git word diff bug?

git word diff bug?

[Count of San Francisco]

Hi All,

Here is my "git bugreport":

Thank you for filling out a Git bug report!
Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue)
   git diff --word-diff=porcelain file0.txt file1.txt
     or
   git diff --word-diff file0.txt file1.txt

What did you expect to happen? (Expected behavior)

   I expected the diff for porcelain or default word-diff to be clear on 
which lines got removed and which changes belong to which line. I 
explain more in details below.

What happened instead? (Actual behavior)

   The diff was not clear.

What's different between what you expected and what actually happened?

   The diff made it looked like all the removed text were on one line 
and a later change in a line look like it was meant for a different 
line. When in fact, the later changes were for the same line (i.e. the 
first line). More details below.

Anything else you want to add:

Here are the details to reproduce and more details on how I interpreted 
the diff. If I am writing a script to highlight changes or to do extra 
processing for my specific use case, my script would get confused as to 
what really changed.

file0.txt content:
*** Begin Content *** --> this line is not in the actual file but just a 
marker here for clarity.
The fox jumped over the wall.
Blah1e32
q432423
qe23234
  233
253
345235

53243
afsfffas
*** End Content ****

file1.txt content:
*** Begin Content ***
The fox jumped over the river.
   He made it over.
*** End Content ****

git diff --word-diff file0.txt file1.txt produced this:
diff --git a/file0.txt b/file1.txt
index c8756ba..3413f10 100644
--- a/file0.txt
+++ b/file1.txt
@@ -1,11 +1,2 @@
The fox jumped over the [-wall.-]
[-Blah1e32-]
[-q432423-]
[-qe23234-]
[- 233-]
[-253-]
[-345235-]

[-53243-]
[-afsfffas-]{+river.+}
{+  He made it over.+}

The diff above does not make it clear that the "{+river+}" is really to 
be appended (or related) to the first line.
I expected the first diff line to look like this:
The fox jumped over the [-wall.-]{+river+} and the rest of the lines are 
delete lines.

git diff --word-diff=porcelain file0.txt file1.txt produced this:
diff --git a/file0.txt b/file1.txt
index c8756ba..3413f10 100644
--- a/file0.txt
+++ b/file1.txt
@@ -1,11 +1,2 @@
  The fox jumped over the
-wall.
~
-Blah1e32
~
-q432423
~
-qe23234
~
- 233
~
-253
~
-345235
~
~
-53243
~
-afsfffas
+river.
~
+  He made it over.
~

This is more non-discernable. The git diff --help documentation says 
that "Newlines in the input are represented by a tilde ~ on a line of 
its own". So a script would see the '~' character and interpret that as 
a new line. The script would have mistaken the "+river" for a different 
line. The git diff --help documentation does not explain what to do in 
this scenario.

I expected this:
  The fox jumped over the
-wall.
+river.
~

Is this a bug? If not, how do I make the distinction that the {+river+} 
(in the first case) and the +river (in the 2nd case) is really for the 
first line?

Please review the rest of the bug report below.
You can delete any lines you don't wish to share.


[System Info]
git version:
git version 2.30.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Darwin 20.3.0 Darwin Kernel Version 20.3.0: Thu Jan 21 00:07:06 
PST 2021; root:xnu-7195.81.3~1/RELEASE_X86_64 x86_64
compiler info: clang: 12.0.0 (clang-1200.0.32.28)
libc info: no libc information available
$SHELL (typically, interactive shell): /usr/local/bin/bash


[Enabled Hooks]
not run from a git repository - no hooks to show