Tools/TestWebKitAPI/Tests/WTF/StdLibExtrasTests.cpp - external/github.com/WebKit/webkit - Git at Google

 /*
  * Copyright (C) 2020-2024 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"

 #include <wtf/CryptographicallyRandomNumber.h>
 #include <wtf/MathExtras.h>
 #include <wtf/StdLibExtras.h>
 #include <wtf/Vector.h>

 #if !USE(SYSTEM_MALLOC)
 #include <bmalloc/Algorithm.h>
 #endif
 namespace TestWebKitAPI {

 template<typename WordType>
 void testFindBitInWord()
 {
     constexpr size_t bitsInWord = sizeof(WordType) * 8;
     constexpr size_t numberOfShiftValues = bitsInWord + 1;
     constexpr size_t testPermutationsPerShift = 100;

     constexpr size_t numberOfTestValues = numberOfShiftValues * testPermutationsPerShift;
     uint8_t startIndex[numberOfTestValues];
     uint8_t endIndex[numberOfTestValues];

     auto initTestValues = [&] () {
         // Set some internal and boundary cases.
         uint8_t specialCases[] = {
             0,
             bitsInWord / 2,
             bitsInWord - 1,
             bitsInWord,
         };

         constexpr size_t numberOfSpecialCases = sizeof(specialCases) / sizeof(specialCases[0]);

         size_t nextTestValue = 0;
         for (size_t i = 0; i < numberOfSpecialCases; ++i) {
             for (size_t j = 0; j < numberOfSpecialCases; ++j) {
                 startIndex[nextTestValue] = specialCases[i];
                 endIndex[nextTestValue++] = specialCases[j];
             }
         }

         // Fill in some random cases.
         for (size_t i = nextTestValue; i < numberOfTestValues; ++i) {
             startIndex[i] = static_cast<uint8_t>(cryptographicallyRandomUnitInterval() * bitsInWord);
             uint8_t remainingBits = bitsInWord - startIndex[i];
             endIndex[i] = static_cast<uint8_t>(cryptographicallyRandomUnitInterval() * remainingBits) + startIndex[i];
         }
     };

     auto expectedBitInWord = [] (WordType word, size_t& index, size_t endIndex, bool value) -> bool {
         word >>= index;
         while (index < endIndex) {
             if ((word & 1) == static_cast<WordType>(value))
                 return true;
             index++;
             word >>= 1;
         }
         index = endIndex;
         return false;
     };

     auto test = [&] (bool value, size_t shift) {
         constexpr uint64_t baseWord = std::numeric_limits<uint64_t>::max();
         uint64_t word = (shift < bitsInWord) ? baseWord << shift : 0;

         for (size_t i = 0; i < numberOfTestValues; ++i) {
             size_t index = startIndex[i];
             bool result = findBitInWord(word, index, endIndex[i], value);

             size_t expectedIndex = startIndex[i];
             bool expectedResult = expectedBitInWord(word, expectedIndex, endIndex[i], value);

             ASSERT_EQ(result, expectedResult);
             ASSERT_EQ(index, expectedIndex);
         }
     };

     initTestValues();

     // Testing find a set bit.
     for (size_t i = 0; i < numberOfShiftValues; ++i)
         test(true, i);

     // Testing find a cleared bit.
     for (size_t i = 0; i < numberOfShiftValues; ++i)
         test(false, i);
 }

 TEST(WTF_StdLibExtras, findBitInWord_uint32_t) { testFindBitInWord<uint32_t>(); }
 TEST(WTF_StdLibExtras, findBitInWord_uint64_t) { testFindBitInWord<uint64_t>(); }

