gcc 4.5 has a stricter linking behaviour where all required libraries need to be specified explicitly, you can't rely on transitive dependencies of libraries any more.
Current 0.99/git head fails to build with
/usr/bin/ld.bfd.real: polkit_agent_helper_1-polkitagenthelperprivate.o: undefined reference to symbol 'g_type_init'
/usr/bin/ld.bfd.real: note: 'g_type_init' is defined in DSO /usr/lib64/libgobject-2.0.so.0 so try adding it to the linker command line
/usr/lib64/libgobject-2.0.so.0: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
with gcc 4.5. Indeed polkitagenthelperprivate.c calls g_type_init() which is in libgobject, but the Makefile misses the linking to this.
Created attachment 40813 [details] [review]
Fix linking of polkitagenthelperprivate.c with gcc 4.5
Sorry, this only happens with -Wl,--as-needed (our compiler does that by default now, to reduce/eliminate unnecessary library dependencies).
Looks like a dupe of bug 29871 (which was recently resolved).
*** This bug has been marked as a duplicate of bug 29871 ***