Set rustcSource to "discover" to be able to automatically detect rustc-dev;

Author: bnjbvr

crates/project_model/src/cargo_workspace.rs

@@ -63,8 +63,10 @@ pub struct CargoConfig {
     /// when debugging isolated issues.
     pub no_sysroot: bool,
 
-    /// rustc private crate source
-    pub rustc_source: Option<AbsPathBuf>,
+    /// Text-form path to the rustc's private crates source, or "discover" to find them
+    /// automatically.
+    /// Keep the root path around so we can reference relative paths to the private crates source.
+    pub rustc_source: Option<(AbsPathBuf, String)>,
 }
 
 pub type Package = Idx<PackageData>;

crates/project_model/src/workspace.rs

@@ -126,10 +126,12 @@ impl ProjectWorkspace {
                     })?
                 };
 
-                let rustc_dir = if let Some(rustc_dir) = &config.rustc_source {
-                    Some(rustc_dir)
-                } else if let Some(rustc_dir) = &sysroot.rustc_src_dir {
-                    Some(rustc_dir)
+                let rustc_dir = if let Some((root_dir, path_to_rustc_src)) = &config.rustc_source {
+                    if path_to_rustc_src == "discover" {
+                        sysroot.rustc_src_dir.clone()
+                    } else {
+                        Some(root_dir.join(path_to_rustc_src))
+                    }
                 } else {
                     None
                 };

crates/rust-analyzer/src/config.rs

@@ -177,8 +177,9 @@ config_data! {
         /// tests or binaries.\nFor example, it may be `--release`.
         runnables_cargoExtraArgs: Vec<String>   = "[]",
 
-        /// Path to the rust compiler sources, for usage in rustc_private projects.
-        rustcSource : Option<PathBuf> = "null",
+        /// Path to the rust compiler sources, for usage in rustc_private projects, or "discover"
+        /// to try to automatically find it.
+        rustcSource : Option<String> = "null",
 
         /// Additional arguments to `rustfmt`.
         rustfmt_extraArgs: Vec<String>               = "[]",
@@ -473,7 +474,8 @@ impl Config {
         self.data.cargo_loadOutDirsFromCheck
     }
     pub fn cargo(&self) -> CargoConfig {
-        let rustc_source = self.data.rustcSource.as_ref().map(|it| self.root_path.join(&it));
+        let rustc_source =
+            self.data.rustcSource.as_ref().map(|path| (self.root_path.clone(), path.clone()));
 
         CargoConfig {
             no_default_features: self.data.cargo_noDefaultFeatures,

docs/user/generated_config.adoc

@@ -105,7 +105,7 @@
 [[rust-analyzer.runnables.cargoExtraArgs]]rust-analyzer.runnables.cargoExtraArgs (default: `[]`)::
  Additional arguments to be passed to cargo for runnables such as  tests or binaries.\nFor example, it may be `--release`.
 [[rust-analyzer.rustcSource]]rust-analyzer.rustcSource (default: `null`)::
- Path to the rust compiler sources, for usage in rustc_private projects.
+ Path to the rust compiler sources, for usage in rustc_private projects, or "discover"  to try to automatically find it.
 [[rust-analyzer.rustfmt.extraArgs]]rust-analyzer.rustfmt.extraArgs (default: `[]`)::
  Additional arguments to `rustfmt`.
 [[rust-analyzer.rustfmt.overrideCommand]]rust-analyzer.rustfmt.overrideCommand (default: `null`)::

editors/code/package.json

@@ -707,7 +707,7 @@
                     }
                 },
                 "rust-analyzer.rustcSource": {
-                    "markdownDescription": "Path to the rust compiler sources, for usage in rustc_private projects.",
+                    "markdownDescription": "Path to the rust compiler sources, for usage in rustc_private projects, or \"discover\" to try to automatically find it.",
                     "default": null,
                     "type": [
                         "null",