Thread: [PATCH] Add diff directives to gitattributes

Hi hackers,

Attached is a patch which adds diff= directives to .gitattributes for C,
Perl and (X|SG)ML files.  This makes word diffs and the function
indicator in the diff chunk header and more useful.

>From 57d7d4ec5b94783bf68b2959128e33c28547a6b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dagfinn=20Ilmari=20Manns=C3=A5ker?= <ilmari@ilmari.org>
Date: Tue, 29 Nov 2016 19:47:36 +0000
Subject: [PATCH] Add diff directives to .gitattributes

This makes the function indicator in the diff chunk header and word
diffs more useful for the specified languages.
---
 .gitattributes | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/.gitattributes b/.gitattributes
index 4dfc131..3805f90 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,11 +1,11 @@
 *        whitespace=space-before-tab,trailing-space
-*.[chly]    whitespace=space-before-tab,trailing-space,indent-with-non-tab,tabwidth=4
+*.[chly]    whitespace=space-before-tab,trailing-space,indent-with-non-tab,tabwidth=4 diff=cpp
 *.dsl        whitespace=space-before-tab,trailing-space,tab-in-indent
 *.patch        -whitespace
-*.pl        whitespace=space-before-tab,trailing-space,tabwidth=4
+*.pl        whitespace=space-before-tab,trailing-space,tabwidth=4 diff=perl
 *.po        whitespace=space-before-tab,trailing-space,tab-in-indent,-blank-at-eof
-*.sgml        whitespace=space-before-tab,trailing-space,tab-in-indent,-blank-at-eol
-*.x[ms]l    whitespace=space-before-tab,trailing-space,tab-in-indent
+*.sgml        whitespace=space-before-tab,trailing-space,tab-in-indent,-blank-at-eol diff=html
+*.x[ms]l    whitespace=space-before-tab,trailing-space,tab-in-indent diff=html

 # Avoid confusing ASCII underlines with leftover merge conflict markers
 README        conflict-marker-size=32
--
2.7.4


--
"A disappointingly low fraction of the human race is,
 at any given time, on fire." - Stig Sandbeck Mathisen

ilmari@ilmari.org (Dagfinn Ilmari Mannsåker) writes:
> Attached is a patch which adds diff= directives to .gitattributes for C,
> Perl and (X|SG)ML files.  This makes word diffs and the function
> indicator in the diff chunk header and more useful.

Could you provide some examples of what that actually does to the output?
        regards, tom lane

On Wed, Nov 30, 2016 at 5:16 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> ilmari@ilmari.org (Dagfinn Ilmari Mannsåker) writes:
>> Attached is a patch which adds diff= directives to .gitattributes for C,
>> Perl and (X|SG)ML files.  This makes word diffs and the function
>> indicator in the diff chunk header and more useful.
>
> Could you provide some examples of what that actually does to the output?

Per the git documentation [1], this is aimed at making the hunk
headers in a diff output more readable. For example, take this dummy
patch on a perl file:
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 1764b17..729bc6d 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -5,6 +5,13 @@ use Test::More tests => 8;
use RewindTest;

+sub run_test2
+{
+       my $test_mode = shift;
+
+       master_sql();
+}
+sub run_test{       my $test_mode = shift;

The point to focus on is that, which is what you get on HEAD:
@@ -5,6 +5,13 @@ use Test::More tests => 8;
But what you get with this patch is that:
@@ -5,6 +5,13 @@
So this makes the detection of a subroutine being changed by a diff
more intelligent.

With or without this patch, for example I patch a subroutine I am
still getting that for both cases:
@@ -30,6 +37,10 @@ sub run_test

And as far as I can read from the docs, it is perfectly possible to
set up that at a global level with a dedicated section like [diff
"perl"]. And in short, this is a change to decide if we decide to
still rely on GNU diff -p or on what git decides is good. Honestly I
am -1 to enforce that to everybody doing serious hacking.

[1]: https://www.kernel.org/pub/software/scm/git/docs/gitattributes.html
-- 
Michael