Merge branch 'so/separate-field-for-m-and-diff-merges'

Internal API clean-up to handle two options "diff-index" and "log"
have, which happen to share the same short form, more sensibly.

* so/separate-field-for-m-and-diff-merges:
  revision: add separate field for "-m" of "diff-index -m"

diff-lib.c

@@ -405,14 +405,8 @@ static void do_oneway_diff(struct unpack_trees_options *o,
 	/* if the entry is not checked out, don't examine work tree */
 	cached = o->index_only ||
 		(idx && ((idx->ce_flags & CE_VALID) || ce_skip_worktree(idx)));
-	/*
-	 * Backward compatibility wart - "diff-index -m" does
-	 * not mean "do not ignore merges", but "match_missing".
-	 *
-	 * But with the revision flag parsing, that's found in
-	 * "!revs->ignore_merges".
-	 */
-	match_missing = !revs->ignore_merges;
+
+	match_missing = revs->match_missing;
 
 	if (cached && idx && ce_stage(idx)) {
 		struct diff_filepair *pair;

revision.c

@@ -2352,7 +2352,13 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		revs->diffopt.flags.recursive = 1;
 		revs->diffopt.flags.tree_in_recursive = 1;
 	} else if (!strcmp(arg, "-m")) {
+		/*
+		 * To "diff-index", "-m" means "match missing", and to the "log"
+		 * family of commands, it means "show full diff for merges". Set
+		 * both fields appropriately.
+		 */
 		revs->ignore_merges = 0;
+		revs->match_missing = 1;
 	} else if ((argcount = parse_long_opt("diff-merges", argv, &optarg))) {
 		if (!strcmp(optarg, "off")) {
 			revs->ignore_merges = 1;

revision.h

@@ -188,6 +188,7 @@ struct rev_info {
 	unsigned int	diff:1,
 			full_diff:1,
 			show_root_diff:1,
+			match_missing:1,
 			no_commit_id:1,
 			verbose_header:1,
 			combine_merges:1,