Re: C++20 and gcc12/10

[Greg Troxel <gdt%lexort.com@localhost>]

Havard Eidnes <he%NetBSD.org@localhost> writes:

> What to do when "older" GCCs do not produce a working result?
> Such as e.g. gcc < 12 fails to build a working LLVM 18.x as part
> of the rust package on sparc64?  That's sort of hard to express
> using the *_FEATURES settings.

Maybe, maybe not.

If a feature is used, and gcc 12 is known to miscompile that feature,
then that feature should be marked for a higher version.

> Same goes for our 32-bit powerpc ports needing GCC >= 14 to build
> without falling over with
>
> assertion "memcmp(mf_ptr(mf) - 1, mf_ptr(mf) - matches[i].dist - 2, matches[i].len) == 0" failed: file "xz-5.2/src/liblzma/lz/lz_encoder_mf.c", line 40, function "lzma_mf_find"
>
> (tested and failed both with in-tree gcc10 and pkgsrc gcc12 on
> NetBSD/macppc 10.0)

That sounds like it need to be in platform/mk/NetBSD.mk ifdef on ppc, or
else in gcc.mk ifdef on ppc if it is believed to be true on non-NetBSD
ppc systems.   I don't think it's good to sprinkle this logic.