Shader validation seems to erroneously decide the geometry shader is writing to PointSize

[bpeel]

If I compile this simple geometry shader with glslang and pass it through the validation layer it reports an error about writing to PointSize and not enabling shaderTessellationAndGeometryPointSize.

#version 450

layout(points) in;
layout(triangle_strip, max_vertices = 4) out;

void
main()
{
        for (int y = -1; y <= 1; y += 2) {
                for (int x = -1; x <= 1; x += 2) {
                        gl_Position = vec4(gl_in[0].gl_Position.xy + vec2(x, y),
                                           0.0,
                                           1.0);
                        EmitVertex();
                }
        }
        EndPrimitive();
}

The shader clearly isn’t using gl_PointSize at all. glslang seems to declare two structs with point size members anyway. The first is used for the output and the second is used for gl_in. I think there is something going wrong with this line in shader_validation.cpp:

bool found_write = !init_complete && (type == spv::OpMemberDecorate);

init_complete ends up being false for gl_in because there is no variable that writes to it.

If I remove the part that reads from gl_in then glslang no longer adds a declaration for its type and the validation error disappears.

This can be seen with the geometry.shader_test example in VkRunner with a command like this:

VK_INSTANCE_LAYERS=VK_LAYER_LUNARG_standard_validation \
./src/vkrunner examples/geometry.shader_test