http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55095
--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-10-28 17:58:55 UTC --- The constant folder (fold-const.c:int_const_binop_1) would seem to be the place where overflow information would most readily be available for this: as I understand it, it's specifically about constants, rather than the generic issue that almost any left shift with nonconstant operands might overflow. If diagnosing there, you'd want to pass down a location a few levels from fold_binary_loc (so changing lots of calls to const_binop to pass a location). (In any case, double-int will need a new interface to report whether shift overflow has occurred.)
