https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106469
--- Comment #3 from Henry <hbucher at gmail dot com> --- I agree that technically it is not UB. However I still think it is bad practice. So far that single line is the only place in all libstdc++ that triggers that undefined. I cannot believe that a developer consciously chose to let unsigned underflow happen in such simple expression. So instead of K + (M - N) why not just change it to (K + M) - N? It is such a simple change. I have modified it and tested but not to the extent to run all the libstdc++ unit tests.
