Provide overloads to avoid unnecessary boxing

src/Compilers/Core/Portable/Collections/ImmutableArrayExtensions.cs

@@ -276,6 +276,26 @@ public static ImmutableArray<TResult> SelectManyAsArray<TItem, TResult>(this Imm
             return builder.ToImmutableAndFree();
         }
 
+        /// <summary>
+        /// Maps and flattens a subset of immutable array to another immutable array.
+        /// </summary>
+        /// <typeparam name="TItem">Type of the source array items</typeparam>
+        /// <typeparam name="TResult">Type of the transformed array items</typeparam>
+        /// <param name="array">The array to transform</param>
+        /// <param name="selector">A transform function to apply to each element.</param>
+        /// <returns>If the array's length is 0, this will return an empty immutable array.</returns>
+        public static ImmutableArray<TResult> SelectManyAsArray<TItem, TResult>(this ImmutableArray<TItem> array, Func<TItem, ImmutableArray<TResult>> selector)
+        {
+            if (array.Length == 0)
+                return ImmutableArray<TResult>.Empty;
+
+            var builder = ArrayBuilder<TResult>.GetInstance();
+            foreach (var item in array)
+                builder.AddRange(selector(item));
+
+            return builder.ToImmutableAndFree();
+        }
+
         /// <summary>
         /// Maps and flattens a subset of immutable array to another immutable array.
         /// </summary>
@@ -288,17 +308,37 @@ public static ImmutableArray<TResult> SelectManyAsArray<TItem, TResult>(this Imm
         public static ImmutableArray<TResult> SelectManyAsArray<TItem, TResult>(this ImmutableArray<TItem> array, Func<TItem, bool> predicate, Func<TItem, IEnumerable<TResult>> selector)
         {
             if (array.Length == 0)
-            {
                 return ImmutableArray<TResult>.Empty;
+
+            var builder = ArrayBuilder<TResult>.GetInstance();
+            foreach (var item in array)
+            {
+                if (predicate(item))
+                    builder.AddRange(selector(item));
             }
 
+            return builder.ToImmutableAndFree();
+        }
+
+        /// <summary>
+        /// Maps and flattens a subset of immutable array to another immutable array.
+        /// </summary>
+        /// <typeparam name="TItem">Type of the source array items</typeparam>
+        /// <typeparam name="TResult">Type of the transformed array items</typeparam>
+        /// <param name="array">The array to transform</param>
+        /// <param name="predicate">The condition to use for filtering the array content.</param>
+        /// <param name="selector">A transform function to apply to each element that is not filtered out by <paramref name="predicate"/>.</param>
+        /// <returns>If the items's length is 0, this will return an empty immutable array.</returns>
+        public static ImmutableArray<TResult> SelectManyAsArray<TItem, TResult>(this ImmutableArray<TItem> array, Func<TItem, bool> predicate, Func<TItem, ImmutableArray<TResult>> selector)
+        {
+            if (array.Length == 0)
+                return ImmutableArray<TResult>.Empty;
+
             var builder = ArrayBuilder<TResult>.GetInstance();
             foreach (var item in array)
             {
                 if (predicate(item))
-                {
                     builder.AddRange(selector(item));
-                }
             }
 
             return builder.ToImmutableAndFree();