Raise the minimum GCC version to 12.1 [BZ #32539]

For all Linux distros with glibc 2.40 which I can find, GCC 14.2 is used
to compile glibc 2.40:

OS                    GCC      URL
AOSC                  14.2.0   https://aosc.io/
Arch Linux            14.2.0   https://archlinux.org/
ArchPOWER             14.2.0   https://archlinuxpower.org/
Artix                 14.2.0   https://artixlinux.org/
Debian                14.2.0   https://www.debian.org/
Devuan                14.2.0   https://www.devuan.org/
Exherbo               14.2.0   https://www.exherbolinux.org/
Fedora                14.2.1   https://fedoraproject.org/
Gentoo                14.2.1   https://gentoo.org/
Kali Linux            14.2.0   https://www.kali.org/
KaOS                  14.2.0   https://kaosx.us/
LiGurOS               14.2.0   https://liguros.gitlab.io/
Mageia                14.2.0   https://www.mageia.org/en/
Manjaro               14.2.0   https://manjaro.org/
NixOS                 14.2.0   https://nixos.org/
openmamba             14.2.0   https://openmamba.org/
OpenMandriva          14.2.0   https://openmandriva.org/
openSUSE              14.2.0   https://www.opensuse.org/
Parabola              14.2.0   https://www.parabola.nu/
PLD Linux             14.2.0   https://pld-linux.org/
PureOS                14.2.0   https://pureos.net/
Raspbian              14.2.0   http://raspbian.org/
Slackware             14.2.0   http://www.slackware.com/
Solus                 14.2.0   https://getsol.us/
T2 SDE                14.2.0   http://t2sde.org/
Ubuntu                14.2.0   https://www.ubuntu.com/
Wikidata              14.2.0   https://wikidata.org/

Support older versions of GCC to build glibc 2.42:

1. Need to work around bugs in older versions of GCC.
2. Can't use the new features in newer versions of GCC, which may be
required for new features, like _Float16 which requires GCC 12.1 or
above, in glibc,

The main benefit of supporting older versions of GCC is easier backport
of bug fixes to the older releases of glibc, which can be mitigated by
avoiding incompatible features in newer versions of GCC for critical bug
fixes.  Require GCC 12.1 or newer to build.  Remove GCC version check for
PowerPC and s390x.

TEST_CC and TEST_CXX can be used to test the glibc build with the older
versions of GCC.

For glibc developers who are using Linux OSes which don't come with GCC
12.1 or newer, they should build and install GCC 12.1 or newer to work
on glibc.

This fixes BZ #32539.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>

1 files changed, 3 insertions, 20 deletions

diff --git a/INSTALL b/INSTALL
index a56179a9c9..d3200f271f 100644
--- a/INSTALL
+++ b/INSTALL
@@ -488,31 +488,14 @@ build the GNU C Library:
      As of release time, GNU 'make' 4.4.1 is the newest verified to work
      to build the GNU C Library.
 
-   * GCC 6.2 or newer
+   * GCC 12.1 or newer
 
-     GCC 6.2 or higher is required.  In general it is recommended to use
-     the newest version of the compiler that is known to work for
+     GCC 12.1 or higher is required.  In general it is recommended to
+     use the newest version of the compiler that is known to work for
      building the GNU C Library, as newer compilers usually produce
      better code.  As of release time, GCC 14.2.1 is the newest compiler
      verified to work to build the GNU C Library.
 
-     For PowerPC 64-bits little-endian (powerpc64le), a GCC version with
-     support for '-mno-gnu-attribute', '-mabi=ieeelongdouble', and
-     '-mabi=ibmlongdouble' is required.  Likewise, the compiler must
-     also support passing '-mlong-double-128' with the preceding
-     options.  As of release, this implies GCC 7.4 and newer (excepting
-     GCC 7.5.0, see GCC PR94200).  These additional features are
-     required for building the GNU C Library with support for IEEE long
-     double.
-
-     For ARC architecture builds, GCC 8.3 or higher is needed.
-
-     For s390x architecture builds, GCC 7.1 or higher is needed (See gcc
-     Bug 98269).
-
-     For AArch64 architecture builds with mathvec enabled, GCC 10 or
-     higher is needed due to dependency on arm_sve.h.
-
      For multi-arch support it is recommended to use a GCC which has
      been built with support for GNU indirect functions.  This ensures
      that correct debugging information is generated for functions