Formatter Compilation Error

[petrasvestartas]

Formatter is not fully supported for C++20.

I am using MacBook Pro with Intel Chip that has Clang 14.
CMakeLists: https://github.com/petrasvestartas/wood/tree/main/cmake

Windows and Mac M1 have no problems compiling recent cgal but on this machine I get errors stated below.

Is there any CMake flag to disable formatter?

/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1005:8: error: explicit specialization of undeclared template struct 'formatter'
struct formatter<CGAL::Output_rep<T, F>, CharT> : public std::formatter<std::basic_string<CharT>>
       ^        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1005:63: error: too few template arguments for class template 'formatter'
struct formatter<CGAL::Output_rep<T, F>, CharT> : public std::formatter<std::basic_string<CharT>>
                                                              ^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1005:8: note: template is declared here
struct formatter<CGAL::Output_rep<T, F>, CharT> : public std::formatter<std::basic_string<CharT>>
       ^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1007:29: error: no template named 'basic_format_parse_context' in namespace 'std'
  constexpr auto parse(std::basic_format_parse_context<CharT>& ctx)
                       ~~~~~^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1015:18: error: no member named 'format_error' in namespace 'std'
      throw std::format_error("formatter for CGAL::Output_rep only support precision, like `{:.6}`");
            ~~~~~^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1018:18: error: no member named 'format_error' in namespace 'std'
      throw std::format_error("Missing precision");
            ~~~~~^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1020:18: error: no member named 'format_error' in namespace 'std'
      throw std::format_error("Invalid value for precision");
            ~~~~~^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1036:17: error: too few template arguments for class template 'formatter'
    return std::formatter<std::basic_string<CharT>>::format(ss.str(), ctx);
                ^
/Users/petras/brg/2_code/wood_nano/src/wood/cmake/build/install/cgal/include/CGAL/IO/io.h:1005:8: note: template is declared here
struct formatter<CGAL::Output_rep<T, F>, CharT> : public std::formatter<std::basic_string<CharT>>

[sloriot]

formatter is hidden behind the macro CGAL_CAN_USE_CXX20_FORMAT.

in config.h we have:

#if __cpp_lib_format >= 201907L
#  define CGAL_CAN_USE_CXX20_FORMAT 1
#endif

The test plaform cezanne is also an intel chip with AppleClang 14.0.0.14000029, and it does not have the issue.
Could you try commenting the define in CGAL/config.h (in Installation package) just to make sure it would fix the issue?

[petrasvestartas]

In which folder I could find the config.h?

[sloriot]

include/CGAL/config.h

[petrasvestartas]

compiles after commenting out source code!

how to undefine this flag?

I tried cmakelist no effect:
add_definitions(-DCGAL_CAN_USE_CXX20_FORMAT=0)

I tried in main stdafx define this, no effect:

#undef CGAL_CAN_USE_CXX20_FORMAT
#define CGAL_CAN_USE_CXX20_FORMAT 0

[sloriot]

Could you try modifying in config.h:

#if __cpp_lib_format >= 201907L
#  define CGAL_CAN_USE_CXX20_FORMAT 1
#endif

into

#if __cpp_lib_format >= 201907L && __has_include(<format>)
#  define CGAL_CAN_USE_CXX20_FORMAT 1
#endif

[afabri]

@petrasvestartas ping

[petrasvestartas]

Very sorry, I will try again and let you know.