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[clang] Fix name conflict with sys/mac.h on AIX #88644

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Merged
merged 3 commits into from
Apr 14, 2024
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[clang] Fix name conflict with sys/mac.h on AIX #88644

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[clang] Fix name conflict with `sys/mac.h` on AIX
Endilll Apr 14, 2024
33b767c
Merge remote-tracking branch 'upstream/main' into semacuda-aix-fix
Endilll Apr 14, 2024
52e1d6e
Update clang/include/clang/Basic/Cuda.h
Endilll Apr 14, 2024
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4 changes: 4 additions & 0 deletions clang/include/clang/Basic/Cuda.h
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Expand Up @@ -50,6 +50,10 @@ const char *CudaVersionToString(CudaVersion V);
// Input is "Major.Minor"
CudaVersion CudaStringToVersion(const llvm::Twine &S);

// We have a name conflict with sys/mac.h on AIX
#ifdef SM_32
#undef SM_32
#endif
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@Artem-B Artem-B Apr 15, 2024 •
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Ugh. What could possibly go wrong, if someone who needed the original definition of SM_32 ends up transitively including this header and losing the macro definition?

A better way to handle it as a workaround would be to push the macro definition, undef it, and then pop it back at the end of the header.

Even better would be to add prefixes to the macros and/or the enum here to disambiguate them

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We already do that, the problem is that CudaArch::SM_32 will still invoke the preprocessorr, see https://godbolt.org/z/84xKej5K9. We can't do this from a header level, we'd need to do it around every single use as far as I know, which might be doable?

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We could always just make all of these lower case instead?

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We could always just make all of these lower case instead?

That would be odd. LLVM style wants them to be CamelCased.
This enum is rarely used, so renaming them to something more CUDA/NVPTXspecific would be best, IMO.
E.g NVSM_32

Or we could rename only SM_32. The constant is rather inconsequential and is used in a few places only. Renaming it to _SM_32 with a comment that AIX headers have SM_32 defined.

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I mean, modern CUDA installations don't even allow you to build for anything older than sm_52 now. We could also just delete those enums entirely.

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@jhuber6 jhuber6 Apr 15, 2024 •
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Just naming it like _SM_32 works for me, with a note that they'll get removed in the future. I can make the PR if you want.

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_SM_32 is a reserved identifier so we should not use that as a name.

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Good point, totally forgot that _<uppercase> was reserved (Would've been nice if the AIX headers followed that rule).

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SGTM. Thank you for taking care of this issue.

On a side note, do we know if there's a way to file a bug for AIX? They should not be setting macros with names that could conceivably be defined by a user. In theory. I think normally they should be double-underscore-prefixed.

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Done in #88779

enum class CudaArch {
UNUSED,
UNKNOWN,
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