@langri-sha/projen-cargo

projen components for authoring Cargo workspaces and the crates in them.

Usage

npm install -D projen @langri-sha/projen-cargo

CargoWorkspace writes the workspace root — Cargo.toml, rust-toolchain.toml, rustfmt.toml, a deny.toml if you ask for one, and /target/ into .gitignore:

import { Project } from 'projen'
import { CargoWorkspace } from '@langri-sha/projen-cargo'

const project = new Project({
  name: 'my-project',
})

new CargoWorkspace(project, {
  workspace: {
    resolver: '3',
    members: ['apps/api'],
    package: {
      edition: '2024',
      license: 'MIT',
    },
    dependencies: {
      anyhow: '1.0.100',
      tokio: { version: '1.48.0', features: ['full'] },
    },
  },
  toolchain: {
    channel: '1.93.0',
    components: ['clippy', 'rustfmt'],
  },
})

CargoPackage writes a crate, which inherits from the workspace rather than restating it, and a sample src/main.rs so it compiles before anything has been written into it:

import { CargoPackage } from '@langri-sha/projen-cargo'

new CargoPackage(crate, {
  package: {
    edition: { workspace: true },
    license: { workspace: true },
  },
  dependencies: {
    tokio: { workspace: true },
  },
})

The crate's name defaults to the project's own; pass sampleCode: false to skip src/main.rs.

Members added after construction still reach the manifest, which is what @langri-sha/projen-project uses to keep [workspace] members in step with the subprojects that declare a crate:

workspace.addMember('apps/worker')

Manifest typings

Manifest options come from SchemaStore's Cargo Manifest schema, compiled on install. The schema closes the manifest and its [package] table to unknown keys, so it lags Cargo by whatever the latest release added — [hints], at the time of writing. Reach past it through the file rather than waiting on SchemaStore:

workspace.manifest.addOverride('hints.mostly-unused', true)

rustfmt.toml is typed the same way, from SchemaStore's rustfmt schema. rust-toolchain.toml and deny.toml are not: rustup's schema types its one table as an open bag, and no schema is published for cargo deny at all, so both are written out by hand.

rustfmt and the edition

cargo fmt reads the edition out of Cargo.toml, but rustfmt invoked directly — as editors and rustfmt --check do — falls back to 2015 and formats differently. rustfmt.toml therefore carries over the edition [workspace.package] declares, unless you set one yourself.