glGetString displays (null) for nvidia-340xx

[wojnilowicz]

Steps to reproduce:

1. unpack gl3.zip
2. compile gl3.cxx with "cc -o gl3 gl3.cxx -Dwith_epoxy=1 -lGL -lX11 -lepoxy"
3. run "./gl3"

Result:
OpenGL vendor string: (null)

Expected result:
OpenGL vendor string: NVIDIA Corporation

Additional info:

1. compiling gl3.cxx with "cc -o gl3 gl3.cxx -Dwith_epoxy=0 -lGL -lX11 -lepoxy" gives
   OpenGL vendor string: NVIDIA Corporation

2. compiling gl3.cxx with "cc -o gl3 gl3.cxx -Dwith_epoxy=1 /usr/lib64/libOpenGL.so /usr/lib64/libGLX.so -lX11 -lepoxy" gives
   OpenGL vendor string: (null)

3. compiling gl3.cxx with "cc -o gl3 gl3.cxx -Dwith_epoxy=0 /usr/lib64/libOpenGL.so /usr/lib64/libGLX.so -lX11 -lepoxy" gives
   libGL error: No matching fbConfigs or visuals found
   libGL error: failed to load driver: swrast
   X Error of failed request: GLXBadFBConfig
   Major opcode of failed request: 154 (GLX)
   Minor opcode of failed request: 0 ()
   Serial number of failed request: 37
   Current serial number in output stream: 37

4. reverting dbfa4b2 helps

5. KDE relies on info returned from glGetString to enable compositing, and after getting (null) for every query, the compositor remains disabled.

6. Fedora 34 X86_64, libepoxy 1.5.7, nvidia 340.108

Please fix this.

[Emmanuele Bassi]

This is a duplicate of #252.

[Yar]

@wojnilowicz is it the same with cc -o gl3 gl3.cxx -Dwith_epoxy=1 -lX11 -lepoxy (just dropped linking with libOpenGL.so and libGLX.so, libepoxy should load them dynamically)

[Yar]

@wojnilowicz also, could you, please, check if libGLX.so is provided by libglvnd?

[wojnilowicz]

@wojnilowicz is it the same with cc -o gl3 gl3.cxx -Dwith_epoxy=1 -lX11 -lepoxy (just dropped linking with libOpenGL.so and libGLX.so, libepoxy should load them dynamically)

Yes.

@wojnilowicz also, could you, please, check if libGLX.so is provided by libglvnd?

Yes.