lists in removeSubtypes to avoid spurious circularity problems - #46981
Merged
Ryan Cavanaugh (RyanCavanaugh) merged 4 commits intoMar 8, 2022
Merged
Conversation
removeSubtypes to avoid spurious circularity problemsremoveSubtypes to avoid spurious circularity problemsRyan Cavanaugh (RyanCavanaugh) added a commit
to RyanCavanaugh/lens
that referenced
this pull request
Dec 1, 2021
This code has a type circularity that previously went undetected. Adding an `as Wizard` assertion here removes the circularity. See microsoft/TypeScript#46939 / microsoft/TypeScript#46981
Ryan Cavanaugh (RyanCavanaugh)
commented
Dec 1, 2021
MemberAuthor
TypeScript Bot (@typescript-bot) perf test this |
Contributor
Heya Ryan Cavanaugh (@RyanCavanaugh), I've started to run the perf test suite on this PR at dd91ab7. You can monitor the build here. Update: The results are in! |
TypeScript Bot (typescript-bot)
commented
Dec 1, 2021
Contributor
Ryan Cavanaugh (@RyanCavanaugh) Here they are:Comparison Report - main..46981
System
Hosts
Scenarios
Developer Information: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Nathan Shively-Sanders (sandersn)
requested review from
Anders Hejlsberg (ahejlsberg) and Wesley Wigham (weswigham)December 16, 2021 23:17
Member
I'm want to merge this, because I think the early bail is fine to have regardless of anything else, however I think there's another underlying issue that probably needs fixing, so it'd be nice if we had a tweaked example that still triggered an issue and an issue to track fixing it. Likely something like typeBox={content?: Foo|Box};declareconstb: Box;classFoo{getfoo(){return{content: thisasFoo|Box,
...b};}}will continue to trigger a new-ish circularity error. |
Wesley Wigham (weswigham)
approved these changes
Mar 5, 2022
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for freeto subscribe to this conversation on GitHub.
Already have an account?
Sign in.
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Creates a reasonable workaround for #46939
Another example for illustration:
When resolving the type of
Foo#foo, we need to compute the type of the object literal in the return position. This has two parts: thecontentfrom thecontent:property (typeFoo), and thecontentproperty from typeBox(which isFoo | missing).We want the type of
contenthere to be subtype-reduced when creating the union of the two possible constituents,FooandFoo. That list gets deduped ingetUnionTypeto just[Foo], then passed toremoveSubTypes, which computes this value ahead of thewhileloop below it which in reality runs zero iterations:That call to
resolveStructuredTypeMembersattempts to resolve the type ofFoo#foo, triggering a circularity even though none actually exists.Instead we can just bail out earlier in the function, saving time (I hope?) and avoiding this computation until later when doing so won't introduce a circularity.