http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59871
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I'd say easiest would be at the spot where we warn currently about the left-hand ... check if the left hand operand is a COMPOUND_EXPR, in that case find the rightmost operand of all the nested COMPOUND_EXPRs and complain about right-hand operand instead of left-hand. Perhaps needs some tweaks to get the locus right.
