Add doc examples for std::alloc::{alloc,alloc_zeroed}.

diff --git a/src/liballoc/alloc.rs b/src/liballoc/alloc.rs
index 84bd275df347c9c73b376c37e900ff3212be6900..c69b2fb5e1c2a3e27619f5994f767d8f49d036db 100644 (file)
--- a/src/liballoc/alloc.rs
+++ b/src/liballoc/alloc.rs
@@ -56,6 +56,22 @@ fn __rust_realloc(ptr: *mut u8,
 /// # Safety
 ///
 /// See [`GlobalAlloc::alloc`].
+///
+/// # Examples
+///
+/// ```
+/// use std::alloc::{alloc, dealloc, Layout};
+///
+/// unsafe {
+///     let layout = Layout::new::<u16>();
+///     let ptr = alloc(layout);
+///
+///     *(ptr as *mut u16) = 42;
+///     assert_eq!(*(ptr as *mut u16), 42);
+///
+///     dealloc(ptr, layout);
+/// }
+/// ```
 #[stable(feature = "global_alloc", since = "1.28.0")]
 #[inline]
 pub unsafe fn alloc(layout: Layout) -> *mut u8 {
@@ -110,6 +126,21 @@ pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8
 /// # Safety
 ///
 /// See [`GlobalAlloc::alloc_zeroed`].
+///
+/// # Examples
+///
+/// ```
+/// use std::alloc::{alloc_zeroed, dealloc, Layout};
+///
+/// unsafe {
+///     let layout = Layout::new::<u16>();
+///     let ptr = alloc_zeroed(layout);
+///
+///     assert_eq!(*(ptr as *mut u16), 0);
+///
+///     dealloc(ptr, layout);
+/// }
+/// ```
 #[stable(feature = "global_alloc", since = "1.28.0")]
 #[inline]
 pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {