/usr/lib/libgnomemm-2.6/proc/m4/convert_libgnomemm.m4 is in libgnomemm-2.6-dev 2.30.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | _CONVERSION(`const char*',`Glib::ustring',`$3')
_CONVERSION(`GnomeProgram*',`Glib::RefPtr<Program>',`Glib::wrap($3)')
|