Use which instead of running rustc --version

Cargo.lock

@@ -195,6 +195,12 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
 
+[[package]]
+name = "either"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "11157ac094ffbdde99aa67b23417ebdd801842852b500e395a45a9c0aac03e4a"
+
 [[package]]
 name = "encode_unicode"
 version = "0.3.6"
@@ -207,6 +213,16 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
 
+[[package]]
+name = "errno"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a258e46cdc063eb8519c00b9fc845fc47bcfca4130e2f08e88665ceda8474245"
+dependencies = [
+ "libc",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "filetime"
 version = "0.2.23"
@@ -354,6 +370,12 @@ version = "0.2.153"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01cda141df6706de531b6c46c3a33ecca755538219bd484262fa09410c13539c"
+
 [[package]]
 name = "log"
 version = "0.4.21"
@@ -521,6 +543,19 @@ version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
 
+[[package]]
+name = "rustix"
+version = "0.38.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "65e04861e65f21776e67888bfbea442b3642beaa0138fdb1dd7a84a52dffdb89"
+dependencies = [
+ "bitflags 2.4.2",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "rustlings"
 version = "5.6.1"
@@ -537,6 +572,7 @@ dependencies = [
  "serde",
  "serde_json",
  "toml",
+ "which",
 ]
 
 [[package]]
@@ -694,6 +730,18 @@ version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "which"
+version = "6.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8211e4f58a2b2805adfbefbc07bab82958fc91e3836339b1ab7ae32465dce0d7"
+dependencies = [
+ "either",
+ "home",
+ "rustix",
+ "winsafe",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -865,3 +913,9 @@ checksum = "dffa400e67ed5a4dd237983829e66475f0a4a26938c4b04c21baede6262215b8"
 dependencies = [
  "memchr",
 ]
+
+[[package]]
+name = "winsafe"
+version = "0.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d135d17ab770252ad95e9a872d365cf3090e3be864a34ab46f48555993efc904"

Cargo.toml

@@ -19,6 +19,7 @@ regex = "1.10.3"
 serde_json = "1.0.114"
 serde = { version = "1.0.197", features = ["derive"] }
 toml = "0.8.10"
+which = "6.0.1"
 
 [[bin]]
 name = "rustlings"

src/main.rs

@@ -10,7 +10,7 @@ use std::ffi::OsStr;
 use std::fs;
 use std::io::{self, prelude::*};
 use std::path::Path;
-use std::process::{Command, Stdio};
+use std::process::Command;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::mpsc::{channel, RecvTimeoutError};
 use std::sync::{Arc, Mutex};
@@ -100,7 +100,7 @@ fn main() {
         std::process::exit(1);
     }
 
-    if !rustc_exists() {
+    if which::which("rustc").is_err() {
         println!("We cannot find `rustc`.");
         println!("Try running `rustc --version` to diagnose your problem.");
         println!("For instructions on how to install Rust, check the README.");
@@ -403,18 +403,6 @@ fn watch(
     }
 }
 
-fn rustc_exists() -> bool {
-    Command::new("rustc")
-        .args(["--version"])
-        .stdout(Stdio::null())
-        .stderr(Stdio::null())
-        .stdin(Stdio::null())
-        .spawn()
-        .and_then(|mut child| child.wait())
-        .map(|status| status.success())
-        .unwrap_or(false)
-}
-
 const DEFAULT_OUT: &str = r#"Thanks for installing Rustlings!
 
 Is this your first time? Don't worry, Rustlings was made for beginners! We are