Change the -S and -t options to override each other so that the last one

specified wins to make their interaction less confusing.

bin/ls/ls.1

@@ -272,6 +272,13 @@ options all override each other; the last one specified determines
 the file time used.
 .Pp
 The
+.Fl S
+and
+.Fl t
+options override each other; the last one specified determines
+the sort order used.
+.Pp
+The
 .Fl B , b , w ,
 and
 .Fl q

bin/ls/ls.c

@@ -304,11 +304,14 @@ main(int argc, char *argv[])
 		case 'T':
 			f_sectime = 1;
 			break;
+		/* The -t and -S options override each other. */
 		case 't':
 			f_timesort = 1;
+			f_sizesort = 0;
 			break;
 		case 'S':
 			f_sizesort = 1;
+			f_timesort = 0;
 			break;
 		case 'W':
 			f_whiteout = 1;