Always get the apparent type when retrieving a contextual type#3724
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@ahejlsberg Whenever you have a chance, I'm curious what you think of this change. |
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Looks good to me. Particularly makes sense that an inferred type for a type parameter with a constraint that has an index signature also gets an index signature. |
JsonFreeman
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Always get the apparent type when retrieving a contextual type
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The purpose of contextual typing is to enrich our typing of an expression based on type information from its context. Naturally, this works best when the contextual type is as rich as possible. Looking at getApparentType in the compiler, the type it returns is always at least as rich as the type it takes. So why not make the contextual type even richer by using its apparent type?
This is a language change, and must be reflected in the spec. The difficulty is that apparent type has been removed from the spec. Maybe we should put it back.
Fixes #3708.