static_assert failed due to requirement 'detail::count_v<TestEnum, false> > 0'

[morph208]

Hello,

I have a compilation issue with magic_enum::enum_cast using a string as input with the compiler clang 12.0.1. More precisely I am using enum_cast to cast a string into an enum into 2 locations in my code, one was compiling fine but not the others. It took me a while to discover the cause.

We are using the library g3log for our logs and I realised that if the header g3log.hpp was included before magic_enum.hpp, the call to emum_cast does not compile.

More specifically, this is the piece of code causing the issue with magic_enum:

#if !defined(__PRETTY_FUNCTION__)
#define __PRETTY_FUNCTION__   __FUNCTION__
#endif

You can see a reproductible code here: https://godbolt.org/z/dEnf1Gq56.

I am not very familiar with PRETTY_FUNCTION but I would have expected it to be defined with clang. It seems not to be the case for some reason so it is defined with FUNCTION and I'm guessing that magic_enum has a problem with that. At first glance it does not seem too crazy for g3log to define PRETTY_FUNCTION if it does not exist.

And if it is not defined, why magic_enum compiles successfully since magic_enum makes use of it?

I am not sure who is at fault here, g3log or magic_enum, but there are definitely not working together with clang. What is your take on that? Thank you in advance for your help.

[Neargye]

You can make a quick patch to the magic_enum, just add in heder #undef __PRETTY_FUNCTION__, it's should work https://godbolt.org/z/bd4P6Y64P.

But I'm not sure if it's worth adding this directly to the library, it looks rather strange.

[morph208]

Thanks for your quick reply. I know it looks strange, that's why I was interested into your take on that. I am planning to add

#if defined( __clang__ )
#    undef __PRETTY_FUNCTION__
#endif

before including magic_enum header in my code. I need to be able to compile with visual studio too so a general undef does not work. But if PRETTY_FUNCTION is not defined by clang (and I read the opposite everywhere), why magic_enum compiles with clang using PRETTY_FUNCTION that is not defined. It seems that I am missing something...

[Neargye]

I think the problem here is that PRETTY_FUNCTION is not a macro, it's magic constants

[morph208]

I think the problem here is that __PRETTY_FUNCTION__ not a macro, it's magic constants

I stumbled accross this page. Yeah maybe the test defined(__PRETTY_FUNCTION__) is not valid since it is not a macro...