[1.x] Please install .pc file for easy discoverability

[yurivict]

The ustream project that uses janus fails to find the janus headers:
In file included from src/acap.c:43:
In file included from src/logging.h:23:
/usr/local/include/janus/plugins/plugin.h:162:10: fatal error: 'refcount.h' file not found
162 | #include "refcount.h"
| ^~~~~~~~~~~~
1 error generated.

This is because janus doesn't provide any way to discover it or to determine what CFLAGS does it need.

The actual reason is that this CFLAGS argument is missing: -I$(PREFIX)/include/janson.

CFLAGS and LDFLAGS should be supplied by the .pc file so that pkg-config --cflags --libs janus would print all necessary flags.

[mdevaev]

If I will use I$(PREFIX)/include/janus, I will loose ability to include header with janus/ path part like #include <janus/debug.h> and I'll have to do #include <debug.h>. This is quite inconvenient because the file name is too general and may overlap with something else.

I have my own Janus package for Arch in which after make install I'm doing a path replacement like:

sed -i -e 's|^#include "refcount.h"$|#include "../refcount.h"|g' "$pkgdir/usr/include/janus/plugins/plugin.h"

It looks like a bug because in a similar situation src/events/eventhandler.h uses a relative include: #include "../utils.h"

[lminiero]

I don't have any immediate plan to provide .pc files, but I'll add the enhancement tag to this issue and keep it open so that we don't forget it may be useful to have in the future. Of course PRs we can evaluate are always welcome.

[mdevaev]

@lminiero PR is here: #3525

It's just a build fix, but I didn't write .pc because I personally don't really need it right now.