When compiling with libfmt-11.1.0 and newer the following compile errors occur:
In file included from ../src/decoder/DecoderPrint.cxx:23:
../src/client/Response.hxx: In instantiation of 'bool Response::Fmt(const S&, Args&& ...) [with S = decoder_plugin_print(Response&, const DecoderPlugin&)::<lambda()>::FMT_COMPILE_STRING; Args = {const char* const&}]':
../src/decoder/DecoderPrint.cxx:38:7: required from here
38 | r.Fmt(FMT_STRING("plugin: {}\n"), plugin.name);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/client/Response.hxx:86:28: error: cannot convert 'const decoder_plugin_print(Response&, const DecoderPlugin&)::<lambda()>::FMT_COMPILE_STRING' to 'fmt::v11::string_view' {aka 'fmt::v11::basic_string_view<char>'}
86 | return VFmt(format_str,
| ~~~~^~~~~~~~~~~~
87 | fmt::make_format_args(args...));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/client/Response.hxx:81:36: note: initializing argument 1 of 'bool Response::VFmt(fmt::v11::string_view, fmt::v11::format_args)'
81 | bool VFmt(fmt::string_view format_str, fmt::format_args args) noexcept;
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~
../src/client/Response.hxx: In instantiation of 'bool Response::Fmt(const S&, Args&& ...) [with S = decoder_plugin_print(Response&, const DecoderPlugin&)::<lambda()>::FMT_COMPILE_STRING; Args = {const char* const&}]':
The error is due to the use of FMT_STRING. The libfmt team shared the following:
The correct way of using FMT_STRING is to wrap a format string when passing to a
function with compile-time checks (i.e. that takes format_string) as documented
in https://fmt.dev/11.1/api/#legacy-compile-time-checks.
Noting that FMT_STRING is a legacy API and has been superseded by consteval-based
API starting from version 8: https://github.com/fmtlib/fmt/releases/tag/8.0.0. It
looks like MPD is trying to emulate {fmt}'s old way of implementing compile-time
checks which was never properly documented because it was basically a hack. So the
correct fix is to switch to format_string and, possibly, remove usage of FMT_STRING.
The old way of doing compile-time checks (fmt::make_args_checked) was documented
in https://fmt.dev/7.1/api.html#argument-lists but it looks like MPD is not using
that API so the problematic uses of FMT_STRING have no effect and can just be removed.
The FMT_STRING has been removed in this change based on the fmt-7.1 API and now MPD is
successfully compile against the current libfmt-11.1.0 which highlighted the issue that
had been present in the codebase as it is now triggering the error, is legacy and was
not using the API for which FMT_STRING was aligned with.
The former was deprecated with C++14.
According to the C++11 and C++17 standards, both files are identical.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Since we switched from autotools to Meson in commit
94592c1406, we don't need to include
`config.h` early to properly enable large file support. Meson passes
the required macros on the compiler command line instead of defining
them in `config.h`.
This means we can include `config.h` at any time, whenever we want to
check its macros, and there are no ordering constraints.
The "pure" and "const" attributes are not so well-defined, and a
recent clang version implements an optimization which pushes the
definition's boundary beyond what I believed it was. clang now
assumes that functions declared "pure" cannot throw exceptions, even
if they lack the "noexcept" specification.
When compiled with this new clang version, MPD will crash randomly if
an exception happens to get thrown by such as "pure" function
(https://github.com/MusicPlayerDaemon/MPD/issues/41).
This commit removes all such misplaced "pure" and "const" attributes,
closing #41.
Rudi Heitbaum