"Elijah Newren via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
> From: Elijah Newren <newren@xxxxxxxxx>
>
> The last few patches have introduced a new preliminary step when rename
> detection is on but both break detection and copy detection are off.
> Document this new step. While we're at it, add a testcase that checks
> the new behavior as well.
>
> Signed-off-by: Elijah Newren <newren@xxxxxxxxx>
> ---
> Documentation/gitdiffcore.txt | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt
> index c970d9fe438a..36ebe364d874 100644
> --- a/Documentation/gitdiffcore.txt
> +++ b/Documentation/gitdiffcore.txt
> @@ -168,6 +168,23 @@ a similarity score different from the default of 50% by giving a
> number after the "-M" or "-C" option (e.g. "-M8" to tell it to use
> 8/10 = 80%).
>
> +Note that when rename detection is on but both copy and break
> +detection are off, rename detection adds a preliminary step that first
> +checks if files are moved across directories while keeping their
> +filename the same. If there is a file added to a directory whose
> +contents is sufficiently similar to a file with the same name that got
> +deleted from a different directory, it will mark them as renames and
> +exclude them from the later quadratic step (the one that pairwise
> +compares all unmatched files to find the "best" matches, determined by
> +the highest content similarity). So, for example, if
> +docs/extensions.txt and docs/config/extensions.txt have similar
> +content, then they will be marked as a rename even if it turns out
> +that docs/extensions.txt was more similar to src/extension-checks.c.
I'd rather use docs/extensions.md instead of src/extension-checks.c;
it would be more realistic for .md to be similar to .txt than .c.
With a raised bar for this step, the equation changes a bit, no?
So, for example, if a deleted docs/ext.txt and an added
docs/config/ext.txt are similar enough, they will be marked as a
rename and prevent an added docs/ext.md that may be even similar
to the deleted docs/ext.txt from being considered as the rename
destination in the later step. For this reason, the preliminary
"match same filename" step uses a bit higher threshold to mark a
file pair as a rename and stop considering other candidates for
better matches.
or something?
> +At most, one comparison is done per file in this preliminary pass; so
> +if there are several extensions.txt files throughout the directory
> +hierarchy that were added and deleted, this preliminary step will be
> +skipped for those files.
Other than that, the whole series looked sensible to my cursory
read.
Thanks.
