src/filesystem.rs

@@ -55,6 +55,9 @@ fn strip_verbatim_prefix(path: &Path) -> PathBuf {      let has_root = matches!(components.clone().next(), Some(Component::RootDir));     let mut base = OsString::new();+    // `Prefix::Disk` / `Prefix::UNC` cannot rebuild this prefix: a `Prefix` is a+    // parse label, not the bytes of the path, and `PrefixComponent` has no stable+    // constructor. Writing it out by hand is the only way to drop `\\?\`.     match prefix.kind() {         Prefix::VerbatimDisk(drive) => {             base.push(format!("{}:", drive as char));@@ -76,14 +79,19 @@ fn strip_verbatim_prefix(path: &Path) -> PathBuf {         _ => return path.to_path_buf(),     } -    let mut stripped = PathBuf::from(base);-    for component in components {-        if component == Component::RootDir {-            continue;-        }-        stripped.push(component.as_os_str());+    if has_root {+        // The root separator is already part of `base`, and `join` would append+        // it again; skipping the root component keeps the prefix we just built+        // instead of letting `join` replace it.+        let _ = components.next();+    }+    if components.as_path().is_empty() {+        // `\\?\C:` and `\\?\UNC\server\share`: the verbatim form is the whole+        // path, and joining an empty tail would append a separator the input+        // did not have.+        return PathBuf::from(base);     }-    stripped+    Path::new(&base).join(components) }  pub fn is_existing_directory(path: &Path) -> bool {@@ -237,6 +245,14 @@ mod windows_tests {             strip_verbatim_prefix(Path::new(r"\\?\UNC\server\share")),             Path::new(r"\\server\share")         );+        // ... and keeps the exact bytes: joining an empty tail would have+        // appended a separator the input did not have.+        assert_eq!(+            strip_verbatim_prefix(Path::new(r"\\?\UNC\server\share"))+                .as_os_str()+                .as_encoded_bytes(),+            Path::new(r"\\server\share").as_os_str().as_encoded_bytes()+        );         assert_eq!(             strip_verbatim_prefix(Path::new(r"\\?\UNC\server\share\")),             Path::new(r"\\server\share\")