ld linker error "cpu model hidden symbol"

Question

I'm getting an ld error when attempting to compile an sfml program on ubuntu 16.04. This is apparently a known issue, and there is supposed to be a workaround, but I don't understand what is it...

http://web.archive.org/web/20160509014317/https://gitlab.peach-bun.com/pinion/SFML/commit/3383b4a472f0bd16a8161fb8760cd3e6333f1782.patch

The error spat out by ld is

hidden symbol `__cpu_model' in /usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc.a(cpuinfo.o) is referenced by DSO

There is no relevant code to this - as I understand it this error is produced on all ubuntu 16.04 systems with g++ 5, if the program to be linked contains objects such as sf::Texture and sf::Sprite. (I don't know any more detail than this.)

I have tried also compiling with g++ 4.9, but the same error occurs.

My compile line is g++-4.9 --std=c++11 -Wall main.cpp -lsfml-graphics -lsfml-window -lsfml-system -o a.out

Has anyone else experienced this error and resolved it successfully?

Answer 1

I've had to fix this issue several times. Instead of applying the patch, you can manually fix it by editing the file SFML/src/SFML/Graphics/CMakeLists.txt. At line 149, you will find the following:

if(SFML_COMPILER_GCC)
 set_source_files_properties(${SRCROOT}/ImageLoader.cpp PROPERTIES COMPILE_FLAGS -fno-strict-aliasing)
endif()

After the endif(), insert the following:

if(SFML_COMPILER_GCC AND BUILD_SHARED_LIBS)
    list(APPEND GRAPHICS_EXT_LIBS "-lgcc_s -lgcc")
endif()

Then, in the top-level SFML folder, run the following:

mkdir build && cd build
cmake .. -DSFML_BUILD_EXAMPLES=ON -DSFML_BUILD_DOCS=ON
make
sudo make install
sudo ldconfig

This will get it built and installed without the compiler error. (Note: Remove the -D flags from cmake if you don't want docs or examples)

Answer 2

I ran this in the SFML source directory before running the standard cmake...make:

curl https://gitlab.peach-bun.com/pinion/SFML/commit/3383b4a472f0bd16a8161fb8760cd3e6333f1782.patch \
  | patch -p1

and that solved the problem