From 137e445d4d028cd7a640ee7ad50e1f927e51689f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kaya=20Da=CC=81vid?= <mail@davidkaya.sk>
Date: Sat, 14 Jul 2018 12:34:21 +0200
Subject: [PATCH 1/5] Extensions for immutable builders (#21055)

Added extensions for immutable builders, which should be prefered over the extensions on IEnumerable because of performance benefits.
---
 .../src/System/Collections/Immutable/ImmutableArray.cs   | 8 ++++++++
 .../System/Collections/Immutable/ImmutableDictionary.cs  | 8 ++++++++
 .../src/System/Collections/Immutable/ImmutableHashSet.cs | 9 +++++++++
 .../src/System/Collections/Immutable/ImmutableList.cs    | 8 ++++++++
 .../System/Collections/Immutable/ImmutableSortedSet.cs   | 8 ++++++++
 5 files changed, 41 insertions(+)

diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs
index aadeceeb7eff..42bfcff4115e 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs
@@ -395,6 +395,14 @@ public static ImmutableArray<TSource> ToImmutableArray<TSource>(this IEnumerable
             return CreateRange(items);
         }
 
+        /// <summary>
+        /// Returns an immutable copy of the current contents of the builder's collection.
+        /// </summary>
+        /// <param name="builder">The builder to create the immutable array from.</param>
+        /// <returns>An immutable array.</returns>
+        [Pure]
+        public static ImmutableArray<TSource> ToImmutableArray<TSource>(this ImmutableArray<TSource>.Builder builder) => builder.ToImmutable();
+
         /// <summary>
         /// Searches an entire one-dimensional sorted <see cref="ImmutableArray{T}"/> for a specific element,
         /// using the <see cref="IComparable{T}"/> generic interface implemented by each element
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs
index 4ea02da39f59..7df3b5f2f2d7 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs
@@ -166,6 +166,14 @@ public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TSource, T
                 .AddRange(source.Select(element => new KeyValuePair<TKey, TValue>(keySelector(element), elementSelector(element))));
         }
 
+        /// <summary>
+        /// Returns an immutable copy of the current contents of the builder's collection.
+        /// </summary>
+        /// <param name="builder">The builder to create the immutable dictionary from.</param>
+        /// <returns>An immutable dictionary.</returns>
+        [Pure]
+        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this ImmutableDictionary<TKey, TValue>.Builder builder) => builder.ToImmutable();
+
         /// <summary>
         /// Constructs an immutable dictionary based on some transformation of a sequence.
         /// </summary>
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs
index a281afd915a6..23f166e77d0f 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs
@@ -156,6 +156,15 @@ public static ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this IEnumer
             return ImmutableHashSet<TSource>.Empty.WithComparer(equalityComparer).Union(source);
         }
 
+        /// <summary>
+        /// Returns an immutable copy of the current contents of the builder's collection.
+        /// </summary>
+        /// <param name="builder">The builder to create the immutable set from.</param>
+        /// <returns>An immutable set.</returns>
+        [Pure]
+        public static ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this ImmutableHashSet<TSource>.Builder builder) => builder.ToImmutable();
+
+
         /// <summary>
         /// Enumerates a sequence exactly once and produces an immutable set of its contents.
         /// </summary>
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs
index ecb16b5f083b..68d32786c205 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs
@@ -73,6 +73,14 @@ public static ImmutableList<TSource> ToImmutableList<TSource>(this IEnumerable<T
             return ImmutableList<TSource>.Empty.AddRange(source);
         }
 
+        /// <summary>
+        /// Returns an immutable copy of the current contents of the builder's collection.
+        /// </summary>
+        /// <param name="builder">The builder to create the immutable list from.</param>
+        /// <returns>An immutable list.</returns>
+        [Pure]
+        public static ImmutableList<TSource> ToImmutableList<TSource>(this ImmutableList<TSource>.Builder builder) => builder.ToImmutable();
+
         /// <summary>
         /// Replaces the first equal element in the list with the specified element.
         /// </summary>
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs
index 36a3856d77cb..424a59acf2eb 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs
@@ -167,5 +167,13 @@ public static ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this IEn
         {
             return ToImmutableSortedSet(source, null);
         }
+
+        /// <summary>
+        /// Returns an immutable copy of the current contents of the builder's collection.
+        /// </summary>
+        /// <param name="builder">The builder to create the immutable set from.</param>
+        /// <returns>An immutable set.</returns>
+        [Pure]
+        public static ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this ImmutableSortedSet<TSource>.Builder builder) => builder.ToImmutable();
     }
 }

