Sema: Fix two problems in checkReferencedGenericParams() analysis [5.9] #67939
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slavapestov
commented
Aug 15, 2023
slavapestov
commented
- Description: We require that all generic parameters are referenced in a function signature, because otherwise there is no way to call a function if a generic parameter isn't fixed by at least one constraint generated by the solver at the call site. This logic was wrong for pack expansion types, so you could in fact declare a function that cannot be called.
- Risk: Low. This might break source if someone accidentally shipped an API that cannot be called for this reason.
- Tested: New test added.
- Reviewed by: @hborla
- Don't walk into the count type of a PackExpansionType, because when matching two PackExpansionTypes, the solver only introduces a shape constraint between the count types, which does not fix it to a concrete type. - Similarly, don't walk into type alias substitutions, because only the desugared type is considered by the constraint solver. This is mildly source breaking, in that before we let you declare generic functions that could not be called.
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@swift-ci Please test |
hborla
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Aug 15, 2023
slavapestov
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Sep 20, 2023
…param-fix-5.9 Sema: Partial revert of #67939 [5.9]
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