Hi, I have a question about the intended declarations of ::abs in gcc when we #include <cstdlib>. I am aware that the standard does not require cstdlib to provide any declaration of ::abs at all, and that compliant code should either use std::abs, or #include <stdlib.h> (deprecated) before using ::abs. So, I expected cstdlib to either: 1. not provide ::abs at all, or 2. provide all the overloads of abs (::abs(int), ::abs(long), ::abs(long long)) - the same set that are required to be provided if we include <stdlib.h> In practice, using gcc 5.4.0/6.3.0 on both OSX 10.10.5 and Fedora Core 17 (glibc 2.15), I was surprised to find that including cstdlib provides only ::abs(int), as per the C library spec. It therefore seems easy to end up calling ::abs(int) with a long by mistake if you mistakenly believe stdlib.h was included. (I realise that -Wconversion would also catch this). I'm not suggesting this is an error, for the reasons above. My question is: - Is this intentional behaviour? - If not, is it possible/useful to change it to one of the above? I also looked at the behaviour of #include <stdlib.h>, which AFAIK is required to provide all the overrides of ::abs, and on my test systems it does indeed do that with gcc 6.3.0 (since bug 60401 was fixed). Also just for information, with llvm 3.9.0 clang++/libc++, #include <cstdlib> and #include <stdlib.h> both seem to provide all the overloads of ::abs. Thanks Dave
