SYS_MADVISE        = 75  // { int sys_madvise(void *addr, size_t len, int behav); }
	SYS_UTIMES         = 76  // { int sys_utimes(const char *path, const struct timeval *tptr); }
	SYS_FUTIMES        = 77  // { int sys_futimes(int fd, const struct timeval *tptr); }
	SYS_MINCORE        = 78  // { int sys_mincore(void *addr, size_t len, char *vec); }
	SYS_GETGROUPS      = 79  // { int sys_getgroups(int gidsetsize, gid_t *gidset); }

	SYS_MKDIR                    = 136 // { int mkdir(char *path, int mode); }
	SYS_RMDIR                    = 137 // { int rmdir(char *path); }
	SYS_UTIMES                   = 138 // { int utimes(char *path, struct timeval *tptr); }
	SYS_ADJTIME                  = 140 // { int adjtime(struct timeval *delta, struct timeval *olddelta); }
	SYS_SETSID                   = 147 // { int setsid(void); }

	SYS_MKDIR                    = 136 // { int mkdir(char *path, int mode); }
	SYS_RMDIR                    = 137 // { int rmdir(char *path); }
	SYS_UTIMES                   = 138 // { int utimes(char *path, struct timeval *tptr); }
	SYS_ADJTIME                  = 140 // { int adjtime(struct timeval *delta, struct timeval *olddelta); }
	SYS_SETSID                   = 147 // { int setsid(void); }

	SYS_MKDIR                    = 136 // { int mkdir(char *path, int mode); }
	SYS_RMDIR                    = 137 // { int rmdir(char *path); }
	SYS_UTIMES                   = 138 // { int utimes(char *path, struct timeval *tptr); }
	SYS_ADJTIME                  = 140 // { int adjtime(struct timeval *delta, struct timeval *olddelta); }
	SYS_SETSID                   = 147 // { int setsid(void); }

	// but I'd like to use the @ notation only when strictly necessary.)
	if visited == nil {
		visited = map[*Type]int{}
	}
	visited[t] = b.Len()
	defer delete(visited, t)

	switch t.Kind() {
	case TPTR:
		b.WriteByte('*')
		switch mode {
		case fmtTypeID, fmtTypeIDName:
			if verb == 'S' {
				tconv2(b, t.Elem(), 'S', mode, visited)
				return
			}
		}
		tconv2(b, t.Elem(), 'v', mode, visited)

	SYS_MUNLOCK                  = 204 // { int munlock(const void *addr, size_t len); }
	SYS_UNDELETE                 = 205 // { int undelete(char *path); }
	SYS_FUTIMES                  = 206 // { int futimes(int fd, struct timeval *tptr); }
	SYS_GETPGID                  = 207 // { int getpgid(pid_t pid); }
	SYS_POLL                     = 209 // { int poll(struct pollfd *fds, u_int nfds, \

	SYS_MUNLOCK                  = 204 // { int munlock(const void *addr, size_t len); }
	SYS_UNDELETE                 = 205 // { int undelete(char *path); }
	SYS_FUTIMES                  = 206 // { int futimes(int fd, struct timeval *tptr); }
	SYS_GETPGID                  = 207 // { int getpgid(pid_t pid); }
	SYS_POLL                     = 209 // { int poll(struct pollfd *fds, u_int nfds, \

	SYS_MUNLOCK                  = 204 // { int munlock(const void *addr, size_t len); }
	SYS_UNDELETE                 = 205 // { int undelete(char *path); }
	SYS_FUTIMES                  = 206 // { int futimes(int fd, struct timeval *tptr); }
	SYS_GETPGID                  = 207 // { int getpgid(pid_t pid); }
	SYS_POLL                     = 209 // { int poll(struct pollfd *fds, u_int nfds, \

	}
	verifyMapBucket(t,
		Tscalar, Tptr,
		map[Xscalar]Xptr(nil),
		join(hdr, rep(bucketCount, lit(0)), rep(bucketCount, lit(1)), lit(1)))
	verifyMapBucket(t,
		Tscalarptr, Tptr,
		map[Xscalarptr]Xptr(nil),
		join(hdr, rep(bucketCount, lit(0, 1)), rep(bucketCount, lit(1)), lit(1)))
	verifyMapBucket(t, Tint64, Tptr,
		map[int64]Xptr(nil),

			return ir.OCONVNOP, ""
		}
	}

	// 5. src is the predeclared identifier nil and dst is a nillable type.
	if src.Kind() == types.TNIL {
		switch dst.Kind() {
		case types.TPTR,
			types.TFUNC,
			types.TMAP,
			types.TCHAN,
			types.TINTER,
			types.TSLICE:
			return ir.OCONVNOP, ""
		}
	}

	// 6. rule about untyped constants - already converted by DefaultLit.