Merge pull request intel#174 from elbeno/add-type-traits

Add `is_scoped_enum`

Author: lukevalenty

include/stdx/bitset.hpp

@@ -135,8 +135,8 @@ class bitset {
 
     template <typename... Bs>
     constexpr explicit bitset(place_bits_t, Bs... bs) {
-        static_assert((std::is_integral_v<Bs> and ...),
-                      "Bit places must be integral!");
+        static_assert(((std::is_integral_v<Bs> or std::is_enum_v<Bs>) and ...),
+                      "Bit places must be integral or enumeration types!");
         (set(static_cast<std::size_t>(bs)), ...);
     }
 

include/stdx/type_traits.hpp

@@ -114,8 +114,9 @@ constexpr auto is_specialization_of()
 
 template <typename E>
 constexpr bool is_scoped_enum_v =
-    std::is_enum_v<E> and
-    not std::is_convertible_v<E, std::underlying_type_t<E>>;
+    std::is_enum_v<E> and not std::is_convertible_v<E, underlying_type_t<E>>;
+template <typename E>
+using is_scoped_enum = std::bool_constant<is_scoped_enum_v<E>>;
 
 template <typename...> struct type_list {};
 template <auto...> struct value_list {};

test/bitset.cpp

@@ -427,7 +427,7 @@ namespace {
 enum struct Bits : std::uint8_t { ZERO, ONE, TWO, THREE, MAX };
 }
 
-TEST_CASE("use bitset with enum struct (construct)", "[bitset]") {
+TEST_CASE("use bitset with enum struct (default construct)", "[bitset]") {
     constexpr auto bs = stdx::bitset<Bits::MAX>{};
     static_assert(bs.size() == stdx::to_underlying(Bits::MAX));
 }
@@ -455,6 +455,11 @@ TEST_CASE("use bitset with enum struct (read index)", "[bitset]") {
     static_assert(bs[Bits::THREE]);
 }
 
+TEST_CASE("use bitset with enum struct (place_bits construct)", "[bitset]") {
+    constexpr auto bs = stdx::bitset<Bits::MAX>{stdx::place_bits, Bits::ZERO};
+    static_assert(bs.to_natural() == 1);
+}
+
 #if __cplusplus >= 202002L
 TEST_CASE("construct with a ct_string", "[bitset]") {
     using namespace stdx::literals;

test/type_traits.cpp

@@ -77,8 +77,13 @@ enum struct E2 {};
 } // namespace
 
 TEST_CASE("is_scoped_enum", "[type_traits]") {
+    static_assert(not stdx::is_scoped_enum_v<int>);
     static_assert(not stdx::is_scoped_enum_v<E1>);
     static_assert(stdx::is_scoped_enum_v<E2>);
+
+    static_assert(not stdx::is_scoped_enum<int>::value);
+    static_assert(not stdx::is_scoped_enum<E1>::value);
+    static_assert(stdx::is_scoped_enum<E2>::value);
 }
 
 TEST_CASE("type_identity", "[type_traits]") {