Handle & and | types when computing tuple arity #15330
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bishabosha
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May 30, 2022
nicolasstucki
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bishabosha
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Jun 9, 2022
| * | ||
| * @param relaxEmptyTuple if true then TypeRef(EmptyTuple$) =:= EmptyTuple.type | ||
| */ | ||
| def tupleArity(relaxEmptyTuple: Boolean = false)(using Context): Int = self match { |
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Edit: I think this will affect the RefinedPrinter which will no longer pretty print generic tuple types
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ok it seems to work for refined printer I see you made the change, disregard all :)
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For other that may read this thread: the important thing here is that tupleElementTypes handles the EmptyTuple type alias but tupleArity does not (see comment on dealiasing)
bishabosha
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Jun 9, 2022
There are cases where we know the tuple arity but cannot know the flat element types of the tuple. For example `(A, B) | (C, D)` has arity 2 but we cannot create a single tuple containing these elements. In tupleArity we are missing a dealias. We need to investigate this further. At first glance it seems that the signature of `Tuple.apply(x)` is erased to `(Object): Product` and not `(Object): Tuple1`. This would have been caused be the missing dealias. Unfortunately, if this is the case we might not be able to fix the erasure without breaking binary compatibility of the standard library.
bishabosha
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Jun 9, 2022
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Fixes #15302