1 files changed, 32 insertions, 37 deletions

diff --git a/crates/ra_toolchain/src/lib.rs b/crates/ra_toolchain/src/lib.rs
index afa76619d..3c307a0ea 100644
--- a/crates/ra_toolchain/src/lib.rs
+++ b/crates/ra_toolchain/src/lib.rs
@@ -1,21 +1,26 @@
 //! This crate contains a single public function
 //! [`get_path_for_executable`](fn.get_path_for_executable.html).
 //! See docs there for more information.
-use std::{
-    env,
-    path::{Path, PathBuf},
-    process::Command,
-};
+use std::{env, iter, path::PathBuf};
 
-use anyhow::{bail, Result};
+pub fn cargo() -> PathBuf {
+    get_path_for_executable("cargo")
+}
+
+pub fn rustc() -> PathBuf {
+    get_path_for_executable("rustc")
+}
+
+pub fn rustup() -> PathBuf {
+    get_path_for_executable("rustup")
+}
 
 /// Return a `PathBuf` to use for the given executable.
 ///
 /// E.g., `get_path_for_executable("cargo")` may return just `cargo` if that
 /// gives a valid Cargo executable; or it may return a full path to a valid
 /// Cargo.
-pub fn get_path_for_executable(executable_name: &'static str) -> Result<PathBuf> {
-    assert!(executable_name == "rustc" || executable_name == "cargo");
+fn get_path_for_executable(executable_name: &'static str) -> PathBuf {
     // The current implementation checks three places for an executable to use:
     // 1) Appropriate environment variable (erroring if this is set but not a usable executable)
     //      example: for cargo, this checks $CARGO environment variable; for rustc, $RUSTC; etc
@@ -25,45 +30,35 @@ pub fn get_path_for_executable(executable_name: &'static str) -> Result<PathBuf>
     //      example: for cargo, this tries ~/.cargo/bin/cargo
     //      It seems that this is a reasonable place to try for cargo, rustc, and rustup
     let env_var = executable_name.to_ascii_uppercase();
-    if let Ok(path) = env::var(&env_var) {
-        return if is_valid_executable(&path) {
-            Ok(path.into())
-        } else {
-            bail!(
-                "`{}` environment variable points to something that's not a valid executable",
-                env_var
-            )
-        };
+    if let Some(path) = env::var_os(&env_var) {
+        return path.into();
     }
 
-    if is_valid_executable(executable_name) {
-        return Ok(executable_name.into());
+    if lookup_in_path(executable_name) {
+        return executable_name.into();
     }
 
     if let Some(mut path) = home::home_dir() {
         path.push(".cargo");
         path.push("bin");
         path.push(executable_name);
-        if is_valid_executable(&path) {
-            return Ok(path);
+        if path.is_file() {
+            return path;
         }
     }
-    // This error message may also be caused by $PATH or $CARGO/$RUSTC/etc not being set correctly
-    // for VSCode, even if they are set correctly in a terminal.
-    // On macOS in particular, launching VSCode from terminal with `code <dirname>` causes VSCode
-    // to inherit environment variables including $PATH, $CARGO, $RUSTC, etc from that terminal;
-    // but launching VSCode from Dock does not inherit environment variables from a terminal.
-    // For more discussion, see #3118.
-    bail!(
-        "Failed to find `{}` executable. Make sure `{}` is in `$PATH`, or set `${}` to point to a valid executable.",
-        executable_name, executable_name, env_var
-    )
+    executable_name.into()
 }
 
-/// Does the given `Path` point to a usable executable?
-///
-/// (assumes the executable takes a `--version` switch and writes to stdout,
-/// which is true for `cargo`, `rustc`, and `rustup`)
-fn is_valid_executable(p: &'static str) -> bool {
-    Command::new(p).arg("--version").output().is_ok()
+fn lookup_in_path(exec: &str) -> bool {
+    let paths = env::var_os("PATH").unwrap_or_default();
+    let mut candidates = env::split_paths(&paths).flat_map(|path| {
+        let candidate = path.join(&exec);
+        let with_exe = if env::consts::EXE_EXTENSION == "" {
+            None
+        } else {
+            Some(candidate.with_extension(env::consts::EXE_EXTENSION))
+        };
+        iter::once(candidate).chain(with_exe)
+    });
+    candidates.any(|it| it.is_file())
 }