Add some more raw vec methods so AllocInit::Zeroed is always used

Author: Ericson2314

library/alloc/src/raw_vec.rs

@@ -111,6 +111,12 @@ impl<T> RawVec<T, Global> {
         Self::with_capacity_zeroed_in(capacity, Global)
     }
 
+    /// Like `try_with_capacity`, but guarantees a successfully allocated buffer is zeroed.
+    #[inline]
+    pub fn try_with_capacity_zeroed(capacity: usize) -> Result<Self, TryReserveError> {
+        Self::try_with_capacity_zeroed_in(capacity, Global)
+    }
+
     /// Reconstitutes a `RawVec` from a pointer and capacity.
     ///
     /// # Safety
@@ -170,6 +176,13 @@ impl<T, A: Allocator> RawVec<T, A> {
         Self::allocate_in(capacity, AllocInit::Zeroed, alloc)
     }
 
+    /// Like `with_capacity_zeroed`, but parameterized over the choice
+    /// of allocator for the returned `RawVec`.
+    #[inline]
+    pub fn try_with_capacity_zeroed_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
+        Self::try_allocate_in(capacity, AllocInit::Zeroed, alloc)
+    }
+
     /// Converts a `Box<[T]>` into a `RawVec<T>`.
     pub fn from_box(slice: Box<[T], A>) -> Self {
         unsafe {