Re: diff-filter can't identify renaming if not done directly

[Jeff King <peff@peff.net>]

On Fri, Dec 04, 2020 at 03:59:03PM +0100, Sofia Syria wrote:

> quick question about using diff-filter in linux. In the scenario
> that in my repository, I first copy file1 to file2, then move file2 to
> file3 and delete file1, "git diff" returns:
> 
> diff --git a/file1 b/file3
> similarity index 100%
> rename from file1
> rename to file3
> 
>  but running "git diff --diff-filter=r" doesn't return anything. Only
> flag "t" will return the change. Can this be considered as a bug?

Lowercase filters exclude particular types. From "git help diff":

    --diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]]
	   Select only files that are Added (A), Copied (C), Deleted
	   (D), Modified (M), Renamed (R), have their type (i.e. regular
	   file, symlink, submodule, ...) changed (T), are Unmerged (U),
	   are Unknown (X), or have had their pairing Broken (B). Any
	   combination of the filter characters (including none) can be
	   used. When * (All-or-none) is added to the combination, all
	   paths are selected if there is any file that matches other
	   criteria in the comparison; if there is no file that matches
	   other criteria, nothing is selected.

	   Also, these upper-case letters can be downcased to exclude.
	   E.g. --diff-filter=ad excludes added and deleted paths.

So "--diff-filter=R" asks to see only renames. But "--diff-filter=r"
asks to exclude them. And "--diff-filter=t" excludes typechanges, which
means that renames are still OK. Doing "--diff-filter=a", etc, would
still show it as well.

-Peff