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Merged
merged 2 commits into from
Sep 8, 2021
Merged

Stop looking at binding patterns for type argument inference #45719

merged 2 commits into from
Sep 8, 2021

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andrewbranch
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Binding patterns are already sketchy enough as contextual types where type argument inference is not involved, but I see no good reason to let them play a part in actual generic inference.

Fixes #45663
Fixes #43605

Related: #39081

@typescript-bot typescript-bot added Author: Team For Milestone Bug PRs that fix a bug with a specific milestone labels Sep 3, 2021
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@typescript-bot user test this inline
@typescript-bot run dt
@typescript-bot test this

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Heya @andrewbranch, I'm starting to run the extended test suite on this PR at c8f6392. Hold tight - I'll update this comment with the log link once the build has been queued.

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Heya @andrewbranch, I'm starting to run the parallelized Definitely Typed test suite on this PR at c8f6392. Hold tight - I'll update this comment with the log link once the build has been queued.

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Heya @andrewbranch, I'm starting to run the inline community code test suite on this PR at c8f6392. Hold tight - I'll update this comment with the log link once the build has been queued.

@andrewbranch andrewbranch added the Breaking Change Would introduce errors in existing code label Sep 3, 2021
@andrewbranch andrewbranch added the Experiment A fork with an experimental idea which might not make it into master label Sep 3, 2021
andrewbranch
andrewbranch commented Sep 3, 2021
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tests/baselines/reference/destructuringTuple.types
>[1, 2, 3].reduce((accu, el) => accu.concat(el), []) : number
>oops1 : never
>[1, 2, 3].reduce((accu, el) => accu.concat(el), []) : never[]
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We used to think [1, 2, 3].reduce((accu, el) => accu.concat(el), []) is a number. You probably need the (unfortunate) overload resolution error in the function body to get that far off track in the first place, but there’s really no reason why destructuring [oops1] from the result should have any effect on what we think this type is.

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@typescript-bot user test this inline
@typescript-bot run dt
@typescript-bot test this

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typescript-bot commented Sep 7, 2021 •
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Heya @andrewbranch, I've started to run the inline community code test suite on this PR at c8f6392. You can monitor the build here.

Update: The results are in!

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typescript-bot commented Sep 7, 2021 •
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Heya @andrewbranch, I've started to run the extended test suite on this PR at c8f6392. You can monitor the build here.

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typescript-bot commented Sep 7, 2021 •
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Heya @andrewbranch, I've started to run the parallelized Definitely Typed test suite on this PR at c8f6392. You can monitor the build here.

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Great news! no new errors were found between main..refs/pull/45719/merge

sandersn
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This sounds reasonable to me, although I'd like a second opinion from @weswigham in case there are any unforeseen consequences.

(Although shipping early in 4.5 is probably enough to turn up those consequences as well.)

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Yeah, I mean - I made the original change to elide them when type parameters had defaults; binding patterns are pretty bad inference sources - probably the worst ones we have.

@andrewbranch andrewbranch merged commit be618b1 into microsoft:main Sep 8, 2021
@andrewbranch andrewbranch deleted the bug/43605 branch September 8, 2021 00:14
@andrewbranch andrewbranch mentioned this pull request Sep 13, 2021
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@rbuckton rbuckton mentioned this pull request Sep 16, 2021
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@andrewbranch andrewbranch mentioned this pull request Sep 22, 2021
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andrewbranch added a commit that referenced this pull request Sep 22, 2021
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Revert "Stop looking at binding patterns for type argument inference (#…
c0e5bad 
…45719)"

This reverts commit be618b1.
@andrewbranch andrewbranch mentioned this pull request Sep 22, 2021
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andrewbranch added a commit that referenced this pull request Sep 23, 2021
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Revert "Stop looking at binding patterns for type argument inference" (…
0396723 
…#46013)

* Revert "Stop looking at binding patterns for type argument inference (#45719)"

This reverts commit be618b1.

* Update error baseline for moved lib file declaration
@andrewbranch andrewbranch mentioned this pull request May 12, 2022
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@sandersn sandersn sandersn approved these changes

@weswigham weswigham weswigham approved these changes

@ahejlsberg ahejlsberg Awaiting requested review from ahejlsberg

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