[v3,3/4] diffcore-rename: treat a rename_limit of 0 as unlimited

Commit Message

Elijah Newren July 15, 2021, 12:45 a.m. UTC

From: Elijah Newren <[e-mail]>

In commit 89973554b52c (diffcore-rename: make diff-tree -l0 mean
-l<large>, 2017-11-29), -l0 was given a special magical "large" value,
but one which was not large enough for some uses (as can be seen from
commit 9f7e4bfa3b6d (diff: remove silent clamp of renameLimit,
2017-11-13).  Make 0 (or a negative value) be treated as unlimited
instead and update the documentation to mention this.

Signed-off-by: Elijah Newren <[e-mail]>
---
 Documentation/diff-options.txt | 1 +
 diffcore-rename.c              | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

Comments

Junio C Hamano July 15, 2021, 11:17 p.m. UTC | #1

"Elijah Newren via GitGitGadget" <[e-mail]> writes:

> diff --git a/diffcore-rename.c b/diffcore-rename.c
> index 3375e24659e..513ba7b05f1 100644
> --- a/diffcore-rename.c
> +++ b/diffcore-rename.c
> @@ -1021,7 +1021,7 @@ static int too_many_rename_candidates(int num_destinations, int num_sources,
>  	 * memory for the matrix anyway.
>  	 */
>  	if (rename_limit <= 0)
> -		rename_limit = 32767;
> +		return 0; /* treat as unlimited */

OK.  As this short-cuts, the impact a non-positive value may have on
all the remainder of the function (like limit squared must be larger
than the matrix) would not have to be compensated for.  Very simple
and clean.

>  	if (st_mult(num_destinations, num_sources)
>  	    <= st_mult(rename_limit, rename_limit))
>  		return 0;

Patch

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 58acfff9289..0aebe832057 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -598,6 +598,7 @@  of a delete/create pair.
 	prevents the exhaustive portion of rename/copy detection from
 	running if the number of source/destination files involved
 	exceeds the specified number.  Defaults to diff.renameLimit.
+	Note that a value of 0 is treated as unlimited.
 
 ifndef::git-format-patch[]
 --diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]]::
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 3375e24659e..513ba7b05f1 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -1021,7 +1021,7 @@  static int too_many_rename_candidates(int num_destinations, int num_sources,
 	 * memory for the matrix anyway.
 	 */
 	if (rename_limit <= 0)
-		rename_limit = 32767;
+		return 0; /* treat as unlimited */
 	if (st_mult(num_destinations, num_sources)
 	    <= st_mult(rename_limit, rename_limit))
 		return 0;