From e3dd165a4af89bd1b17efaa449557ce8d6ad283f Mon Sep 17 00:00:00 2001
From: Neargye <neargye@gmail.com>
Date: Sat, 25 Jan 2020 23:51:50 +0500
Subject: [PATCH] add compile check at enum_name

---
 include/magic_enum.hpp | 5 ++++-
 test/test.cpp          | 4 ----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/magic_enum.hpp b/include/magic_enum.hpp
index e7e833b..4a4c566 100644
--- a/include/magic_enum.hpp
+++ b/include/magic_enum.hpp
@@ -511,7 +511,10 @@ template <typename E>
 // This version is much lighter on the compile times and is not restricted to the enum_range limitation.
 template <auto V>
 [[nodiscard]] constexpr auto enum_name() noexcept -> detail::enable_if_enum_t<decltype(V), std::string_view> {
-  return detail::name_v<std::decay_t<decltype(V)>, V>;
+  constexpr std::string_view name = detail::name_v<std::decay_t<decltype(V)>, V>;
+  static_assert(name.size() > 0, "Enum value does not have a name.");
+
+  return name;
 }
 
 // Returns string enum name from enum value.
diff --git a/test/test.cpp b/test/test.cpp
index b5929ee..1f765f2 100644
--- a/test/test.cpp
+++ b/test/test.cpp
@@ -271,7 +271,6 @@ TEST_CASE("enum_name") {
     REQUIRE(cr_name == "RED");
     REQUIRE(enum_name<Color::BLUE>() == "BLUE");
     REQUIRE(enum_name<cm[1]>() == "GREEN");
-    REQUIRE(enum_name<static_cast<Color>(0)>().empty());
 
     constexpr Numbers no = Numbers::one;
     constexpr auto no_name = enum_name<no>();
@@ -279,7 +278,6 @@ TEST_CASE("enum_name") {
     REQUIRE(enum_name<Numbers::two>() == "two");
     REQUIRE(enum_name<Numbers::three>() == "three");
     REQUIRE(enum_name<Numbers::many>() == "many");
-    REQUIRE(enum_name<static_cast<Numbers>(0)>().empty());
 
     constexpr Directions dr = Directions::Right;
     constexpr auto dr_name = enum_name<dr>();
@@ -287,7 +285,6 @@ TEST_CASE("enum_name") {
     REQUIRE(enum_name<Directions::Down>() == "Down");
     REQUIRE(dr_name == "Right");
     REQUIRE(enum_name<Directions::Left>() == "Left");
-    REQUIRE(enum_name<static_cast<Directions>(0)>().empty());
 
     constexpr number nt = number::three;
     constexpr auto nt_name = enum_name<nt>();
@@ -295,7 +292,6 @@ TEST_CASE("enum_name") {
     REQUIRE(enum_name<number::two>() == "two");
     REQUIRE(nt_name == "three");
     REQUIRE(enum_name<number::four>() == "four");
-    REQUIRE(enum_name<static_cast<number>(0)>().empty());
   }
 }