https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67650
Bug ID: 67650 Summary: undef reference with -fdevirtualize Product: gcc Version: 5.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: vincent.lextrait at gmail dot com Target Milestone: --- I get an undefined symbol when using -O2, more specifically, after trying all additional options on top of -O1, this is due to -fdevirtualize. With -O1 -devirtualize, the symbol is missing. It's not missing with just -O1. The symbol is a virtual member function of a class template. I checked that the issue does not occur with gcc-4.9.2, it is new in gcc-5. Is it worth it to try reducing my code and produce a code snippet exhibiting the issue? Or is the issue known already? I didn't find any track of it. gcc version: /usr/local/bin/g++-5 -v Using built-in specs. COLLECT_GCC=/usr/local/bin/g++-5 COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/5.2.0/libexec/gcc/x86_64-apple-darwin14.4.0/5.2.0/lto-wrapper Target: x86_64-apple-darwin14.4.0 Configured with: ../configure --build=x86_64-apple-darwin14.4.0 --prefix=/usr/local/Cellar/gcc/5.2.0 --libdir=/usr/local/Cellar/gcc/5.2.0/lib/gcc/5 --enable-languages=c,c++,objc,obj-c++,fortran --program-suffix=-5 --with-gmp=/usr/local/opt/gmp --with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc --with-isl=/usr/local/opt/isl --with-system-zlib --enable-libstdcxx-time=yes --enable-stage1-checking --enable-checking=release --enable-lto --with-build-config=bootstrap-debug --disable-werror --with-pkgversion='Homebrew gcc 5.2.0' --with-bugurl=https://github.com/Homebrew/homebrew/issues --enable-plugin --disable-nls --enable-multilib Thread model: posix gcc version 5.2.0 (Homebrew gcc 5.2.0)