--- /dev/null
+++ xnu/xnu-8019.41.5/tests/bounded_ptr_src/ctor.convert.cpp
@@ -0,0 +1,142 @@
+//
+// Tests for
+//  template <typename U, typename Policy>
+//  bounded_ptr(bounded_ptr<U, Policy> const& other);
+//
+
+#include <libkern/c++/bounded_ptr.h>
+#include <array>
+#include <type_traits>
+#include <darwintest.h>
+#include <darwintest_utils.h>
+#include "test_utils.h"
+
+#define _assert(...) T_ASSERT_TRUE((__VA_ARGS__), # __VA_ARGS__)
+
+struct Base { int i; };
+struct Derived : Base { };
+
+struct Base1 { int i; };
+struct Base2 { long l; };
+struct DerivedMultiple : Base1, Base2 {
+	DerivedMultiple(int i) : Base1{i}, Base2{i + 10}
+	{
+	}
+};
+
+struct Unrelated { };
+
+struct dummy_policy1 {
+	static constexpr void
+	trap(char const*)
+	{
+	}
+};
+struct dummy_policy2 {
+	static constexpr void
+	trap(char const*)
+	{
+	}
+};
+
+template <typename Stored, typename From, typename To>
+static void
+tests()
+{
+	std::array<Stored, 5> array = {Stored{0}, Stored{1}, Stored{2}, Stored{3}, Stored{4}};
+	Stored* const ptr = array.begin() + 2;
+
+	{
+		test_bounded_ptr<From> const from(ptr, array.begin(), array.end());
+		test_bounded_ptr<To> to = from; // conversion (implicit)
+		_assert(to.discard_bounds() == static_cast<To const*>(ptr));
+	}
+	{
+		test_bounded_ptr<From> const from(ptr, array.begin(), array.end());
+		test_bounded_ptr<To> to(from); // conversion (explicit)
+		_assert(to.discard_bounds() == static_cast<To const*>(ptr));
+	}
+	{
+		test_bounded_ptr<From> const from(ptr, array.begin(), array.end());
+		test_bounded_ptr<To> to{from}; // conversion (explicit)
+		_assert(to.discard_bounds() == static_cast<To const*>(ptr));
+	}
+	{
+		test_bounded_ptr<From> const from(ptr, array.begin(), array.end());
+		test_bounded_ptr<To> to = static_cast<test_bounded_ptr<To> >(from); // conversion (explicit)
+		_assert(to.discard_bounds() == static_cast<To const*>(ptr));
+	}
+
+	// Test converting from a null pointer
+	{
+		test_bounded_ptr<From> from = nullptr;
+		test_bounded_ptr<To> to = from; // conversion (implicit)
+		_assert(to.unsafe_discard_bounds() == nullptr);
+	}
+
+	// Test with different policies
+	{
+		libkern::bounded_ptr<From, dummy_policy1> from(ptr, array.begin(), array.end());
+		libkern::bounded_ptr<To, dummy_policy2> to = from; // conversion (implicit)
+		_assert(to.discard_bounds() == static_cast<To const*>(ptr));
+	}
+
+	// T{0}     T{1}     T{2}     T{3}     T{4}     <one-past-last>
+	//   ^        ^                                       ^
+	//   |        |                                       |
+	// from     begin                                    end
+	{
+		test_bounded_ptr<From> const from(array.begin(), array.begin() + 1, array.end());
+		test_bounded_ptr<To> to(from);
+		_assert(to.unsafe_discard_bounds() == static_cast<To const*>(array.begin()));
+	}
+}
+
+T_DECL(ctor_convert, "bounded_ptr.ctor.convert") {
+	tests</*stored*/ Derived, /*from*/ Derived, /*to*/ Derived>();
+	tests</*stored*/ Derived, /*from*/ Derived const, /*to*/ Derived const>();
+	tests</*stored*/ Derived, /*from*/ Derived volatile, /*to*/ Derived volatile>();
+	tests</*stored*/ Derived, /*from*/ Derived const volatile, /*to*/ Derived const volatile>();
+
+	tests</*stored*/ Derived, /*from*/ Derived, /*to*/ Base>();
+	tests</*stored*/ Derived, /*from*/ Derived const, /*to*/ Base const>();
+	tests</*stored*/ Derived, /*from*/ Derived volatile, /*to*/ Base volatile>();
+	tests</*stored*/ Derived, /*from*/ Derived const volatile, /*to*/ Base const volatile>();
+
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple, /*to*/ Base1>();
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple const, /*to*/ Base1 const>();
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple volatile, /*to*/ Base1 volatile>();
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple const volatile, /*to*/ Base1 const volatile>();
+
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple, /*to*/ Base2>();
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple const, /*to*/ Base2 const>();
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple volatile, /*to*/ Base2 volatile>();
+	tests</*stored*/ DerivedMultiple, /*from*/ DerivedMultiple const volatile, /*to*/ Base2 const volatile>();
+
+	tests</*stored*/ Derived, /*from*/ Derived, /*to*/ void>();
+	tests</*stored*/ Derived, /*from*/ Derived const, /*to*/ void const>();
+	tests</*stored*/ Derived, /*from*/ Derived volatile, /*to*/ void volatile>();
+	tests</*stored*/ Derived, /*from*/ Derived const volatile, /*to*/ void const volatile>();
+
+	// Make sure downcasts are disabled
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Base>, /*to*/ test_bounded_ptr<Derived> >);
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Base1>, /*to*/ test_bounded_ptr<DerivedMultiple> >);
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Base2>, /*to*/ test_bounded_ptr<DerivedMultiple> >);
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Base1>, /*to*/ test_bounded_ptr<Base2> >);
+
+	// Make sure const-casting away doesn't work
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Derived const>, /*to*/ test_bounded_ptr<Derived> >);
+
+	// Make sure casting to unrelated types doesn't work implicitly
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Derived>, /*to*/ test_bounded_ptr<char> >);
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Derived>, /*to*/ test_bounded_ptr<Unrelated> >);
+	static_assert(!std::is_convertible_v</*from*/ test_bounded_ptr<Base1>, /*to*/ test_bounded_ptr<Base2> >);
+
+	// Make sure even explicit conversion to unrelated types doesn't work
+	static_assert(!std::is_constructible_v</*to*/ test_bounded_ptr<char>, /*from*/ test_bounded_ptr<Derived> >);
+	static_assert(!std::is_constructible_v</*to*/ test_bounded_ptr<Unrelated>, /*from*/ test_bounded_ptr<Derived> >);
+	static_assert(!std::is_constructible_v</*to*/ test_bounded_ptr<Base2>, /*from*/ test_bounded_ptr<Base1> >);
+
+	// Make sure construction from a raw pointer doesn't work
+	static_assert(!std::is_constructible_v</*to*/ test_bounded_ptr<Derived>, /*from*/ Derived*>);
+}