error: call to non-‘constexpr’ function ‘void fmt::v8::detail::error_handler::on_error(const char*)’

[boxerab]

I just updated my project to the latest master version of spdlog.

Now, these lines trigger a compiler error:
(g++ 10.3 )

char* s = "cat";
char sep = ',';
spdlog::error("Could not parse precinct dimension: {} {0:x}", s, sep);

/home/src/grok/src/bin/jp2/grk_compress.cpp:963:74:   in ‘constexpr’ expansion of ‘fmt::v8::basic_format_string<char, char*&, char&>("Could not parse precinct dimension: {} {0:x}")’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2845:40:   in ‘constexpr’ expansion of ‘fmt::v8::detail::parse_format_string<true, char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char> >(((fmt::v8::basic_format_string<char, char*&, char&>*)this)->fmt::v8::basic_format_string<char, char*&, char&>::str_, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>(fmt::v8::basic_string_view<char>(((const char*)s)), (fmt::v8::detail::error_handler(), fmt::v8::detail::error_handler())))’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2430:36:   in ‘constexpr’ expansion of ‘fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>&>(p, end, (* & handler))’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2366:25:   in ‘constexpr’ expansion of ‘fmt::v8::detail::parse_arg_id<char, fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>&>::id_adapter&>(begin, end, adapter)’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2197:51:   in ‘constexpr’ expansion of ‘fmt::v8::detail::do_parse_arg_id<char, fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>&>::id_adapter&>(begin, end, (* & handler))’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2178:14:   in ‘constexpr’ expansion of ‘(& handler)->fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>&>::id_adapter::operator()(index)’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2349:71:   in ‘constexpr’ expansion of ‘(&((fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>&>::id_adapter*)this)->fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>&>::id_adapter::handler)->fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>::on_arg_id(id)’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2694:33:   in ‘constexpr’ expansion of ‘((fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>*)this)->fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, char*, char>::context_.fmt::v8::detail::compile_parse_context<char, fmt::v8::detail::error_handler>::check_arg_id(id)’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:2472:23:   in ‘constexpr’ expansion of ‘((fmt::v8::detail::compile_parse_context<char, fmt::v8::detail::error_handler>*)this)->fmt::v8::detail::compile_parse_context<char, fmt::v8::detail::error_handler>::<anonymous>.fmt::v8::basic_format_parse_context<char>::check_arg_id(id)’
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:672:15: error: ‘constexpr void fmt::v8::basic_format_parse_context<Char, ErrorHandler>::on_error(const char*) [with Char = char; ErrorHandler = fmt::v8::detail::error_handler]’ called in a constant expression
  672 |       on_error("cannot switch from automatic to manual argument indexing");
      |       ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:679:22: note: ‘constexpr void fmt::v8::basic_format_parse_context<Char, ErrorHandler>::on_error(const char*) [with Char = char; ErrorHandler = fmt::v8::detail::error_handler]’ is not usable as a ‘constexpr’ function because:
  679 |   FMT_CONSTEXPR void on_error(const char* message) {
      |                      ^~~~~~~~
/home/src/grok/src/include/spdlog/fmt/bundled/core.h:680:27: error: call to non-‘constexpr’ function ‘void fmt::v8::detail::error_handler::on_error(const char*)’
  680 |     ErrorHandler::on_error(message);

[gabime]

Seems like gcc 10 specific issue (are you compiling with c++ 20?)

[boxerab]

Yes, c++20

[gabime]

You could try different version of gcc or turn off c++20 if you must use this particular gcc version..

[boxerab]

I'm afraid I need c++20 for other parts of the code.

[Jackson-soft]

same issue, C++20

Apple clang version 12.0.5 (clang-1205.0.22.9)

[dkavolis]

/home/src/grok/src/include/spdlog/fmt/bundled/core.h:672:15: error: ‘constexpr void fmt::v8::basic_format_parse_context<Char, ErrorHandler>::on_error(const char*) [with Char = char; ErrorHandler = fmt::v8::detail::error_handler]’ called in a constant expression
  672 |       on_error("cannot switch from automatic to manual argument indexing");
      |       ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

fmt gives an explanation on what is wrong with the format string, it is not an issue with the library. The error is caught at compile time instead of runtime.

[gabime]

@boxerab What is the format string that causing this? could be like @dkavolis said a bad format string.

[dkavolis]

@boxerab What is the format string that causing this? could be like @dkavolis said a bad format string.

"Could not parse precinct dimension: {} {0:x}" is mixing automatic and manual indexing, fmt does not allow this as indicated by the error.

[gabime]

@boxerab does fixing the format string solves it?

[boxerab]

@gabime yep, that fixed it. I will close this now - @Jackson-soft, please can you please open a new issue if this is still a problem for you ?