diff: fix modified lines stats with --stat and --numstat

Only skip diffstats when both oids are valid and identical. This check
was causing both false-positives (files included in diffstats with no
actual changes (0 lines modified) and false-negatives (showing 0 lines
modified in stats when files had actually changed).

Also replaced same_contents with may_differ to avoid confusion.

Signed-off-by: Thomas Guyot-Sionnest <tguyot@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index ee8e8189e934b322ae53fc227859d1f74e30b6e3..2bb2f8f57e8b7ce5a6d861b7a1d598a7fbaf68e9 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -3663,7 +3663,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
 {
        mmfile_t mf1, mf2;
        struct diffstat_file *data;
-       int same_contents;
+       int may_differ;
        int complete_rewrite = 0;
 
        if (!DIFF_PAIR_UNMERGED(p)) {
@@ -3681,12 +3681,14 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                return;
        }
 
-       same_contents = oideq(&one->oid, &two->oid);
+       /* saves some reads if true, not a guarantee of diff outcome */
+       may_differ = !(one->oid_valid && two->oid_valid &&
+                       oideq(&one->oid, &two->oid));
 
        if (diff_filespec_is_binary(o->repo, one) ||
            diff_filespec_is_binary(o->repo, two)) {
                data->is_binary = 1;
-               if (same_contents) {
+               if (!may_differ) {
                        data->added = 0;
                        data->deleted = 0;
                } else {
@@ -3702,7 +3704,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                data->added = count_lines(two->data, two->size);
        }
 
-       else if (!same_contents) {
+       else if (may_differ) {
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;
@@ -3727,7 +3729,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                                diffstat->files[diffstat->nr - 1];
                        /*
                         * Omit diffstats of modified files where nothing changed.
-                        * Even if !same_contents, this might be the case due to
+                        * Even if may_differ, this might be the case due to
                         * ignoring whitespace changes, etc.
                         *
                         * But note that we special-case additions, deletions,

diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
index e024cff65cb73e3d5db18ea417bd233618689008..6eb344be0312a4e125a036d673b56f9b236a822c 100755 (executable)
--- a/t/t3206-range-diff.sh
+++ b/t/t3206-range-diff.sh
@@ -252,17 +252,13 @@ test_expect_success 'changed commit with --stat diff option' '
        git range-diff --no-color --stat topic...changed >actual &&
        cat >expect <<-EOF &&
        1:  $(test_oid t1) = 1:  $(test_oid c1) s/5/A/
-            a => b | 0
-            1 file changed, 0 insertions(+), 0 deletions(-)
        2:  $(test_oid t2) = 2:  $(test_oid c2) s/4/A/
-            a => b | 0
-            1 file changed, 0 insertions(+), 0 deletions(-)
        3:  $(test_oid t3) ! 3:  $(test_oid c3) s/11/B/
-            a => b | 0
-            1 file changed, 0 insertions(+), 0 deletions(-)
+            a => b | 2 +-
+            1 file changed, 1 insertion(+), 1 deletion(-)
        4:  $(test_oid t4) ! 4:  $(test_oid c4) s/12/B/
-            a => b | 0
-            1 file changed, 0 insertions(+), 0 deletions(-)
+            a => b | 2 +-
+            1 file changed, 1 insertion(+), 1 deletion(-)
        EOF
        test_cmp expect actual
 '