The Rust programming language uses deterministic versioning for toolchain releases. Stable versions use SemVer, while nightly, beta and historical builds can be accessed by using dated builds (YY-MM-DD).
Unfortunately, a clean index of releases is not available any more. I decided to research which resources where still available and found the following solutions:
1) Use the AWS index (e.g. aws --no-sign-request s3 ls static-rust-lang-org/dist/ > dist.txt)
* Rate-limited (only obtaining the index took ~40 seconds)
* source
2) Build from individual release manifests
* Requires parsing many documents
* Approx. one week delay after a new release
* Also has more specific toolchain information
* Rate-limited
* source
3) Parse Rust in-repo RELEASES.md
* Fast
* Stable channel only
Each of these options requires additional parsing, which is where this crate comes in: the rust-releases crate
can obtain, parse and build an index from the above resources.
For each solution, the Strategy trait has been implemented, which provides a build_index method. This method
returns a ReleaseIndex, which can be used to iterate over Rust releases. In addition, some implement a FetchResources
trait which, through the fetch_channel method, can obtain the resources necessary to build the index of releases.
| strategy name | trait | implemented | notes |
|---|---|---|---|
| DistIndex | Strategy | ✅ | |
| FetchResources | ❌ | slow (~1 minute) | |
| FromManifests | Strategy | ✅ | |
| FetchResources | ✅ | very slow | |
| ReleasesMd | Strategy | ✅ | |
| FetchResources | ✅ | stable channel only |
cargo-msrv is a tool which can be used to determine the minimal supported Rust version (MSRV). In cargo-msrv I started by parsing the latest channel manifest, and then decreasing the minor semver version.
This is not great for many reasons: * Except for the latest released version, we are left guessing the decreased version numbers actually exist * Only stable versions are supported, not nightly, beta, or other channels * Only 1.x.0 versions are supported
This is not ideal, thus rust-releases was born. Now cargo-msrv can iterate over Rust releases of which we know they exist and are available.