A bug in DiffText1

[tkf]

With some texts, DiffText1 returns a wrong result. An example of such data is dmp.go of revision b94bf7 and b94bf7^. To see this, get text1.go (which just prints DiffText1) from https://gist.github.com/tkf/12bde871bf794e59bea88b659ed5b95b and run it as:

cd PATH/TO/go-diff/diffmatchpatch
diff <(go run PATH/TO/text1.go <(git show 'b94bf7:./dmp.go') <(git show 'b94bf7^:./dmp.go')) <(git show 'b94bf7:./dmp.go')

which pints

471c471
<

---
>                                       break
658c658
<

---
>

i.e., dmp.DiffText1(diffs) != text1.

The above gist also includes text1.bash which automates finding such examples. For example, I found many such examples by running:

git clone https://go.googlesource.com/go
cd go/src
PATH/TO/text1.bash **/*.go > examples

[alecmev]

There is DiffTimeout = 0 commented out in the Gist. Which version of text1.go did you run, with timeout of time.Hour or 0?

[zimmski]

Along the way, this got fixed. I tested this with the version you were probably using bc2ef12 and then with master:

$ git checkout bc2ef1260ca6e3888a54bae1bd3260b0aae53e52
$ go install ./...
$ diff <(go run text1.go <(git show 'b94bf7:./diffmatchpatch/dmp.go') <(git show 'b94bf7^:./diffmatchpatch/dmp.go')) <(git show 'b94bf7:./diffmatchpatch/dmp.go')
471c471
< 
---
>                                       break
658c658
< 
---
> 
$ git checkout master
$ go install ./...
$ diff <(go run text1.go <(git show 'b94bf7:./diffmatchpatch/dmp.go') <(git show 'b94bf7^:./diffmatchpatch/dmp.go')) <(git show 'b94bf7:./diffmatchpatch/dmp.go')

Master does not output anything for your test case.

[zimmski]

Thanks for reporting this! I will add a test case if there isn't already one.

[zimmski]

The problem is only triggered with checklines=true