xtask: generate rust-analyzer shim

userspace/rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "ygg-stage1"

xtask/src/build/toolchain.rs

@@ -1,6 +1,9 @@
 // use std::{collections::HashMap, path::Path};
 
-use std::{collections::HashMap, path::Path, process::Command};
+use std::{
+    collections::HashMap, fs::OpenOptions, os::unix::fs::OpenOptionsExt, path::Path,
+    process::Command,
+};
 
 use crate::{env::BuildEnv, error::Error, util};
 
@@ -102,6 +105,38 @@ fn do_build<P: AsRef<Path>>(toolchain_root: P) -> Result<(), Error> {
     }
 }
 
+fn install_shims<P: AsRef<Path>>(env: &BuildEnv, toolchain_root: P) -> Result<(), Error> {
+    use std::io::Write;
+
+    let toolchain_root = toolchain_root.as_ref();
+    let build_dir = toolchain_root.join("build").join(&env.host_triple);
+    let stage1_rustlib = build_dir
+        .join("stage1/lib/rustlib/")
+        .join(&env.host_triple)
+        .join("lib");
+    let stage1_tools_bin = build_dir.join("stage1-tools-bin");
+    let stage1_bin = build_dir.join("stage1/bin");
+
+    let rust_analyzer = stage1_bin.join("rust-analyzer");
+
+    let mut file = OpenOptions::new()
+        .write(true)
+        .truncate(true)
+        .create(true)
+        .mode(0o755)
+        .open(rust_analyzer)?;
+
+    writeln!(file, "#!/bin/sh")?;
+    writeln!(
+        file,
+        "LD_LIBRARY_PATH={} {}/rust-analyzer",
+        stage1_rustlib.display(),
+        stage1_tools_bin.display()
+    )?;
+
+    Ok(())
+}
+
 pub fn fetch(env: &BuildEnv, branch: &str) -> Result<(), Error> {
     let path = env.workspace_root.join("toolchain");
 
@@ -137,6 +172,8 @@ pub fn build(env: &BuildEnv) -> Result<(), Error> {
 
     log::info!("Building toolchain");
     do_build(&toolchain_path)?;
+    log::info!("Installing rust tool shims");
+    install_shims(env, &toolchain_path)?;
 
     if !is_toolchain_linked() {
         log::info!("Linking the newly built toolchain to +ygg-stage1");