GCC 5.0 has them: > A new set of built-in functions for arithmetics with overflow checking has been added: __builtin_add_overflow, __builtin_sub_overflow and _

GCC 5.0 has them: > A new set of built-in functions for arithmetics with overflow checking has been added: __builtin_add_overflow, __builtin_sub_overflow and __builtin_mul_overflow and for compatibility with clang also other variants -- https://gcc.gnu.org/gcc-5/changes.html https://gcc.gnu.org/gcc-5/changes.html