Possible bug with argument parsing in git blame

Possible bug with argument parsing in git blame

[Debayan Banerjee]

debayan@deep-blur:~/testrepo$ git blame 22621a32..8486802f --
dir/subdir/newsubdir/b

81531975 b                      (debayan 2010-05-13 15:32:17 +0530  1) four
81531975 b                      (debayan 2010-05-13 15:32:17 +0530  2) five
d700ac9c b                      (debayan 2010-05-13 15:33:27 +0530  3) blah
2656ab56 b                      (debayan 2010-05-13 15:33:34 +0530  4) bleh
d0c6e851 b                      (debayan 2010-05-13 15:42:21 +0530  5) foo
7bf5510e b                      (debayan 2010-05-13 15:42:53 +0530  6) yo
c4515289 b                      (debayan 2010-05-13 15:43:10 +0530  7) lala
a257c7e4 b                      (debayan 2010-05-13 16:03:46 +0530  8) yes
ed8e4601 b                      (debayan 2010-05-13 16:03:55 +0530  9) np
e96d14bf dir/subdir/newsubdir/b (debayan 2010-05-13 16:05:05 +0530 10) yo
dace00d1 dir/subdir/newsubdir/b (debayan 2010-05-13 16:05:11 +0530 11) boye
8486802f dir/subdir/newsubdir/b (debayan 2010-05-13 16:07:51 +0530 12) what?

debayan@deep-blur:~/testrepo$ git blame 22621a32..8486802f
dir/subdir/newsubdir/b
fatal: cannot stat path 22621a32..8486802f: No such file or directory

The only difference between the first and the second command is the
"--" separator.  Is this normal behaviour?

-- 
Debayan Banerjee
Software Engineer

Re: Possible bug with argument parsing in git blame

[Jeff King]

On Mon, May 17, 2010 at 03:51:18PM +0530, Debayan Banerjee wrote:

> debayan@deep-blur:~/testrepo$ git blame 22621a32..8486802f --
> dir/subdir/newsubdir/b
> 
> 81531975 b                      (debayan 2010-05-13 15:32:17 +0530  1) four
> 81531975 b                      (debayan 2010-05-13 15:32:17 +0530  2) five
> d700ac9c b                      (debayan 2010-05-13 15:33:27 +0530  3) blah
> 2656ab56 b                      (debayan 2010-05-13 15:33:34 +0530  4) bleh
> d0c6e851 b                      (debayan 2010-05-13 15:42:21 +0530  5) foo
> 7bf5510e b                      (debayan 2010-05-13 15:42:53 +0530  6) yo
> c4515289 b                      (debayan 2010-05-13 15:43:10 +0530  7) lala
> a257c7e4 b                      (debayan 2010-05-13 16:03:46 +0530  8) yes
> ed8e4601 b                      (debayan 2010-05-13 16:03:55 +0530  9) np
> e96d14bf dir/subdir/newsubdir/b (debayan 2010-05-13 16:05:05 +0530 10) yo
> dace00d1 dir/subdir/newsubdir/b (debayan 2010-05-13 16:05:11 +0530 11) boye
> 8486802f dir/subdir/newsubdir/b (debayan 2010-05-13 16:07:51 +0530 12) what?
> 
> debayan@deep-blur:~/testrepo$ git blame 22621a32..8486802f
> dir/subdir/newsubdir/b
> fatal: cannot stat path 22621a32..8486802f: No such file or directory
> 
> The only difference between the first and the second command is the
> "--" separator.  Is this normal behaviour?

I can't reproduce the problem here. For example, in git.git, both of the
following produce the same output:

  git blame HEAD~5..HEAD~3 alloc.c
  git blame HEAD~5..HEAD~3 -- alloc.c

Can you provide the exact set of commands to replicate your repository
state and show the failure?

Also, I tested with the current 'master'. Are you using an older version
of git?

-Peff

Re: Possible bug with argument parsing in git blame

[Jeff King]

On Sun, May 23, 2010 at 07:22:41PM +0530, Debayan Banerjee wrote:

> > I can't reproduce the problem here. For example, in git.git, both of the
> > following produce the same output:
> >
> >  git blame HEAD~5..HEAD~3 alloc.c
> >  git blame HEAD~5..HEAD~3 -- alloc.c
> 
> It seems to happen only if the path has '/' in it. For example alloc.c
> will be parsed fine, but dir/alloc.c wont.

Sorry, I still can't reproduce with:

  mkdir repo && cd repo && git init
  mkdir subdir

  commit() {
    echo content >>subdir/file
    git add subdir/file
    git commit -m foo
  }

  commit; commit; commit; commit; commit

  git blame HEAD~3..HEAD~1 subdir/file >no-dash &&
  git blame HEAD~3..HEAD~1 -- subdir/file >dash &&
  diff no-dash dash &&
  echo ok

So there must be some difference between your setup and my test case.
Can you give more details?

-Peff

PS I tested on a variety of git versions back to v1.5.5, and I couldn't
trigger the problem, so I don't think it is a version issue.

Re: Possible bug with argument parsing in git blame

[Debayan Banerjee]

On 24 May 2010 01:38, Jeff King <peff@peff.net> wrote:
> On Sun, May 23, 2010 at 07:22:41PM +0530, Debayan Banerjee wrote:
>
>> > I can't reproduce the problem here. For example, in git.git, both of the
>> > following produce the same output:
>> >

I used master too. The test cases you provided work fine for me too.
It also seems that '/' is not a problem. I tested myself with some
combinations and i could not reproduced the bug. But the strange
behaviour i reported with my particular case still exists.
My repo structure can be cloned from http://github.com/debayan/git-blame-test .
-- 
Debayan Banerjee
Software Engineer

Re: Possible bug with argument parsing in git blame

[Jeff King]

On Mon, May 24, 2010 at 11:47:02AM +0530, Debayan Banerjee wrote:

> I used master too. The test cases you provided work fine for me too.
> It also seems that '/' is not a problem. I tested myself with some
> combinations and i could not reproduced the bug. But the strange
> behaviour i reported with my particular case still exists.  My repo
> structure can be cloned from http://github.com/debayan/git-blame-test
> .

OK, I see what is happening. The issue is that you are blaming a file
from some revision, but that file doesn't exist in the working tree. You
can recreate it with:

  git init
  echo contents >>foo && git add foo && git commit -m one
  echo contents >>foo && git add foo && git commit -m two
  echo contents >>foo && git add foo && git commit -m three
  git mv foo bar && git commit -m moved

Now "git blame HEAD~2..HEAD~1 -- foo" will work, but "git blame
HEAD~2..HEAD~1 foo" will not work.

This is as expected. When parsing revision/filename combinations, if
there is no explicit "--" separator, then we only allow filenames if the
file exists in the working tree. The idea is to prevent typos. For
example, in the same repo:

  git bar ;# works, we have bar in the working tree
  git log foo ;# complains, foo is not a revision and not a file, so
               # maybe a typo
  git log -- foo ;# works, filters on foo. The "--" makes it explicit

Things are a little bit funny with blame because:

  1. It should take exactly one filename, so it doesn't have this
     ambiguity.

  2. The error message isn't very helpful. I think this is because blame
     actually accepts several different combinations (like "<path>
     <rev>", and it ends up confused.

I would be tempted to improve this, but I think (1) may no longer be the
case soon. As I understand it, some of Bo Yang's work in this area may
mean that blame will soon accept multiple files, and the argument
parsing may change.

-Peff