Build failed due to the side effect of homebrew

[wold9168]

Since Homebrew includes pkg-config as a dependency for some software packages, on systems where Homebrew and specific Homebrew packages are installed, the deployment of such packages may fail due to pkg-config's inability to locate libsystemd — even if the corresponding system has already installed systemd-devel and its equivalent packages.

$ cargo build --release
# ... Unimportant output
  --- stderr
  pkg_config could not find "libsystemd": 
  pkg-config exited with status code 1
  > PKG_CONFIG_ALLOW_SYSTEM_LIBS=1 PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=1 pkg-config --libs --cflags libsystemd

  The system library `libsystemd` required by crate `libsystemd-sys` was not found.
  The file `libsystemd.pc` needs to be installed and the PKG_CONFIG_PATH environment variable must contain its parent directory.
  The PKG_CONFIG_PATH environment variable is not set.

  HINT: if you have installed the library, try setting PKG_CONFIG_PATH to the directory containing `libsystemd.pc`.

warning: build failed, waiting for other jobs to finish...

This issue arises because Homebrew places its binaries‘ path early in the $PATH environment variable.

$ which pkg-config
/home/linuxbrew/.linuxbrew/bin/pkg-config
$ pkg-config --libs libsystemd
Package libsystemd was not found in the pkg-config search path.
Perhaps you should add the directory containing `libsystemd.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libsystemd' not found
$ /bin/pkg-config --libs libsystemd
-lsystemd
$ PKG_CONFIG_PATH=/usr/lib64/pkgconfig pkg-config --libs libsystemd
-L/usr/lib64 -lsystemd
$ rpm -qa | grep systemd-devel
systemd-devel-257.7-1.fc42.x86_64
$ rpm -ql systemd-devel|grep 'libsystemd.pc'
/usr/lib64/pkgconfig/libsystemd.pc

Homebrew is used by a large number of users, and many of them have installed software packages like pyenv that depend on pkg-config exactly provided by Homebrew. Therefore, this issue deserves attention.

Here is a temporary solution.

export PKG_CONFIG_PATH=/usr/lib64/pkgconfig # use pkg-config files provided by system

Or just remove Homebrew's bin from your $PATH temporarily:

export PATH=$(echo $PATH | awk -v RS=: -v ORS=: '/homebrew|linuxbrew|\/usr\/local\/(bin|sbin)/ {next} {print}' | sed 's/:$//')