Re: [Mesa3d-dev] Segfault on glClear of non-existent stencil buffer caused by bd1ce874728c06d08a1f9881f51edbdd2f1c9db0

[Luca B. <lu...@lu...>]

The problem seems to be in st_manager.c:
   if (visual->depth_stencil_format != PIPE_FORMAT_NONE) {
      mode->haveDepthBuffer = GL_TRUE;
      mode->haveStencilBuffer = GL_TRUE;

      mode->depthBits =
         util_format_get_component_bits(visual->depth_stencil_format,
               UTIL_FORMAT_COLORSPACE_ZS, 0);
      mode->stencilBits =
         util_format_get_component_bits(visual->depth_stencil_format,
               UTIL_FORMAT_COLORSPACE_ZS, 1);
   }

This sets haveStencilBuffer even for depth-only buffers.

How about fixing this to set haveDepthBuffer and haveStencilBuffer
only if bits > 0, and later removing haveStencilBuffer,
haveDepthBuffer and haveAccumBuffer in favor of just testing the *bits
counterparts?

BTW, what if we have a floating-point depth buffer, or, say, a shared
exponent floating-point color buffer? How do we represent that with
the visual structure?
Shouldn't we be using the actual formats instead of this *bits stuff,
maybe by having Mesa look at its internal structures instead of a
GLXVisual-like struct?