Common: Replace enable_if with concepts and other minor modernizations.

9 files changed, 32 insertions, 50 deletions

diff --git a/Source/Core/Common/BitField.h b/Source/Core/Common/BitField.h
index bbd40f5414..9a2e2032a0 100644
--- a/Source/Core/Common/BitField.h
+++ b/Source/Core/Common/BitField.h
@@ -114,12 +114,9 @@
  */
 #pragma pack(1)
 template <std::size_t position, std::size_t bits, typename T,
-          // StorageType is T for non-enum types and the underlying type of T if
-          // T is an enumeration. Note that T is wrapped within an enable_if in the
-          // former case to workaround compile errors which arise when using
-          // std::underlying_type<T>::type directly.
-          typename StorageType = typename std::conditional_t<
-              std::is_enum<T>::value, std::underlying_type<T>, std::enable_if<true, T>>::type>
+          // StorageType is T for non-enum or the underlying-type for an enum.
+          typename StorageType = std::conditional_t<std::is_enum_v<T>, std::underlying_type<T>,
+                                                    std::type_identity<T>>::type>
 struct BitField
 {
 private:
@@ -212,12 +209,9 @@ class BitFieldArrayIterator;
 
 #pragma pack(1)
 template <std::size_t position, std::size_t bits, std::size_t size, typename T,
-          // StorageType is T for non-enum types and the underlying type of T if
-          // T is an enumeration. Note that T is wrapped within an enable_if in the
-          // former case to workaround compile errors which arise when using
-          // std::underlying_type<T>::type directly.
-          typename StorageType = typename std::conditional_t<
-              std::is_enum<T>::value, std::underlying_type<T>, std::enable_if<true, T>>::type>
+          // StorageType is T for non-enum or the underlying-type for an enum.
+          typename StorageType = std::conditional_t<std::is_enum_v<T>, std::underlying_type<T>,
+                                                    std::type_identity<T>>::type>
 struct BitFieldArray
 {
   using Ref = BitFieldArrayRef<position, bits, size, T, StorageType>;
diff --git a/Source/Core/Common/BitUtils.h b/Source/Core/Common/BitUtils.h
index 8b1b196c24..581305d345 100644
--- a/Source/Core/Common/BitUtils.h
+++ b/Source/Core/Common/BitUtils.h
@@ -7,7 +7,6 @@
 #include <bit>
 #include <climits>
 #include <cstddef>
-#include <cstdint>
 #include <cstring>
 #include <initializer_list>
 #include <type_traits>
@@ -117,8 +116,8 @@ constexpr Result ExtractBits(const T src) noexcept
 template <typename T>
 constexpr bool IsValidLowMask(const T mask) noexcept
 {
-  static_assert(std::is_integral<T>::value, "Mask must be an integral type.");
-  static_assert(std::is_unsigned<T>::value, "Signed masks can introduce hard to find bugs.");
+  static_assert(std::is_integral_v<T>, "Mask must be an integral type.");
+  static_assert(std::is_unsigned_v<T>, "Signed masks can introduce hard to find bugs.");
 
   // Can be efficiently determined without looping or bit counting. It's the counterpart
   // to https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2
@@ -138,11 +137,10 @@ public:
   explicit BitCastPtrType(PtrType* ptr) : m_ptr(ptr) {}
 
   // Enable operator= only for pointers to non-const data
-  template <typename S>
-  inline typename std::enable_if<std::is_same<S, T>() && !std::is_const<PtrType>()>::type
-  operator=(const S& source)
+  auto& operator=(const T& source) requires(!std::is_const_v<PtrType>)
   {
     std::memcpy(m_ptr, &source, sizeof(source));
+    return *this;
   }
 
   inline operator T() const
diff --git a/Source/Core/Common/ChunkFile.h b/Source/Core/Common/ChunkFile.h
index ef9be1b7ce..7e48e6e913 100644
--- a/Source/Core/Common/ChunkFile.h
+++ b/Source/Core/Common/ChunkFile.h
@@ -32,7 +32,6 @@
 #include "Common/EnumMap.h"
 #include "Common/Flag.h"
 #include "Common/Inline.h"
-#include "Common/Logging/Log.h"
 
