Rollup merge of #144870 - Kivooeo:file_prefix-stabilize, r=tgross35

Stabilize `path_file_prefix` feature

This stabilises `Path::file_prefix`, following the FCP in [tracking issue ](#86319)

(FCP ended almost a year ago, so if it's needed for proccess we could rerun it)

Closes: #86319

Author: Kobzol

library/std/src/path.rs

@@ -2678,7 +2678,6 @@ impl Path {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(path_file_prefix)]
     /// use std::path::Path;
     ///
     /// assert_eq!("foo", Path::new("foo.rs").file_prefix().unwrap());
@@ -2693,7 +2692,7 @@ impl Path {
     ///
     /// [`Path::file_stem`]: Path::file_stem
     ///
-    #[unstable(feature = "path_file_prefix", issue = "86319")]
+    #[stable(feature = "path_file_prefix", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn file_prefix(&self) -> Option<&OsStr> {
         self.file_name().map(split_file_at_dot).and_then(|(before, _after)| Some(before))

library/std/tests/path.rs

@@ -1,10 +1,4 @@
-#![feature(
-    clone_to_uninit,
-    path_add_extension,
-    path_file_prefix,
-    maybe_uninit_slice,
-    normalize_lexically
-)]
+#![feature(clone_to_uninit, path_add_extension, maybe_uninit_slice, normalize_lexically)]
 
 use std::clone::CloneToUninit;
 use std::ffi::OsStr;

src/tools/clippy/tests/missing-test-files.rs

@@ -1,6 +1,6 @@
 #![warn(rust_2018_idioms, unused_lifetimes)]
 #![allow(clippy::assertions_on_constants)]
-#![feature(path_file_prefix)]
+#![cfg_attr(bootstrap, feature(path_file_prefix))]
 
 use std::cmp::Ordering;
 use std::ffi::OsStr;