Bug: conflict in the last file line results in wrong combined diff
From: Danil Pristupov <hidden>
Date: 2022-08-18 13:56:14
I found another bug in the combined diff. It is slightly related to the one I reported some time ago (combined diff always misses 'NoEolAtEof' pragma), but it's different. Description: A simple conflict in the last line in a file with no EOL at EOF results in a wrong -cc diff with a weird (invalid?) formatting. Steps to reproduce:
git init
echo -n "1\n2" > m.txt
git add m.txt
git commit -m "initial commit"
echo -n "1m\n2m" > m.txt
git commit -am "master change"
git checkout -b branch1 HEAD^
echo -n "1b\n2b" > m.txt
git commit -am "branch1 change"
git merge master
git log --all --graph --oneline
git diff m.txt
Actual diff:
diff --cc m.txt
index d53cefe,cf67f83..0000000
--- a/m.txt
+++ b/m.txt
@@@ -1,2 -1,2 +1,7 @@@
++<<<<<<< HEAD
+1b
- 2b <- wrong! there was no '2b' in the initial commit
++2b <- wrong! '++' ('both added') doesn't make sense inside a
conflict block
++=======
+ 1m
-2m <- wrong! there was no '2m' in the initial commit
++2m <- wrong! '++' ('both added') doesn't make sense inside a
conflict block
++>>>>>>> master
Expected diff (I intentionally missed `\ No newline at end of file` pragmas to simplify the idea):
$ git diff m.txt
diff --cc m.txt
index 7d8e479,73a8b45..0000000
--- a/m.txt
+++ b/m.txt
@@@ -1,2 -1,2 +1,7 @@@
++<<<<<<< HEAD
+1b
+2b
++=======
+ 1m
+ 2m
++>>>>>>> master
It looks like `\ No newline at end of file` handling is involved because removing `-n` from the `echo` command in the steps to reproduce makes diff to produce the correct output.