[PATCH] D140726: lld: CHECK->LLD_CHECK to reduce chance of conflict with other libraries

Wed Dec 28 09:36:40 PST 2022

chandlerc added a comment.

In D140726#4018463 <https://reviews.llvm.org/D140726#4018463>, @dblaikie wrote:

> In D140726#4018459 <https://reviews.llvm.org/D140726#4018459>, @thakis wrote:
>
>> This is only used in lld cpp files, and lld's header files aren't meant to be used outside it. So halide is doing something unsupported.
>
> I don't think Halide's doing something wrong here - it's including `lld/Common/Driver.h` which states:
>
>   // Generic entry point when using LLD as a library, safe for re-entry, supports
>   // crash recovery.
>
> And that includes `lld/Common/CommonLinkerContext.h` which includes `lld/Common/ErrorHandler.h`
>
>> Could halide undef this macro after including the lld header and before including absl headers instead?
>
> Perhaps? I guess alternatively `lld/Common/Driver.h` could undef it at the end, but including any other lld header would risk breakage (since they might expect the macro to still be defined) - would probably make implementing that header tricky - needing to redefine that macro back again in the implementation file, etc.

Not sure this would help. If the colliding header were included *before* LLD's, this would still break.

I don't think it's realistic for any code that intends to be usable as a library with other code to be defining an un-prefixed macro. (That goes for *both* of the colliding cases here to be clear, not just LLD.) Not sure why this would be controversial.

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https://reviews.llvm.org/D140726