Hi Danny!

> since cairo is meant to be a portable and backend-agnostic vector graphics
> library, I find it hard to believe it needs to propagate fontconfig, freetype,
> glib, libpng, pixman, x11, xcb, xext and xrender.
> 
> Are you sure that cairo actually exposes those libraries' interfaces to its
> users?

I took a brief look at the manual
(https://cairographics.org/manual/cairo-surfaces.html), it appears it
does exposes them.

> The cairo.pc file also suggests otherwise:
> 
> Requires.private:   gobject-2.0 glib-2.0 >= 2.14       pixman-1 >= 0.30.0    fontconfig >= 2.2.95 freetype2 >= 9.7.3   libpng xcb-shm xcb >= 1.6 xcb-render >= 1.6 xrender >= 0.6 x11 xext 
> Libs: -L${libdir} -lcairo
> Libs.private:            -lz -lz   -lz      
> 
> "Requires.private" means that those are implementation details and not to be
> exposed to the users of the library.

The other reason I left them in propagated inputs is because, the
packages that depend on cairo doesn't build without them. If I
de-propagate them in cairo, then I have to replicate them as inputs on
other packages.

> Also, please do not make libsigc++ public twice.  It's already in the
> module's #:export list.
> 
> Same for glibmm and maybe others.

Hmm. Without that, I get "package not found" while doing `./pre-inst-env
guix build foo`.

> Pushed the pixman and hplip patches to wip-desktop.

Thanks!

Regards,
RG.