https://sourceware.org/bugzilla/show_bug.cgi?id=21934
--- Comment #15 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to Brett Neumeier from comment #14) > (In reply to H.J. Lu from comment #13) > > There is cast to (unsigned char). Why does GCC see that? Why does > > it only happen on arm? Also does 'hh" work with all compilers on all > > supported hosts? > > Per Martin Sebor's comment, the possible-truncation warning "tends to be > sensitive to char (and short) conversions because of limitations in its > integration with the Value Range Propagation pass." I am not sure precisely > what that means, but I presume that's why the cast is not sufficient to > suppress the false positive warning. This is just a speculation. There could be a real bug in GCC. Please open a new GCC bug since your old one is lost during bugzilla server crash. > I don't know what circumstances trigger this false positive. I stumbled upon > it in an arm-to-x86_64 cross-binutils build, but I expect that there are > other scenarios where it can occur -- possibly some native builds do, and > possibly other cross-builds do. I don't have the time or energy to do > exhaustive tests to see which combinations trigger the issue. Please follow: https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction to reduce your testcase. > I don't know everything that is included in the "all compilers and all > supported hosts" set. I do see that the "hh" flag is mandated by C99, but > not by C89. > > Are there C89 compilers that binutils needs to support? If so, would a > preprocessor test that adds the "hh" flag only in C99 and later make this > patch acceptable? Yes, we support C89. I still like to understand what the problem is before deciding what to do since it is possible that "hh" may not workaround the issue tomorrow. -- You are receiving this mail because: You are on the CC list for the bug. _______________________________________________ bug-binutils mailing list bug-binutils@gnu.org https://lists.gnu.org/mailman/listinfo/bug-binutils
