Trying to use an old compiler, and all the dependencies are broken? Here's a workaround.
This is a proof of concept of an alternative crates registry that contains crates compatible with old Rust versions.
You can set crates-io registry state per project to contain only crates that are compatible with a selected Rust version.
git command in PATH.Tested on macOS and Linux.
The current implementation just rewinds the crates-io registry to a previous commit from a date of release of a specific Rust version, and configures Cargo to use the truncated registry. This means that the registry won't contain any newer crates, even if they'd be compatible.
A future implementation will use a specially-filtered custom registry, allowing use of all crate versions as long as they're compatible.
sh
cargo install -f lts
cd to your project's directory (where Cargo.toml is), and run:
sh
cargo lts
It will configure the current project to use registry compatible with the current compiler. On the first run, it may take a few minutes to download the full registry.
You can specify an old Rust version as a compatibility target cargo lts 1.26.0 or a specific date cargo lts 2018-01-01.
And then run:
sh
cargo update
to update Cargo.lock from the stale registry. To go back to the future, delete [source.crates-io] replace-with = … from ./.cargo/config.
You can set CARGO_MANIFEST_DIR environmental variable to modify other than the current directory. cargo lts assumes the index is in $CARGO_HOME/registry/index/github.com-1ecc6299db9ec823/.git. You can set CARGO_REGISTRY_GIT_DIR to reference another checkout of the index.
cargo lts prefetch fetches the registry without altering the local project. Useful to cache registry state in Docker images.