From fd9f13e6426bcce85ee45d63a8cd7331489d7148 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kaya=20Da=CC=81vid?= <mail@davidkaya.sk>
Date: Sat, 14 Jul 2018 13:18:47 +0200
Subject: [PATCH 2/5] Extension for immutable sorted dictionary builder
 (#21055)

---
 .../Collections/Immutable/ImmutableSortedDictionary.cs    | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs
index d2138fa8bfd3..5bf66d89729a 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs
@@ -162,6 +162,14 @@ public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionar
                 .AddRange(source.Select(element => new KeyValuePair<TKey, TValue>(keySelector(element), elementSelector(element))));
         }
 
+        /// <summary>
+        /// Returns an immutable copy of the current contents of the builder's collection.
+        /// </summary>
+        /// <param name="builder">The builder to create the immutable map from.</param>
+        /// <returns>An immutable map.</returns>
+        [Pure]
+        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this ImmutableSortedDictionary<TKey, TValue>.Builder builder) => builder.ToImmutable();
+
         /// <summary>
         /// Constructs an immutable sorted dictionary based on some transformation of a sequence.
         /// </summary>

From ee9e1d34434402f6c54f8b3e8ed1d944b4450ab4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kaya=20Da=CC=81vid?= <mail@davidkaya.sk>
Date: Sat, 14 Jul 2018 13:19:56 +0200
Subject: [PATCH 3/5] Extensions for immutable builders in the reference api
 (#21055)

