add the directory containing `cairo-gobject.pc'

I'm trying to install PyGObject on a RH Linux system, using the command

    python3 /usr/local/bin/pip3.6 install PyGObject

But it dies with the ff. error msg:

    Package cairo-gobject was not found in the pkg-config search path.
    Perhaps you should add the directory containing `cairo-gobject.pc'
    to the PKG_CONFIG_PATH environment variable

I think the cairo-gobject should already have been installed, and I would gladly tell pip where to look for cairo-gobject.pc--if only I knew. But I don't have a clue where it is.

I'm generally following the instructions for installing PyGObject on Fedora systems, although a lot of things seem to have changed since that write-up. For example, using yum instead of dnf. Also, following the instructions, I initially did

    yum install cairo-devel

But yum search revealed that there are actually two such packages: cairo-devel.i686 and cairo-devel.x86_64. It's not clear to me which one was actually installed, nor whether yum automagically selects the right one.

And while our system interprets python as python2, we also have python3 installed, and we need to use this program I'm trying to install with v3. So instructions for calling pip, python etc. need to be modified to use Python3. I think I've done that everywhere, although it's of course possible that I goofed, and cairo-gobject is somewhere that only P2 knows.

Packages I've installed: gcc, gobject_introspection-devel, cairo-devel, pkg-config, python3-devel, python36-devel, python36-setuptools, gtk3, pycairo. But still, when I try to do

    python3 /usr/local/bin/pip3.6 install PyGObject

it dies (as I said above) with Package cairo-gobject was not found in the pkg-config search path.

What lack I yet? Where might I look for this cairo-gobject.pc thing? I know that cairo.pc is under /usr/lib64/pkgconfig/, but cairo-gobject.pc is nowhere under /usr/. Where else might it be?

Last Minute: While making sure I'd dotted every 'i' before posting, I noticed a 't' I'd forgotten to cross, namely a msg I'd overlooked while trying to install PyGObject:

    Building wheel for PyGObject (PEP 517) ... error

But the build goes on past that error (that's my excuse for missing it before), until it finally quits with the above-referenced message about cairo-gobject.pc. There's some discussion about this PEP517-related issue here, but I don't see a resolution. Or if there is, I don't know how to apply it.

I had the same issue -- indeed, cairo-gobject-devel does it, as Uli suggested.