Fix `-Wundef` warnings

Reviewed By: ot

Differential Revision: D31763384

fbshipit-source-id: ef666193f83a16d4eedf65a499361d967809163f

folly/CPortability.h

@@ -104,12 +104,12 @@
 /* Define a convenience macro to test when thread sanitizer is being used
  * across the different compilers (e.g. clang, gcc) */
 #ifndef FOLLY_SANITIZE_THREAD
-#if FOLLY_HAS_FEATURE(thread_sanitizer) || __SANITIZE_THREAD__
+#if FOLLY_HAS_FEATURE(thread_sanitizer) || defined(__SANITIZE_THREAD__)
 #define FOLLY_SANITIZE_THREAD 1
 #endif
 #endif
 
-#if FOLLY_SANITIZE_THREAD
+#ifdef FOLLY_SANITIZE_THREAD
 #define FOLLY_DISABLE_THREAD_SANITIZER \
   __attribute__((no_sanitize_thread, noinline))
 #else
@@ -121,12 +121,12 @@
  * across the different compilers (e.g. clang, gcc)
  */
 #ifndef FOLLY_SANITIZE_MEMORY
-#if FOLLY_HAS_FEATURE(memory_sanitizer) || __SANITIZE_MEMORY__
+#if FOLLY_HAS_FEATURE(memory_sanitizer) || defined(__SANITIZE_MEMORY__)
 #define FOLLY_SANITIZE_MEMORY 1
 #endif
 #endif
 
-#if FOLLY_SANITIZE_MEMORY
+#ifdef FOLLY_SANITIZE_MEMORY
 #define FOLLY_DISABLE_MEMORY_SANITIZER \
   __attribute__((no_sanitize_memory, noinline))
 #else

folly/FBString.h

@@ -2545,7 +2545,7 @@ operator<<(
         typename basic_fbstring<E, T, A, S>::value_type,
         typename basic_fbstring<E, T, A, S>::traits_type>& os,
     const basic_fbstring<E, T, A, S>& str) {
-#if _LIBCPP_VERSION
+#ifdef _LIBCPP_VERSION
   typedef std::basic_ostream<
       typename basic_fbstring<E, T, A, S>::value_type,
       typename basic_fbstring<E, T, A, S>::traits_type>

folly/Function.h

@@ -678,7 +678,7 @@ class Function final : private detail::function::FunctionTraits<FunctionType> {
   // not copyable
   Function(const Function&) = delete;
 
-#if __OBJC__
+#ifdef __OBJC__
   // Make sure Objective C blocks are copied
   template <class ReturnType, class... Args>
   /*implicit*/ Function(ReturnType (^objCBlock)(Args... args))
@@ -766,7 +766,7 @@ class Function final : private detail::function::FunctionTraits<FunctionType> {
 
   Function& operator=(const Function&) = delete;
 
-#if __OBJC__
+#ifdef __OBJC__
   // Make sure Objective C blocks are copied
   template <class ReturnType, class... Args>
   /* implicit */ Function& operator=(ReturnType (^objCBlock)(Args... args)) {

folly/Portability.h

@@ -46,7 +46,7 @@ constexpr bool kHasUnalignedAccess = false;
 // msvc should come first, so if clang is in msvc mode it gets the right defines
 
 // NOTE: this will only do checking in msvc with versions that support /analyze
-#if _MSC_VER
+#ifdef _MSC_VER
 #ifdef _USE_ATTRIBUTES_FOR_SAL
 #undef _USE_ATTRIBUTES_FOR_SAL
 #endif
@@ -143,7 +143,7 @@ constexpr bool kIsSanitizeAddress = true;
 constexpr bool kIsSanitizeAddress = false;
 #endif
 
-#if FOLLY_SANITIZE_THREAD
+#ifdef FOLLY_SANITIZE_THREAD
 constexpr bool kIsSanitizeThread = true;
 #else
 constexpr bool kIsSanitizeThread = false;
@@ -220,7 +220,7 @@ constexpr bool kIsSanitize = false;
 // It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
 // the 'std' namespace; the latter uses inline namespaces. Wrap this decision
 // up in a macro to make forward-declarations easier.
-#if FOLLY_USE_LIBCPP
+#ifdef FOLLY_USE_LIBCPP
 #include <__config> // @manual
 #define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
 #define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
@@ -366,6 +366,8 @@ constexpr auto kHasWeakSymbols = false;
 #ifndef FOLLY_NEON
 #if defined(__ARM_NEON) || defined(__ARM_NEON__)
 #define FOLLY_NEON 1
+#else
+#define FOLLY_NEON 0
 #endif
 #endif
 