---
 .../ref/System.Collections.Immutable.cs                     | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/System.Collections.Immutable/ref/System.Collections.Immutable.cs b/src/System.Collections.Immutable/ref/System.Collections.Immutable.cs
index d78033ec633e..960b0fed0881 100644
--- a/src/System.Collections.Immutable/ref/System.Collections.Immutable.cs
+++ b/src/System.Collections.Immutable/ref/System.Collections.Immutable.cs
@@ -92,6 +92,7 @@ public static partial class ImmutableArray
         public static System.Collections.Immutable.ImmutableArray<T> Create<T>(params T[] items) { throw null; }
         public static System.Collections.Immutable.ImmutableArray<T> Create<T>(T[] items, int start, int length) { throw null; }
         public static System.Collections.Immutable.ImmutableArray<TSource> ToImmutableArray<TSource>(this System.Collections.Generic.IEnumerable<TSource> items) { throw null; }
+        public static System.Collections.Immutable.ImmutableArray<TSource> ToImmutableArray<TSource>(this System.Collections.Immutable.ImmutableArray<TSource>.Builder builder) { throw null; }
     }
     public partial struct ImmutableArray<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlyList<T>, System.Collections.ICollection, System.Collections.IEnumerable, System.Collections.IList, System.Collections.Immutable.IImmutableList<T>, System.Collections.IStructuralComparable, System.Collections.IStructuralEquatable, System.IEquatable<System.Collections.Immutable.ImmutableArray<T>>
     {
@@ -270,6 +271,7 @@ public static partial class ImmutableDictionary
         public static System.Collections.Immutable.ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TSource, TKey, TValue>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TValue> elementSelector) { throw null; }
         public static System.Collections.Immutable.ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TSource, TKey, TValue>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TValue> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> keyComparer) { throw null; }
         public static System.Collections.Immutable.ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TSource, TKey, TValue>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TValue> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> keyComparer, System.Collections.Generic.IEqualityComparer<TValue> valueComparer) { throw null; }
+        public static System.Collections.Immutable.ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this System.Collections.Immutable.ImmutableDictionary<TKey, TValue>.Builder builder) { throw null; }
     }
     public sealed partial class ImmutableDictionary<TKey, TValue> : System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IDictionary<TKey, TValue>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IReadOnlyCollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IReadOnlyDictionary<TKey, TValue>, System.Collections.ICollection, System.Collections.IDictionary, System.Collections.IEnumerable, System.Collections.Immutable.IImmutableDictionary<TKey, TValue>
     {
@@ -398,6 +400,7 @@ public static partial class ImmutableHashSet
         public static System.Collections.Immutable.ImmutableHashSet<T> Create<T>(params T[] items) { throw null; }
         public static System.Collections.Immutable.ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource> source) { throw null; }
         public static System.Collections.Immutable.ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, System.Collections.Generic.IEqualityComparer<TSource> equalityComparer) { throw null; }
+        public static System.Collections.Immutable.ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this System.Collections.Immutable.ImmutableHashSet<TSource>.Builder builder) { throw null; }
     }
     public sealed partial class ImmutableHashSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.ISet<T>, System.Collections.ICollection, System.Collections.IEnumerable, System.Collections.Immutable.IImmutableSet<T>
     {
@@ -522,6 +525,7 @@ public static partial class ImmutableList
         public static System.Collections.Immutable.IImmutableList<T> Remove<T>(this System.Collections.Immutable.IImmutableList<T> list, T value) { throw null; }
         public static System.Collections.Immutable.IImmutableList<T> Replace<T>(this System.Collections.Immutable.IImmutableList<T> list, T oldValue, T newValue) { throw null; }
         public static System.Collections.Immutable.ImmutableList<TSource> ToImmutableList<TSource>(this System.Collections.Generic.IEnumerable<TSource> source) { throw null; }
+        public static System.Collections.Immutable.ImmutableList<TSource> ToImmutableList<TSource>(this System.Collections.Immutable.ImmutableList<TSource>.Builder builder) { throw null; }
     }
     public sealed partial class ImmutableList<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlyList<T>, System.Collections.ICollection, System.Collections.IEnumerable, System.Collections.IList, System.Collections.Immutable.IImmutableList<T>
     {
@@ -746,6 +750,7 @@ public static partial class ImmutableSortedDictionary
         public static System.Collections.Immutable.ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TSource, TKey, TValue>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TValue> elementSelector) { throw null; }
         public static System.Collections.Immutable.ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TSource, TKey, TValue>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TValue> elementSelector, System.Collections.Generic.IComparer<TKey> keyComparer) { throw null; }
         public static System.Collections.Immutable.ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TSource, TKey, TValue>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TValue> elementSelector, System.Collections.Generic.IComparer<TKey> keyComparer, System.Collections.Generic.IEqualityComparer<TValue> valueComparer) { throw null; }
+        public static System.Collections.Immutable.ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this System.Collections.Immutable.ImmutableSortedDictionary<TKey, TValue>.Builder source) { throw null; }
     }
     public sealed partial class ImmutableSortedDictionary<TKey, TValue> : System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IDictionary<TKey, TValue>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IReadOnlyCollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IReadOnlyDictionary<TKey, TValue>, System.Collections.ICollection, System.Collections.IDictionary, System.Collections.IEnumerable, System.Collections.Immutable.IImmutableDictionary<TKey, TValue>
     {
@@ -881,6 +886,7 @@ public static partial class ImmutableSortedSet
         public static System.Collections.Immutable.ImmutableSortedSet<T> Create<T>(params T[] items) { throw null; }
         public static System.Collections.Immutable.ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this System.Collections.Generic.IEnumerable<TSource> source) { throw null; }
         public static System.Collections.Immutable.ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, System.Collections.Generic.IComparer<TSource> comparer) { throw null; }
+        public static System.Collections.Immutable.ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this System.Collections.Immutable.ImmutableSortedSet<TSource>.Builder builder) { throw null; }
     }
     public sealed partial class ImmutableSortedSet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlyList<T>, System.Collections.Generic.ISet<T>, System.Collections.ICollection, System.Collections.IEnumerable, System.Collections.IList, System.Collections.Immutable.IImmutableSet<T>
     {

From bbdfc66d5e7aa707295f0b64046f13b4d68ca88f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kaya=20Da=CC=81vid?= <mail@davidkaya.sk>
Date: Sat, 14 Jul 2018 14:12:41 +0200
Subject: [PATCH 4/5] Tests for immutable builder extensions (#21055)

