[PATCH v5 2/4] diff: add option to skip resolving diff statuses

[Justin Tobler <jltobler@gmail.com>]

By default, `diffcore_std()` resolves the statuses for queued diff file
pairs by calling `diff_resolve_rename_copy()`. If status information is
already manually set, invoking `diffcore_std()` may change the status
value.

Introduce the `skip_resolving_statuses` diff option that prevents
`diffcore_std()` from resolving file pair statuses when enabled.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
---
 diff.c | 2 +-
 diff.h | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/diff.c b/diff.c
index b5a779f997..37cc88c75b 100644
--- a/diff.c
+++ b/diff.c
@@ -7081,7 +7081,7 @@ void diffcore_std(struct diff_options *options)
 		diffcore_order(options->orderfile);
 	if (options->rotate_to)
 		diffcore_rotate(options);
-	if (!options->found_follow)
+	if (!options->found_follow && !options->skip_resolving_statuses)
 		/* See try_to_follow_renames() in tree-diff.c */
 		diff_resolve_rename_copy();
 	diffcore_apply_filter(options);
diff --git a/diff.h b/diff.h
index 63afa17e84..fc791ee2cc 100644
--- a/diff.h
+++ b/diff.h
@@ -353,6 +353,14 @@ struct diff_options {
 	/* to support internal diff recursion by --follow hack*/
 	int found_follow;
 
+	/*
+	 * By default, diffcore_std() resolves the statuses for queued diff file
+	 * pairs by calling diff_resolve_rename_copy(). If status information
+	 * has already been manually set, this option prevents diffcore_std()
+	 * from resetting statuses.
+	 */
+	int skip_resolving_statuses;
+
 	/* Callback which allows tweaking the options in diff_setup_done(). */
 	void (*set_default)(struct diff_options *);
 
-- 
2.49.0.rc0