https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61317
--- Comment #2 from Richard Riley <richard at rjriley dot info> --- "When postfix ++ is applied to an lvalue the result is the value of the object referred to by the lvalue. After the result is noted, the object is incremented in the same manner as for the prefix ++ operator. The type of the result is the same as the type of the lvalue expression." Page 187, "The C Programming Language" Kernighan and Ritchie, 1978
