Add UnordMap::try_insert

compiler/rustc_data_structures/src/lib.rs

@@ -25,6 +25,7 @@
 #![feature(lazy_cell)]
 #![feature(lint_reasons)]
 #![feature(macro_metavar_expr)]
+#![feature(map_try_insert)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(min_specialization)]
 #![feature(negative_impls)]

compiler/rustc_data_structures/src/unord.rs

@@ -4,6 +4,7 @@
 
 use rustc_hash::{FxHashMap, FxHashSet};
 use rustc_macros::{Decodable_Generic, Encodable_Generic};
+use std::collections::hash_map::OccupiedError;
 use std::{
     borrow::{Borrow, BorrowMut},
     collections::hash_map::Entry,
@@ -469,6 +470,11 @@ pub fn insert(&mut self, k: K, v: V) -> Option<V> {
         self.inner.insert(k, v)
     }
 
+    #[inline]
+    pub fn try_insert(&mut self, k: K, v: V) -> Result<&mut V, OccupiedError<'_, K, V>> {
+        self.inner.try_insert(k, v)
+    }
+
     #[inline]
     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
     where