Rollup merge of rust-lang#78735 - danielhenrymantilla:simplify-unsafecell-getmut, r=RalfJung

JohnTitor · web-flow · commit 41d11a165010 · 2020-11-05T12:51:24.000+09:00
Simplify the implementation of `get_mut` (no unsafe)

Quick PR to reduce one use of `unsafe` pointed out in the previous PR

r? `@RalfJung`
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
@@ -1733,8 +1733,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     #[inline]
     #[unstable(feature = "unsafe_cell_get_mut", issue = "76943")]
     pub fn get_mut(&mut self) -> &mut T {
-        // SAFETY: (outer) `&mut` guarantees unique access.
-        unsafe { &mut *self.get() }
+        &mut self.value
     }
 
     /// Gets a mutable pointer to the wrapped value.

Original file line number	Diff line number	Diff line change
`@@ -1733,8 +1733,7 @@ impl<T: ?Sized> UnsafeCell<T> {`
`1733`	`1733`	`#[inline]`
`1734`	`1734`	`#[unstable(feature = "unsafe_cell_get_mut", issue = "76943")]`
`1735`	`1735`	`pub fn get_mut(&mut self) -> &mut T {`
`1736`		- // SAFETY: (outer) `&mut` guarantees unique access.
`1737`		`- unsafe { &mut *self.get() }`
	`1736`	`+ &mut self.value`
`1738`	`1737`	`}`
`1739`	`1738`
`1740`	`1739`	`/// Gets a mutable pointer to the wrapped value.`