possible API break upgrading form 6.1.2 to 6.2.1

[prince-chrismc]

I am using many third_party libraries, one of which is this string_view implementation.

My code in question looks like the following...

const nonstd::string_view path = "path/to/file";
const auto err_msg = fmt::format(FMT_STRING("Endpoint - {:s}"), path);

...which compiled with v6.1.2

However, with upgrading to v6.2.1 I need to call path.to_string() for an std::string in order for it to compile. There is no runtime error if I remove the compile time check.

compile error

1>C:\Users\cmcarthu\.conan\data\fmt\6.2.1\_\_\package\8cf01e2f50fcd6b63525e70584df0326550364e1\include\fmt/format.h(2705): error C2131: expression did not evaluate to a constant
1>C:\Users\cmcarthu\.conan\data\fmt\6.2.1\_\_\package\8cf01e2f50fcd6b63525e70584df0326550364e1\include\fmt/format.h(2638): note: failure was caused by call of undefined function or one not declared 'constexpr'
1>C:\Users\cmcarthu\.conan\data\fmt\6.2.1\_\_\package\8cf01e2f50fcd6b63525e70584df0326550364e1\include\fmt/format.h(2638): note: see usage of 'fmt::v6::internal::fallback_formatter<T,Char,void>::parse'
1>        with
1>        [
1>            T=nonstd::sv_lite::basic_string_view<char,std::char_traits<char>>,
1>            Char=char
1>        ]
1>c:\users\cmcarthu\.conan\data\fmt\6.2.1\_\_\package\8cf01e2f50fcd6b63525e70584df0326550364e1\include\fmt\core.h(1655): note: see reference to function template instantiation 'void fmt::v6::internal::check_format_string<const restinio::string_view_t&,S,0>(S)' being compiled
1>        with
1>        [
1>            S=verifyRequest::<lambda_354ff5390c6b7230341c10874149fa5c>::()::FMT_COMPILE_STRING
1>        ]
1>c:\users\cmcarthu\.conan\data\fmt\6.2.1\_\_\package\8cf01e2f50fcd6b63525e70584df0326550364e1\include\fmt\core.h(1747): note: see reference to function template instantiation 'fmt::v6::format_arg_store<fmt::v6::basic_format_context<std::back_insert_iterator<fmt::v6::internal::buffer<char>>,char>,const nonstd::sv_lite::basic_string_view<char,std::char_traits<char>>> fmt::v6::internal::make_args_checked<const restinio::string_view_t&,S,char>(const S &,const nonstd::sv_lite::basic_string_view<char,std::char_traits<char>> &)' being compiled
1>        with
1>        [
1>            S=verifyRequest::<lambda_354ff5390c6b7230341c10874149fa5c>::()::FMT_COMPILE_STRING
1>        ]
1>Y:\repository\file.cpp(848): note: see reference to function template instantiation 'std::basic_string<char,std::char_traits<char>,std::allocator<char>> fmt::v6::format<verifyRequest::<lambda_354ff5390c6b7230341c10874149fa5c>::()::FMT_COMPILE_STRING,const nonstd::string_view&,char>(const S &,const nonstd::string_view &)' being compiled
1>        with
1>        [
1>            S=verifyRequest::<lambda_354ff5390c6b7230341c10874149fa5c>::()::FMT_COMPILE_STRING
1>        ]
1>C:\Users\cmcarthu\.conan\data\string-view-lite\1.3.0\_\_\package\5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9\include\nonstd/string_view.hpp(1183): note: see reference to class template instantiation 'nonstd::sv_lite::basic_string_view<char,std::char_traits<char>>' being compiled

Reading the release notes, there were improvements to this area. Perhaps there's a bug? Or is there something with the library I am using?

[vitaut]

Looks like the same issue as #1692 which has been already fixed in master.