spdlog @1.12.0: package 'fmt', required by 'spdlog', not found; consider updating segregated libfmtXX ports, to be discoverable via standard prefix path

[ryandesign (Ryan Carsten Schmidt)]

Not sure if spdlog bug or libfmt10 bug:

% port -q installed spdlog libfmt10
  libfmt10 @10.1.1_0 (active)
  spdlog @1.12.0_3+fmt_external (active)

% pkg-config spdlog --cflags    
Package fmt was not found in the pkg-config search path.
Perhaps you should add the directory containing `fmt.pc'
to the PKG_CONFIG_PATH environment variable
Package 'fmt', required by 'spdlog', not found

[mascguy (Christopher Nielsen)]

Ryan, bear in mind that all of the libfmtXX ports are purposely segregated, to avoid conflicts:

$ port -q contents libfmt10 | ggrep "/opt/local/lib/"
  /opt/local/lib/libfmt10/cmake/fmt/fmt-config-version.cmake
  /opt/local/lib/libfmt10/cmake/fmt/fmt-config.cmake
  /opt/local/lib/libfmt10/cmake/fmt/fmt-targets-relwithdebinfo.cmake
  /opt/local/lib/libfmt10/cmake/fmt/fmt-targets.cmake
  /opt/local/lib/libfmt10/libfmt.10.1.0.dylib
  /opt/local/lib/libfmt10/libfmt.10.dylib
  /opt/local/lib/libfmt10/libfmt.dylib
  /opt/local/lib/libfmt10/pkgconfig/fmt.pc

Regardless, spdlog is correctly setting the cmake module path for variant fmt_external. And everything has been working fine for quite a while.

Was your concern based on something in the configure log, or...?

[ryandesign (Ryan Carsten Schmidt)]

My concern was that, while investigating pkg-config in general, I happened to try out spdlog's pkg-config file and received an unexpected error.

[mascguy (Christopher Nielsen)]

Replying to ryandesign:

My concern was that, while investigating pkg-config in general, I happened to try out spdlog's pkg-config file and received an unexpected error.

No worries. So can this be closed then?

[ryandesign (Ryan Carsten Schmidt)]

So you don't consider it a bug that pkg-config cannot be used to get spdlog's flags?

[mascguy (Christopher Nielsen)]

Replying to ryandesign:

So you don't consider it a bug that pkg-config cannot be used to get spdlog's flags?

It works fine when things are properly set, per segregation of libfmt10:

$ PKG_CONFIG_PATH=/opt/local/lib/libfmt10/pkgconfig:/opt/local/lib/pkgconfig: pkg-config spdlog --cflags
-DSPDLOG_SHARED_LIB -DSPDLOG_COMPILED_LIB -DSPDLOG_FMT_EXTERNAL -I/opt/local/include/libfmt10 -I/opt/local/include

So no, that doesn't seem like a bug. Do you disagree?

[ryandesign (Ryan Carsten Schmidt)]

Joe Random User who just wants to use spdlog in software they compile outside of MacPorts may not know that you expect them to set PKG_CONFIG_PATH to a nonstandard value.

Can't the libfmt10 pc file go in the standard pkg-config directory, perhaps with a version suffix, and then spdlog's pc file adjusted to match?

[mascguy (Christopher Nielsen)]

Replying to ryandesign:

Joe Random User who just wants to use spdlog in software they compile outside of MacPorts may not know that you expect them to set PKG_CONFIG_PATH to a nonstandard value.

Can't the libfmt10 pc file go in the standard pkg-config directory, perhaps with a version suffix, and then spdlog's pc file adjusted to match?

Sure, and that would certainly make things easier for dependents.

I'll do some local proof-of-concept work, and get back to you.

[mouse07410 (Mouse)]

As of yesterday, this did not work. In order to build/install port(s) that depend on spdlog, such as doxygen and range-v3, I had to do sudo port -f install spdlog -fmt_external. That took care of the problem.

Perhaps, you could/should make the -fmt_external the default port.

[ryandesign (Ryan Carsten Schmidt)]

I don't know why spdlog has an fmt_external variant but no, deselecting it is not the preferred solution. We want ports to use other ports for their dependencies rather than likely-outdated bundled versions.

So the variant should be removed, the use of external fmt should be mandated, and it should be made to work without the need to change PKG_CONFIG_PATH, as already discussed.