Re: Bug report: checkout --recurse-submodules failing

[Philippe Blain <levraiphilippeblain@gmail.com>]

Hi Carlos,

Le 2023-01-12 à 07:17, Carlos Gonzalez a écrit :
> What did you do before the bug happened? 
> 
> Checking out a custom commit or tag using `--recurse-submodules`, where the specific commit contained a submodule
> not included in the main branch. The checkout command failed. (Detailed steps below)
> 
> What did you expect to happen? 
> 
> The repository should be checked out to the specified commit and submodules updated, and the one missing in the main 
> branch, cloned.

It's a reasonable expectation, but the current 'checkout' code does not
know how to clone missing submodules.

> 
> What happened instead? 
> 
> git checkout --recurse-submodules submodule
> fatal: not a git repository: ../.git/modules/sycl-blas
> fatal: could not reset submodule index
> 
> What's different between what you expected and what actually happened?
> 
> This only fails when the repository was cloned with --recursive flag.
> 
> Anything else you want to add:
> 
> I wrote these simple steps to reproduce:
> 
> mkdir repo1 && cd repo1
> git init
> git submodule add --name sycl-blas  https://github.com/codeplaysoftware/sycl-blas.git
> git commit -m "Adding submodule"
> git tag -a submodule -m submodule
> git submodule deinit sycl-blas
> truncate -s 0 .gitmodules
> rm -rf sycl-blas/
> git add .gitmodules
> git rm sycl-blas
> git commit -m "Remove submodule"
> cd ../
> 
> # When repository is cloned without `--recursive`, checkout works
> git clone repo1 cloned-repo1
> cd cloned-repo1
> git checkout --recurse-submodules submodule # ok
> cd ../
> # When repository is cloned with `--recursive`, checkout fails
> git clone --recursive repo1 cloned-repo2
> cd cloned-repo2
> git checkout --recurse-submodules submodule
> fatal: not a git repository: ../.git/modules/sycl-blas
> fatal: could not reset submodule index

Thanks for a complete reproducer. This has been reported before,
see the threads linked at [1].

I was working on that issue last month, so that at least the checkout fails
in a clean way, but have not gone back to it yet.

In the meantime, as you've discovered, a workaround is to clone without
'--recurse-submodules', then manually run 'git submodule update --init --recursive'
after switching branches.

Cheers,

Philippe.

[1] https://github.com/gitgitgadget/git/issues/752