 // Wrapper class
 class PointerWrap
@@ -195,13 +194,15 @@ public:
     DoArray(x.data(), static_cast<u32>(x.size()));
   }
 
-  template <typename T, typename std::enable_if_t<std::is_trivially_copyable_v<T>, int> = 0>
+  template <typename T>
+  requires(std::is_trivially_copyable_v<T>)
   void DoArray(T* x, u32 count)
   {
     DoVoid(x, count * sizeof(T));
   }
 
-  template <typename T, typename std::enable_if_t<!std::is_trivially_copyable_v<T>, int> = 0>
+  template <typename T>
+  requires(!std::is_trivially_copyable_v<T>)
   void DoArray(T* x, u32 count)
   {
     for (u32 i = 0; i < count; ++i)
diff --git a/Source/Core/Common/Config/ConfigInfo.h b/Source/Core/Common/Config/ConfigInfo.h
index be3d00108b..e8d904fae2 100644
--- a/Source/Core/Common/Config/ConfigInfo.h
+++ b/Source/Core/Common/Config/ConfigInfo.h
@@ -6,21 +6,14 @@
 #include <mutex>
 #include <shared_mutex>
 #include <string>
-#include <type_traits>
 #include <utility>
 
 #include "Common/CommonTypes.h"
 #include "Common/Config/Enums.h"
+#include "Common/TypeUtils.h"
 
 namespace Config
 {
-namespace detail
-{
-// std::underlying_type may only be used with enum types, so make sure T is an enum type first.
-template <typename T>
-using UnderlyingType = typename std::enable_if_t<std::is_enum<T>{}, std::underlying_type<T>>::type;
-}  // namespace detail
-
 struct Location
 {
   System system{};
@@ -54,8 +47,7 @@ public:
 
   // Make it easy to convert Info<Enum> into Info<UnderlyingType<Enum>>
   // so that enum settings can still easily work with code that doesn't care about the enum values.
-  template <typename Enum,
-            std::enable_if_t<std::is_same<T, detail::UnderlyingType<Enum>>::value>* = nullptr>
+  template <Common::TypedEnum<T> Enum>
   Info(const Info<Enum>& other)
   {
     *this = other;
@@ -80,8 +72,7 @@ public:
 
   // Make it easy to convert Info<Enum> into Info<UnderlyingType<Enum>>
   // so that enum settings can still easily work with code that doesn't care about the enum values.
-  template <typename Enum,
-            std::enable_if_t<std::is_same<T, detail::UnderlyingType<Enum>>::value>* = nullptr>
+  template <Common::TypedEnum<T> Enum>
   Info<T>& operator=(const Info<Enum>& other)
   {
     m_location = other.GetLocation();
diff --git a/Source/Core/Common/Config/Layer.h b/Source/Core/Common/Config/Layer.h
index e82b411c29..3234cc0638 100644
--- a/Source/Core/Common/Config/Layer.h
+++ b/Source/Core/Common/Config/Layer.h
@@ -23,7 +23,8 @@ struct DefaultState
 
 namespace detail
 {
-template <typename T, std::enable_if_t<!std::is_enum<T>::value>* = nullptr>
+template <typename T>
+requires(!Common::Enum<T>)
 std::optional<T> TryParse(const std::string& str_value)
 {
   T value;
@@ -32,7 +33,7 @@ std::optional<T> TryParse(const std::string& str_value)
   return value;
 }
 
-template <typename T, std::enable_if_t<std::is_enum<T>::value>* = nullptr>
+template <Common::Enum T>
 std::optional<T> TryParse(const std::string& str_value)
 {
   const auto result = TryParse<std::underlying_type_t<T>>(str_value);
diff --git a/Source/Core/Common/EnumFormatter.h b/Source/Core/Common/EnumFormatter.h
index 2df7399fc7..77c25989ad 100644
--- a/Source/Core/Common/EnumFormatter.h
+++ b/Source/Core/Common/EnumFormatter.h
@@ -42,11 +42,10 @@
  *   constexpr formatter() : EnumFormatter(names) {}
  * };
  */
-template <auto last_member>
+template <Common::Enum auto last_member>
 class EnumFormatter
 {
   using T = decltype(last_member);
-  static_assert(std::is_enum_v<T>);
 
 public:
   constexpr auto parse(fmt::format_parse_context& ctx)
diff --git a/Source/Core/Common/EnumMap.h b/Source/Core/Common/EnumMap.h
index 1eba9fe513..8f877a3a01 100644
--- a/Source/Core/Common/EnumMap.h
+++ b/Source/Core/Common/EnumMap.h
@@ -4,7 +4,6 @@
 #pragma once
 
