diffcore-rename: make diff-tree -l0 mean -l<large>

jonathantanmy · gitster · commit 89973554b52c · 2017-12-02T22:16:57.000-08:00
In the documentation of diff-tree, it is stated that the -l option "prevents rename/copy detection from running if the number of rename/copy targets exceeds the specified number". The documentation does not mention any special handling for the number 0, but the implementation before commit 9f7e4bf ("diff: remove silent clamp of renameLimit", 2017-11-13) treated 0 as a special value indicating that the rename limit is to be a very large number instead. The commit 9f7e4bf changed that behavior, treating 0 as 0. Revert this behavior to what it was previously. This allows existing scripts and tools that use "-l0" to continue working. The alternative (to have "-l0" suppress rename detection) is probably much less useful, since users can just refrain from specifying -M and/or -C to have the same effect. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Reviewed-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diffcore-rename.c b/diffcore-rename.c
@@ -392,6 +392,8 @@ static int too_many_rename_candidates(int num_create,
 	 *
 	 *    num_create * num_src > rename_limit * rename_limit
 	 */
+	if (rename_limit <= 0)
+		rename_limit = 32767;
 	if ((num_create <= rename_limit || num_src <= rename_limit) &&
 	    ((uint64_t)num_create * (uint64_t)num_src
 	     <= (uint64_t)rename_limit * (uint64_t)rename_limit))
diff --git a/t/t4001-diff-rename.sh b/t/t4001-diff-rename.sh
@@ -230,4 +230,19 @@ test_expect_success 'rename pretty print common prefix and suffix overlap' '
 	test_i18ngrep " d/f/{ => f}/e " output
 '
 
+test_expect_success 'diff-tree -l0 defaults to a big rename limit, not zero' '
+	test_write_lines line1 line2 line3 >myfile &&
+	git add myfile &&
+	git commit -m x &&
+
+	test_write_lines line1 line2 line4 >myotherfile &&
+	git rm myfile &&
+	git add myotherfile &&
+	git commit -m x &&
+
+	git diff-tree -M -l0 HEAD HEAD^ >actual &&
+	# Verify that a rename from myotherfile to myfile was detected
+	grep "myotherfile.*myfile" actual
+'
+
 test_done

Original file line number	Diff line number	Diff line change
`@@ -392,6 +392,8 @@ static int too_many_rename_candidates(int num_create,`
`392`	`392`	`*`
`393`	`393`	`* num_create * num_src > rename_limit * rename_limit`
`394`	`394`	`*/`
	`395`	`+ if (rename_limit <= 0)`
	`396`	`+ rename_limit = 32767;`
`395`	`397`	`if ((num_create <= rename_limit \|\| num_src <= rename_limit) &&`
`396`	`398`	`((uint64_t)num_create * (uint64_t)num_src`
`397`	`399`	`<= (uint64_t)rename_limit * (uint64_t)rename_limit))`