Exclude undefined from constraints of mapped type type parameters#59995
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Andarist wants to merge 1 commit intomicrosoft:mainfrom
Open
Exclude undefined from constraints of mapped type type parameters#59995Andarist wants to merge 1 commit intomicrosoft:mainfrom
undefined from constraints of mapped type type parameters#59995Andarist wants to merge 1 commit intomicrosoft:mainfrom
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fixes #59987
see @ahejlsberg's comment here about homomorphic mapped types and their constraints
given that
keyof X(and the same is true about[K in ...]) should never includeundefined, I think it should be fairly OK to eliminateundefinedfrom such rogue instantiations that might happen