 // Tests that function-local types can be instantiated with makeUnique.
 // Style check would complain about use of std::make_unique, enforcing use of
 // makeUnique. The makeUnique needs WTF_DEPRECATED_..._DEPRECATED_MAKE_FAST_ALLOCATED.
 // There used to be a warn-unused-typedef errors when using these.
 TEST(WTF_StdLibExtras, MakeUniqueFunctionLocalTypeCompiles)
 {
     struct LocalStruct {
         WTF_DEPRECATED_MAKE_STRUCT_FAST_ALLOCATED(LocalStruct);
     };
     IGNORE_CLANG_WARNINGS_BEGIN("unused-local-typedef")
     class LocalClass {
         WTF_DEPRECATED_MAKE_FAST_ALLOCATED(LocalClass);
     };
     IGNORE_CLANG_WARNINGS_END
     auto s = makeUnique<LocalStruct>();
     auto c = makeUnique<LocalClass>();
 }

 TEST(WTF_StdLibExtras, RoundUpToMultipleOfWorks)
 {
     EXPECT_EQ(2u, roundUpToMultipleOf(static_cast<uint8_t>(2), static_cast<uint8_t>(1)));
     EXPECT_EQ(254u, roundUpToMultipleOf(static_cast<uint8_t>(2), static_cast<uint8_t>(254)));
 }

 TEST(WTF_StdLibExtras, RoundUpToMultipleOfNonPowerOfTwoWorks)
 {
     {
         uint16_t x = 65534;
         uint16_t divisor = 7;
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedUint16 { divisor }, CheckedUint16 { x }));
     }
     {
         uint32_t x = std::numeric_limits<uint32_t>::max() - 2;
         uint32_t divisor = 9241;
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedUint32 { divisor }, CheckedUint32 { x }));
     }
     {
         uint64_t x = std::numeric_limits<uint64_t>::max() - 2;
         uint64_t divisor = 13;
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedUint64 { divisor }, CheckedUint64 { x }));
     }

 #if !USE(SYSTEM_MALLOC)
     // Test that bmalloc::roundUpToMultipleOfNonPowerOfTwo does not have the bug. The function uses size_t.
     {
         size_t x = std::numeric_limits<size_t>::max() - 2;
         size_t divisor = sizeof(size_t) == 4 ? 9241 : 13;
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
         EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedSize { divisor }, CheckedSize { x }));
         EXPECT_EQ(x, bmalloc::roundUpToMultipleOfNonPowerOfTwo(divisor, x));
     }
 #endif

     {
         size_t x = std::numeric_limits<size_t>::max();
         EXPECT_TRUE(roundUpToMultipleOfNonPowerOfTwo(CheckedSize { 2 }, CheckedSize { x }).hasOverflowed());
     }

     EXPECT_TRUE(roundUpToMultipleOfNonPowerOfTwo(CheckedSize { WTF::ResultOverflowed }, CheckedSize { 78 }).hasOverflowed());
     EXPECT_TRUE(roundUpToMultipleOfNonPowerOfTwo(CheckedSize { 78 }, CheckedSize { WTF::ResultOverflowed }).hasOverflowed());

 }

 TEST(WTF_StdLibExtras, ByteCast)
 {
     uint8_t u8 = 0;
     const uint8_t cu8 = 0;
     std::span su8 = { &u8, 1 };
     std::span scu8 = { &cu8, 1 };
     static_assert(std::same_as<char, decltype(byteCast<char>(u8))>);
     static_assert(std::same_as<char8_t, decltype(byteCast<char8_t>(u8))>);
     static_assert(std::same_as<std::byte, decltype(byteCast<std::byte>(u8))>);
     static_assert(std::same_as<char, decltype(byteCast<char>(cu8))>);
     static_assert(std::same_as<char8_t, decltype(byteCast<char8_t>(cu8))>);
     static_assert(std::same_as<std::byte, decltype(byteCast<std::byte>(cu8))>);
     static_assert(std::same_as<char*, decltype(byteCast<char>(&u8))>);
     static_assert(std::same_as<char8_t*, decltype(byteCast<char8_t>(&u8))>);
     static_assert(std::same_as<std::byte*, decltype(byteCast<std::byte>(&u8))>);
     static_assert(std::same_as<const char*, decltype(byteCast<char>(&cu8))>);
     static_assert(std::same_as<const char8_t*, decltype(byteCast<char8_t>(&cu8))>);
     static_assert(std::same_as<const std::byte*, decltype(byteCast<std::byte>(&cu8))>);
     static_assert(std::same_as<std::span<char>, decltype(byteCast<char>(su8))>);
     static_assert(std::same_as<std::span<char8_t>, decltype(byteCast<char8_t>(su8))>);
     static_assert(std::same_as<std::span<std::byte>, decltype(byteCast<std::byte>(su8))>);
     static_assert(std::same_as<std::span<const char>, decltype(byteCast<char>(scu8))>);
     static_assert(std::same_as<std::span<const char8_t>, decltype(byteCast<char8_t>(scu8))>);
     static_assert(std::same_as<std::span<const std::byte>, decltype(byteCast<std::byte>(scu8))>);
 }

