Bug report: checkout --recurse-submodules failing

Bug report: checkout --recurse-submodules failing

[Carlos Gonzalez]

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.

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

[System Info]
git version:
git version 2.34.1
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Linux 5.14.0-1055-oem #62-Ubuntu SMP Wed Nov 30 04:54:03 UTC 2022 x86_64
compiler info: gnuc: 11.2
libc info: glibc: 2.35
$SHELL (typically, interactive shell): <unset>


[Enabled Hooks]

Best regards, 
Carlos


Carlos Gonzalez Vila

Codeplay Software Ltd
This message is private and confidential. If you have received this message in error, please notify us and remove it from your system. Company registered in England and Wales, number: 04567874. Registered office: 2 New Bailey, 6 Stanley Street, Salford, Greater Manchester, United Kingdom, M3 5GS

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

[Philippe Blain]

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