Nico Williams <[email protected]> writes:
> On Wed, Jun 03, 2026 at 05:08:55PM -0400, Tom Lane wrote:
>> Concretely, I'm imagining that we'd do more or less the attached in
>> c.h, and then the rest of the work would just be to remove the
>> not-very-large number of references to the alternative CPU symbols.
> Can a pre-processor make it an error for users to define __ macros?
I don't believe so. We have done similar things elsewhere, eg
before 25f36066d we had this in solaris.h:
/*
* Sort this out for all operating systems some time. The __xxx
* symbols are defined on both GCC and Solaris CC, although GCC
* doesn't document them. The __xxx__ symbols are only on GCC.
*/
#if defined(__i386) && !defined(__i386__)
#define __i386__
#endif
#if defined(__amd64) && !defined(__amd64__)
#define __amd64__
#endif
#if defined(__x86_64) && !defined(__x86_64__)
#define __x86_64__
#endif
#if defined(__sparc) && !defined(__sparc__)
#define __sparc__
#endif
Of course that only proves that Sun Studio didn't complain.
regards, tom lane