 TEST(WTF_StdLibExtras, SpanReinterpretCast_DynamicExtent)
 {
     Vector<int32_t> signedInt { -3, -2, -1, 0, 1, 2 };
     auto signedIntSpan = signedInt.span();
     static_assert(std::same_as<std::span<const int32_t, std::dynamic_extent>, decltype(signedIntSpan)>);

     // Cast from 4 bytes to 1 byte per item.
     auto unsignedIntByteSpan = asByteSpan(signedIntSpan);
     static_assert(std::same_as<std::span<const uint8_t, std::dynamic_extent>, decltype(unsignedIntByteSpan)>);
     EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntByteSpan.data(), unsignedIntByteSpan.size_bytes()));

     // Cast from 4 bytes to 4 bytes per item.
     auto unsignedIntSpan = spanReinterpretCast<const uint32_t>(signedIntSpan);
     static_assert(std::same_as<std::span<const uint32_t, std::dynamic_extent>, decltype(unsignedIntSpan)>);
     EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntSpan.data(), unsignedIntSpan.size_bytes()));

     // Cast from 4 bytes to 8 bytes per item.
     auto unsignedLongSpan = spanReinterpretCast<const uint64_t>(signedIntSpan);
     static_assert(std::same_as<std::span<const uint64_t, std::dynamic_extent>, decltype(unsignedLongSpan)>);
     EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedLongSpan.data(), unsignedLongSpan.size_bytes()));
 }

 /*
 TEST(WTF_StdLibExtras, SpanReinterpretCast_DynamicExtent_ManualRuntimeErrors)
 {
     // Manual tests to check this release assert in WTF::spanReinterpretCast<>.
     // if constexpr (sizeof(U) < sizeof(T) || sizeof(U) % sizeof(T))
     //     RELEASE_ASSERT_WITH_MESSAGE(!(span.size_bytes() % sizeof(T)), "spanReinterpretCast will not change size in bytes from source");

     // Cast from 1 byte per item to 4 bytes per item, with non-multiple of 4.
     // Test 'sizeof(U) < sizeof(T)' results in a runtime crash.
     //Vector<int8_t> signedIntByte { 1, 2, 3, 4, 5, 6, 7 };
     //auto signedIntByteSpan = signedIntByte.span();
     //(void)spanReinterpretCast<const int>(signedIntByteSpan);

     // Cast from 4 bytes per item to 3 bytes per item, with non-multiple of 3.
     // Test that '(sizeof(U) > sizeof(T)) && (sizeof(U) % sizeof(T))' results in a runtime crash.
     //Vector<int32_t> signedInt { 1, 2, 3, 4 };
     //auto signedIntSpan = signedInt.span();
     //(void)spanReinterpretCast<const int8_t[3]>(signedIntSpan);
 }
 */

 TEST(WTF_StdLibExtras, SpanReinterpretCast_NonDynamicExtent)
 {
     Vector<int32_t> signedInt { -3, -2, -1, 0, 1, 2 };
     std::span<const int32_t, 6> signedIntSpan { signedInt.span() };
     static_assert(std::same_as<std::span<const int32_t, 6>, decltype(signedIntSpan)>);

     // Cast from 4 bytes to 1 byte per item.
     auto unsignedIntByteSpan = asByteSpan(signedIntSpan);
     static_assert(std::same_as<std::span<const uint8_t>, decltype(unsignedIntByteSpan)>);
     EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntByteSpan.data(), unsignedIntByteSpan.size_bytes()));

