From 3bcb85ee658e7a5362f5e381c337f07381f916dc Mon Sep 17 00:00:00 2001
From: Josef Reinhard Brandl <mail@josefbrandl.de>
Date: Sat, 23 Jun 2018 13:32:53 +0200
Subject: [PATCH] `PinMut`: Add safe `get_mut` and rename unsafe fns to
 `get_mut_unchecked` and `map_unchecked`

---
 src/libcore/mem.rs    | 14 ++++++++++----
 src/libcore/option.rs |  2 +-
 src/libstd/future.rs  |  2 +-
 src/libstd/panic.rs   | 11 +++--------
 4 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 31635ffa53c83..08bd9289ab487 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -1119,6 +1119,12 @@ impl<'a, T: ?Sized + Unpin> PinMut<'a, T> {
     pub fn new(reference: &'a mut T) -> PinMut<'a, T> {
         PinMut { inner: reference }
     }
+
+    /// Get a mutable reference to the data inside of this `PinMut`.
+    #[unstable(feature = "pin", issue = "49150")]
+    pub fn get_mut(this: PinMut<'a, T>) -> &'a mut T {
+        this.inner
+    }
 }
 
 
@@ -1150,21 +1156,21 @@ impl<'a, T: ?Sized> PinMut<'a, T> {
     /// the data out of the mutable reference you receive when you call this
     /// function.
     #[unstable(feature = "pin", issue = "49150")]
-    pub unsafe fn get_mut(this: PinMut<'a, T>) -> &'a mut T {
+    pub unsafe fn get_mut_unchecked(this: PinMut<'a, T>) -> &'a mut T {
         this.inner
     }
 
     /// Construct a new pin by mapping the interior value.
     ///
-    /// For example, if you  wanted to get a `PinMut` of a field of something, you
-    /// could use this to get access to that field in one line of code.
+    /// For example, if you  wanted to get a `PinMut` of a field of something,
+    /// you could use this to get access to that field in one line of code.
     ///
     /// This function is unsafe. You must guarantee that the data you return
     /// will not move so long as the argument value does not move (for example,
     /// because it is one of the fields of that value), and also that you do
     /// not move out of the argument you receive to the interior function.
     #[unstable(feature = "pin", issue = "49150")]
-    pub unsafe fn map<U, F>(this: PinMut<'a, T>, f: F) -> PinMut<'a, U> where
+    pub unsafe fn map_unchecked<U, F>(this: PinMut<'a, T>, f: F) -> PinMut<'a, U> where
         F: FnOnce(&mut T) -> &mut U
     {
         PinMut { inner: f(this.inner) }
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index 1e615042a6d88..70979f631cdbf 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -275,7 +275,7 @@ impl<T> Option<T> {
     #[unstable(feature = "pin", issue = "49150")]
     pub fn as_pin_mut<'a>(self: PinMut<'a, Self>) -> Option<PinMut<'a, T>> {
         unsafe {
-            PinMut::get_mut(self).as_mut().map(|x| PinMut::new_unchecked(x))
+            PinMut::get_mut_unchecked(self).as_mut().map(|x| PinMut::new_unchecked(x))
         }
     }
 
diff --git a/src/libstd/future.rs b/src/libstd/future.rs
index 2da775fdc949e..c1cc36f3b419a 100644
--- a/src/libstd/future.rs
+++ b/src/libstd/future.rs
@@ -43,7 +43,7 @@ impl<T: Generator<Yield = ()>> !Unpin for GenFuture<T> {}
 impl<T: Generator<Yield = ()>> Future for GenFuture<T> {
     type Output = T::Return;
     fn poll(self: PinMut<Self>, cx: &mut task::Context) -> Poll<Self::Output> {
-        set_task_cx(cx, || match unsafe { PinMut::get_mut(self).0.resume() } {
+        set_task_cx(cx, || match unsafe { PinMut::get_mut_unchecked(self).0.resume() } {
             GeneratorState::Yielded(()) => Poll::Pending,
             GeneratorState::Complete(x) => Poll::Ready(x),
         })
diff --git a/src/libstd/panic.rs b/src/libstd/panic.rs
index 2c11c262488b2..451420ae88ad8 100644
--- a/src/libstd/panic.rs
+++ b/src/libstd/panic.rs
@@ -327,14 +327,9 @@ impl<T: fmt::Debug> fmt::Debug for AssertUnwindSafe<T> {
 impl<'a, F: Future> Future for AssertUnwindSafe<F> {
     type Output = F::Output;
 
-    fn poll(mut self: PinMut<Self>, cx: &mut task::Context) -> Poll<Self::Output> {
-        unsafe {
-            let pinned_field = PinMut::new_unchecked(
-                &mut PinMut::get_mut(self.reborrow()).0
-            );
-
-            pinned_field.poll(cx)
-        }
+    fn poll(self: PinMut<Self>, cx: &mut task::Context) -> Poll<Self::Output> {
+        let pinned_field = unsafe { PinMut::map_unchecked(self, |x| &mut x.0) };
+        pinned_field.poll(cx)
     }
 }