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lib/fmt: drop use of FMT_STRING

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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    Noting that FMT_STRING is a legacy API and has been superseded by consteval-based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.
This commit is contained in:
Rudi Heitbaum
2025-01-11 21:33:04 +00:00
parent b5bd294e5c
commit 9db7144d0f
25 changed files with 109 additions and 109 deletions
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2
src/client/Idle.cxx
View File

@@ -32,7 +32,7 @@ WriteIdleResponse(Response &r, unsigned flags) noexcept
const char *const*idle_names = idle_get_names();
for (unsigned i = 0; idle_names[i]; ++i) {
if (flags & (1 << i))
r.Fmt(FMT_STRING("changed: {}\n"), idle_names[i]);
r.Fmt("changed: {}\n", idle_names[i]);
}
r.Write("OK\n");

4
src/client/Response.cxx
View File

@@ -66,7 +66,7 @@ Response::WriteBinary(ConstBuffer<void> payload) noexcept
void
Response::Error(enum ack code, const char *msg) noexcept
{
Fmt(FMT_STRING("ACK [{}@{}] {{{}}} "),
Fmt("ACK [{}@{}] {{{}}} ",
(int)code, list_index, command);
Write(msg);
@@ -77,7 +77,7 @@ void
Response::VFmtError(enum ack code,
fmt::string_view format_str, fmt::format_args args) noexcept
{
Fmt(FMT_STRING("ACK [{}@{}] {{{}}} "),
Fmt("ACK [{}@{}] {{{}}} ",
(int)code, list_index, command);
VFmt(format_str, args);