     // Cast from 4 bytes to 4 bytes per item.
     auto unsignedIntSpan = spanReinterpretCast<const uint32_t>(signedIntSpan);
     static_assert(std::same_as<std::span<const uint32_t, 6>, decltype(unsignedIntSpan)>);
     EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntSpan.data(), unsignedIntSpan.size_bytes()));

     // Cast from 4 bytes to 8 bytes per item.
     auto unsignedLongSpan = spanReinterpretCast<const uint64_t>(signedIntSpan);
     static_assert(std::same_as<std::span<const uint64_t, 3>, decltype(unsignedLongSpan)>);
     EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedLongSpan.data(), unsignedLongSpan.size_bytes()));
 }

 /*
 TEST(WTF_StdLibExtras, SpanReinterpretCast_NonDynamicExtent_CompileTimeErros)
 {
     // Manual tests to check this static assert in WTF::spanReinterpretCast<>.
     //     static_assert(!((sizeof(U) * Extent) % sizeof(T)), "spanReinterpretCast will not change size in bytes from source");

     // Cast from 1 byte per item to 4 bytes per item, with non-multiple of 4.
     //Vector<int8_t> signedIntByte { 1, 2, 3, 4, 5, 6, 7 };
     //std::span<const int8_t, 7> signedIntByteSpan { signedIntByte.data(), signedIntByte.size() };
     //(void)spanReinterpretCast<const int>(signedIntByteSpan);

     // Cast from 4 bytes per item to 3 bytes per item, with non-multiple of 3.
     //Vector<int32_t> signedInt { 1, 2, 3, 4 };
     //std::span<const int32_t, 4> signedIntSpan { signedInt.data(), signedInt.size() };
     //(void)spanReinterpretCast<const int8_t[3]>(signedIntSpan);
 }
 */

 } // namespace TestWebKitAPI
	/*
	* Copyright (C) 2020-2024 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
	* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
	* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"

	#include <wtf/CryptographicallyRandomNumber.h>
	#include <wtf/MathExtras.h>
	#include <wtf/StdLibExtras.h>
	#include <wtf/Vector.h>

	#if !USE(SYSTEM_MALLOC)
	#include <bmalloc/Algorithm.h>
	#endif
	namespace TestWebKitAPI {

	template<typename WordType>
	void testFindBitInWord()
	{
	constexpr size_t bitsInWord = sizeof(WordType) * 8;
	constexpr size_t numberOfShiftValues = bitsInWord + 1;
	constexpr size_t testPermutationsPerShift = 100;

	constexpr size_t numberOfTestValues = numberOfShiftValues * testPermutationsPerShift;
	uint8_t startIndex[numberOfTestValues];
	uint8_t endIndex[numberOfTestValues];

	auto initTestValues = [&] () {
	// Set some internal and boundary cases.
	uint8_t specialCases[] = {
	0,
	bitsInWord / 2,
	bitsInWord - 1,
	bitsInWord,
	};

	constexpr size_t numberOfSpecialCases = sizeof(specialCases) / sizeof(specialCases[0]);

	size_t nextTestValue = 0;
	for (size_t i = 0; i < numberOfSpecialCases; ++i) {
	for (size_t j = 0; j < numberOfSpecialCases; ++j) {
	startIndex[nextTestValue] = specialCases[i];
	endIndex[nextTestValue++] = specialCases[j];
	}
	}

