Re: Sparse Checkout Trouble (2.5.0)

[Derrick Stolee <stolee@gmail.com>]

On 1/21/2020 8:19 PM, Derrick Stolee wrote:
> On 1/21/2020 7:42 PM, JunkYardMail1 wrote:
>> Reverting back to the previous version (2.24.1) allowed to un-stage the
>> files and reset the changes.
> 
> This is definitely pointing to a regression, and the feature did get a
> bit of an overhaul. The goal was to not change how existing users
> interacted with it, though, so this is a bit alarming.
> 
> I did find a behavior change related to these paths in Git for Windows
> 2.25.0 versus 2.24.1:
> 
>   $ git clone https://github.com/derrickstolee/git-sparse-checkout-test
>   Cloning into 'git-sparse-checkout-test'...
>   remote: Enumerating objects: 6, done.
>   remote: Counting objects: 100% (6/6), done.
>   remote: Compressing objects: 100% (4/4), done.
>   remote: Total 6 (delta 0), reused 6 (delta 0), pack-reused 0
>   Receiving objects: 100% (6/6), done.
>   error: invalid path 'directory-1/prn/a'
>   fatal: unable to checkout working tree
>   warning: Clone succeeded, but checkout failed.
>   You can inspect what was checked out with 'git status'
>   and retry with 'git restore --source=HEAD :/'
>   
> The checkout here is _expected_ to fail, due to the protected
> filenames. What is troublesome is the following sparse-checkout
> commands fail, and the read-tree command fails in a way that
> 2.24.1 does not:
>  
>   $ git sparse-checkout init
>   error: invalid path 'directory-1/prn/a'
>   error: invalid path 'directory-1/prn/a'
>   
>   $ git sparse-checkout set "/*" "\!/*/"
>   error: invalid path 'directory-1/prn/a'
>   error: invalid path 'directory-1/prn/a'
>   
>   $ git read-tree -mu HEAD
>   error: invalid path 'directory-1/prn/a'
> 
> The double error messages are due to the "try with an in-memory
> pattern set, then roll back if there is a failure." The patterns
> we are trying to create do not include the directory that is failing.
> 
> I'll keep looking into this.

I am still struggling to find out exactly what goes wrong here.

I'm CC'ing Elijah because he also made changes to dir.c, and
perhaps he has some idea of what's going on.

Using GIT_TRACE2_PERF=1, I can see that the error appears during
the traverse_trees() which is after the sparse-checkout patterns
have applied the skip-worktree bit. 

Thanks,
-Stolee