Add a configuration to Cargo.toml to specify which git submodules have to be fetched

[sdroege]

Problem

In gtk-rs we have various git submodules that are only necessary for running the code generator. That is, they're not necessary for compiling the crates inside the repository.

If a crate currently depends on a git version of gtk-rs then cargo will download all those (not very small) git submodules too, unnecessarily.

That it downloads all git submodules currently as a default seems like reasonable behaviour as they might be required for building the crates, but it's not optimal in all cases.

Proposed Solution

Something like the following in Cargo.toml for the repository example above

[package.metadata.git.submodules.gir]
fetch = false

[package.metadata.git.submodules.gir-files]
fetch = false

For backwards compatibility reasons this would obviously default to fetch = true.

Notes

No response

[GuillaumeGomez]

Nice idea1 👍

[ehuss]

Thanks for the suggestion! I believe this is essentially a duplicate of #4247, so closing in favor of that. If possible, you can adjust the submodule update strategy in .gitmodules.

[sdroege]

Thanks, I was not aware of the configuration in .gitmodules. I believe this would work but I'll have to try that. Apart from that, yes this is a duplicate of that other issue :)

[sdroege]

Yes that solves it nicely for our use case, thanks!