Hello. I received the report below from the Debian bug system.
I see a recent commit from Paul Eggert regarding glibc 2.43, so I guess this is already known. Should I try to cherry-pick fixes from the git repo (and if so, which ones?) or maybe I can expect a new release of m4 soon? Thanks. ----- Forwarded message from Aurelien Jarno <[email protected]> ----- Date: Sun, 01 Feb 2026 23:34:57 +0100 From: Aurelien Jarno <[email protected]> To: Debian Bug Tracking System <[email protected]> Subject: Bug#1126817: m4: FTBFS with glibc 2.43 due to ISO C23 const return types Source: m4 Version: 1.4.20-2 Severity: important Tags: ftbfs upstream Justification: fails to build from source User: [email protected] Usertags: glibc-2.43 Dear maintainer, m4 fails to build from source with glibc 2.43, currently in experimental. From the build log: | gcc -I. -Wdate-time -D_FORTIFY_SOURCE=2 -Wno-cast-qual -Wno-conversion -Wno-float-equal -Wno-sign-compare -Wno-undef -Wno-unused-function -Wno-unused-parameter -Wno-float-conversion -Wimplicit-fallthrough -Wno-pedantic -Wno-sign-conversion -Wno-type-limits -Wno-unused-const-variable -Wno-unsuffixed-float-constants -Wno-error -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/m4-1.4.20=. -fstack-protector-strong -fstack-clash-protection -fcf-protection -c -o libm4_a-asyncsafe-spin.o `test -f 'asyncsafe-spin.c' || echo './'`asyncsafe-spin.c | In file included from /usr/include/features.h:539, | from /usr/include/x86_64-linux-gnu/sys/types.h:25, | from ./sys/types.h:46, | from ./signal.h:49, | from asyncsafe-spin.h:43, | from asyncsafe-spin.c:22: | ./stdlib.h:827:20: error: expected identifier or '(' before '_Generic' | 827 | _GL_EXTERN_C void *bsearch (const void *__key, | | ^~~~~~~ | make[4]: *** [Makefile:4118: libm4_a-asyncsafe-spin.o] Error 1 | make[4]: Leaving directory '/build/reproducible-path/m4-1.4.20/lib' | make[3]: *** [Makefile:3608: all] Error 2 | make[3]: Leaving directory '/build/reproducible-path/m4-1.4.20/lib' | make[2]: *** [Makefile:2530: all-recursive] Error 1 | make[2]: Leaving directory '/build/reproducible-path/m4-1.4.20' | make[1]: *** [Makefile:2486: all] Error 2 | make[1]: Leaving directory '/build/reproducible-path/m4-1.4.20' | dh_auto_build: error: make -j1 returned exit code 2 | make: *** [debian/rules:8: binary] Error 25 | dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2 The full build log is attached to this bug report. The issue is due to ISO C23 declaration of bsearch, which now returns a pointer to a const-qualified type when the input argument is a pointer to a const-qualified type [1]. Regards Aurelien [1] https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;h=e271fb2e4d76903c77a302aaec1ca22ce31027d0;hb=f762ccf84f122d1354f103a151cba8bde797d521#l19 ----- End forwarded message -----