---
 .../tests/ImmutableArrayBuilderTest.cs        | 20 +++++++++++++++++
 .../tests/ImmutableDictionaryBuilderTest.cs   | 22 +++++++++++++++++++
 .../tests/ImmutableHashSetBuilderTest.cs      | 22 +++++++++++++++++++
 .../tests/ImmutableListBuilderTest.cs         | 22 +++++++++++++++++++
 .../ImmutableSortedDictionaryBuilderTest.cs   | 22 +++++++++++++++++++
 .../tests/ImmutableSortedSetBuilderTest.cs    | 22 +++++++++++++++++++
 6 files changed, 130 insertions(+)

diff --git a/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
index 490a996f8618..73d32d82fa22 100644
--- a/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
@@ -455,6 +455,26 @@ public void ToImmutable()
             Assert.True(builder.ToImmutable().IsEmpty);
         }
 
+        [Fact]
+        public void ToImmutableArray()
+        {
+            var builder = new ImmutableArray<int>.Builder();
+            builder.AddRange(0, 1, 2);
+
+            var array = builder.ToImmutableArray();
+            Assert.Equal(0, array[0]);
+            Assert.Equal(1, array[1]);
+            Assert.Equal(2, array[2]);
+            
+            builder[1] = 5;
+            Assert.Equal(5, builder[1]);
+            Assert.Equal(1, array[1]);
+
+            builder.Clear();
+            Assert.True(builder.ToImmutableArray().IsEmpty);
+            Assert.False(array.IsEmpty);
+        }
+
         [Fact]
         public void CopyTo()
         {
diff --git a/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs
index e3727b3fdd68..e26427d5ac2d 100644
--- a/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs
@@ -270,6 +270,28 @@ public static void TestDebuggerAttributes_Null()
             Assert.IsType<ArgumentNullException>(tie.InnerException);
         }
 
+        [Fact]
+        public void ToImmutableDictionary()
+        {
+            ImmutableDictionary<int, int>.Builder builder =  ImmutableDictionary.CreateBuilder<int, int>();
+            builder.Add(0, 0);
+            builder.Add(1, 1);
+            builder.Add(2, 2);
+
+            var dictionary = builder.ToImmutableDictionary();
+            Assert.Equal(0, dictionary[0]);
+            Assert.Equal(1, dictionary[1]);
+            Assert.Equal(2, dictionary[2]);
+
+            builder[1] = 5;
+            Assert.Equal(5, builder[1]);
+            Assert.Equal(1, dictionary[1]);
+
+            builder.Clear();
+            Assert.True(builder.ToImmutableDictionary().IsEmpty);
+            Assert.False(dictionary.IsEmpty);
+        }
+
         protected override IImmutableDictionary<TKey, TValue> GetEmptyImmutableDictionary<TKey, TValue>()
         {
             return ImmutableDictionary.Create<TKey, TValue>();
diff --git a/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs
index ac86a031beaf..05cef23a7a13 100644
--- a/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs
@@ -308,5 +308,27 @@ public void DebuggerAttributesValid()
         {
             DebuggerAttributes.ValidateDebuggerDisplayReferences(ImmutableHashSet.CreateBuilder<int>());
         }
+
+        [Fact]
+        public void ToImmutableHashSet()
+        {
+            ImmutableHashSet<int>.Builder builder = ImmutableHashSet.CreateBuilder<int>();
+            builder.Add(1);
+            builder.Add(2);
+            builder.Add(3);
+
+            var set = builder.ToImmutableSortedSet();
+            Assert.True(builder.Contains(1));
+            Assert.True(builder.Contains(2));
+            Assert.True(builder.Contains(3));
+
+            builder.Remove(3);
+            Assert.False(builder.Contains(3));
+            Assert.True(set.Contains(3));
+
+            builder.Clear();
+            Assert.True(builder.ToImmutableHashSet().IsEmpty);
+            Assert.False(set.IsEmpty);
+        }
     }
 }
diff --git a/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs
index 831fce435b52..6c2050e57928 100644
--- a/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs
@@ -390,6 +390,28 @@ public void ItemRef_OutOfBounds()
             Assert.Throws<ArgumentOutOfRangeException>(() => builder.ItemRef(5));
         }
 
