bootstrap/core/
metadata.rs

1//! This module interacts with Cargo metadata to collect and store information about
2//! the packages in the Rust workspace.
3//!
4//! It runs `cargo metadata` to gather details about each package, including its name,
5//! source, dependencies, targets, and available features. The collected metadata is then
6//! used to update the `Build` structure, ensuring proper dependency resolution and
7//! compilation flow.
8use std::collections::BTreeMap;
9use std::path::PathBuf;
10
11use serde_derive::Deserialize;
12
13use crate::utils::exec::command;
14use crate::{Build, Crate, t};
15
16/// For more information, see the output of
17/// <https://doc.rust-lang.org/nightly/cargo/commands/cargo-metadata.html>
18#[derive(Debug, Deserialize)]
19struct Output {
20    packages: Vec<Package>,
21}
22
23/// For more information, see the output of
24/// <https://doc.rust-lang.org/nightly/cargo/commands/cargo-metadata.html>
25#[derive(Debug, Deserialize)]
26struct Package {
27    name: String,
28    source: Option<String>,
29    manifest_path: String,
30    dependencies: Vec<Dependency>,
31    features: BTreeMap<String, Vec<String>>,
32}
33
34/// For more information, see the output of
35/// <https://doc.rust-lang.org/nightly/cargo/commands/cargo-metadata.html>
36#[derive(Debug, Deserialize)]
37struct Dependency {
38    name: String,
39    source: Option<String>,
40}
41
42/// Collects and stores package metadata of each workspace members into `build`,
43/// by executing `cargo metadata` commands.
44pub fn build(build: &mut Build) {
45    for package in workspace_members(build) {
46        if package.source.is_none() {
47            let name = package.name;
48            let mut path = PathBuf::from(package.manifest_path);
49            path.pop();
50            let deps = package
51                .dependencies
52                .into_iter()
53                .filter(|dep| dep.source.is_none())
54                .map(|dep| dep.name)
55                .collect();
56            let krate = Crate {
57                name: name.clone(),
58                deps,
59                path,
60                features: package.features.keys().cloned().collect(),
61            };
62            let relative_path = krate.local_path(build);
63            build.crates.insert(name.clone(), krate);
64            let existing_path = build.crate_paths.insert(relative_path, name);
65            assert!(
66                existing_path.is_none(),
67                "multiple crates with the same path: {}",
68                existing_path.unwrap()
69            );
70        }
71    }
72}
73
74/// Invokes `cargo metadata` to get package metadata of each workspace member.
75///
76/// This is used to resolve specific crate paths in `fn should_run` to compile
77/// particular crate (e.g., `x build sysroot` to build library/sysroot).
78fn workspace_members(build: &Build) -> Vec<Package> {
79    let collect_metadata = |manifest_path| {
80        let mut cargo = command(&build.initial_cargo);
81        cargo
82            // Will read the libstd Cargo.toml
83            // which uses the unstable `public-dependency` feature.
84            .env("RUSTC_BOOTSTRAP", "1")
85            .arg("metadata")
86            .arg("--format-version")
87            .arg("1")
88            .arg("--no-deps")
89            .arg("--manifest-path")
90            .arg(build.src.join(manifest_path));
91        let metadata_output = cargo.run_always().run_capture_stdout(build).stdout();
92        let Output { packages, .. } = t!(serde_json::from_str(&metadata_output));
93        packages
94    };
95
96    // Collects `metadata.packages` from the root and library workspaces.
97    let mut packages = vec![];
98    packages.extend(collect_metadata("Cargo.toml"));
99    packages.extend(collect_metadata("library/Cargo.toml"));
100    packages
101}
bootstrap/core/metadata.rs

bootstrap/core/
metadata.rs
