Auto merge of #91902 - matthiaskrgr:rollup-hjjyhow, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #91529 (add BinaryHeap::try_reserve and BinaryHeap::try_reserve_exact)
 - #91820 (Suggest to specify a target triple when lang item is missing)
 - #91851 (Make `MaybeUninit::zeroed` `const`)
 - #91875 (Use try_normalize_erasing_regions in RevealAllVisitor)
 - #91887 (Remove `in_band_lifetimes` from `rustc_const_eval`)
 - #91892 (Fix HashStable implementation on InferTy)
 - #91893 (Remove `in_band_lifetimes` from `rustc_hir`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 79 insertions, 0 deletions

diff --git a/library/alloc/src/collections/binary_heap.rs b/library/alloc/src/collections/binary_heap.rs
index 76fbfa9fc59..6fc6002d551 100644
--- a/library/alloc/src/collections/binary_heap.rs
+++ b/library/alloc/src/collections/binary_heap.rs
@@ -149,6 +149,7 @@ use core::mem::{self, swap, ManuallyDrop};
 use core::ops::{Deref, DerefMut};
 use core::ptr;
 
+use crate::collections::TryReserveError;
 use crate::slice;
 use crate::vec::{self, AsIntoIter, Vec};
 
@@ -953,6 +954,84 @@ impl<T> BinaryHeap<T> {
         self.data.reserve(additional);
     }
 
+    /// Tries to reserve the minimum capacity for exactly `additional`
+    /// elements to be inserted in the given `BinaryHeap<T>`. After calling
+    /// `try_reserve_exact`, capacity will be greater than or equal to
+    /// `self.len() + additional` if it returns `Ok(())`.
+    /// Does nothing if the capacity is already sufficient.
+    ///
+    /// Note that the allocator may give the collection more space than it
+    /// requests. Therefore, capacity can not be relied upon to be precisely
+    /// minimal. Prefer [`try_reserve`] if future insertions are expected.
+    ///
+    /// [`try_reserve`]: BinaryHeap::try_reserve
+    ///
+    /// # Errors
+    ///
+    /// If the capacity overflows, or the allocator reports a failure, then an error
+    /// is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(try_reserve_2)]
+    /// use std::collections::BinaryHeap;
+    /// use std::collections::TryReserveError;
+    ///
+    /// fn find_max_slow(data: &[u32]) -> Result<Option<u32>, TryReserveError> {
+    ///     let mut heap = BinaryHeap::new();
+    ///
+    ///     // Pre-reserve the memory, exiting if we can't
+    ///     heap.try_reserve_exact(data.len())?;
+    ///
+    ///     // Now we know this can't OOM in the middle of our complex work
+    ///     heap.extend(data.iter());
+    ///
+    ///     Ok(heap.pop())
+    /// }
+    /// # find_max_slow(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
+    /// ```
+    #[unstable(feature = "try_reserve_2", issue = "91789")]
+    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        self.data.try_reserve_exact(additional)
+    }
+
+    /// Tries to reserve capacity for at least `additional` more elements to be inserted
+    /// in the given `BinaryHeap<T>`. The collection may reserve more space to avoid
+    /// frequent reallocations. After calling `try_reserve`, capacity will be
+    /// greater than or equal to `self.len() + additional`. Does nothing if
+    /// capacity is already sufficient.
+    ///
+    /// # Errors
+    ///
+    /// If the capacity overflows, or the allocator reports a failure, then an error
+    /// is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(try_reserve_2)]
+    /// use std::collections::BinaryHeap;
+    /// use std::collections::TryReserveError;
+    ///
+    /// fn find_max_slow(data: &[u32]) -> Result<Option<u32>, TryReserveError> {
+    ///     let mut heap = BinaryHeap::new();
+    ///
+    ///     // Pre-reserve the memory, exiting if we can't
+    ///     heap.try_reserve(data.len())?;
+    ///
+    ///     // Now we know this can't OOM in the middle of our complex work
+    ///     heap.extend(data.iter());
+    ///
+    ///     Ok(heap.pop())
+    /// }
+    /// # find_max_slow(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
+    /// ```
+    #[unstable(feature = "try_reserve_2", issue = "91789")]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        self.data.try_reserve(additional)
+    }
+
     /// Discards as much additional capacity as possible.
     ///
     /// # Examples