bool __builtin_sadd_overflow (int a, int b, int *res) not declared

Question

I found the "integer overflow builtins" in the gcc manual, but it is not known to the compiler

'__builtin_sadd_overflow' was not declared in this scope

Called using

int x=0x7fffffff;
__builtin_sadd_overflow(2,x, &x);

The compiler version is

gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2

on i686.

Here is the manual: https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html

Answer 1

https://gcc.gnu.org/onlinedocs/gcc-4.8.3/gcc/C-Extensions.html (documentation for the 4.8.3 release) does not mention the overflow builtins. The unversioned address https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html corresponds to the documentation for the development version of gcc (the future gcc-5). You can wait until March or April, or start playing with a snapshot, or use clang's equivalent.