+        [Fact]
+        public void ToImmutableList()
+        {
+            ImmutableList<int>.Builder builder = ImmutableList.CreateBuilder<int>();
+            builder.Add(0);
+            builder.Add(1);
+            builder.Add(2);
+
+            var list = builder.ToImmutableList();
+            Assert.Equal(0, builder[0]);
+            Assert.Equal(1, builder[1]);
+            Assert.Equal(2, builder[2]);
+
+            builder[1] = 5;
+            Assert.Equal(5, builder[1]);
+            Assert.Equal(1, list[1]);
+
+            builder.Clear();
+            Assert.True(builder.ToImmutableList().IsEmpty);
+            Assert.False(list.IsEmpty);
+        }
+
         protected override IEnumerable<T> GetEnumerableOf<T>(params T[] contents)
         {
             return ImmutableList<T>.Empty.AddRange(contents).ToBuilder();
diff --git a/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs
index 6dc3fb3d3290..7fc0849fb144 100644
--- a/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs
@@ -310,6 +310,28 @@ public void ValueRef_NonExistentKey()
             Assert.Throws<KeyNotFoundException>(() => builder.ValueRef("c"));
         }
 
+        [Fact]
+        public void ToImmutableSortedDictionary()
+        {
+            ImmutableSortedDictionary<int, int>.Builder builder = ImmutableSortedDictionary.CreateBuilder<int, int>();
+            builder.Add(1, 1);
+            builder.Add(2, 2);
+            builder.Add(3, 3);
+
+            var dictionary = builder.ToImmutableSortedDictionary();
+            Assert.Equal(1, dictionary[1]);
+            Assert.Equal(2, dictionary[2]);
+            Assert.Equal(3, dictionary[3]);
+
+            builder[2] = 5;
+            Assert.Equal(5, builder[2]);
+            Assert.Equal(2, dictionary[2]);
+
+            builder.Clear();
+            Assert.True(builder.ToImmutableSortedDictionary().IsEmpty);
+            Assert.False(dictionary.IsEmpty);
+        }
+
         protected override IImmutableDictionary<TKey, TValue> GetEmptyImmutableDictionary<TKey, TValue>()
         {
             return ImmutableSortedDictionary.Create<TKey, TValue>();
diff --git a/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs
index dd780623636b..5628bb6829ee 100644
--- a/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs
@@ -401,5 +401,27 @@ public void ItemRef_OutOfBounds()
 
             Assert.Throws<ArgumentOutOfRangeException> (() => builder.ItemRef(5));
         }
+
+        [Fact]
+        public void ToImmutableSortedSet()
+        {
+            ImmutableSortedSet<int>.Builder builder = ImmutableSortedSet.CreateBuilder<int>();
+            builder.Add(1);
+            builder.Add(5);
+            builder.Add(10);
+
+            var set = builder.ToImmutableSortedSet();
+            Assert.Equal(1, builder[0]);
+            Assert.Equal(5, builder[1]);
+            Assert.Equal(10, builder[2]);
+
+            builder.Remove(10);
+            Assert.False(builder.Contains(10));
+            Assert.True(set.Contains(10));
+
+            builder.Clear();
+            Assert.True(builder.ToImmutableSortedSet().IsEmpty);
+            Assert.False(set.IsEmpty);
+        }
     }
 }

From 4f9efa486863212d66fade5ca2839057bf77f5df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kaya=20Da=CC=81vid?= <mail@davidkaya.sk>
Date: Sun, 15 Jul 2018 07:18:07 +0200
Subject: [PATCH 5/5] Null check in extensions for immutable collection
 builders (#21055)

