Fix copy marking from diffcore-rename.

When (A,B) ==> (B,C) rename-copy was detected, we incorrectly said
that C was created by copying B.  This is because we only check if the
path of rename/copy source still exists in the resulting tree to see
if the file is renamed out of existence.  In this case, the new B is
created by copying or renaming A, so the original B is lost and we
should say C is a rename of B not a copy of B.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/diff.c b/diff.c
index 71696c5..f8e3cbf 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -955,7 +955,9 @@ static void diff_resolve_rename_copy(void)
                        }
                        /* See if there is some other filepair that
                         * copies from the same source as us.  If so
-                        * we are a copy.  Otherwise we are a rename.
+                        * we are a copy.  Otherwise we are either a
+                        * copy if the path stays, or a rename if it
+                        * does not, but we already handled "stays" case.
                         */
                        for (j = i + 1; j < q->nr; j++) {
                                pp = q->queue[j];

diff --git a/diffcore-rename.c b/diffcore-rename.c
index 6a52699..dbc8522 100644 (file)
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -55,12 +55,12 @@ static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 /* Table of rename/copy src files */
 static struct diff_rename_src {
        struct diff_filespec *one;
-       unsigned src_stays : 1;
+       unsigned src_path_left : 1;
 } *rename_src;
 static int rename_src_nr, rename_src_alloc;
 
 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
-                                                  int src_stays)
+                                                  int src_path_left)
 {
        int first, last;
 
@@ -90,7 +90,7 @@ static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
                memmove(rename_src + first + 1, rename_src + first,
                        (rename_src_nr - first - 1) * sizeof(*rename_src));
        rename_src[first].one = one;
-       rename_src[first].src_stays = src_stays;
+       rename_src[first].src_path_left = src_path_left;
        return &(rename_src[first]);
 }
 
@@ -220,7 +220,7 @@ static void record_rename_pair(struct diff_queue_struct *renq,
 
        dp = diff_queue(renq, one, two);
        dp->score = score;
-       dp->source_stays = rename_src[src_index].src_stays;
+       dp->source_stays = rename_src[src_index].src_path_left;
        rename_dst[dst_index].pair = dp;
 }
 
@@ -234,6 +234,21 @@ static int score_compare(const void *a_, const void *b_)
        return b->score - a->score;
 }
 
+static int compute_stays(struct diff_queue_struct *q,
+                        struct diff_filespec *one)
+{
+       int i;
+       for (i = 0; i < q->nr; i++) {
+               struct diff_filepair *p = q->queue[i];
+               if (strcmp(one->path, p->two->path))
+                       continue;
+               if (DIFF_PAIR_RENAME(p)) {
+                       return 0; /* something else is renamed into this */
+               }
+       }
+       return 1;
+}
+
 void diffcore_rename(int detect_rename, int minimum_score)
 {
        struct diff_queue_struct *q = &diff_queued_diff;
@@ -406,6 +421,23 @@ void diffcore_rename(int detect_rename, int minimum_score)
        *q = outq;
        diff_debug_queue("done collapsing", q);
 
+       /* We need to see which rename source really stays here;
+        * earlier we only checked if the path is left in the result,
+        * but even if a path remains in the result, if that is coming
+        * from copying something else on top of it, then the original
+        * source is lost and does not stay.
+        */
+       for (i = 0; i < q->nr; i++) {
+               struct diff_filepair *p = q->queue[i];
+               if (DIFF_PAIR_RENAME(p) && p->source_stays) {
+                       /* If one appears as the target of a rename-copy,
+                        * then mark p->source_stays = 0; otherwise
+                        * leave it as is.
+                        */
+                       p->source_stays = compute_stays(q, p->one);
+               }
+       }
+
        free(rename_dst);
        rename_dst = NULL;
        rename_dst_nr = rename_dst_alloc = 0;