In ImmutableArray.ToDictionary, presize Dictionary (#27280)

danmoseley · stephentoub · commit 9ea258987e6b · 2018-02-20T15:49:48.000-05:00
diff --git a/src/System.Collections.Immutable/src/System/Linq/ImmutableArrayExtensions.cs b/src/System.Collections.Immutable/src/System/Linq/ImmutableArrayExtensions.cs
@@ -608,7 +608,7 @@ public static Dictionary<TKey, T> ToDictionary<TKey, T>(this ImmutableArray<T> i
         {
             Requires.NotNull(keySelector, nameof(keySelector));
 
-            var result = new Dictionary<TKey, T>(comparer);
+            var result = new Dictionary<TKey, T>(immutableArray.Length, comparer);
             foreach (var v in immutableArray)
             {
                 result.Add(keySelector(v), v);

Original file line number	Diff line number	Diff line change
`@@ -608,7 +608,7 @@ public static Dictionary<TKey, T> ToDictionary<TKey, T>(this ImmutableArray<T> i`
`608`	`608`	`{`
`609`	`609`	`Requires.NotNull(keySelector, nameof(keySelector));`
`610`	`610`
`611`		`- var result = new Dictionary<TKey, T>(comparer);`
	`611`	`+ var result = new Dictionary<TKey, T>(immutableArray.Length, comparer);`
`612`	`612`	`foreach (var v in immutableArray)`
`613`	`613`	`{`
`614`	`614`	`result.Add(keySelector(v), v);`