 #include <array>
-#include <type_traits>
 
 #include "Common/TypeUtils.h"
 
@@ -15,11 +14,10 @@ namespace Common
 {
 // A type that allows lookup of values associated with an enum as the key.
 // Designed for enums whose numeric values start at 0 and increment continuously with few gaps.
-template <typename V, auto last_member>
+template <typename V, Common::Enum auto last_member>
 class EnumMap final
 {
   using T = decltype(last_member);
-  static_assert(std::is_enum_v<T>);
   static constexpr size_t s_size = static_cast<size_t>(last_member) + 1;
 
   using array_type = std::array<V, s_size>;
@@ -34,8 +32,9 @@ public:
   constexpr EnumMap& operator=(EnumMap&& other) = default;
 
   // Constructor that accepts exactly size Vs (enforcing that all must be specified).
-  template <typename... T, typename = std::enable_if_t<Common::IsNOf<V, s_size, T...>::value>>
-  constexpr EnumMap(T... values) : m_array{static_cast<V>(values)...}
+  template <typename... T>
+  constexpr EnumMap(T... values) requires(Common::IsNOf<V, s_size, T...>::value)
+      : m_array{static_cast<V>(values)...}
   {
   }
 
diff --git a/Source/Core/Common/SFMLHelper.h b/Source/Core/Common/SFMLHelper.h
index cd8bb2303b..f3bf968823 100644
--- a/Source/Core/Common/SFMLHelper.h
+++ b/Source/Core/Common/SFMLHelper.h
@@ -3,26 +3,25 @@
 
 #pragma once
 
-#include <type_traits>
-
 #include <SFML/Network/Packet.hpp>
 
 #include "Common/CommonTypes.h"
+#include "Common/EnumUtils.h"
 #include "Common/Swap.h"
+#include "Common/TypeUtils.h"
 
 sf::Packet& operator>>(sf::Packet& packet, Common::BigEndianValue<u16>& data);
 sf::Packet& operator>>(sf::Packet& packet, Common::BigEndianValue<u32>& data);
 sf::Packet& operator>>(sf::Packet& packet, Common::BigEndianValue<u64>& data);
 
-template <typename Enum, std::enable_if_t<std::is_enum_v<Enum>>* = nullptr>
+template <Common::Enum Enum>
 sf::Packet& operator<<(sf::Packet& packet, Enum e)
 {
-  using Underlying = std::underlying_type_t<Enum>;
-  packet << static_cast<Underlying>(e);
+  packet << Common::ToUnderlying(e);
   return packet;
 }
 
-template <typename Enum, std::enable_if_t<std::is_enum_v<Enum>>* = nullptr>
+template <Common::Enum Enum>
 sf::Packet& operator>>(sf::Packet& packet, Enum& e)
 {
   using Underlying = std::underlying_type_t<Enum>;
diff --git a/Source/Core/Common/TypeUtils.h b/Source/Core/Common/TypeUtils.h
index 0b1a2683eb..59a6393444 100644
--- a/Source/Core/Common/TypeUtils.h
+++ b/Source/Core/Common/TypeUtils.h
@@ -70,8 +70,8 @@ static_assert(!std::is_same_v<ObjectType<&Bar::c>, Bar>);
 
 // Template for checking if Types is count occurrences of T.
 template <typename T, size_t count, typename... Ts>
-struct IsNOf : std::integral_constant<bool, std::conjunction_v<std::is_convertible<Ts, T>...> &&
-                                                sizeof...(Ts) == count>
+struct IsNOf : std::bool_constant<std::conjunction_v<std::is_convertible<Ts, T>...> &&
+                                  sizeof...(Ts) == count>
 {
 };