Fix dist overlay: persistent toolchain dirs and sysroot packaging

src/bin/sccache-dist/build.rs

@@ -190,7 +190,12 @@ impl OverlayBuilder {
                 entry.clone()
             } else {
                 trace!("Creating toolchain directory for {}", tc.archive_id);
-                fs::create_dir(&toolchain_dir)?;
+                // The directory can persist on disk from a previous server
+                // process (or a toolchain evicted from the in-memory map
+                // without its directory). Treat it as already-prepared.
+                if !toolchain_dir.exists() {
+                    fs::create_dir(&toolchain_dir)?;
+                }
 
                 let mut tccache = tccache.lock().unwrap();
                 let toolchain_rdr = match tccache.get(tc) {

src/compiler/rust.rs

@@ -2285,10 +2285,18 @@ impl pkg::ToolchainPackager for RustToolchainPackager {
         let sysroot_executable = bins_path.join("rustc").with_extension(EXE_EXTENSION);
         package_builder.add_executable_and_deps(sysroot_executable)?;
 
-        package_builder.add_dir_contents(&bins_path)?;
+        // Package the Rust standard library subtree instead of the entire
+        // sysroot lib directory. Distros like Void Linux report `/usr` as the
+        // sysroot, so packaging `$sysroot/lib` would drag in the whole system
+        // library tree (several GiB) rather than just the Rust stdlib.
         if BINS_DIR != LIBS_DIR {
             let libs_path = sysroot.join(LIBS_DIR);
-            package_builder.add_dir_contents(&libs_path)?;
+            let rustlib_path = libs_path.join("rustlib");
+            if rustlib_path.is_dir() {
+                package_builder.add_dir_contents(&rustlib_path)?;
+            } else {
+                package_builder.add_dir_contents(&libs_path)?;
+            }
         }
 
         package_builder.into_compressed_tar(f)