%define gccver %(gcc -o %_builddir/gccver %_sourcedir/gccver.c >/dev/null 2>&1 ; %_builddir/gccver -v)

Source1000: gccver.c

#if library
Provides: lib%name-c++compiled = %gccver

Requires: libqt3-c++compiled = %gccver
# or
Requires: kdelibs-c++compiled = %gccver
# or
Requires: lib_koe_chto-c++compiled = %gccver