Rollup merge of #38513 - GuillaumeGomez:thread_fn_docs, r=frewsxcv

Add missing examples in some thread functions

r? @frewsxcv

src/libstd/thread/mod.rs

@@ -318,20 +318,38 @@ impl Builder {
 // Free functions
 ////////////////////////////////////////////////////////////////////////////////
 
-/// Spawns a new thread, returning a `JoinHandle` for it.
+/// Spawns a new thread, returning a [`JoinHandle`] for it.
 ///
 /// The join handle will implicitly *detach* the child thread upon being
 /// dropped. In this case, the child thread may outlive the parent (unless
 /// the parent thread is the main thread; the whole process is terminated when
-/// the main thread finishes.) Additionally, the join handle provides a `join`
+/// the main thread finishes). Additionally, the join handle provides a [`join`]
 /// method that can be used to join the child thread. If the child thread
-/// panics, `join` will return an `Err` containing the argument given to
-/// `panic`.
+/// panics, [`join`] will return an [`Err`] containing the argument given to
+/// [`panic`].
 ///
 /// # Panics
 ///
-/// Panics if the OS fails to create a thread; use `Builder::spawn`
+/// Panics if the OS fails to create a thread; use [`Builder::spawn`]
 /// to recover from such errors.
+///
+/// [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html
+/// [`join`]: ../../std/thread/struct.JoinHandle.html#method.join
+/// [`Err`]: ../../std/result/enum.Result.html#variant.Err
+/// [`panic!`]: ../../std/macro.panic.html
+/// [`Builder::spawn`]: ../../std/thread/struct.Builder.html#method.spawn
+///
+/// # Examples
+///
+/// ```
+/// use std::thread;
+///
+/// let handler = thread::spawn(|| {
+///     // thread code
+/// });
+///
+/// handler.join().unwrap();
+/// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn spawn<F, T>(f: F) -> JoinHandle<T> where
     F: FnOnce() -> T, F: Send + 'static, T: Send + 'static
@@ -341,7 +359,7 @@ pub fn spawn<F, T>(f: F) -> JoinHandle<T> where
 
 /// Gets a handle to the thread that invokes it.
 ///
-/// #Examples
+/// # Examples
 ///
 /// Getting a handle to the current thread with `thread::current()`:
 ///
@@ -366,6 +384,14 @@ pub fn current() -> Thread {
 }
 
 /// Cooperatively gives up a timeslice to the OS scheduler.
+///
+/// # Examples
+///
+/// ```
+/// use std::thread;
+///
+/// thread::yield_now();
+/// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn yield_now() {
     imp::Thread::yield_now()
@@ -375,7 +401,7 @@ pub fn yield_now() {
 ///
 /// # Examples
 ///
-/// ```rust,should_panic
+/// ```should_panic
 /// use std::thread;
 ///
 /// struct SomeStruct;
@@ -413,6 +439,15 @@ pub fn panicking() -> bool {
 /// specifics or platform-dependent functionality. Note that on unix platforms
 /// this function will not return early due to a signal being received or a
 /// spurious wakeup.
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::thread;
+///
+/// // Let's sleep for 2 seconds:
+/// thread::sleep_ms(2000);
+/// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::thread::sleep`")]
 pub fn sleep_ms(ms: u32) {
@@ -433,7 +468,7 @@ pub fn sleep_ms(ms: u32) {
 ///
 /// # Examples
 ///
-/// ```rust,no_run
+/// ```no_run
 /// use std::{thread, time};
 ///
 /// let ten_millis = time::Duration::from_millis(10);