• promote SCO OpenServer and UnixWare to !oswarn
• omit trying -O2/-O on OpenServer 5 and USL C
• cast mksh_ari_t to int, mksh_uari_t to unsigned int for printf
• skip ulimit-1 on syllable (which is still too broken)
• write ((mksh_ari_t)-2147483648) ipv UB ((mksh_ari_t)1 << 31)
and add a comment that that is actually meant
• rewrite functions returning !void ending in NOTREACHED
so they’ve got a jump target returning an error at the
end, to aid older compilers and just to be safe
• cast struct stat.st_size to off_t or size_t explicitly when needed
• shorten struct env by two bytes and an alignment, at least
also, optimise control flow and fix more paren matching cases