Installed gnat-gcc-4.4.5. Have eselect-gnat-1.5 installed FWIW. Tried to compile a simple hello world program (i.e. gnatmake hello_world_1.adb). The compilation fails during linking with the following errors
gnatbind -x hello_world_1.ali
/usr/lib64/gnat-gcc/x86_64-pc-linux-gnu/4.4/adalib/libgnat.a(a-finali.o): In function `ada__finalization___assign__3':
(.text+0x21e): undefined reference to `_Unwind_Resume'
Tried to roll back to gnat-gcc-4.4.3 and 4.3.5, but those ebuilds don't appear to bootstrap.
If I tell the linker to link against the c++ std library, i.e.
>gnatmake hello_world.adb -largs -lstdc++
then i get what appears to be a working program. This does not feel like the right fix for this.
Did a reinstall just to see what would happen, and I no longer have this issue.