Rollup merge of rust-lang#59284 - RalfJung:maybe-uninit, r=sfackler

adjust MaybeUninit API to discussions

uninitialized -> uninit
into_initialized -> assume_init
read_initialized -> read
set -> write

Author: Centril

Diff for: src/liballoc/collections/btree/node.rs

@@ -109,7 +109,7 @@ impl<K, V> LeafNode<K, V> {
             keys: uninitialized_array![_; CAPACITY],
             vals: uninitialized_array![_; CAPACITY],
             parent: ptr::null(),
-            parent_idx: MaybeUninit::uninitialized(),
+            parent_idx: MaybeUninit::uninit(),
             len: 0
         }
     }
@@ -129,7 +129,7 @@ unsafe impl Sync for NodeHeader<(), ()> {}
 // ever take a pointer past the first key.
 static EMPTY_ROOT_NODE: NodeHeader<(), ()> = NodeHeader {
     parent: ptr::null(),
-    parent_idx: MaybeUninit::uninitialized(),
+    parent_idx: MaybeUninit::uninit(),
     len: 0,
     keys_start: [],
 };
@@ -261,7 +261,7 @@ impl<K, V> Root<K, V> {
             -> NodeRef<marker::Mut<'_>, K, V, marker::Internal> {
         debug_assert!(!self.is_shared_root());
         let mut new_node = Box::new(unsafe { InternalNode::new() });
-        new_node.edges[0].set(unsafe { BoxedNode::from_ptr(self.node.as_ptr()) });
+        new_node.edges[0].write(unsafe { BoxedNode::from_ptr(self.node.as_ptr()) });
 
         self.node = BoxedNode::from_internal(new_node);
         self.height += 1;
@@ -737,7 +737,7 @@ impl<'a, K, V> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
         unsafe {
             ptr::write(self.keys_mut().get_unchecked_mut(idx), key);
             ptr::write(self.vals_mut().get_unchecked_mut(idx), val);
-            self.as_internal_mut().edges.get_unchecked_mut(idx + 1).set(edge.node);
+            self.as_internal_mut().edges.get_unchecked_mut(idx + 1).write(edge.node);
 
             (*self.as_leaf_mut()).len += 1;
 
@@ -1080,7 +1080,7 @@ impl<'a, K, V> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>, marker::
         let mut child = self.descend();
         unsafe {
             (*child.as_leaf_mut()).parent = ptr;
-            (*child.as_leaf_mut()).parent_idx.set(idx);
+            (*child.as_leaf_mut()).parent_idx.write(idx);
         }
     }
 

Diff for: src/libcore/fmt/float.rs

@@ -10,8 +10,8 @@ fn float_to_decimal_common_exact<T>(fmt: &mut Formatter, num: &T,
     where T: flt2dec::DecodableFloat
 {
     unsafe {
-        let mut buf = MaybeUninit::<[u8; 1024]>::uninitialized(); // enough for f32 and f64
-        let mut parts = MaybeUninit::<[flt2dec::Part; 4]>::uninitialized();
+        let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
+        let mut parts = MaybeUninit::<[flt2dec::Part; 4]>::uninit();
         // FIXME(#53491): Technically, this is calling `get_mut` on an uninitialized
         // `MaybeUninit` (here and elsewhere in this file).  Revisit this once
         // we decided whether that is valid or not.
@@ -32,8 +32,8 @@ fn float_to_decimal_common_shortest<T>(fmt: &mut Formatter, num: &T,
 {
     unsafe {
         // enough for f32 and f64
-        let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninitialized();
-        let mut parts = MaybeUninit::<[flt2dec::Part; 4]>::uninitialized();
+        let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninit();
+        let mut parts = MaybeUninit::<[flt2dec::Part; 4]>::uninit();
         // FIXME(#53491)
         let formatted = flt2dec::to_shortest_str(flt2dec::strategy::grisu::format_shortest, *num,
                                                  sign, precision, false, buf.get_mut(),
@@ -71,8 +71,8 @@ fn float_to_exponential_common_exact<T>(fmt: &mut Formatter, num: &T,
     where T: flt2dec::DecodableFloat
 {
     unsafe {
-        let mut buf = MaybeUninit::<[u8; 1024]>::uninitialized(); // enough for f32 and f64
-        let mut parts = MaybeUninit::<[flt2dec::Part; 6]>::uninitialized();
+        let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
+        let mut parts = MaybeUninit::<[flt2dec::Part; 6]>::uninit();
         // FIXME(#53491)
         let formatted = flt2dec::to_exact_exp_str(flt2dec::strategy::grisu::format_exact,
                                                   *num, sign, precision,
@@ -91,8 +91,8 @@ fn float_to_exponential_common_shortest<T>(fmt: &mut Formatter,
 {
     unsafe {
         // enough for f32 and f64
-        let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninitialized();
-        let mut parts = MaybeUninit::<[flt2dec::Part; 6]>::uninitialized();
+        let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninit();
+        let mut parts = MaybeUninit::<[flt2dec::Part; 6]>::uninit();
         // FIXME(#53491)
         let formatted = flt2dec::to_shortest_exp_str(flt2dec::strategy::grisu::format_shortest,
                                                      *num, sign, (0, 0), upper,

Diff for: src/libcore/fmt/num.rs

@@ -60,7 +60,7 @@ trait GenericRadix {
             for byte in buf.iter_mut().rev() {
                 let n = x % base;               // Get the current place value.
                 x = x / base;                   // Deaccumulate the number.
-                byte.set(Self::digit(n.to_u8())); // Store the digit in the buffer.
+                byte.write(Self::digit(n.to_u8())); // Store the digit in the buffer.
                 curr -= 1;
                 if x == zero {
                     // No more digits left to accumulate.
@@ -72,7 +72,7 @@ trait GenericRadix {
             for byte in buf.iter_mut().rev() {
                 let n = zero - (x % base);      // Get the current place value.
                 x = x / base;                   // Deaccumulate the number.
-                byte.set(Self::digit(n.to_u8())); // Store the digit in the buffer.
+                byte.write(Self::digit(n.to_u8())); // Store the digit in the buffer.
                 curr -= 1;
                 if x == zero {
                     // No more digits left to accumulate.

Diff for: src/libcore/macros.rs

@@ -626,12 +626,12 @@ macro_rules! todo {
 #[macro_export]
 #[unstable(feature = "maybe_uninit_array", issue = "53491")]
 macro_rules! uninitialized_array {
-    // This `into_initialized` is safe because an array of `MaybeUninit` does not
+    // This `assume_init` is safe because an array of `MaybeUninit` does not
     // require initialization.
     // FIXME(#49147): Could be replaced by an array initializer, once those can
     // be any const expression.
     ($t:ty; $size:expr) => (unsafe {
-        MaybeUninit::<[MaybeUninit<$t>; $size]>::uninitialized().into_initialized()
+        MaybeUninit::<[MaybeUninit<$t>; $size]>::uninit().assume_init()
     });
 }