From 080f466590c161664f2a3c5d21e05bd31cc9c8c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Sun, 30 Aug 2026 18:02:11 +0000
Subject: [PATCH] Added bx::hasUniqueObjectRepresentation type trait. (#420)

---
 include/bx/inline/typetraits.inl |  9 +++++++++
 include/bx/typetraits.h          |  5 +++++
 tests/typetraits_test.cpp        | 15 +++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/bx/inline/typetraits.inl b/include/bx/inline/typetraits.inl
index a6ba3e6..5b7a2b2 100644
--- a/include/bx/inline/typetraits.inl
+++ b/include/bx/inline/typetraits.inl
@@ -366,6 +366,15 @@ namespace bx
 		return IsTriviallyCopyableT<Ty>::value;
 	}
 
+	//---
+	template<typename Ty> struct HasUniqueObjectRepresentationT : public BoolConstantT<__has_unique_object_representations(Ty)> {};
+
+	template<typename Ty>
+	inline constexpr bool hasUniqueObjectRepresentation()
+	{
+		return HasUniqueObjectRepresentationT<Ty>::value;
+	}
+
 	//---
 	template<typename Ty> struct IsTriviallyDestructibleT : public BoolConstantT<
 #if BX_COMPILER_GCC
diff --git a/include/bx/typetraits.h b/include/bx/typetraits.h
index 0c8b160..c40ffee 100644
--- a/include/bx/typetraits.h
+++ b/include/bx/typetraits.h
@@ -129,6 +129,11 @@ namespace bx
 	template<typename Ty>
 	constexpr bool isTriviallyCopyable();
 
+	/// Returns true if any two objects of type `Ty` that hold the same value also have the
+	/// same object representation, otherwise returns false. False for a type with padding.
+	template<typename Ty>
+	constexpr bool hasUniqueObjectRepresentation();
+
 	/// Returns true if type `Ty` has trivial destructor, otherwise returns false.
 	template<typename Ty>
 	constexpr bool isTriviallyDestructible();
diff --git a/tests/typetraits_test.cpp b/tests/typetraits_test.cpp
index 8ded209..ce2f74d 100644
--- a/tests/typetraits_test.cpp
+++ b/tests/typetraits_test.cpp
@@ -25,6 +25,8 @@ struct TestClassDerivedB        /*
 		: TestClassDerivedA     {                                                                        };
 struct TestClassDerivedX        /*                                                                       */
 		: TestClassVirtualDtor  {                                                                        };
+struct TestClassPadded          { uint32_t x; uint16_t y; uint8_t z;                                     };
+struct TestClassNoPadding       { uint32_t x; uint16_t y; uint8_t z; uint8_t w;                          };
 union  TestUnionEmpty           {                                                                        };
 union  TestUnion                { int32_t x; float y;                                                    };
 enum   TestEnumEmpty            {                                                                        };
@@ -210,6 +212,19 @@ TEST_CASE("type-traits isTriviallyCopyable", "")
 	STATIC_REQUIRE(!bx::isTriviallyCopyable<TestClassVirtualDtor >() );
 }
 
+TEST_CASE("type-traits hasUniqueObjectRepresentation", "")
+{
+	STATIC_REQUIRE( 8 == sizeof(TestClassPadded) );
+	STATIC_REQUIRE( 8 == sizeof(TestClassNoPadding) );
+
+	STATIC_REQUIRE( bx::hasUniqueObjectRepresentation<int32_t              >() );
+	STATIC_REQUIRE( bx::hasUniqueObjectRepresentation<TestClassMember      >() );
+	STATIC_REQUIRE( bx::hasUniqueObjectRepresentation<TestClassNoPadding   >() );
+	STATIC_REQUIRE(!bx::hasUniqueObjectRepresentation<TestClassPadded      >() );
+	STATIC_REQUIRE(!bx::hasUniqueObjectRepresentation<TestClassVirtualDtor >() );
+	STATIC_REQUIRE(!bx::hasUniqueObjectRepresentation<float                >() );
+}
+
 TEST_CASE("type-traits isTriviallyConstructible", "")
 {
 	STATIC_REQUIRE( bx::isTriviallyConstructible<int32_t              >() );