@@ -423,7 +425,7 @@ constexpr bool const kHasRtti = FOLLY_HAS_RTTI;
 
 namespace folly {
 
-#if __OBJC__
+#ifdef __OBJC__
 constexpr auto kIsObjC = true;
 #else
 constexpr auto kIsObjC = false;
@@ -476,7 +478,7 @@ constexpr auto kGlibcxxAssertions = true;
 constexpr auto kGlibcxxAssertions = false;
 #endif
 
-#if _LIBCPP_VERSION
+#ifdef _LIBCPP_VERSION
 constexpr auto kIsLibcpp = true;
 #else
 constexpr auto kIsLibcpp = false;
@@ -488,7 +490,7 @@ constexpr auto kIsLibstdcpp = true;
 constexpr auto kIsLibstdcpp = false;
 #endif
 
-#if _MSC_VER
+#ifdef _MSC_VER
 constexpr auto kMscVer = _MSC_VER;
 #else
 constexpr auto kMscVer = 0;
@@ -508,7 +510,7 @@ constexpr auto kIsClang = false;
 constexpr auto kClangVerMajor = 0;
 #endif
 
-#if FOLLY_MICROSOFT_ABI_VER
+#ifdef FOLLY_MICROSOFT_ABI_VER
 constexpr auto kMicrosoftAbiVer = FOLLY_MICROSOFT_ABI_VER;
 #else
 constexpr auto kMicrosoftAbiVer = 0;
@@ -516,7 +518,7 @@ constexpr auto kMicrosoftAbiVer = 0;
 
 // cpplib is an implementation of the standard library, and is the one typically
 // used with the msvc compiler
-#if _CPPLIB_VER
+#ifdef _CPPLIB_VER
 constexpr auto kCpplibVer = _CPPLIB_VER;
 #else
 constexpr auto kCpplibVer = 0;
@@ -534,7 +536,7 @@ constexpr auto kCpplibVer = 0;
 //    FOLLY_STORAGE_CONSTEXPR int const num = 3;
 //
 //  True as of MSVC 2017.
-#if _MSC_VER
+#ifdef _MSC_VER
 #define FOLLY_STORAGE_CONSTEXPR
 #else
 #define FOLLY_STORAGE_CONSTEXPR constexpr

folly/Range.h

@@ -1486,7 +1486,7 @@ constexpr Range<char const*> operator"" _sp(
   return Range<char const*>(str, len);
 }
 
-#if __cpp_char8_t >= 201811L
+#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
 constexpr Range<char8_t const*> operator"" _sp(
     char8_t const* str, size_t len) noexcept {
   return Range<char8_t const*>(str, len);

folly/io/async/EventUtil.h

@@ -22,7 +22,7 @@
 
 namespace folly {
 
-#if LIBEVENT_VERSION_NUMBER <= 0x02010101
+#if !defined(LIBEVENT_VERSION_NUMBER) || LIBEVENT_VERSION_NUMBER <= 0x02010101
 #define FOLLY_LIBEVENT_COMPAT_PLUCK(name) ev_##name
 #define FOLLY_LIBEVENT_COMPAT_PLUCK2(name) ev_##name
 #else

folly/lang/Bits.h

@@ -73,7 +73,7 @@
 
 namespace folly {
 
-#if __cpp_lib_bit_cast
+#ifdef __cpp_lib_bit_cast
 
 using std::bit_cast;
 

folly/portability/Time.h

@@ -27,10 +27,11 @@
 // solve that by pretending we have it here in the header and
 // then enable our implementation on the source side so that
 // gets linked in instead.
-#if __MACH__ &&                                                       \
+#if defined(__MACH__) &&                                              \
         ((!defined(TARGET_OS_OSX) || TARGET_OS_OSX) &&                \
          (MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12)) || \
-    (TARGET_OS_IPHONE && (__IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_10_0))
+    (defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE != 0 &&            \
+     (__IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_10_0))
 
 #ifdef FOLLY_HAVE_CLOCK_GETTIME
 #undef FOLLY_HAVE_CLOCK_GETTIME