commit 787b52c26eeeda427472846673e3c7b2c6f8fd8f
author Louis Dionne <ldionne.2@gmail.com> Tue Aug 24 10:30:39 2021 -0400
committer Copybara-Service <copybara-worker@google.com> Fri Sep 03 11:29:59 2021 -0700
tree c57b67dbad2d984daa52414904de9d39d4693749
parent d337bd3330cd798371ecba682321f8127f4549ec

[libc++] Remove _LIBCPP_HAS_NO_LONG_LONG in favour of using_if_exists

_LIBCPP_HAS_NO_LONG_LONG was only defined on FreeBSD. Instead, use the
using_if_exists attribute to skip over declarations that are not available
on the base system. Note that there's an annoying limitation that we can't
conditionally define a function based on whether the base system provides
a function, so for example we still need preprocessor logic to define the
abs() and div() overloads.

Differential Revision: https://reviews.llvm.org/D108630

NOKEYCHECK=True
GitOrigin-RevId: c137a0754c4e13181c226359687ae9f3d8b488f0

include/stdlib.h

diff --git a/include/stdlib.h b/include/stdlib.h
index 242eedc..a2b7cbd 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -96,10 +96,14 @@
 extern "C++" {
 // abs
 
-#undef abs
-#undef labs
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
-#undef llabs
+#ifdef abs
+# undef abs
+#endif
+#ifdef labs
+# undef labs
+#endif
+#ifdef llabs
+# undef llabs
 #endif
 
 // MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
@@ -107,11 +111,9 @@
 inline _LIBCPP_INLINE_VISIBILITY long abs(long __x) _NOEXCEPT {
   return __builtin_labs(__x);
 }
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
 inline _LIBCPP_INLINE_VISIBILITY long long abs(long long __x) _NOEXCEPT {
   return __builtin_llabs(__x);
 }
-#endif // _LIBCPP_HAS_NO_LONG_LONG
 #endif // !defined(_LIBCPP_MSVCRT) && !defined(__sun__)
 
 #if !defined(__sun__)
@@ -131,10 +133,14 @@
 
 // div
 
-#undef div
-#undef ldiv
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
-#undef lldiv
+#ifdef div
+# undef div
+#endif
+#ifdef ldiv
+# undef ldiv
+#endif
+#ifdef lldiv
+# undef lldiv
 #endif
 
 // MSVCRT already has the correct prototype in <stdlib.h> if __cplusplus is defined
@@ -142,12 +148,12 @@
 inline _LIBCPP_INLINE_VISIBILITY ldiv_t div(long __x, long __y) _NOEXCEPT {
   return ::ldiv(__x, __y);
 }
-#ifndef _LIBCPP_HAS_NO_LONG_LONG
+#if !(defined(__FreeBSD__) && !defined(__LONG_LONG_SUPPORTED))
 inline _LIBCPP_INLINE_VISIBILITY lldiv_t div(long long __x,
                                              long long __y) _NOEXCEPT {
   return ::lldiv(__x, __y);
 }
-#endif // _LIBCPP_HAS_NO_LONG_LONG
+#endif
 #endif // _LIBCPP_MSVCRT / __sun__
 } // extern "C++"
 #endif // __cplusplus