glsl: Refuse to link GLSL 1.40+ shaders that would use fixed function.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/linker.cpp

@@ -2225,6 +2225,20 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       goto done;
    }
 
+   if (max_version >= 140) {
+      /* Note that this will change with GL_ARB_separate_shader_objects */
+      if (num_vert_shaders == 0) {
+	 linker_error(prog,
+		      "GLSL %.02f without GL_ARB_compatibility requires a "
+		      "vertex shader", max_version / 100.0);
+      }
+      if (num_frag_shaders == 0) {
+	 linker_error(prog,
+		      "GLSL %.02f without GL_ARB_compatibility requires a "
+		      "fragment shader", max_version / 100.0);
+      }
+   }
+
    prog->Version = max_version;
 
    for (unsigned int i = 0; i < MESA_SHADER_TYPES; i++) {