Don't ask tidy users to run npm install eslint

`npx` already obviates the need to have the package installed locally, we can just ask `npx` to run the pre-configured version of `eslint`

Author: yotamofek

src/tools/tidy/src/rustdoc_js.rs

@@ -9,9 +9,9 @@ use ignore::DirEntry;
 
 use crate::walk::walk_no_read;
 
-fn run_eslint(args: &[PathBuf], config_folder: PathBuf, bad: &mut bool) {
+fn run_eslint(eslint_version: &str, args: &[PathBuf], config_folder: PathBuf, bad: &mut bool) {
     let mut child = match Command::new("npx")
-        .arg("eslint")
+        .arg(format!("eslint@{eslint_version}"))
         .arg("-c")
         .arg(config_folder.join(".eslintrc.js"))
         .args(args)
@@ -36,19 +36,8 @@ fn run_eslint(args: &[PathBuf], config_folder: PathBuf, bad: &mut bool) {
     *bad = true;
 }
 
-fn get_eslint_version_inner(global: bool) -> Option<String> {
-    let mut command = Command::new("npm");
-    command.arg("list").arg("--parseable").arg("--long").arg("--depth=0");
-    if global {
-        command.arg("--global");
-    }
-    let output = command.output().ok()?;
-    let lines = String::from_utf8_lossy(&output.stdout);
-    lines.lines().find_map(|l| l.split(':').nth(1)?.strip_prefix("eslint@")).map(|v| v.to_owned())
-}
-
-fn get_eslint_version() -> Option<String> {
-    get_eslint_version_inner(false).or_else(|| get_eslint_version_inner(true))
+fn has_npx() -> bool {
+    Command::new("npx").arg("--version").output().is_ok_and(|output| output.status.success())
 }
 
 pub fn check(librustdoc_path: &Path, tools_path: &Path, src_path: &Path, bad: &mut bool) {
@@ -62,26 +51,10 @@ pub fn check(librustdoc_path: &Path, tools_path: &Path, src_path: &Path, bad: &m
             return;
         }
     };
-    match get_eslint_version() {
-        Some(version) => {
-            if version != eslint_version {
-                *bad = true;
-                eprintln!(
-                    "⚠️ Installed version of eslint (`{version}`) is different than the \
-                     one used in the CI (`{eslint_version}`)",
-                );
-                eprintln!(
-                    "You can install this version using `npm update eslint` or by using \
-                     `npm install eslint@{eslint_version}`",
-                );
-                return;
-            }
-        }
-        None => {
-            eprintln!("`eslint` doesn't seem to be installed. Skipping tidy check for JS files.");
-            eprintln!("You can install it using `npm install eslint@{eslint_version}`");
-            return;
-        }
+    if !has_npx() {
+        eprintln!("`npx` doesn't seem to be installed. Skipping tidy check for JS files.");
+        eprintln!("Installing `node` should also install `npm` and `npx` on your system.");
+        return;
     }
     let mut files_to_check = Vec::new();
     walk_no_read(
@@ -92,8 +65,18 @@ pub fn check(librustdoc_path: &Path, tools_path: &Path, src_path: &Path, bad: &m
         },
     );
     println!("Running eslint on rustdoc JS files");
-    run_eslint(&files_to_check, librustdoc_path.join("html/static"), bad);
+    run_eslint(&eslint_version, &files_to_check, librustdoc_path.join("html/static"), bad);
 
-    run_eslint(&[tools_path.join("rustdoc-js/tester.js")], tools_path.join("rustdoc-js"), bad);
-    run_eslint(&[tools_path.join("rustdoc-gui/tester.js")], tools_path.join("rustdoc-gui"), bad);
+    run_eslint(
+        &eslint_version,
+        &[tools_path.join("rustdoc-js/tester.js")],
+        tools_path.join("rustdoc-js"),
+        bad,
+    );
+    run_eslint(
+        &eslint_version,
+        &[tools_path.join("rustdoc-gui/tester.js")],
+        tools_path.join("rustdoc-gui"),
+        bad,
+    );
 }