Prevent error if varying assigned but not used (push warning instead)

servers/rendering/shader_language.cpp

@@ -946,7 +946,9 @@ void ShaderLanguage::_parse_used_identifier(const StringName &p_identifier, Iden
 			break;
 		case IdentifierType::IDENTIFIER_VARYING:
 			if (HAS_WARNING(ShaderWarning::UNUSED_VARYING_FLAG) && used_varyings.has(p_identifier)) {
-				used_varyings[p_identifier].used = true;
+				if (shader->varyings[p_identifier].stage != ShaderNode::Varying::STAGE_VERTEX && shader->varyings[p_identifier].stage != ShaderNode::Varying::STAGE_FRAGMENT) {
+					used_varyings[p_identifier].used = true;
+				}
 			}
 			break;
 		case IdentifierType::IDENTIFIER_UNIFORM:
@@ -7862,15 +7864,6 @@ Error ShaderLanguage::_parse_shader(const Map<StringName, FunctionInfo> &p_funct
 
 		tk = _get_token();
 	}
-
-	for (Map<StringName, ShaderNode::Varying>::Element *E = shader->varyings.front(); E; E = E->next()) {
-		if (E->get().stage == ShaderNode::Varying::STAGE_VERTEX || E->get().stage == ShaderNode::Varying::STAGE_FRAGMENT) {
-			_set_tkpos(E->get().tkpos);
-			_set_error(RTR("Varying must only be used in two different stages, which can be 'vertex' 'fragment' and 'light'"));
-			return ERR_PARSE_ERROR;
-		}
-	}
-
 	return OK;
 }