Merge #7891

7891: Improve handling of rustc_private r=matklad a=DJMcNab

This PR changes how `rust-analyzer` handles `rustc_private`. In particular, packages now must opt-in to using `rustc_private` in `Cargo.toml`, by adding:
```toml
[package.metadata.rust-analyzer]
rustc_private=true
```

This means that depending on crates which also use `rustc_private` will be significantly improved, since their dependencies on the `rustc_private` crates will be resolved properly.

A similar approach could be used in #6714 to allow annotating that your package uses the `test` crate, although I have not yet handled that in this PR.

Additionally, we now only index the crates which are transitive dependencies of `rustc_driver` in the `rustcSource` directory. This should not cause any change in behaviour when using `rustcSource: "discover"`, as the source used then will only be a partial clone. However, if `rustcSource` pointing at a local checkout of rustc, this should significantly improve the memory usage and lower indexing time. This is because we avoids indexing all crates in `src/tools/`, which includes `rust-analyzer` itself.

Furthermore, we also prefer named dependencies over dependencies from `rustcSource`. This ensures that feature resolution for crates which are depended on by both `rustc` and your crate uses the correct set for analysing your crate.

See also [introductory zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/Fixed.20crate.20graphs.20and.20optional.20builtin.20crates/near/229086673)

I have tested this in [priroda](https://github.com/oli-obk/priroda/), and it provides a significant improvement to the development experience (once I give `miri` the required data in `Cargo.toml`)

Todo:
- [ ] Documentation

This is ready to review, and I will add documentation if this would be accepted (or if I get time to do so anyway)

Co-authored-by: Daniel McNab <[email protected]>

1 files changed, 21 insertions, 2 deletions

diff --git a/crates/project_model/src/cargo_workspace.rs b/crates/project_model/src/cargo_workspace.rs
index f7241b711..bc6e20341 100644
--- a/crates/project_model/src/cargo_workspace.rs
+++ b/crates/project_model/src/cargo_workspace.rs
@@ -9,6 +9,8 @@ use cargo_metadata::{CargoOpt, MetadataCommand};
 use la_arena::{Arena, Idx};
 use paths::{AbsPath, AbsPathBuf};
 use rustc_hash::FxHashMap;
+use serde::Deserialize;
+use serde_json::from_value;
 
 use crate::build_data::BuildDataConfig;
 use crate::utf8_stdout;
@@ -104,6 +106,13 @@ pub struct PackageData {
     pub active_features: Vec<String>,
     // String representation of package id
     pub id: String,
+    // The contents of [package.metadata.rust-analyzer]
+    pub metadata: RustAnalyzerPackageMetaData,
+}
+
+#[derive(Deserialize, Default, Debug, Clone, Eq, PartialEq)]
+pub struct RustAnalyzerPackageMetaData {
+    pub rustc_private: bool,
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
@@ -161,6 +170,13 @@ impl PackageData {
     }
 }
 
+#[derive(Deserialize, Default)]
+// Deserialise helper for the cargo metadata
+struct PackageMetadata {
+    #[serde(rename = "rust-analyzer")]
+    rust_analyzer: Option<RustAnalyzerPackageMetaData>,
+}
+
 impl CargoWorkspace {
     pub fn from_cargo_metadata(
         cargo_toml: &AbsPath,
@@ -244,8 +260,10 @@ impl CargoWorkspace {
 
         meta.packages.sort_by(|a, b| a.id.cmp(&b.id));
         for meta_pkg in &meta.packages {
-            let cargo_metadata::Package { id, edition, name, manifest_path, version, .. } =
-                meta_pkg;
+            let cargo_metadata::Package {
+                id, edition, name, manifest_path, version, metadata, ..
+            } = meta_pkg;
+            let meta = from_value::<PackageMetadata>(metadata.clone()).unwrap_or_default();
             let is_member = ws_members.contains(&id);
             let edition = edition
                 .parse::<Edition>()
@@ -262,6 +280,7 @@ impl CargoWorkspace {
                 dependencies: Vec::new(),
                 features: meta_pkg.features.clone().into_iter().collect(),
                 active_features: Vec::new(),
+                metadata: meta.rust_analyzer.unwrap_or_default(),
             });
             let pkg_data = &mut packages[pkg];
             pkg_by_id.insert(id, pkg);