Return chroot unsupported error for vxworks and fuchsia

library/std/src/os/unix/fs.rs

@@ -1064,7 +1064,6 @@ pub fn lchown<P: AsRef<Path>>(dir: P, uid: Option<u32>, gid: Option<u32>) -> io:
 /// }
 /// ```
 #[stable(feature = "unix_chroot", since = "1.56.0")]
-#[cfg(not(any(target_os = "fuchsia", target_os = "vxworks")))]
 pub fn chroot<P: AsRef<Path>>(dir: P) -> io::Result<()> {
     sys::fs::chroot(dir.as_ref())
 }

library/std/src/sys/pal/unix/fs.rs

@@ -1980,14 +1980,20 @@ pub fn lchown(path: &Path, uid: u32, gid: u32) -> io::Result<()> {
 #[cfg(target_os = "vxworks")]
 pub fn lchown(path: &Path, uid: u32, gid: u32) -> io::Result<()> {
     let (_, _, _) = (path, uid, gid);
-    Err(io::const_io_error!(io::ErrorKind::Unsupported, "lchown not supported by vxworks",))
+    Err(io::const_io_error!(io::ErrorKind::Unsupported, "lchown not supported by vxworks"))
 }
 
 #[cfg(not(any(target_os = "fuchsia", target_os = "vxworks")))]
 pub fn chroot(dir: &Path) -> io::Result<()> {
     run_path_with_cstr(dir, &|dir| cvt(unsafe { libc::chroot(dir.as_ptr()) }).map(|_| ()))
 }
 
+#[cfg(any(target_os = "fuchsia", target_os = "vxworks"))]
+pub fn chroot(dir: &Path) -> io::Result<()> {
+    let _ = dir;
+    Err(io::const_io_error!(io::ErrorKind::Unsupported, "chroot not supported."))
+}
+
 pub use remove_dir_impl::remove_dir_all;
 
 // Fallback for REDOX, ESP-ID, Horizon, Vita, Vxworks and Miri