Properly append global uniform buffer name in gl_compatibility shaders

Also error when using instance uniforms

drivers/gles3/storage/material_storage.cpp

@@ -1546,6 +1546,8 @@ MaterialStorage::MaterialStorage() {
 		actions.render_mode_defines["unshaded"] = "#define MODE_UNSHADED\n";
 		actions.render_mode_defines["light_only"] = "#define MODE_LIGHT_ONLY\n";
 
+		actions.global_buffer_array_variable = "global_shader_uniforms";
+
 		shaders.compiler_canvas.initialize(actions);
 	}
 
@@ -1719,6 +1721,7 @@ MaterialStorage::MaterialStorage() {
 		actions.default_repeat = ShaderLanguage::REPEAT_ENABLE;
 
 		actions.check_multiview_samplers = true;
+		actions.global_buffer_array_variable = "global_shader_uniforms";
 
 		shaders.compiler_scene.initialize(actions);
 	}
@@ -1775,6 +1778,8 @@ MaterialStorage::MaterialStorage() {
 		actions.default_filter = ShaderLanguage::FILTER_LINEAR_MIPMAP;
 		actions.default_repeat = ShaderLanguage::REPEAT_ENABLE;
 
+		actions.global_buffer_array_variable = "global_shader_uniforms";
+
 		shaders.compiler_particles.initialize(actions);
 	}
 
@@ -1828,6 +1833,8 @@ MaterialStorage::MaterialStorage() {
 		actions.default_filter = ShaderLanguage::FILTER_LINEAR_MIPMAP;
 		actions.default_repeat = ShaderLanguage::REPEAT_ENABLE;
 
+		actions.global_buffer_array_variable = "global_shader_uniforms";
+
 		shaders.compiler_sky.initialize(actions);
 	}
 }

servers/rendering/shader_language.cpp

@@ -8243,6 +8243,10 @@ Error ShaderLanguage::_parse_shader(const HashMap<StringName, FunctionInfo> &p_f
 						_set_error(vformat(RTR("Uniform instances are not yet implemented for '%s' shaders."), shader_type_identifier));
 						return ERR_PARSE_ERROR;
 					}
+					if (OS::get_singleton()->get_current_rendering_method() == "gl_compatibility") {
+						_set_error(RTR("Uniform instances are not supported in gl_compatibility shaders."));
+						return ERR_PARSE_ERROR;
+					}
 					if (uniform_scope == ShaderNode::Uniform::SCOPE_LOCAL) {
 						tk = _get_token();
 						if (tk.type != TK_UNIFORM) {