	// Fill in some random cases.
	for (size_t i = nextTestValue; i < numberOfTestValues; ++i) {
	startIndex[i] = static_cast<uint8_t>(cryptographicallyRandomUnitInterval() * bitsInWord);
	uint8_t remainingBits = bitsInWord - startIndex[i];
	endIndex[i] = static_cast<uint8_t>(cryptographicallyRandomUnitInterval() * remainingBits) + startIndex[i];
	}
	};

	auto expectedBitInWord = [] (WordType word, size_t& index, size_t endIndex, bool value) -> bool {
	word >>= index;
	while (index < endIndex) {
	if ((word & 1) == static_cast<WordType>(value))
	return true;
	index++;
	word >>= 1;
	}
	index = endIndex;
	return false;
	};

	auto test = [&] (bool value, size_t shift) {
	constexpr uint64_t baseWord = std::numeric_limits<uint64_t>::max();
	uint64_t word = (shift < bitsInWord) ? baseWord << shift : 0;

	for (size_t i = 0; i < numberOfTestValues; ++i) {
	size_t index = startIndex[i];
	bool result = findBitInWord(word, index, endIndex[i], value);

	size_t expectedIndex = startIndex[i];
	bool expectedResult = expectedBitInWord(word, expectedIndex, endIndex[i], value);

	ASSERT_EQ(result, expectedResult);
	ASSERT_EQ(index, expectedIndex);
	}
	};

	initTestValues();

	// Testing find a set bit.
	for (size_t i = 0; i < numberOfShiftValues; ++i)
	test(true, i);

	// Testing find a cleared bit.
	for (size_t i = 0; i < numberOfShiftValues; ++i)
	test(false, i);
	}

	TEST(WTF_StdLibExtras, findBitInWord_uint32_t) { testFindBitInWord<uint32_t>(); }
	TEST(WTF_StdLibExtras, findBitInWord_uint64_t) { testFindBitInWord<uint64_t>(); }

	// Tests that function-local types can be instantiated with makeUnique.
	// Style check would complain about use of std::make_unique, enforcing use of
	// makeUnique. The makeUnique needs WTF_DEPRECATED_..._DEPRECATED_MAKE_FAST_ALLOCATED.
	// There used to be a warn-unused-typedef errors when using these.
	TEST(WTF_StdLibExtras, MakeUniqueFunctionLocalTypeCompiles)
	{
	struct LocalStruct {
	WTF_DEPRECATED_MAKE_STRUCT_FAST_ALLOCATED(LocalStruct);
	};
	IGNORE_CLANG_WARNINGS_BEGIN("unused-local-typedef")
	class LocalClass {
	WTF_DEPRECATED_MAKE_FAST_ALLOCATED(LocalClass);
	};
	IGNORE_CLANG_WARNINGS_END
	auto s = makeUnique<LocalStruct>();
	auto c = makeUnique<LocalClass>();
	}

	TEST(WTF_StdLibExtras, RoundUpToMultipleOfWorks)
	{
	EXPECT_EQ(2u, roundUpToMultipleOf(static_cast<uint8_t>(2), static_cast<uint8_t>(1)));
	EXPECT_EQ(254u, roundUpToMultipleOf(static_cast<uint8_t>(2), static_cast<uint8_t>(254)));
	}

	TEST(WTF_StdLibExtras, RoundUpToMultipleOfNonPowerOfTwoWorks)
	{
	{
	uint16_t x = 65534;
	uint16_t divisor = 7;
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedUint16 { divisor }, CheckedUint16 { x }));
	}
	{
	uint32_t x = std::numeric_limits<uint32_t>::max() - 2;
	uint32_t divisor = 9241;
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedUint32 { divisor }, CheckedUint32 { x }));
	}
	{
	uint64_t x = std::numeric_limits<uint64_t>::max() - 2;
	uint64_t divisor = 13;
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedUint64 { divisor }, CheckedUint64 { x }));
	}

	#if !USE(SYSTEM_MALLOC)
	// Test that bmalloc::roundUpToMultipleOfNonPowerOfTwo does not have the bug. The function uses size_t.
	{
	size_t x = std::numeric_limits<size_t>::max() - 2;
	size_t divisor = sizeof(size_t) == 4 ? 9241 : 13;
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(divisor, x));
	EXPECT_EQ(x, roundUpToMultipleOfNonPowerOfTwo(CheckedSize { divisor }, CheckedSize { x }));
	EXPECT_EQ(x, bmalloc::roundUpToMultipleOfNonPowerOfTwo(divisor, x));
	}
	#endif

