On Mon, 10 Apr 2023, 12:34 Kalamatee via Gcc-help, <gcc-help@gcc.gnu.org>
wrote:

> Hi,
>
> When im trying to build gcc12, I get the following error -:
>
> /bin/bash ../../libtool --tag CXX --tag disable-shared   --mode=compile
> /home/test/gcc12/./gcc/xgcc -shared-libgcc -B/home/test/gcc12/./gcc
> -nostdinc++ -L/home/test/gcc12/x86_64-aros/libstdc++-v3/src
> -L/home/test/gcc12/x86_64-aros/libstdc++-v3/src/.libs
> -L/home/test/gcc12/x86_64-aros/libstdc++-v3/libsupc++/.libs
>
> -B/home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/bin/
>
> -B/home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/lib/
> -isystem
>
> /home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/include
> -isystem
>
> /home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/sys-include
>    -I/home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/../libgcc
> -I/home/test/gcc12/x86_64-aros/libstdc++-v3/include/x86_64-aros
> -I/home/test/gcc12/x86_64-aros/libstdc++-v3/include
> -I/home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/libsupc++   -std=gnu++17
> -nostdinc++   -fno-implicit-templates  -Wall -Wextra -Wwrite-strings
> -Wcast-qual -Wabi=2  -fdiagnostics-show-location=once   -ffunction-sections
> -fdata-sections  -frandom-seed=floating_from_chars.lo  -fimplicit-templates
> -g -O2  -c -o floating_from_chars.lo
>
> /home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/src/c++17/floating_from_chars.cc
> libtool: compile:  /home/test/gcc12/./gcc/xgcc -shared-libgcc
> -B/home/test/gcc12/./gcc -nostdinc++
> -L/home/test/gcc12/x86_64-aros/libstdc++-v3/src
> -L/home/test/gcc12/x86_64-aros/libstdc++-v3/src/.libs
> -L/home/test/gcc12/x86_64-aros/libstdc++-v3/libsupc++/.libs
>
> -B/home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/bin/
>
> -B/home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/lib/
> -isystem
>
> /home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/include
> -isystem
>
> /home/kalam/builds/pc-x86_64-gcc12-clean/bin/linux-x86_64/tools/crosstools/x86_64-aros/sys-include
> -I/home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/../libgcc
> -I/home/test/gcc12/x86_64-aros/libstdc++-v3/include/x86_64-aros
> -I/home/test/gcc12/x86_64-aros/libstdc++-v3/include
> -I/home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/libsupc++ -std=gnu++17
> -nostdinc++ -fno-implicit-templates -Wall -Wextra -Wwrite-strings
> -Wcast-qual -Wabi=2 -fdiagnostics-show-location=once -ffunction-sections
> -fdata-sections -frandom-seed=floating_from_chars.lo -fimplicit-templates
> -g -O2 -c
>
> /home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/src/c++17/floating_from_chars.cc
> -o floating_from_chars.o
> In file included from
>
> /home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/src/c++17/floating_from_chars.cc:77:
>
> /home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/src/c++17/fast_float/fast_float.h:
> In function 'void
> {anonymous}::fast_float::round_nearest_tie_even(adjusted_mantissa&,
> int32_t, callback)':
>
> /home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/src/c++17/fast_float/fast_float.h:2500:12:
> error: 'UINT64_MAX' was not declared in this scope
>  2500 |     mask = UINT64_MAX;
>       |            ^~~~~~~~~~
>
> /home/test/gcc12/src/gcc-12.2.0/libstdc++-v3/src/c++17/fast_float/fast_float.h:1:1:
> note: 'UINT64_MAX' is defined in header '<cstdint>'; did you forget to
> '#include <cstdint>'?
>   +++ |+#include <cstdint>
>     1 | // fast_float by Daniel Lemire
> make[7]: *** [Makefile:585: floating_from_chars.lo] Error 1
>
> I can see from the preprocessor output, the necessary header is included -
> but is protected with
> #if !defined(__cplusplus) || defined(__STDC_LIMIT_MACROS)
> #endif
>
> And since the compiler doesn't define __STDC_LIMIT_MACROS on the command
> line, or in the source file - it is resolved.
>
> I'm not sure though, where is the correct place to fix this?
>


In the C library. The C++ standard is very clear that __STDC_LIMIT_MACROS
has no meaning whatsoever in C++. The C library's <stdint.h> must define
those macros unconditionally for C++. The C99 standard said the macros are
required for C++, so some C libraries follow that rule, but they should
follow the C++ standard for C++ code, since C99 only defines C and had no
business trying to specify how C++ works.

If you cannot fix the libc headers then you can #define __STDC_LIMIT_MACROS
in your target's os_defines.h header in libstdc++ (I think that's the right
workaround, but I'm not at my desk to check it ... Search for that macro in
the libstdc++ source to see how other targets handle non-conforming libc
headers.

>