Created attachment 371614 [details] Build Log Complains that it cannot find gtk2hsChs2, which is in my PATH.
Created attachment 371616 [details] emerge --info '=dev-haskell/glib-0.12.4-r1::gentoo'
Created attachment 371618 [details] emerge -pqv '=dev-haskell/glib-0.12.4-r1::gentoo'
By creating the following symlinks: gtk2hsC2hs2 -> gtk2hsC2hs gtk2hsHookGenerator2 -> gtk2hsHookGenerator gtk2hsTypeGen2 -> gtk2hsTypeGen dev-haskell/gtk compiles successfully.
Thanks for report! Code in prepare phase assumed that GTK SLOTS are used, fixed now. No revbump as it's a buildtime failure.