View Compilation Error

0_0_25490160_30086.cpp: In function 'double abs(int)':
0_0_25490160_30086.cpp:13:30: error: ambiguating new declaration of 'double abs(int)'
 inline double abs(const int a){
                              ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cstdlib:72:0,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_algo.h:59,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/algorithm:62,
                 from 0_0_25490160_30086.cpp:3:
GCC4.9.2/x86_64-w64-mingw32/include/stdlib.h:329:15: note: old declaration 'int abs(int)'
   int __cdecl abs(int _X);
               ^