There are a lot of failures building glibc with mainline GCC right now <https://sourceware.org/pipermail/libc-testresults/2021q3/008335.html> (previously, there were ICEs building glibc on various architectures, so these might be hard to bisect):
* x86_64-linux-gnu: "error: array subscript 0 is outside array bounds of '__seg_fs struct pthread * __seg_fs[0]' [-Werror=array-bounds]". This is the one discussed in <https://gcc.gnu.org/pipermail/gcc/2021-July/236922.html>. In file included from ../sysdeps/generic/libc-tsd.h:44, from ../include/../locale/localeinfo.h:224, from ../include/ctype.h:26, from loadmsgcat.c:29: loadmsgcat.c: In function '_nl_load_domain': ../sysdeps/x86_64/nptl/tls.h:185:4: error: array subscript 0 is outside array bounds of '__seg_fs struct pthread * __seg_fs[0]' [-Werror=array-bounds] 185 | (*(struct pthread *__seg_fs *) offsetof (struct pthread, header.self)) | ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../sysdeps/nptl/libc-lock.h:92:18: note: in expansion of macro 'THREAD_SELF' 92 | void *self = THREAD_SELF; \ | ^~~~~~~~~~~ loadmsgcat.c:770:3: note: in expansion of macro '__libc_lock_lock_recursive' 770 | __libc_lock_lock_recursive (lock); | ^~~~~~~~~~~~~~~~~~~~~~~~~~ * i686-gnu: hurdselect.c: In function '_hurd_select': hurdselect.c:555:7: error: 'ss' may be used uninitialized in this function [-Werror=maybe-uninitialized] 555 | _hurd_sigstate_unlock (ss); | ^~~~~~~~~~~~~~~~~~~~~~~~~~ As far as I can tell, this is a false positive from the compiler (this code is only reached if (sigport != MACH_PORT_NULL), in which case ss has been initialized). * Several architectures (all of them 32-bit), powerpc-linux-gnu for example: In file included from t.61.c:437: In function 'from_t_61_single', inlined from 'gconv' at ../iconv/skeleton.c:568:15: ../iconv/loop.c:440:22: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] 440 | bytebuf[inlen++] = *inptr++; | ~~~~~~~~~~~~~~~~~^~~~~~~~~~ ../iconv/loop.c: In function 'gconv': ../iconv/loop.c:382:17: note: at offset 2 into destination object 'bytebuf' of size 2 382 | unsigned char bytebuf[MAX_NEEDED_INPUT]; | ^~~~~~~ I don't know if this is a false positive or not. * powerpc64-linux-gnu: In file included from ../sysdeps/powerpc/dl-tls.c:20: In function '_dl_allocate_tls_init', inlined from '_dl_allocate_tls' at ../elf/dl-tls.c:621:10: ../elf/dl-tls.c:529:10: error: array subscript -1 is outside array bounds of 'void[9223372036854775807]' [-Werror=array-bounds] 529 | dtv_t *dtv = GET_DTV (result); | ^~~ In file included from ../elf/dl-tls.c:28, from ../sysdeps/powerpc/dl-tls.c:20: ../sysdeps/powerpc/nptl/tls.h:136:34: error: array subscript -1 is outside array bounds of 'void[9223372036854775807]' [-Werror=array-bounds] 136 | ((tcbhead_t *) (tcbp))[-1].dtv = dtvp + 1 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~ ../elf/dl-tls.c:544:7: note: in expansion of macro 'INSTALL_DTV' 544 | INSTALL_DTV (result, &dtv[-1]); | ^~~~~~~~~~~ * powerpc64le-linux-gnu: "error: '-mabi=ibmlongdouble' requires '-mlong-double-128'". See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100909>. -- Joseph S. Myers jos...@codesourcery.com
