[PATCH] glibc __builtin_add_overflow problem with GCC < 7

[Joseph Myers]

On Thu, 7 Jan 2021, Stefan Liebler via Libc-alpha wrote:

> On s390x perspective, I'm fine with requiring GCC 7.1.
> For all other platforms, can somebody else (perhaps Joseph Myers) please
> comment on requiring GCC 7.1 instead of GCC 6.2 and/or rejecting ICC?

Typically the minimum version of a tool for building glibc is increased 
when the new version is old enough *and* the increase allows significant 
cleanups in glibc.  In this case there are quite a lot of __GNUC_PREREQ 
conditionals that could be removed by requiring GCC 7 (but you can't 
remove those in installed headers, of which there are also quite a lot, 
and increasing the minimum does make it harder to test the older-GCC 
conditionals in installed headers, since we don't have any way in the 
glibc testsuite to test header functionality with older-GCC and non-GCC 
compilers; <tgmath.h> is a specific case where GCC 6, 7 and >= 8 all use 
significantly different header code).

-- 
Joseph S. Myers
joseph@codesourcery.com