From 4376bbe40b017a01f3026aebca2d348ff94aacf4 Mon Sep 17 00:00:00 2001
From: Michele Caini <michele.caini@gmail.com>
Date: Sat, 19 Oct 2019 22:08:11 +0200
Subject: [PATCH] workaround for an issue with clang 6

---
 src/entt/meta/factory.hpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/entt/meta/factory.hpp b/src/entt/meta/factory.hpp
index 4302b0547..51aa96329 100644
--- a/src/entt/meta/factory.hpp
+++ b/src/entt/meta/factory.hpp
@@ -712,9 +712,9 @@ class extended_meta_factory: public meta_factory<Type> {
     }
 
     template<typename Func>
-    auto unpack(choice_t<1>, Func func)
-    -> decltype(unpack(choice<3>, func())) {
-        unpack(choice<3>, func());
+    std::enable_if_t<std::is_invocable_v<Func>, void>
+    unpack(choice_t<1>, Func &&func) {
+        unpack(choice<3>, std::forward<Func>(func)());
     }
 
     template<typename Key, typename... Value>