From c9ef05c4b37e837f5c18fca6068681066fb63d53 Mon Sep 17 00:00:00 2001
From: iwubcode <iwubcode@users.noreply.github.com>
Date: Wed, 24 Dec 2025 15:32:42 -0600
Subject: [PATCH] Common: update Flags to allow const object usage

Co-authored-by: Jordan Woyak <jordan.woyak@gmail.com>
---
 Source/Core/Common/BitUtils.h | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/Source/Core/Common/BitUtils.h b/Source/Core/Common/BitUtils.h
index e052c8aeff..9385b9d8d9 100644
--- a/Source/Core/Common/BitUtils.h
+++ b/Source/Core/Common/BitUtils.h
@@ -13,6 +13,7 @@
 #include <type_traits>
 
 #include "Common/CommonTypes.h"
+#include "Common/EnumUtils.h"
 
 namespace Common
 {
@@ -208,23 +209,20 @@ template <typename T>
 class FlagBit
 {
 public:
-  FlagBit(std::underlying_type_t<T>& bits, T bit) : m_bits(bits), m_bit(bit) {}
-  explicit operator bool() const
-  {
-    return (m_bits & static_cast<std::underlying_type_t<T>>(m_bit)) != 0;
-  }
-  FlagBit& operator=(const bool rhs)
+  FlagBit(T* bits, std::type_identity_t<T> bit) : m_bits(*bits), m_bit(bit) {}
+  explicit operator bool() const { return (m_bits & m_bit) != 0; }
+  FlagBit& operator=(const bool rhs) requires(!std::is_const_v<T>)
   {
     if (rhs)
-      m_bits |= static_cast<std::underlying_type_t<T>>(m_bit);
+      m_bits |= m_bit;
     else
-      m_bits &= ~static_cast<std::underlying_type_t<T>>(m_bit);
+      m_bits &= ~m_bit;
     return *this;
   }
 
 private:
-  std::underlying_type_t<T>& m_bits;
-  T m_bit;
+  T& m_bits;
+  const T m_bit;
 };
 
 template <typename T>
@@ -239,7 +237,8 @@ public:
       m_hex |= static_cast<std::underlying_type_t<T>>(bit);
     }
   }
-  FlagBit<T> operator[](T bit) { return FlagBit(m_hex, bit); }
+  auto operator[](T bit) { return FlagBit(&m_hex, Common::ToUnderlying(bit)); }
+  auto operator[](T bit) const { return FlagBit(&m_hex, Common::ToUnderlying(bit)); }
 
   std::underlying_type_t<T> m_hex = 0;
 };