[Mesa-dev] [PATCH] util: no-op __builtin_types_compatible_p() for non-GCC compilers

[Ian Romanick]

On 3/29/19 9:57 AM, Brian Paul wrote:
> __builtin_types_compatible_p() is GCC-specific and breaks the
> MSVC build.
> 
> This intrinsic has been in u_vector_foreach() for a long time, but
> that macro has only recently been used in code
> (nir/nir_opt_comparison_pre.c) that's built with MSVC.
> 
> Fixes: 2cf59861a ("nir: Add partial redundancy elimination for compares")
> ---
>  src/util/u_vector.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/src/util/u_vector.h b/src/util/u_vector.h
> index cd8a95d..6807748 100644
> --- a/src/util/u_vector.h
> +++ b/src/util/u_vector.h
> @@ -80,6 +80,10 @@ u_vector_finish(struct u_vector *queue)
>     free(queue->data);
>  }
>  
> +#ifndef __GNUC__
> +#define __builtin_types_compatible_p(x) 1
> +#endif
> +
>  #define u_vector_foreach(elem, queue)                                  \
>     STATIC_ASSERT(__builtin_types_compatible_p(__typeof__(queue), struct u_vector *)); \

The way this is GCC builtin is used here, this should be fine.  However,
in case it's begin used elsewhere, we should #undef it afterwards.  I'd
hate to mask some other kind of bug that may be introduced later.

>     for (uint32_t __u_vector_offset = (queue)->tail;                                \
>