Somewhat comprehensive list of feature test macros for C/C++. Leave a comment if I forgot anything

platformtest.h

// Compile time info 
#pragma once

//==========================================================//
// Feature test macros. Enjoy (or not)
//==========================================================//
// FORBID_XXX stuff is used to force disable various intrinsics
// See the OS_XXX section (near the bottom) to find which OS you're using

#if ( defined(__AVX__) ) && !( defined(FORBID_SIMD) || defined(FORBID_AVX) )
#	undef USE_AVX
#	define USE_AVX 1
#endif
#if ( defined(__AVX2__) ) && !( defined(FORBID_SIMD) || defined(FORBID_AVX2) )
#	undef USE_AVX2
#	define USE_AVX2 1
#endif
#if ( defined(__SSE__) || defined(_M_X64) || (_M_IX86_FP >= 1) ) &&  !( defined(FORBID_SIMD) || defined(FORBID_SSE) )
#	undef USE_SSE
#	define USE_SSE 1
#endif
#if ( defined(__SSE2__) || defined(_M_X64) || (_M_IX86_FP >= 2) ) &&  !( defined(FORBID_SIMD) || defined(FORBID_SSE2) )
#	undef USE_SSE2
#	define USE_SSE2 1
#endif
#if ( defined(__SSE3__) || defined(_M_X64) ) &&  !( defined(FORBID_SIMD) || defined(FORBID_SSE3) )
#	undef USE_SSE3
#	define USE_SSE3 1
#endif
#if ( defined(__SSE4_1__) ) &&  !( defined(FORBID_SIMD) || defined(FORBID_SSE41) )
#	undef USE_SSE41
#	define USE_SSE41 1
#endif
#if ( defined(__SSE4_2__) ) &&  !( defined(FORBID_SIMD) || defined(FORBID_SSE42) )
#	undef USE_SSE42
#	define USE_SSE42 1
#endif
#if ( defined(__SSSE3__) ) &&  !( defined(FORBID_SIMD) || defined(FORBID_SSSE3) )
#	undef USE_SSSE3
#	define USE_SSSE3 1
#endif
#if ( defined(__ARM_NEON) ) && !( defined(FORBID_SIMD) || defined(FORBID_NEON) )
#	undef USE_NEON
#	define USE_NEON 1
#endif
#if ( defined(__ARM_FEATURE_SVE) ) && !( defined(FORBID_SIMD) || defined(FORBID_SVE) )
#	undef USE_SVE
#	define USE_SVE 1
#endif
#if ( defined(__ARM_FEATURE_SVE2) ) && !( defined(FORBID_SIMD) || defined(FORBID_SVE2) )
#	undef USE_SVE2
#	define USE_SVE2 1
#endif
#if ( defined(__ARM_FEATURE_CRC32) )
#	undef HAS_ARM_CRC32
#	define HAS_ARM_CRC32 1
#endif
#if ( defined(__ARM_FEATURE_FMA) )
#	undef HAS_ARM_FMA
#	define HAS_ARM_FMA 1
#endif
#if ( defined(__ARM_FEATURE_COMPLEX) )
#	undef HAS_ARM_COMPLEX
#	define HAS_ARM_COMPLEX 1
#endif
#if ( defined(__ARM_FEATURE_SVE) )
#	undef HAS_ARM_SVE
#	define HAS_ARM_SVE 1
#endif
#if ( defined(__ARM_FEATURE_SVE2) )
#	undef HAS_ARM_SVE2
#	define HAS_ARM_SVE2 1
#endif
#if ( defined(__amd64__) || defined(_M_X64_) )
#	undef PLATFORM_64BITS
#	undef _X64_
#	undef PLATFORM_AMD64
#	define PLATFORM_64BITS 1
#	define _X64_ 1
#	define PLATFORM_AMD64 1
#endif
#if ( defined(__i386__) || defined(_M_IX86_) )
#	undef PLATFORM_32BITS
#	undef PLATFORM_X86
#	undef _X86_
#	define PLATFORM_32BITS 1
#	define PLATFORM_X86 1
#	define _X86_ 1
#endif
#if ( defined(_M_ARM) || defined(__arm__) )
#	undef PLATFORM_32BITS
#	undef PLATFORM_ARM
#	undef PLATFORM_ARM32
#	define PLATFORM_32BITS 1
#	define PLATFORM_ARM 1
#	define PLATFORM_ARM32 1
#endif
#if ( defined(_M_ARM64) || defined(__aarch64__) )
#	undef PLATFORM_64BITS
#	undef PLATFORM_ARM
#	undef PLATFORM_ARM64
#	define PLATFORM_64BITS 1
#	define PLATFORM_ARM 1
#	define PLATFORM_ARM64 1
#endif
#if ( defined(__ppc64__) )
#	undef PLATFORM_64BITS
#	undef PLATFORM_PPC
#	undef PLATFORM_PPC64
#	define PLATFORM_64BITS 1
#	define PLATFORM_PPC 1
#	define PLATFORM_PPC64 1
#elif ( defined(__ppc__) )
#	undef PLATFORM_32BITS
#	undef PLATFORM_PPC
#	undef PLATFORM_PPC32
#	define PLATFORM_32BITS 1
#	define PLATFORM_PPC 1
#	define PLATFORM_PPC32 1
#endif
#if ( defined(__riscv) )
#	undef PLATFORM_64BITS
#	undef PLATFORM_RISCV
#	undef PLATFORM_RISCV64
#	define PLATFORM_64BITS 1
#	define PLATFORM_RISCV 1
#	define PLATFORM_RISCV64 1
#endif
#if ( defined(__GNUC__) )
#	undef COMPILER_GCC
#	define COMPILER_GCC 1
#endif
#if ( defined(_MSC_VER) )
#	undef COMPILER_MSVC
#	define COMPILER_MSVC 1
#endif
#if ( defined(__clang__) )
#	undef COMPILER_CLANG
#	define COMPILER_CLANG 1
#endif
#if ( defined(__linux__) )
#	undef OS_STRING
#	define OS_STRING "Linux"
#	undef OS_LINUX
#	define OS_LINUX 1
#	undef OS_POSIX
#	define OS_POSIX 1
#endif
#if ( defined(_WIN32) || defined(__CYGWIN__) )
#	undef OS_STRING
#	define OS_STRING "Windows"
#	undef OS_WINDOWS
#	define OS_WINDOWS 1
#endif
#if ( defined(__APPLE__) )
#	undef OS_STRING
#	define OS_STRING "OSX"
#	undef OS_OSX
#	define OS_OSX 1
#	undef OS_POSIX
#	define OS_POSIX 1
#endif
#if ( defined(__ANDROID__) )
#	undef OS_STRING
#	define OS_STRING "Android"
#	undef OS_ANDROID
#	define OS_ANDROID
#	undef OS_POSIX
#	define OS_POSIX 1
#endif

