[PATCH] D72231: [Sema] Adds the pointer-to-int-cast diagnostic

[John McCall via Phabricator via cfe-commits]

rjmccall added a comment.

In D72231#1881760 <https://reviews.llvm.org/D72231#1881760>, @nickdesaulniers wrote:

> In D72231#1879347 <https://reviews.llvm.org/D72231#1879347>, @rjmccall wrote:
>
> > In D72231#1878528 <https://reviews.llvm.org/D72231#1878528>, @nathanchance wrote:
> >
> > > There appear to a be semantic difference between GCC and clang with the current version of this patch which results in a lot of additional warnings in the Linux kernel: https://godbolt.org/z/eHFJd8
> >
> >
> > Warning about casting to an enum seems clearly correct and in scope for this warning.  Warning about casting to `_Bool` seems clearly incorrect and should not be warned about at all.
>
>
> Maybe we should only warn if the size of the `void*` is smaller than the size of the `enum`? (32b `void*`, 64b `enum`)? https://godbolt.org/z/oAts-u
>
> Otherwise this warning creates a massive mess for us to clean up, and I suspect Linux kernel developers will just end up disabling the warning.


If deployment is easier if we split out a subgroup that we can turn off, that seems fine.  But I don't see any good abstract justification for warning about a cast to `int` and not a cast to an `int`-sized `enum`.  What would the reasoning be, just that the latter "couldn't possibly" be intended to preserve the original pointer value, so it must be an opaque value being represented as a `void*`?  That seems pretty weak to me.


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https://reviews.llvm.org/D72231