Re: Bug? Git checkout fails with a wrong error message
From: Thomas Rast <hidden>
Date: 2016-06-15 22:52:49
Yves Goergen [off-list ref] writes:
On 16.01.2012 20:17 CE(S)T, Thomas Rast wrote:quoted
If you work together with developers who have a case-sensitive FS (such as Linux, or with the right options OS X), it's entirely possible that this file exists in both spellings within the repository.Just FTR, I am working on the project alone, only on Windows with Visual Studio 2010 and I have two copies of the repository which I am occasionally synchronising via a USB memory stick when I work on the other machine. I have not pulled anything since the first issue came up on last Friday. No case-sensitive filesystem in the game.
Ok. $ git ls-tree -r HEAD 100644 blob 5369994b8f905514661ee58b396dec31f8575a4d PosterWantsItCensored.Designer.cs 100644 blob 5369994b8f905514661ee58b396dec31f8575a4d PosterWantsItCensored.designer.cs ^ ^ ^ | | content hash | type file mode That tells us that you have identical file contents in two files whose names differ only in case. This is important: Different name for git. Same name for OS. Same contents. That should also settle your remark at the end:
I find it interesting to see that both files with the equal file name (like what the only relevant file system considers equal) have the same hash value. Does that qualify for your description of the "pretty bad bug"?
No, not a bug, just the same contents. [And before you sue me for disclosing the SHA1 above: inferring the contents of the file from the SHA1 is equivalent to breaking SHA1. If anyone could, he'd already be busy writing a paper about it (or perhaps working for the NSA).]
quoted
* You have the byte-for-byte identical file name listed twice in the index. That would be a pretty bad bug.The index should usually be empty here, I guess. I really do not use it. No index interaction at all.
Please read up on the index before making such statements. You do use
the index, because it is a very important part of how git operates
whenever the operation also involves the worktree. And except in border
cases (new empty repo etc.) it should never be empty.
Your paste of
$ git status -s
[no output]
tells us that the index has *no differences* to your worktree, nor to
HEAD.
So in summary, the picture in your repository is:
* Somehow you got a different-only-in-case file pair into your
repository. It's already in HEAD. See below.
* The index and worktree are healthy and unchanged (w.r.t. HEAD) from
Git's POV. (This is possible despite the different-only-in-case files
because they have the same contents.)
For now I'm siding with Erik's theory
Erik Faye-Lund wrote:
} Very speculative comment: This might be a bug in TortoiseGit. Looking
} at the sources, it seems they are using libgit2 to mess around with
} the index; perhaps it's case-sensitivity code isn't as well tested as
} Git for Windows'?
It would also be interesting to know for how long this problem has
existed. You can search for the offending commit with something like
git log --name-status --diff-filter=A -- "PosterWantsItCensored.*"
which should normally give you just one or two commits, namely the
one(s) that introduced the two files.
As for the fix, there are two-and-two-thirds cases. First I'd like to
point out, however, that I have no idea how core.ignoreCase interacts
with rm --cached. I'm assuming you have to set it to 'false' for the
recipes below to work. Erik or Peff may correct me. You should set it
to 'true' again for real work.
Case 1: The commit that introduced the second spelling is HEAD
In this case you're sort of lucky because it's easy to fix. You can
do
git rm --cached PosterWantsItCensored.designer.cs
to get rid of the spelling you do not want. Then run
git status -s
again to verify that it did the right thing; it should say
D PosterWantsItCensored.designer.cs
where it's important that a) the other spelling does *not* show up in
the list anywhere and b) the D is in the leftmost column. Once you
have verified this, run
git commit --amend
to fix HEAD.
Case 2a: The commit that introduced it is older, but you don't care if
you cannot sanely checkout old commits
This is the case that I personally would never choose, since I care
about history, but for completeness: proceed as for case 1, except at
the end run
git commit # no --amend
and write a nice message saying that you fixed the
different-only-in-case issue.
Case 2b: The commit that introduced it is older, but history since its
parent has been linear (use gitk or some such to establish
this)
First run
git log --full-history --oneline -- "PosterWantsItCensored.*"
to see which commits touched the file. Let C be the SHA1 (or a unique
prefix) of the earliest commit that contains
PosterWantsItCensored.designer.cs (i.e., the wrong spelling) as
established earlier. Then run
git rebase -i C^
(That's right, the SHA1 of C and then a hat.)
In the editor that pops up, change 'pick' to 'edit' on every line that
shows a SHA1 you found in the preceding git-log command. Save and
exit.
Whenever rebase stops to let you edit (you can tell by the advice
messages it gives you), run
git ls-tree HEAD -- PosterWantsItCensored.designer.cs PosterWantsItCensored.Designer.cs
and check whether the SHA1s are different. Judging by what you said
they should always be the same (otherwise please come back for more
advice). You can then again do something very similar to Case 1 to
the commit you're editing, like
git rm --cached PosterWantsItCensored.designer.cs
git commit --amend
and finally
git rebase --continue
to edit the next commit. Repeat until the rebase is complete.
Case 2c: History wasn't linear since C; or you're just lazy and have a
good backup
The all-safeties-off, please-fix-it-for-me version goes
git filter-branch --tag-name-filter cat --index-filter '
git rm --ignore-unmatch --cached PosterWantsItCensored.designer.cs
' -- --all
I'm dead serious about the safeties off. You have been warned.
I have not tested most of this because it would simply take even more
time than writing an essay-length email. If something fails or got you
confused, paste everything you did and the full output again so we can
establish what happened.
All sub-items of case 2 rewrite history. You will have to force the
push to your "hub" repository that you use to exchange history, and you
may have to reset or rebase in the other repository. Read e.g. the
'recovering from upstream rebase' section in man git-rebase.
(What a mess it would be if I committed something different than my working directory, however that works.)
You should really read up on this, e.g.
http://tomayko.com/writings/the-thing-about-git
AFAIK everyone who groks the feature uses it daily.
--
Thomas Rast
trast@{inf,student}.ethz.ch