Rollup merge of #90431 - jkugelman:must-use-std-o-through-z, r=joshtriplett

Add #[must_use] to remaining std functions (O-Z)

I've run out of compelling reasons to group functions together across crates so I'm just going to go module-by-module. This is half of the remaining items from the `std` crate, from O-Z.

`panicking::take_hook` has a side effect: it unregisters the current panic hook, returning it. I almost ignored it, but the documentation example shows `let _ = panic::take_hook();`, so following suit I went ahead and added a `#[must_use]`.

```rust
std::panicking   fn take_hook() -> Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>;
```

I added these functions that clippy did not flag:

```rust
std::path::Path   fn starts_with<P: AsRef<Path>>(&self, base: P) -> bool;
std::path::Path   fn ends_with<P: AsRef<Path>>(&self, child: P) -> bool;
std::path::Path   fn with_file_name<S: AsRef<OsStr>>(&self, file_name: S) -> PathBuf;
std::path::Path   fn with_extension<S: AsRef<OsStr>>(&self, extension: S) -> PathBuf;
```

Parent issue: #89692

r? `@joshtriplett`

1 files changed, 5 insertions, 0 deletions

diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index 0c1ffeb1a79..e7944c715ed 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -650,6 +650,7 @@ where
 ///
 /// handler.join().unwrap();
 /// ```
+#[must_use]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn current() -> Thread {
     thread_info::current_thread().expect(
@@ -738,6 +739,7 @@ pub fn yield_now() {
 ///
 /// [Mutex]: crate::sync::Mutex
 #[inline]
+#[must_use]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn panicking() -> bool {
     panicking::panicking()
@@ -1132,6 +1134,7 @@ impl Thread {
     /// assert!(thread::current().id() != other_thread_id);
     /// ```
     #[stable(feature = "thread_id", since = "1.19.0")]
+    #[must_use]
     pub fn id(&self) -> ThreadId {
         self.inner.id
     }
@@ -1174,6 +1177,7 @@ impl Thread {
     ///
     /// [naming-threads]: ./index.html#naming-threads
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[must_use]
     pub fn name(&self) -> Option<&str> {
         self.cname().map(|s| unsafe { str::from_utf8_unchecked(s.to_bytes()) })
     }
@@ -1361,6 +1365,7 @@ impl<T> JoinHandle<T> {
     /// println!("thread id: {:?}", thread.id());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[must_use]
     pub fn thread(&self) -> &Thread {
         &self.0.thread
     }