error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result in a constant expression

[phprus]

Cmake & build log:

F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\build\2019-32-r>cmake -D
CMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=20 -DC
MAKE_CXX_FLAGS_INIT="/Zc:__cplusplus" -G "NMake Makefiles" ..\..
-- CMake version: 3.20.5
-- The CXX compiler identification is MSVC 19.29.30139.0
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studi
o/2019/Community/VC/Tools/MSVC/14.29.30133/bin/Hostx86/x86/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Module support is disabled.
-- Version: 8.1.1
-- Build type: Release
-- CXX_STANDARD: 20
-- Performing Test has_std_20_flag
-- Performing Test has_std_20_flag - Failed
-- Performing Test has_std_2a_flag
-- Performing Test has_std_2a_flag - Failed
-- Performing Test SUPPORTS_USER_DEFINED_LITERALS
-- Performing Test SUPPORTS_USER_DEFINED_LITERALS - Success
-- Performing Test FMT_HAS_VARIANT
-- Performing Test FMT_HAS_VARIANT - Success
-- Required features: cxx_variadic_templates
-- Target 'doc' disabled (requires doxygen)
-- Looking for C++ include pthread.h
-- Looking for C++ include pthread.h - not found
-- Found Threads: TRUE
-- Performing Test HAVE_FNO_DELETE_NULL_POINTER_CHECKS
-- Performing Test HAVE_FNO_DELETE_NULL_POINTER_CHECKS - Failed
-- FMT_PEDANTIC: OFF
-- Configuring done
-- Generating done
-- Build files have been written to: F:/tmp/fmt/fmt-c48353cb753889c38a94809b5bc7
2cedc1dedd26/build/2019-32-r

F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\build\2019-32-r>




cl   /TP -DGTEST_HAS_STD_WSTRING=1 -D_SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING=
1 -IF:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include -IF:\tmp\fmt
\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\gtest\. /Zc:__cplusplus /DWIN
32 /D_WINDOWS /GR /EHsc /O2 /Ob2 /DNDEBUG -MD -std:c++20 /showIncludes /FoCMakeF
iles\compile-test.dir\compile-test.cc.obj /FdCMakeFiles\compile-test.dir\ /FS -c
 F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc

compile-test.cc
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc(333
): error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result
 in a constant expression
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: failure was caused by call of undefined function or one not declared 'c
onstexpr'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: see usage of 'fmt::v8::detail::clz'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc(334
): error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result
 in a constant expression
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: failure was caused by call of undefined function or one not declared 'c
onstexpr'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: see usage of 'fmt::v8::detail::clz'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc(335
): error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result
 in a constant expression
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: failure was caused by call of undefined function or one not declared 'c
onstexpr'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: see usage of 'fmt::v8::detail::clz'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc(336
): error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result
 in a constant expression
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: failure was caused by call of undefined function or one not declared 'c
onstexpr'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: see usage of 'fmt::v8::detail::clz'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc(337
): error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result
 in a constant expression
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: failure was caused by call of undefined function or one not declared 'c
onstexpr'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: see usage of 'fmt::v8::detail::clz'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\test\compile-test.cc(338
): error C3615: constexpr function 'fmt::v8::detail::count_digits' cannot result
 in a constant expression
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: failure was caused by call of undefined function or one not declared 'c
onstexpr'
F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\include\fmt\format.h(995
): note: see usage of 'fmt::v8::detail::clz'
NMAKE : fatal error U1077: '"C:\Program Files\CMake\bin\cmake.exe"' : return cod
e '0x2'
Stop.
NMAKE : fatal error U1077: '"C:\Program Files (x86)\Microsoft Visual Studio\2019
\Community\VC\Tools\MSVC\14.29.30133\bin\HostX86\x86\nmake.exe"' : return code '
0x2'
Stop.
NMAKE : fatal error U1077: '"C:\Program Files (x86)\Microsoft Visual Studio\2019
\Community\VC\Tools\MSVC\14.29.30133\bin\HostX86\x86\nmake.exe"' : return code '
0x2'
Stop.

F:\tmp\fmt\fmt-c48353cb753889c38a94809b5bc72cedc1dedd26\build\2019-32-r>

The error is present only if /Zc:__cplusplus is enabled.