// For mingw/cygwin, we're mostly posix compliant, barring some small problems. Indicate that core posix features are available, but not everything
#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW__) || defined(__MINGW64__) || defined(OS_POSIX)
#	undef OS_PARTIAL_POSIX
#	define OS_PARTIAL_POSIX 1
#endif
#if defined(__MINGW__) || defined(__MINGW64__) || defined(__MINGW32__)
#	undef COMPILER_MINGW 0
#	define COMPILER_MINGW 1
#endif
#if defined(__CYGWIN__)
#	undef COMPILER_CYGWIN 0
#	define COMPILER_CYGWIN 1
#endif

// GCC/Clang only, afaik
#if ( __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ )
#	undef PLATFORM_BIG_ENDIAN
#	define PLATFORM_BIG_ENDIAN 1
#else
#	undef PLATFORM_LITTLE_ENDIAN
#	define PLATFORM_LITTLE_ENDIAN 1
#endif

#ifdef OS_WINDOWS
#	undef DLL_EXT
#	define DLL_EXT ".dll"
#	undef LIB_EXT
#	define LIB_EXT ".lib"
#	undef EXE_EXT
#	define EXE_EXT ".exe"
#elif OS_OSX
#	undef DLL_EXT
#	define DLL_EXT ".dylib"
#	undef LIB_EXT
#	define LIB_EXT ".a"
#	undef EXE_EXT
#	define EXE_EXT ""
#else
#	undef DLL_EXT
#	define DLL_EXT ".so"
#	undef LIB_EXT
#	define LIB_EXT ".a"
#	undef EXE_EXT
#	define EXE_EXT ""
#endif

#if (COMPILER_CLANG == 1) || (COMPILER_GCC == 1)
#	ifdef OS_WINDOWS
#		undef COMPILER_DLLEXPORT
#		define COMPILER_DLLEXPORT __attribute__((dllexport))
#		undef COMPILER_DLLIMPORT
#		define COMPILER_DLLIMPORT __attribute__((dllimport))
#	else
#		undef COMPILER_DLLEXPORT
#		define COMPILER_DLLEXPORT __attribute__((visibility("default")))
#		undef COMPILER_DLLIMPORT
#		define COMPILER_DLLIMPORT /* N/A :) */
#	endif
#else
#	undef COMPILER_DLLEXPORT
#	define COMPILER_DLLEXPORT __declspec(dllexport)
#	undef COMPILER_DLLIMPORT
#	define COMPILER_DLLIMPORT __declspec(dllimport)
#endif

#ifdef OS_POSIX
#undef _POSIX
#define _POSIX 1
#endif

#ifdef OS_LINUX
#undef _LINUX
#define _LINUX 1
#endif