---
 .../src/System/Collections/Immutable/ImmutableArray.cs     | 7 ++++++-
 .../System/Collections/Immutable/ImmutableDictionary.cs    | 7 ++++++-
 .../src/System/Collections/Immutable/ImmutableHashSet.cs   | 7 ++++++-
 .../src/System/Collections/Immutable/ImmutableList.cs      | 7 ++++++-
 .../Collections/Immutable/ImmutableSortedDictionary.cs     | 7 ++++++-
 .../src/System/Collections/Immutable/ImmutableSortedSet.cs | 7 ++++++-
 .../tests/ImmutableArrayBuilderTest.cs                     | 3 +++
 .../tests/ImmutableDictionaryBuilderTest.cs                | 3 +++
 .../tests/ImmutableHashSetBuilderTest.cs                   | 3 +++
 .../tests/ImmutableListBuilderTest.cs                      | 3 +++
 .../tests/ImmutableSortedDictionaryBuilderTest.cs          | 3 +++
 .../tests/ImmutableSortedSetBuilderTest.cs                 | 3 +++
 12 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs
index 42bfcff4115e..74246fbab7ee 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray.cs
@@ -401,7 +401,12 @@ public static ImmutableArray<TSource> ToImmutableArray<TSource>(this IEnumerable
         /// <param name="builder">The builder to create the immutable array from.</param>
         /// <returns>An immutable array.</returns>
         [Pure]
-        public static ImmutableArray<TSource> ToImmutableArray<TSource>(this ImmutableArray<TSource>.Builder builder) => builder.ToImmutable();
+        public static ImmutableArray<TSource> ToImmutableArray<TSource>(this ImmutableArray<TSource>.Builder builder)
+        {
+            Requires.NotNull(builder, nameof(builder));
+
+            return builder.ToImmutable();
+        }
 
         /// <summary>
         /// Searches an entire one-dimensional sorted <see cref="ImmutableArray{T}"/> for a specific element,
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs
index 7df3b5f2f2d7..8b20d5cf222b 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary.cs
@@ -172,7 +172,12 @@ public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TSource, T
         /// <param name="builder">The builder to create the immutable dictionary from.</param>
         /// <returns>An immutable dictionary.</returns>
         [Pure]
-        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this ImmutableDictionary<TKey, TValue>.Builder builder) => builder.ToImmutable();
+        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this ImmutableDictionary<TKey, TValue>.Builder builder)
+        {
+            Requires.NotNull(builder, nameof(builder));
+
+            return builder.ToImmutable();
+        }
 
         /// <summary>
         /// Constructs an immutable dictionary based on some transformation of a sequence.
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs
index 23f166e77d0f..b8ab82d177f2 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet.cs
@@ -162,7 +162,12 @@ public static ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this IEnumer
         /// <param name="builder">The builder to create the immutable set from.</param>
         /// <returns>An immutable set.</returns>
         [Pure]
-        public static ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this ImmutableHashSet<TSource>.Builder builder) => builder.ToImmutable();
+        public static ImmutableHashSet<TSource> ToImmutableHashSet<TSource>(this ImmutableHashSet<TSource>.Builder builder)
+        {
+            Requires.NotNull(builder, nameof(builder));
+
+            return builder.ToImmutable();
+        }
 
 
         /// <summary>
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs
index 68d32786c205..32dfa716e7c0 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList.cs
@@ -79,7 +79,12 @@ public static ImmutableList<TSource> ToImmutableList<TSource>(this IEnumerable<T
         /// <param name="builder">The builder to create the immutable list from.</param>
         /// <returns>An immutable list.</returns>
         [Pure]
-        public static ImmutableList<TSource> ToImmutableList<TSource>(this ImmutableList<TSource>.Builder builder) => builder.ToImmutable();
+        public static ImmutableList<TSource> ToImmutableList<TSource>(this ImmutableList<TSource>.Builder builder)
+        {
+            Requires.NotNull(builder, nameof(builder));
+
+            return builder.ToImmutable();
+        }
 
         /// <summary>
         /// Replaces the first equal element in the list with the specified element.
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs
index 5bf66d89729a..fa35b6aafe5d 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary.cs
@@ -168,7 +168,12 @@ public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionar
         /// <param name="builder">The builder to create the immutable map from.</param>
         /// <returns>An immutable map.</returns>
         [Pure]
-        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this ImmutableSortedDictionary<TKey, TValue>.Builder builder) => builder.ToImmutable();
+        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this ImmutableSortedDictionary<TKey, TValue>.Builder builder)
+        {
+            Requires.NotNull(builder, nameof(builder));
+
+            return builder.ToImmutable();
+        }
 
