✨ Allow bitset construction with enums for place_bits

Problem:
- It is convenient to construct a bitset with bits that are identified with enum
  values.

Solution:
- Allow the `place_bits` constructor to take enumeration values.

Author: elbeno

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)), ...);
     }
 

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;