	{
	size_t x = std::numeric_limits<size_t>::max();
	EXPECT_TRUE(roundUpToMultipleOfNonPowerOfTwo(CheckedSize { 2 }, CheckedSize { x }).hasOverflowed());
	}

	EXPECT_TRUE(roundUpToMultipleOfNonPowerOfTwo(CheckedSize { WTF::ResultOverflowed }, CheckedSize { 78 }).hasOverflowed());
	EXPECT_TRUE(roundUpToMultipleOfNonPowerOfTwo(CheckedSize { 78 }, CheckedSize { WTF::ResultOverflowed }).hasOverflowed());

	}

	TEST(WTF_StdLibExtras, ByteCast)
	{
	uint8_t u8 = 0;
	const uint8_t cu8 = 0;
	std::span su8 = { &u8, 1 };
	std::span scu8 = { &cu8, 1 };
	static_assert(std::same_as<char, decltype(byteCast<char>(u8))>);
	static_assert(std::same_as<char8_t, decltype(byteCast<char8_t>(u8))>);
	static_assert(std::same_as<std::byte, decltype(byteCast<std::byte>(u8))>);
	static_assert(std::same_as<char, decltype(byteCast<char>(cu8))>);
	static_assert(std::same_as<char8_t, decltype(byteCast<char8_t>(cu8))>);
	static_assert(std::same_as<std::byte, decltype(byteCast<std::byte>(cu8))>);
	static_assert(std::same_as<char*, decltype(byteCast<char>(&u8))>);
	static_assert(std::same_as<char8_t*, decltype(byteCast<char8_t>(&u8))>);
	static_assert(std::same_as<std::byte*, decltype(byteCast<std::byte>(&u8))>);
	static_assert(std::same_as<const char*, decltype(byteCast<char>(&cu8))>);
	static_assert(std::same_as<const char8_t*, decltype(byteCast<char8_t>(&cu8))>);
	static_assert(std::same_as<const std::byte*, decltype(byteCast<std::byte>(&cu8))>);
	static_assert(std::same_as<std::span<char>, decltype(byteCast<char>(su8))>);
	static_assert(std::same_as<std::span<char8_t>, decltype(byteCast<char8_t>(su8))>);
	static_assert(std::same_as<std::span<std::byte>, decltype(byteCast<std::byte>(su8))>);
	static_assert(std::same_as<std::span<const char>, decltype(byteCast<char>(scu8))>);
	static_assert(std::same_as<std::span<const char8_t>, decltype(byteCast<char8_t>(scu8))>);
	static_assert(std::same_as<std::span<const std::byte>, decltype(byteCast<std::byte>(scu8))>);
	}

	TEST(WTF_StdLibExtras, SpanReinterpretCast_DynamicExtent)
	{
	Vector<int32_t> signedInt { -3, -2, -1, 0, 1, 2 };
	auto signedIntSpan = signedInt.span();
	static_assert(std::same_as<std::span<const int32_t, std::dynamic_extent>, decltype(signedIntSpan)>);

	// Cast from 4 bytes to 1 byte per item.
	auto unsignedIntByteSpan = asByteSpan(signedIntSpan);
	static_assert(std::same_as<std::span<const uint8_t, std::dynamic_extent>, decltype(unsignedIntByteSpan)>);
	EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntByteSpan.data(), unsignedIntByteSpan.size_bytes()));

	// Cast from 4 bytes to 4 bytes per item.
	auto unsignedIntSpan = spanReinterpretCast<const uint32_t>(signedIntSpan);
	static_assert(std::same_as<std::span<const uint32_t, std::dynamic_extent>, decltype(unsignedIntSpan)>);
	EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntSpan.data(), unsignedIntSpan.size_bytes()));

	// Cast from 4 bytes to 8 bytes per item.
	auto unsignedLongSpan = spanReinterpretCast<const uint64_t>(signedIntSpan);
	static_assert(std::same_as<std::span<const uint64_t, std::dynamic_extent>, decltype(unsignedLongSpan)>);
	EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedLongSpan.data(), unsignedLongSpan.size_bytes()));
	}

