[PATCH] merge-recursive: option to specify rename threshold

[Kevin Ballard <kevin@sb.org>]

The recursive merge strategy turns on rename detection but leaves the
rename score at the default. Add a strategy option to allow the user
to specify a rename score to use.

Signed-off-by: Kevin Ballard <kevin@sb.org>
---
This patch was generated off of the tip of the next branch.

As with the previous version, there are no tests included here. There seem
to be no tests for the rename score in general, and I was not prepared to
try to create my own.

 Documentation/merge-strategies.txt |    4 ++++
 diff.c                             |    6 +++---
 diff.h                             |    2 ++
 merge-recursive.c                  |    6 ++++++
 merge-recursive.h                  |    1 +
 5 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/merge-strategies.txt b/Documentation/merge-strategies.txt
index 91faba5..05eb8f8 100644
--- a/Documentation/merge-strategies.txt
+++ b/Documentation/merge-strategies.txt
@@ -74,6 +74,10 @@ no-renormalize;;
 	Disables the `renormalize` option.  This overrides the
 	`merge.renormalize` configuration variable.
 
+rename-score=<n>;;
+	Controls the similarity threshold used for rename detection.
+	See also linkgit:git-diff[1] `-M`.
+
 subtree[=path];;
 	This option is a more advanced form of 'subtree' strategy, where
 	the strategy makes a guess on how two trees must be shifted to
diff --git a/diff.c b/diff.c
index cc73061..d862234 100644
--- a/diff.c
+++ b/diff.c
@@ -3323,7 +3323,7 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	return 1;
 }
 
-static int parse_num(const char **cp_p)
+int parse_rename_score(const char **cp_p)
 {
 	unsigned long num, scale;
 	int ch, dot;
@@ -3369,7 +3369,7 @@ static int diff_scoreopt_parse(const char *opt)
 	if (cmd != 'M' && cmd != 'C' && cmd != 'B')
 		return -1; /* that is not a -M, -C nor -B option */
 
-	opt1 = parse_num(&opt);
+	opt1 = parse_rename_score(&opt);
 	if (cmd != 'B')
 		opt2 = 0;
 	else {
@@ -3379,7 +3379,7 @@ static int diff_scoreopt_parse(const char *opt)
 			return -1; /* we expect -B80/99 or -B80 */
 		else {
 			opt++;
-			opt2 = parse_num(&opt);
+			opt2 = parse_rename_score(&opt);
 		}
 	}
 	if (*opt != 0)
diff --git a/diff.h b/diff.h
index 1fd44f5..0083d92 100644
--- a/diff.h
+++ b/diff.h
@@ -315,4 +315,6 @@ extern size_t fill_textconv(struct userdiff_driver *driver,
 
 extern struct userdiff_driver *get_textconv(struct diff_filespec *one);
 
+extern int parse_rename_score(const char **cp_p);
+
 #endif /* DIFF_H */
diff --git a/merge-recursive.c b/merge-recursive.c
index 325a97b..2e3ef44 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -334,6 +334,7 @@ static struct string_list *get_renames(struct merge_options *o,
 	opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 			    o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 			    500;
+	opts.rename_score = o->rename_score;
 	opts.warn_on_too_large_rename = 1;
 	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 	if (diff_setup_done(&opts) < 0)
@@ -1576,6 +1577,11 @@ int parse_merge_opt(struct merge_options *o, const char *s)
 		o->renormalize = 1;
 	else if (!strcmp(s, "no-renormalize"))
 		o->renormalize = 0;
+	else if (!prefixcmp(s, "rename-score=")) {
+		const char *score = s + strlen("rename-score=");
+		if ((o->rename_score = parse_rename_score(&score)) == -1 || *score != 0)
+			return -1;
+	}
 	else
 		return -1;
 	return 0;
diff --git a/merge-recursive.h b/merge-recursive.h
index 2eb5d1a..c8135b0 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -19,6 +19,7 @@ struct merge_options {
 	int verbosity;
 	int diff_rename_limit;
 	int merge_rename_limit;
+	int rename_score;
 	int call_depth;
 	struct strbuf obuf;
 	struct string_list current_file_set;
-- 
1.7.3.68.ge6d63