GIO dependency is through libRSVG

[charmander]

When building with --without-rsvg (and without everything else), linking fails on GIO functions, e.g.

libvips/libvips/iofuncs/ginputsource.c

Line 201 in 764b196

if( g_cancellable_set_error_if_cancelled( cancellable, error ) )

I’m not familiar enough with Autotools to know whether this is a correct fix, but I added it to configure.ac here:

PKG_CHECK_MODULES(REQUIRED, glib-2.0 >= 2.6 gmodule-2.0 gobject-2.0 gio-2.0)
PACKAGES_USED="$PACKAGES_USED glib-2.0 gmodule-2.0 gobject-2.0 gio-2.0"

Sorry for not making sure exactly which optional library exclusions are required or listing the exact functions – rebuilding takes a while on my device.

[jcupitt]

That's odd, it's supposed to test for GIO and disable rsvg if it's not available. I'll have a look.

[jcupitt]

OK, I think that fixes it. Thanks!

[lovell]

libvips is dependent on gio (e.g. g_input_stream_get_type) independently of librsvg so I think the original suggestion to modify PKG_CHECK_MODULES is correct. Happy to create a PR for this if you agree John.

[jcupitt]

I think it's guarded by HAVE_GIO, but I've not actually tried building without gio :( It would actually be tricky to test.

gio is glib 2.15 and later, so perhaps we should bump the minimum version of glib to 2.15 as well. We could remove a few other ifdefs too, which would be a useful cleanup.

[lovell]

Thanks John, there's an example build failure at https://travis-ci.org/github/google/oss-fuzz/jobs/665815922 that might help demonstrate.

[jcupitt]

vips.pc has gio-2.0 in Requires.private, so I think that ought to work. Is that link line not being generated by pkg-config?

I'm still completely confused about the differences between Libs, Requires, Requires.private and Libs.private :( I think this is the issue that led to the current state:

#196

[lovell]

The vips.pc file appears to correctly include gio-2.0 in Requires.private.

The build failure occurs when linking tools/vips and tools/vipsedit.

Could commit d4f12a9 have introduced a public "Requires" level dependency on gio similar to commit 366e7e3?