	/*
	TEST(WTF_StdLibExtras, SpanReinterpretCast_DynamicExtent_ManualRuntimeErrors)
	{
	// Manual tests to check this release assert in WTF::spanReinterpretCast<>.
	// if constexpr (sizeof(U) < sizeof(T) \|\| sizeof(U) % sizeof(T))
	// RELEASE_ASSERT_WITH_MESSAGE(!(span.size_bytes() % sizeof(T)), "spanReinterpretCast will not change size in bytes from source");

	// Cast from 1 byte per item to 4 bytes per item, with non-multiple of 4.
	// Test 'sizeof(U) < sizeof(T)' results in a runtime crash.
	//Vector<int8_t> signedIntByte { 1, 2, 3, 4, 5, 6, 7 };
	//auto signedIntByteSpan = signedIntByte.span();
	//(void)spanReinterpretCast<const int>(signedIntByteSpan);

	// Cast from 4 bytes per item to 3 bytes per item, with non-multiple of 3.
	// Test that '(sizeof(U) > sizeof(T)) && (sizeof(U) % sizeof(T))' results in a runtime crash.
	//Vector<int32_t> signedInt { 1, 2, 3, 4 };
	//auto signedIntSpan = signedInt.span();
	//(void)spanReinterpretCast<const int8_t[3]>(signedIntSpan);
	}
	*/

	TEST(WTF_StdLibExtras, SpanReinterpretCast_NonDynamicExtent)
	{
	Vector<int32_t> signedInt { -3, -2, -1, 0, 1, 2 };
	std::span<const int32_t, 6> signedIntSpan { signedInt.span() };
	static_assert(std::same_as<std::span<const int32_t, 6>, decltype(signedIntSpan)>);

	// Cast from 4 bytes to 1 byte per item.
	auto unsignedIntByteSpan = asByteSpan(signedIntSpan);
	static_assert(std::same_as<std::span<const uint8_t>, decltype(unsignedIntByteSpan)>);
	EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntByteSpan.data(), unsignedIntByteSpan.size_bytes()));

	// Cast from 4 bytes to 4 bytes per item.
	auto unsignedIntSpan = spanReinterpretCast<const uint32_t>(signedIntSpan);
	static_assert(std::same_as<std::span<const uint32_t, 6>, decltype(unsignedIntSpan)>);
	EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedIntSpan.data(), unsignedIntSpan.size_bytes()));

	// Cast from 4 bytes to 8 bytes per item.
	auto unsignedLongSpan = spanReinterpretCast<const uint64_t>(signedIntSpan);
	static_assert(std::same_as<std::span<const uint64_t, 3>, decltype(unsignedLongSpan)>);
	EXPECT_TRUE(!memcmp(signedIntSpan.data(), unsignedLongSpan.data(), unsignedLongSpan.size_bytes()));
	}

	/*
	TEST(WTF_StdLibExtras, SpanReinterpretCast_NonDynamicExtent_CompileTimeErros)
	{
	// Manual tests to check this static assert in WTF::spanReinterpretCast<>.
	// static_assert(!((sizeof(U) * Extent) % sizeof(T)), "spanReinterpretCast will not change size in bytes from source");

	// Cast from 1 byte per item to 4 bytes per item, with non-multiple of 4.
	//Vector<int8_t> signedIntByte { 1, 2, 3, 4, 5, 6, 7 };
	//std::span<const int8_t, 7> signedIntByteSpan { signedIntByte.data(), signedIntByte.size() };
	//(void)spanReinterpretCast<const int>(signedIntByteSpan);

	// Cast from 4 bytes per item to 3 bytes per item, with non-multiple of 3.
	//Vector<int32_t> signedInt { 1, 2, 3, 4 };
	//std::span<const int32_t, 4> signedIntSpan { signedInt.data(), signedInt.size() };
	//(void)spanReinterpretCast<const int8_t[3]>(signedIntSpan);
	}
	*/

	} // namespace TestWebKitAPI