Without --disable-visibility, refdbg can not work and it is very hard to debug reference counting bugs in gobject apps. Please disable the visibility stuff (and expose the variables that refdbg needs to work) when glib is compiled with USE=debug
+ 06 Oct 2010; Gilles Dartiguelongue <eva@gentoo.org> glib-2.24.2.ebuild, + glib-2.26.0.ebuild, + +files/glib-2.26.0-disable-locale-sensitive-test.patch, + +files/glib-2.26.0-disable-volumemonitor-broken-test.patch: + Fix testsuite failure on hardened, bug #338891. Disable visibility with + USE=debug, bug #274647. Disable 3 tests in the 2.26 testsuite to allow a + successful run and sync the ebuild back with latest changes in 2.24. + Fixed in 2.24 and later. Thanks for reporting.