Public bug reported: On Ubuntu 16.04 beta 2, there is a regression in g++ 4:5.3.1-1ubuntu1 g++ (Ubuntu 5.3.1-13ubuntu3) 5.3.1 20160330 relative to Ubuntu 15.10 and before. This came to light while compiling an app that uses stb_image.h, see https://github.com/nothings/stb/issues/280
In https://lists.fedoraproject.org/archives/list/de...@lists.fedoraproject.org/thread/ZM2L65WIZEEQHHLFERZYD5FAG7QY2OGB/ Jakub Jelinek suggested a workaround (add -lgcc_s -lgcc at the end of the g++ command that links the shared library) and a real fix "on ppc32 I remember libgcc_s.so is a linker script which links in -lgcc_s -lgcc, perhaps we need it on x86_64/i686 too". His workaround helped me. I don't know if a gcc has been filed yet; I couldn't find one, but at least Jakub is aware of the problem. To reproduce, use __builtin_cpu_supports from a shared library, and link with g++. Example: :::::::::::::: bugapp.c :::::::::::::: #include <stdio.h> extern int foo(); int main(int argc, char **argv) { printf("foo is %d\n", foo()); } :::::::::::::: buglib.c :::::::::::::: int foo(void) { return __builtin_cpu_supports("sse2"); } :::::::::::::: bug.sh :::::::::::::: #!/bin/sh set -x echo Demonstrate gotcha in __builtin_cpu_supports on Ubuntu 16.04 and rawhide / f24 echo See https://lists.fedoraproject.org/archives/list/de...@lists.fedoraproject.org/thread/ZM2L65WIZEEQHHLFERZYD5FAG7QY2OGB/ echo Maybe caused by https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61309 echo Linking with gcc works: gcc -fPIC -shared buglib.c -o buglib.so gcc bugapp.c buglib.so echo Linking with g++ fails: g++ -fPIC -shared buglib.c -o buglib.so g++ bugapp.c buglib.so # /usr/bin/ld: a.out: hidden symbol `__cpu_model' in /usr/lib/gcc/x86_64-linux-gnu/5/libgcc.a(cpuinfo.o) is referenced by DSO # /usr/bin/ld: final link failed: Bad value # collect2: error: ld returned 1 exit status g++ --version echo Rescue by linking libgcc explicitly into shared library: g++ -fPIC -shared buglib.c -lgcc_s -lgcc -o buglib.so g++ bugapp.c buglib.so ** Affects: gcc-5 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1568899 Title: ld: a.out: hidden symbol `__cpu_model' in /usr/lib/gcc/x86_64-linux- gnu/5/libgcc.a(cpuinfo.o) is referenced by DSO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gcc-5/+bug/1568899/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
