Rollup merge of rust-lang#145209 - hanna-kruppe:path_add_extension, r=tgross35

Stabilize `path_add_extension`

FCP in tracking issue rust-lang#127292 finished in January. There was more discussion since then, but [libs-api decided to match `set_extension`][0] by keeping the return type as-is and adding a panic for invalid extensions. The latter was implemented in rust-lang#140163, so this feature should be ready for stabilization. But if anyone's unsure, another FCP could be done to confirm.

Closes rust-lang#127292

[0]: rust-lang#127292 (comment)

Author: Zalathar

library/std/src/path.rs

@@ -1575,8 +1575,6 @@ impl PathBuf {
     /// # Examples
     ///
     /// ```
-    /// #![feature(path_add_extension)]
-    ///
     /// use std::path::{Path, PathBuf};
     ///
     /// let mut p = PathBuf::from("/feel/the");
@@ -1596,7 +1594,7 @@ impl PathBuf {
     /// p.add_extension("");
     /// assert_eq!(Path::new("/feel/the.formatted.dark"), p.as_path());
     /// ```
-    #[unstable(feature = "path_add_extension", issue = "127292")]
+    #[stable(feature = "path_add_extension", since = "CURRENT_RUSTC_VERSION")]
     pub fn add_extension<S: AsRef<OsStr>>(&mut self, extension: S) -> bool {
         self._add_extension(extension.as_ref())
     }
@@ -2878,8 +2876,6 @@ impl Path {
     /// # Examples
     ///
     /// ```
-    /// #![feature(path_add_extension)]
-    ///
     /// use std::path::{Path, PathBuf};
     ///
     /// let path = Path::new("foo.rs");
@@ -2890,7 +2886,7 @@ impl Path {
     /// assert_eq!(path.with_added_extension("xz"), PathBuf::from("foo.tar.gz.xz"));
     /// assert_eq!(path.with_added_extension("").with_added_extension("txt"), PathBuf::from("foo.tar.gz.txt"));
     /// ```
-    #[unstable(feature = "path_add_extension", issue = "127292")]
+    #[stable(feature = "path_add_extension", since = "CURRENT_RUSTC_VERSION")]
     pub fn with_added_extension<S: AsRef<OsStr>>(&self, extension: S) -> PathBuf {
         let mut new_path = self.to_path_buf();
         new_path.add_extension(extension);

library/std/tests/path.rs

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