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GeezerVison is showing github.com — Fix union type parameter inference by ahejlsberg · Pull Request #5895 · microsoft/TypeScript

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@ahejlsberg

@ahejlsberg Anders Hejlsberg (ahejlsberg) commented Dec 2, 2015

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Fixes #5861.

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Anders Hejlsberg (ahejlsberg) added 2 commits December 2, 2015 10:23
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Ensure that different type parameters are never considered identical
181c10a
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Adding regression test
561360d
@msftclas Microsoft Contribution License Agreements (msftclas) added the cla-not-required label Dec 2, 2015
@ahejlsberg

Anders Hejlsberg (ahejlsberg) commented Dec 2, 2015

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A bit more context on the fix. We previously would consider two type parameters identical if they were different type parameters but had identical constraints (but, oddly, wouldn't consider them assignable to each other). This of course isn't right, but it sort of worked when we were comparing constraints in generic signatures which was really the only time it would come up. However, we now sometimes need to compare type parameters for identity during union and intersection type inference (because of #5738) and we want different type parameters to actually be considered different, so we have to remove this logic. The effect is that we won't check whether type parameter constraints are identical when comparing generic signatures, as explained here.
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yuit
yuit reviewed Dec 2, 2015
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Comment thread tests/cases/compiler/unionTypeParameterInference.ts Outdated

@yuit Yui (yuit) Dec 2, 2015

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could you remove the error comment

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@sandersn

Nathan Shively-Sanders (sandersn) commented Dec 2, 2015

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Could you also add a test for the case that type parameter constraints are not identical, but we don't check? It would be good to have as documentation in case do we go back and decide to start checking.
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Anders Hejlsberg (ahejlsberg) added 2 commits December 2, 2015 15:41
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Removing comment from test
3e6d40f
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Adding test to demonstrate limits of signature identity checking
86d4a4c
@sandersn

Nathan Shively-Sanders (sandersn) commented Dec 2, 2015

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👍
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Anders Hejlsberg (ahejlsberg) added a commit that referenced this pull request Dec 3, 2015
@ahejlsberg
Merge pull request #5895 from Microsoft/unionTypeParameterInference
3bb5dc6 
Fix union type parameter inference
@ahejlsberg
Anders Hejlsberg (ahejlsberg) merged commit 3bb5dc6 into master Dec 3, 2015
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Anders Hejlsberg (ahejlsberg) deleted the unionTypeParameterInference branch December 3, 2015 20:23
@mhegazy Mohamed Hegazy (mhegazy) mentioned this pull request Dec 3, 2015
Massive slowdown in compiling complicated union types #5849
Closed
Anders Hejlsberg (ahejlsberg) added a commit that referenced this pull request Dec 3, 2015
@ahejlsberg @vladima
Merge pull request #5895 from Microsoft/unionTypeParameterInference
ccb4326 
Fix union type parameter inference
Conflicts:
	src/compiler/checker.ts
@vladima Vladimir Matveev (vladima) mentioned this pull request Dec 3, 2015
Port union reduction to 1.7 #5919
Merged
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4 participants

@ahejlsberg @sandersn @yuit @msftclas
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