https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62181
--- Comment #2 from Manuel López-Ibáñez <manu at gcc dot gnu.org> --- In both FEs there is a function build_binary_op. Put a break-point inside, examine the operands with debug_tree and figure out how to detect this case and when to warn. Add the new warning option to c-family/c.opt and document it in gcc/doc/invoke.texi. I think the note is useful but we cannot give the fix-it hints yet. Add a FIXME in the code on top of the inform call.