This adds macros for checked addition, subtraction, and multiplication with semantics similar to the builtins gcc and clang have had for years.
Reviewed by: kib, emaste
Differential Revision: https://reviews.freebsd.org/D41734
(cherry picked from commit e6615b1034)
include: Add tests for N2867.
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D41735
(cherry picked from commit 4fbb9c43aa)
less: We have <stdckdint.h> now.
Reviewed by: delphij
Differential Revision: https://reviews.freebsd.org/D41736
(cherry picked from commit cb8dd292c7)
Approved by: re (gjb)
