msvc 17.3.4 c++20 consteval error with master and tag 9.1.0

[ridilculous]

With msvc 17.3.4 i'm getting compilation errors with 9.1.0 and master (for char and wchar_t) but not with 9.0.0:

error C7595: 'fmt::v9::basic_format_string<char,std::string &>::basic_format_string': call to immediate function is not a constant expression
1>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.33.31629\include\xstring(2272,35): message : failure was caused by a read of a variable outside its lifetime
1>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.33.31629\include\xstring(2272,35): message : see usage of 'f'
error C7595: 'fmt::v9::basic_format_string<wchar_t,std::wstring &>::basic_format_string': call to immediate function is not a constant expression
1>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.33.31629\include\xstring(2272,35): message : failure was caused by a read of a variable outside its lifetime
1>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.33.31629\include\xstring(2272,35): message : see usage of 'f'

godbolt string test

godbolt wstring test

This is maybe related to #2455

[vitaut]

Format strings must be known at compile time by default, please see the docs: https://fmt.dev/latest/api.html#core-api.

[ridilculous]

Oh, thanks! I wasn't aware of runtime format strings.

Is there a implicit ctor which makes the wstring version work in contrast to the string version? (example)

[vitaut]

Compile-time checks for wide strings were only enabled recently. I guess the version on godbolt doesn't have them yet.