From 4a6e602c9419cc5ed464343b2373c7fe86fb89d6 Mon Sep 17 00:00:00 2001
From: Benjamin Bouvier <public@benj.me>
Date: Thu, 11 Feb 2021 17:34:56 +0100
Subject: Allow automatically detect the rustc-src directory (fixes #3517).

If the configured rustcSource is set to "discover", try to automatically
detect a source from the sysroot rustc directory.
---
 crates/project_model/src/sysroot.rs | 40 +++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

(limited to 'crates/project_model/src/sysroot.rs')

diff --git a/crates/project_model/src/sysroot.rs b/crates/project_model/src/sysroot.rs
index ff44dae4a..3b0ff506d 100644
--- a/crates/project_model/src/sysroot.rs
+++ b/crates/project_model/src/sysroot.rs
@@ -51,11 +51,18 @@ impl Sysroot {
     pub fn discover(cargo_toml: &AbsPath) -> Result<Sysroot> {
         log::debug!("Discovering sysroot for {}", cargo_toml.display());
         let current_dir = cargo_toml.parent().unwrap();
-        let sysroot_src_dir = discover_sysroot_src_dir(current_dir)?;
+        let sysroot_dir = discover_sysroot_dir(current_dir)?;
+        let sysroot_src_dir = discover_sysroot_src_dir(&sysroot_dir, current_dir)?;
         let res = Sysroot::load(&sysroot_src_dir)?;
         Ok(res)
     }
 
+    pub fn discover_rustc(cargo_toml: &AbsPath) -> Option<AbsPathBuf> {
+        log::debug!("Discovering rustc source for {}", cargo_toml.display());
+        let current_dir = cargo_toml.parent().unwrap();
+        discover_sysroot_dir(current_dir).ok().and_then(|sysroot_dir| get_rustc_src(&sysroot_dir))
+    }
+
     pub fn load(sysroot_src_dir: &AbsPath) -> Result<Sysroot> {
         let mut sysroot = Sysroot { crates: Arena::default() };
 
@@ -110,7 +117,18 @@ impl Sysroot {
     }
 }
 
-fn discover_sysroot_src_dir(current_dir: &AbsPath) -> Result<AbsPathBuf> {
+fn discover_sysroot_dir(current_dir: &AbsPath) -> Result<AbsPathBuf> {
+    let mut rustc = Command::new(toolchain::rustc());
+    rustc.current_dir(current_dir).args(&["--print", "sysroot"]);
+    log::debug!("Discovering sysroot by {:?}", rustc);
+    let stdout = utf8_stdout(rustc)?;
+    Ok(AbsPathBuf::assert(PathBuf::from(stdout)))
+}
+
+fn discover_sysroot_src_dir(
+    sysroot_path: &AbsPathBuf,
+    current_dir: &AbsPath,
+) -> Result<AbsPathBuf> {
     if let Ok(path) = env::var("RUST_SRC_PATH") {
         let path = AbsPathBuf::try_from(path.as_str())
             .map_err(|path| format_err!("RUST_SRC_PATH must be absolute: {}", path.display()))?;
@@ -122,14 +140,6 @@ fn discover_sysroot_src_dir(current_dir: &AbsPath) -> Result<AbsPathBuf> {
         log::debug!("RUST_SRC_PATH is set, but is invalid (no core: {:?}), ignoring", core);
     }
 
-    let sysroot_path = {
-        let mut rustc = Command::new(toolchain::rustc());
-        rustc.current_dir(current_dir).args(&["--print", "sysroot"]);
-        log::debug!("Discovering sysroot by {:?}", rustc);
-        let stdout = utf8_stdout(rustc)?;
-        AbsPathBuf::assert(PathBuf::from(stdout))
-    };
-
     get_rust_src(&sysroot_path)
         .or_else(|| {
             let mut rustup = Command::new(toolchain::rustup());
@@ -149,6 +159,16 @@ try installing the Rust source the same way you installed rustc",
         })
 }
 
+fn get_rustc_src(sysroot_path: &AbsPath) -> Option<AbsPathBuf> {
+    let rustc_src = sysroot_path.join("lib/rustlib/rustc-src/rust/compiler/rustc/Cargo.toml");
+    log::debug!("Checking for rustc source code: {}", rustc_src.display());
+    if rustc_src.exists() {
+        Some(rustc_src)
+    } else {
+        None
+    }
+}
+
 fn get_rust_src(sysroot_path: &AbsPath) -> Option<AbsPathBuf> {
     // Try the new path first since the old one still exists.
     let rust_src = sysroot_path.join("lib/rustlib/src/rust");
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