Fix type parameters upon subsequent visits to a parameter that caused fixing the first time #3787
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| assignContextualParameterTypes(signature, contextualSignature, contextualMapper || identityMapper); | ||
| } | ||
| if (!node.type && !signature.resolvedReturnType) { | ||
| if (mightFixTypeParameters || !node.type && !signature.resolvedReturnType) { |
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why you have to check mightFixTypeParameters again?
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Good question. In this case, I noticed that we are passing the contextualMapper into getReturnTypeFromBody. That indicates to me that we may fix some type parameters if the return expression contains a function expression. So I am ensuring that anywhere that it's possible to fix type parameters, we go through that code path.
… fixingTypeParameters Conflicts: src/compiler/checker.ts
… fixingTypeParameters
… fixingTypeParameters
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@yuit any more feedback? @DanielRosenwasser @ahejlsberg Do you have any feedback on this change? |
… fixingTypeParameters
… fixingTypeParameters
| * | ||
| * 1. undefined - this means we are not doing inferential typing, but we may do contextual typing, | ||
| * which could cause us to assign a parameter type | ||
| * 2. identityMapper - means we want to avoid assigning a parameter type, whether or not we are in |
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👍 |
JsonFreeman
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Jul 17, 2015
Fix type parameters upon subsequent visits to a parameter that caused fixing the first time
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Fixes #2378.
The problem is that if a type parameter has already been given a type in the process of type argument inference, and caused type parameters to be fixed, we don't consistently fix the type parameters on a subsequent visit. See the bug for examples of how this can be observed.
The fix is that if a contextually typed parameter already has a type, we should still fix the type parameters that would have been fixed, had this been the first encounter of the given parameter.