On 12/01/2015 05:11 PM, Martin Sebor wrote: > On 12/01/2015 09:07 AM, Andrew Haley wrote: >> Do we support left shift of a negative value? Technically it's >> undefined and ubsan warns about it. However, a ton of software would >> surely break if we didn't do the obvious right thing. I can't find >> anything in the GCC manual. >> > > I believe gcc does the expected thing but see bug 65179: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=65179 > > There have been discussions on gcc-patches about some of > the issues the warning has exposed (real or otherwise), > for example: > > https://gcc.gnu.org/ml/gcc-patches/2015-05/msg00696.html OK, thanks. I wonder if we should document this as a GCC extension. Leaving it up in the air like this does no-one any good. Andrew.
