On Mon, 17 Mar 2025 at 09:53, Jonathan Wakely <jwak...@redhat.com> wrote: > > > > On Monday, 17 March 2025, Christophe Lyon <christophe.l...@linaro.org> wrote: > > On Sun, 16 Mar 2025 at 21:54, Jonathan Wakely <jwak...@redhat.com> wrote: > >> > >> On Sun, 16 Mar 2025 at 13:16, <ci_not...@linaro.org> wrote: > >> > > >> > Dear contributor, > >> > > >> > Our automatic CI has detected problems related to your patch(es). Please > >> > find some details below. > >> > > >> > In arm-eabi cortex-m23 soft, after: > >> > | commit gcc-15-8035-g7ee31bc9276 > >> > | Author: Jonathan Wakely <jwak...@redhat.com> > >> > | Date: Thu Mar 13 13:34:55 2025 +0000 > >> > | > >> > | libstdc++: Implement <stdbit.h> for C++26 (P3370R1) > >> > | > >> > | This is the first part of the P3370R1 proposal just approved by > >> > the > >> > | committee in Wrocław. This adds C++ equivalents of the functions > >> > added > >> > | to C23 by WG14 N3022. > >> > | ... 16 lines of the commit log omitted. > >> > > >> > Produces 2 regressions: > >> > | > >> > | regressions.sum: > >> > | Running libstdc++:libstdc++-dg/conformance.exp ... > >> > | FAIL: 20_util/stdbit/1.cc -std=gnu++26 (test for excess errors) > >> > | UNRESOLVED: 20_util/stdbit/1.cc -std=gnu++26 compilation failed to > >> > produce executable > >> > > >> > Used configuration : > >> > *CI config* tcwg_gnu_embed_check_gcc arm-eabi -mthumb > >> > -march=armv8-m.base -mtune=cortex-m23 -mfloat-abi=soft -mfpu=auto > >> > *configure and test flags:* --target arm-eabi --disable-multilib > >> > --with-mode=thumb --with-cpu=cortex-m23 --with-float=soft > >> > --target_board=-mthumb/-march=armv8-m.base/-mtune=cortex-m23/-mfloat-abi=soft/-mfpu=auto > >> > qemu_cpu=cortex-m33 > >> > > >> > We track this bug report under > >> > https://linaro.atlassian.net/browse/GNU-1543. Please let us know if you > >> > have a fix. > >> > >> All the errors are of the form: > >> error: 'ULLONG_MAX' was not declared in this scope > >> but the test includes <limits.h>. > >> > >> So this target doesn't support long long? Or just doesn't define > >> ULLONG_MAX? > >> > > > > It does... > > > > I've manually reproduced it, and ISTM the problem is __STDC_VERSION__ > > is not defined, > > as gcc/glimits.h expects: > > https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/glimits.h;h=d5877602bf741383cfddb13236fbba1cf0b5b520;hb=HEAD#l102 > > > Aha! Thanks. > > > Compiling > > ============== > > #include <limits.h> > > unsigned long long var = ULLONG_MAX; > > ================ > > works with the same compiler, in C mode. > > > > But why would that work on arm-linux-gnueabihf and not on arm-none-eabi? > > I think glimits.h use only used if libc doesn't provide one, and I guess > glibc's limits.h is used for gnueabihf > > The C++ standard says it's implementation-defined whether __STDC_VERSION__ is > defined by a C++ compiler, and if defined, it's implementation-defined what > is value is > > GCC/glimits.h should check || (defined(__cplusplus) && __cplusplus >= > 201103L)) > > i.e. long long should be supported for C++11 and later. > > Libstdc++ actually assumes long long is always supported even for C++98 so > I'm surprised we've never noticed this before! I think we probably use the > type without using the LLONG_MAX macro, so it just happens to work. > > I can adjust the test to be agnostic to that macro, but I'll also propose a > patch to check __cplusplus in glimits.h > > Thanks again for finding the cause here.
Hmm, except that libstdc++ provides <climits> which should add ULLONG_MAX if it's not defined by libc: https://gcc.gnu.org/cgit/gcc/tree/libstdc++-v3/include/c_global/climits And <limits.h> should find the libstdc++ version which includes <climits>., but we're not installing the libstdc++ version of <limits.h>. That's a libstdc++ bug.
