Add PKG_CONFIG_PATH to variables set by venv activate

[cptlobster]

What's the problem this feature will solve?

pkg-config doesn't recognize packages that are installed in a virtual environment

Describe the solution you'd like

A solution was proposed 5 years ago in #1159 which was closed for being stale. The changes proposed here (for Bash, I'm unfamiliar with any other shells so I can't attest to how those would be configured):

diff --git a/virtualenv_embedded/activate.sh b/virtualenv_embedded/activate.sh
index 477b7ec..1a93da9 100644
--- a/virtualenv_embedded/activate.sh
+++ b/virtualenv_embedded/activate.sh
@@ -16,6 +16,11 @@ deactivate () {
         export PYTHONHOME
         unset _OLD_VIRTUAL_PYTHONHOME
     fi
+    if ! [ -z "${_OLD_PKG_CONFIG_PATH+_}" ]; then
+        PKG_CONFIG_PATH="$_OLD_PKG_CONFIG_PATH"
+        export PKG_CONFIG_PATH
+        unset _OLD_PKG_CONFIG_PATH
+    fi

     # This should detect bash and zsh, which have a hash command that must
     # be called to get it to forget past commands.  Without forgetting
@@ -47,6 +52,10 @@ _OLD_VIRTUAL_PATH="$PATH"
 PATH="$VIRTUAL_ENV/__BIN_NAME__:$PATH"
 export PATH

+_OLD_PKG_CONFIG_PATH="${PKG_CONFIG_PATH}"
+PKG_CONFIG_PATH="${VIRTUAL_ENV}/lib/pkgconfig:${PKG_CONFIG_PATH}"
+export PKG_CONFIG_PATH
+
 # unset PYTHONHOME if set
 if ! [ -z "${PYTHONHOME+_}" ] ; then
     _OLD_VIRTUAL_PYTHONHOME="$PYTHONHOME"

This would work for libraries that use pkg-config for build/install (so far the only example I have is python-efl, possibly also Qt per this thread)

Alternative Solutions

I've tried adding the proposed modifications to {VIRTUALENV}/bin/activate myself, it seems to function as intended.

Additional context

• Add PKG_CONFIG_PATH to set of enviroment variables configured by activate #1159
• https://stackoverflow.com/a/20373212

[gaborbernat]

PR welcome. Must include support for all supported shells.