there are no arguments to ‘format_as’ that depend on a template parameter, so a declaration of ‘format_as’ must be available [-fpermissive] template <typename U, typename V = decltype(format_as(U()))

[L-Super]

env:

• Clion 2022.2.3
• g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)
• cmake 3.25 (CMAKE_CXX_STANDARD 11)

when I use spdlog v1.11.0 on centos, I meet this error.

In file included from /home/.../include/spdlog/include/spdlog/fmt/fmt.h:27:0,
                 from /home/.../include/spdlog/include/spdlog/common.h:45,
                 from /home/.../include/spdlog/include/spdlog/spdlog.h:12,
                 from /home/.../src/cvr/http_server.cpp:8:
/home/.../include/spdlog/include/spdlog/fmt/bundled/core.h:1334:60: error: there are no arguments to ‘format_as’ that depend on a template parameter, so a declaration of ‘format_as’ must be available [-fpermissive]
   template <typename U, typename V = decltype(format_as(U())),
                                                            ^
/home/.../include/spdlog/include/spdlog/fmt/bundled/core.h:1334:60: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated)
/home/Listening/MonitorStorageServer/include/spdlog/include/spdlog/fmt/bundled/core.h:1334:60: error: there are no arguments to ‘format_as’ that depend on a template parameter, so a declaration of ‘format_as’ must be available [-fpermissive]

I found the same problem on the fmt library.link: 2969

Normally, the problem should have been fixed, but I still encountered this error.I don't know what's wrong

[L-Super]

By the way, when I use version spdlog v1.10.0, it can compile successfully

[tt4g]

Since spdlog v1.11.0, fmt v9 is now bundled, so there are incompatible changes.
I assume you are using a feature that is no longer supported in src/cvr/http_server.cpp:8 shown in the error message.

Note GCC4.8 may not work because the C++11 standard is not complete. This is a compiler issue (https://stackoverflow.com/a/36970437).

[L-Super]

OK, thank you! The compiler is too old maybe