Add UnordMap::try_insert

Author: WaffleLapkin

compiler/rustc_data_structures/src/lib.rs

@@ -26,6 +26,7 @@
 #![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

@@ -3,6 +3,7 @@
 //! as required by the query system.
 
 use rustc_hash::{FxHashMap, FxHashSet};
+use std::collections::hash_map::OccupiedError;
 use std::{
     borrow::{Borrow, BorrowMut},
     collections::hash_map::Entry,
@@ -468,6 +469,11 @@ impl<K: Eq + Hash, V> UnordMap<K, 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