Compile error (probably constexpr problem)

[mmarkeloff]

Hi!

I'm getting this error when trying to compile fmt.cpp:

$ cl -GR -EHsc /O2 /DNDEBUG /GS- /W3 /DWIN2K /DWIN32 /DLLP64 /DWINVER=0x501 /D_WIN32_WINNT=0x501 /DWINNT /D_BIND_TO_CUR
RENT_VCLIBS_VERSION /DYY_NO_UNISTD_H -DSPDLOG_COMPILED_LIB /I'include' /c 'src/fmt.cpp' /Fo'fmt.o'
Microsoft (R) C/C++ Optimizing Compiler Version 19.11.25547 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

fmt.cpp
...\spdlog\include\spdlog\fmt\bundled\core.h(2729): error C2131: expression did not evaluate to a constant
...\spdlog\include\spdlog\fmt\bundled\core.h(2729): note: a non-constant (sub-)expression was encountered
...\spdlog\include\spdlog\fmt\bundled\core.h(2848): note: see reference to function template instantiation 'void fmt::v8::detail::check_format_string<fmt::v8::string_view&,const char(&)[3],S,0>(S)' being compiled
        with
        [
            S=fmt::v8::detail::format_error_code::<lambda_0aa9e4657fec1b144ce80cc145d82a7f>::()::FMT_COMPILE_STRING
        ]
include\spdlog/fmt/bundled/format-inl.h(74): note: see reference to function template instantiation 'fmt::v8::basic_format_string<char,fmt::v8::string_view &,const char (&)[3]>::basic_format_string<fmt::v8::detail::format_error_code::<lambda_0aa9e4657fec1b144ce80cc145d82a7f>::()::FMT_COMPILE_STRING,0>(const S &)' being compiled
        with
        [
            S=fmt::v8::detail::format_error_code::<lambda_0aa9e4657fec1b144ce80cc145d82a7f>::()::FMT_COMPILE_STRING
        ]
include\spdlog/fmt/bundled/format-inl.h(74): note: see reference to function template instantiation 'fmt::v8::basic_format_string<char,fmt::v8::string_view &,const char (&)[3]>::basic_format_string<fmt::v8::detail::format_error_code::<lambda_0aa9e4657fec1b144ce80cc145d82a7f>::()::FMT_COMPILE_STRING,0>(const S &)' being compiled
        with
        [
            S=fmt::v8::detail::format_error_code::<lambda_0aa9e4657fec1b144ce80cc145d82a7f>::()::FMT_COMPILE_STRING
        ]
...\spdlog\include\spdlog\fmt\bundled\core.h(2729): fatal error C1903: unable to recover from previous error(s); stopping compilation

My environment:

• Windows 10
• __cplusplus 199711 (but my compiler supports cpp14 features (not cpp17))
• WINVER 0x501 (also tried 0x600)
• _WIN32_WINNT 0x501 (also tried 0x600)

I'm deleted ifndef branch, and it helps.

[vitaut]

Looks like your compiler doesn't support relaxed constexpr. I guess the workaround would be to change FMT_MSC_VER >= 1910 (to FMT_MSC_VER >= 1912?) in

fmt/include/fmt/core.h

Line 91 in ee63f5f

(FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VER >= 1910 || \

A PR would be welcome.

[mmarkeloff]

Yeah, my _MSC_VER is 1911. Your fix is helps for me.

[tstrutz]

I actually still encountered this problem on the current branch and am using _MSC_VER 1929. (VS2017 V15.7.6)

I had to increment the value of FMT_MSC_VER to 1930 to get it to avoid compiling the statements.

[ebrianne]

I actually still encountered this problem on the current branch and am using _MSC_VER 1929. (VS2017 V15.7.6)

I had to increment the value of FMT_MSC_VER to 1930 to get it to avoid compiling the statements.

Same here using fmt 9.1.0