         /// <summary>
         /// Constructs an immutable sorted dictionary based on some transformation of a sequence.
diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs
index 424a59acf2eb..000e1eed2548 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet.cs
@@ -174,6 +174,11 @@ public static ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this IEn
         /// <param name="builder">The builder to create the immutable set from.</param>
         /// <returns>An immutable set.</returns>
         [Pure]
-        public static ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this ImmutableSortedSet<TSource>.Builder builder) => builder.ToImmutable();
+        public static ImmutableSortedSet<TSource> ToImmutableSortedSet<TSource>(this ImmutableSortedSet<TSource>.Builder builder)
+        {
+            Requires.NotNull(builder, nameof(builder));
+
+            return builder.ToImmutable();
+        }
     }
 }
diff --git a/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
index 73d32d82fa22..7d832ecbafae 100644
--- a/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
@@ -473,6 +473,9 @@ public void ToImmutableArray()
             builder.Clear();
             Assert.True(builder.ToImmutableArray().IsEmpty);
             Assert.False(array.IsEmpty);
+
+            ImmutableArray<int>.Builder nullBuilder = null;
+            AssertExtensions.Throws<ArgumentNullException>("builder", () => nullBuilder.ToImmutableArray());
         }
 
         [Fact]
diff --git a/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs
index e26427d5ac2d..4390e578361a 100644
--- a/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableDictionaryBuilderTest.cs
@@ -290,6 +290,9 @@ public void ToImmutableDictionary()
             builder.Clear();
             Assert.True(builder.ToImmutableDictionary().IsEmpty);
             Assert.False(dictionary.IsEmpty);
+
+            ImmutableDictionary<int, int>.Builder nullBuilder = null;
+            AssertExtensions.Throws<ArgumentNullException>("builder", () => nullBuilder.ToImmutableDictionary());
         }
 
         protected override IImmutableDictionary<TKey, TValue> GetEmptyImmutableDictionary<TKey, TValue>()
diff --git a/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs
index 05cef23a7a13..a91587989720 100644
--- a/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableHashSetBuilderTest.cs
@@ -329,6 +329,9 @@ public void ToImmutableHashSet()
             builder.Clear();
             Assert.True(builder.ToImmutableHashSet().IsEmpty);
             Assert.False(set.IsEmpty);
+
+            ImmutableHashSet<int>.Builder nullBuilder = null;
+            AssertExtensions.Throws<ArgumentNullException>("builder", () => nullBuilder.ToImmutableHashSet());
         }
     }
 }
diff --git a/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs
index 6c2050e57928..9eeb8014f9fb 100644
--- a/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableListBuilderTest.cs
@@ -410,6 +410,9 @@ public void ToImmutableList()
             builder.Clear();
             Assert.True(builder.ToImmutableList().IsEmpty);
             Assert.False(list.IsEmpty);
+
+            ImmutableList<int>.Builder nullBuilder = null;
+            AssertExtensions.Throws<ArgumentNullException>("builder", () => nullBuilder.ToImmutableList());
         }
 
         protected override IEnumerable<T> GetEnumerableOf<T>(params T[] contents)
diff --git a/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs
index 7fc0849fb144..a863dada7518 100644
--- a/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableSortedDictionaryBuilderTest.cs
@@ -330,6 +330,9 @@ public void ToImmutableSortedDictionary()
             builder.Clear();
             Assert.True(builder.ToImmutableSortedDictionary().IsEmpty);
             Assert.False(dictionary.IsEmpty);
+
+            ImmutableSortedDictionary<int, int>.Builder nullBuilder = null;
+            AssertExtensions.Throws<ArgumentNullException>("builder", () => nullBuilder.ToImmutableSortedDictionary());
         }
 
         protected override IImmutableDictionary<TKey, TValue> GetEmptyImmutableDictionary<TKey, TValue>()
diff --git a/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs
index 5628bb6829ee..8bb28d49552f 100644
--- a/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableSortedSetBuilderTest.cs
@@ -422,6 +422,9 @@ public void ToImmutableSortedSet()
             builder.Clear();
             Assert.True(builder.ToImmutableSortedSet().IsEmpty);
             Assert.False(set.IsEmpty);
+
+            ImmutableSortedSet<int>.Builder nullBuilder = null;
+            AssertExtensions.Throws<ArgumentNullException>("builder", () => nullBuilder.ToImmutableSortedSet());
         }
     }
 }