[PATCH] D71241: [OpenMP][WIP] Use overload centric declare variants

[Johannes Doerfert via Phabricator via cfe-commits]

jdoerfert added a comment.

In D71241#1783362 <https://reviews.llvm.org/D71241#1783362>, @ABataev wrote:

> >>> - Take https://godbolt.org/z/2evvtN which shows that the alias solution is incompatible with linking.
> >> 
> >> Undefined behavior according to the standard.
> > 
> > I don't think so. If you do, please reference the rules this would violate.
>
> Page 59, 25-27.


OpenMP 5.0, Page 59, 25-27:

> • If the function has any declarations, then the declare variant directives for any declarations that have one must be equivalent. If the function definition has a declare variant, it must also be equivalent. Otherwise, the result is unspecified.

In the example (https://godbolt.org/z/2evvtN), all `declare variant` directives on declarations *that have one* are equivalent, since only on declaration has a `declare variant`. Since the function definition does not have a `declare variant`, the second restriction is also fulfilled.

To summarize, this example is broken in the current scheme and valid according to the spec.


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https://reviews.llvm.org/D71241