[PATCH] libgomp: Fix GCC build after glibc@cd748a6

The toolchain autobuilds for ia64 failed ([1]) yesterday with:

```
libtool: compile:  /usr/src/t2-src/src.gcc.ia64-toolchain.251121.040147.278918/gcc-16-20251116/objs/gcc/xgcc-wrapper /usr/src/t2-src/src.gcc.ia64-toolchain.251121.040147.278918/gcc-16-20251116/objs/./gcc/xgcc -B/usr/src/t2-src/src.gcc.ia64-toolchain.251121.040147.278918/gcc-16-20251116/objs/./gcc/ -B/usr/src/t2-src/build/ia64-toolchain-24-svn-generic-ia64-itanium2-cross-linux/TOOLCHAIN/cross/usr/ia64-t2-linux-gnu/bin/ -B/usr/src/t2-src/build/ia64-toolchain-24-svn-generic-ia64-itanium2-cross-linux/TOOLCHAIN/cross/usr/ia64-t2-linux-gnu/lib/ -isystem /usr/src/t2-src/build/ia64-toolchain-24-svn-generic-ia64-itanium2-cross-linux/TOOLCHAIN/cross/usr/ia64-t2-linux-gnu/include -isystem /usr/src/t2-src/build/ia64-toolchain-24-svn-generic-ia64-itanium2-cross-linux/TOOLCHAIN/cross/usr/ia64-t2-linux-gnu/sys-include --sysroot=/usr/src/t2-src/build/ia64-toolchain-24-svn-generic-ia64-itanium2-cross-linux -DHAVE_CONFIG_H -I. -I../../../libgomp -I../../../libgomp/config/linux/ia64 -I../../../libgomp/config/linux -I../../../libgomp/config/posix -I../../../libgomp -I../../../libgomp/../include -Wall -Werror -ftls-model=initial-exec -pthread -DUSING_INITIAL_EXEC_TLS -g -O2 -MT oacc-cuda.lo -MD -MP -MF .deps/oacc-cuda.Tpo -c ../../../libgomp/oacc-cuda.c -o oacc-cuda.o >/dev/null 2>&1
../../../libgomp/affinity-fmt.c: In function 'gomp_display_affinity':
../../../libgomp/affinity-fmt.c:330:25: error: initialization discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
  330 |               char *q = strchr (p + 1, '}');
      |                         ^~~~~~
```

[1]: https://github.com/johnny-mnemonic/toolchain-autobuilds/actions/runs/19559235881

This is not ia64-specific but due to the changes in the recent glibc
commit "Implement C23 const-preserving standard library macros" (i.e.
[2]) now requiring "char *q" to be a pointer to a const char to compile
w/o error because of the return value of strchr() .

[2]: https://sourceware.org/git/?p=glibc.git;a=commit;h=cd748a63ab1a7ae846175c532a3daab341c62690

Also see the related discussion at [3] for details.

[3]: https://sourceware.org/pipermail/libc-alpha/2025-November/172809.html

The GCC build is fixed by the attached patch, see [4] for a successful
build with the then latest snapshots of binutils, glibc and GCC.

[4]: https://github.com/johnny-mnemonic/toolchain-autobuilds/actions/runs/19585045571

Idea from Tomas, attached patch from me.

Cheers,
Frank

0001-libgomp-Fix-GCC-build-after-glibc-cd748a6.patch

From 80af9c233c694904174b54a59404d311378f41f8 Mon Sep 17 00:00:00 2001
From: Frank Scheiner <frank.scheiner@web.de>
Date: Sat, 22 Nov 2025 14:58:10 +0100
Subject: [PATCH] libgomp: Fix GCC build after glibc@cd748a6

char *q needs to be a pointer to a const char for the return value of
strchr() with glibc after "Implement C23 const-preserving standard library
macros".

[glibc@cd748a6]: https://sourceware.org/git/?p=glibc.git;a=commit;h=cd748a63ab1a7ae846175c532a3daab341c62690

libgomp/ChangeLog:
	* affinity-fmt.c: Make char *q a pointer to a const char.

diff --git a/libgomp/affinity-fmt.c b/libgomp/affinity-fmt.c
index 1fae893cbaca28bd4cf05f70ce424dc333ef58da..8d3df5f1cd55073341f4a94769de1ffd71940112 100644 (file)
--- a/libgomp/affinity-fmt.c
+++ b/libgomp/affinity-fmt.c
@@ -327,7 +327,7 @@ gomp_display_affinity (char *buffer, size_t size,
              }
          if (c == '{')
            {
-             char *q = strchr (p + 1, '}');
+             const char *q = strchr (p + 1, '}');
              if (q)
                gomp_fatal ("unsupported long type name '%.*s' in affinity "
                            "format", (int) (q - (p + 1)), p + 1);