This folder integrates Rust crates.io fetching into Bazel.

To add or update dependencies, ensure a local Rust environment is available
(eg `source tools/cargo-env`), then install cargo-raze from git, commit
ef58cddd28b64a0c321356acd16201e52cccfb3f

Also install cargo-license:

```
cargo install cargo-license
```

After adding/updating dependencies in ../rslib/Cargo.toml, change to this
folder and run:

$ python update.py

or

$ REPIN=1 python update.py

The former will apply added crates and adjusted version numbers, while leaving
most crate versions alone. The latter will also update pinned dependencies to their
latest compatible versions.

Note: cargo-raze does not currently work when run from Windows, and nobody
has investigated why yet. For now, you'll need a Mac or Linux machine, or
will need to run update.py from within WSL.

A couple of crates need extra work to build with Bazel, and are listed
in ../Cargo.toml. For example:

```toml
[package.metadata.raze.crates.pyo3.'*']
compile_data_attr = "glob([\"**\"])"
```

With minor version updates, you should not normally need to modify
the entries in that file.

Because update.py modifies a lot of files in remote/, it makes it difficult to
review in a PR, and the changes can sometimes break platforms like Windows. For
this reason, please don't submit PRs that do minor version bumps - those will
typically be done after stable releases. If you need a new crate for a feature
you're working on, please raise it in an issue first.

## Reqwest

Things are complicated with reqwest at the moment, because:

-   we're using a fork to implement better timeouts for syncing
-   we want to build it with different features on Linux (where we can't build a
    wheel that links to OpenSSL), and on other platforms.

For minor version bumps, update.py should take care of updating the versions of
reqwest dependencies.

After making a big update to reqwest via an updated fork, the vendored
BUILD.reqwest.\* files may need updating. To do that, comment native-tls from
the features in rslib/Cargo.toml and run update.py, and copy the file in remote/
over the old vendored file. Then comment the other two deps out, add native-tls
back, and repeat the process.
