Revise Path type documentation for clarity

src/std_misc/path.md

@@ -1,9 +1,9 @@
 # Path
 
-The `Path` struct represents file paths in the underlying filesystem. There are
-two flavors of `Path`: `posix::Path`, for UNIX-like systems, and
-`windows::Path`, for Windows. The prelude exports the appropriate
-platform-specific `Path` variant.
+The `Path` type represents file paths in the underlying filesystem. Across all
+platforms there is a single `std::path::Path` that abstracts over
+platform-specific path semantics and separators. Bring it into scope with
+`use std::path::Path;` when needed.
 
 A `Path` can be created from an `OsStr`, and provides several methods to get
 information from the file/directory the path points to.
@@ -47,8 +47,7 @@ fn main() {
 }
 ```
 
-Be sure to check at other `Path` methods (`posix::Path` or `windows::Path`) and
-the `Metadata` struct.
+Be sure to check other `Path` methods and the `Metadata` struct.
 
 ### See also:
 

theme/js/language-picker.js

@@ -40,11 +40,28 @@
         language == "en" ? `${mdbookPathToRoot}` : `${mdbookPathToRoot}../`;
     // The page path (mdbook only gives us access to the path to the Markdown file).
     let path = mdbookPath.replace(/\.md$/, ".html");
-    for (let lang of langList.querySelectorAll("a")) {
+    const langAnchors = Array.from(langList.querySelectorAll("a"));
+    for (let lang of langAnchors) {
         if (lang.id == "en") {
             lang.href = `${full_path_to_root}${path}`;
         } else {
             lang.href = `${full_path_to_root}${lang.id}/${path}`;
         }
     }
+
+    // Hide languages whose target page is not available (e.g., not deployed).
+    // This prevents users from hitting 404s on sites that only ship some locales.
+    for (let lang of langAnchors) {
+        const url = lang.href;
+        // Attempt a lightweight HEAD request; fall back to hiding on failure.
+        fetch(url, { method: "HEAD" }).then((resp) => {
+            if (!resp.ok) {
+                const li = lang.parentNode && lang.parentNode.parentNode;
+                if (li) li.style.display = "none";
+            }
+        }).catch(() => {
+            const li = lang.parentNode && lang.parentNode.parentNode;
+            if (li) li.style.display = "none";
+        });
+    }
 })();