[libcxx-commits] [PATCH] D57778: std::abs should not return double (2735)

[Zoe Carver via Phabricator via libcxx-commits]

zoecarver created this revision.
zoecarver added reviewers: rsmith, mclow.lists.
Herald added subscribers: libcxx-commits, ldionne.

Implement 2735 <https://cplusplus.github.io/LWG/issue2735> by checking to make sure argument both `is_integral` and not `is_unsigned`.

**Question**
The issue describes `abs` returning an int always but for larger int types this would not work. I assume checking to make sure they are integral types is okay, but I am not sure.


Repository:
  rCXX libc++

https://reviews.llvm.org/D57778

Files:
  include/math.h


Index: include/math.h
===================================================================
--- include/math.h
+++ include/math.h
@@ -766,6 +766,14 @@
 inline _LIBCPP_INLINE_VISIBILITY
 long double
 abs(long double __lcpp_x) _NOEXCEPT {return ::fabsl(__lcpp_x);}
+    
+template <class _A1>
+inline _LIBCPP_INLINE_VISIBILITY
+typename std::enable_if<
+    std::is_integral<_A1>::value &&
+    !std::is_unsigned<_A1>::value, // allows for long long int, long int, int
+_A1>::type
+abs(_A1 __lcpp_x) _NOEXCEPT {return abs(__lcpp_x);}
 #endif // !(defined(_AIX) || defined(__sun__))
 
 // acos


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