[RFC PATCH v7 01/10] gitattributes: document how external diff drivers relate to diff features
From: Michael Montalbo <hidden>
Date: 2026-08-01 17:41:59
Subsystem:
documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
The "Defining an external diff driver" section explains how to configure diff.<driver>.command but not how the driver relates to the rest of Git's diff machinery. In particular, the command only replaces the textual patch: word diff, function context, color, and the like cannot apply to its output, while the summary formats, blame, and git log -L do not run it at all and keep using the builtin diff. Spell this out so the scope of an external diff driver is clear. Signed-off-by: Michael Montalbo <redacted> --- Documentation/gitattributes.adoc | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/Documentation/gitattributes.adoc b/Documentation/gitattributes.adoc
index bd76167a45..da773e2924 100644
--- a/Documentation/gitattributes.adoc
+++ b/Documentation/gitattributes.adoc@@ -784,6 +784,17 @@ with the above configuration, i.e. `j-c-diff`, with 7 parameters, just like `GIT_EXTERNAL_DIFF` program is called. See linkgit:git[1] for details. +An external diff driver replaces the patch Git would otherwise +produce for the path: Git runs the command and shows its output in +place of its own. Output features that post-process Git's diff do +not apply to the driver's output; word diff, function context (`-W`), +`--color-moved`, and coloring all act on Git's builtin diff, not the +driver's output. +The driver is consulted only when Git generates a textual patch. The +summary formats (`--stat`, `--numstat`, `--shortstat`, and +`--dirstat`), `git blame`, and `git log -L` do not run it and +continue to use Git's builtin diff. + If the program is able to ignore certain changes (similar to `git diff --ignore-space-change`), then also set the option `trustExitCode` to true. It is then expected to return exit code 1 if
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2.54.0