Remove usage of [Pure] from Immutable Collections

src/libraries/System.Collections.Immutable/Directory.Build.props

@@ -3,7 +3,5 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IsNETCoreApp>true</IsNETCoreApp>
-    <!-- Set CONTRACTS_FULL to preserve usage of Contracts attributes -->
-    <DefineConstants>$(DefineConstants),CONTRACTS_FULL</DefineConstants>
   </PropertyGroup>
-</Project>
+</Project>

src/libraries/System.Collections.Immutable/ref/System.Collections.Immutable.csproj

@@ -9,19 +9,16 @@
   </ItemGroup>
   <ItemGroup Condition="'$(TargetsNetCoreApp)' == 'true'">
     <ProjectReference Include="..\..\System.Collections\ref\System.Collections.csproj" />
-    <ProjectReference Include="..\..\System.Diagnostics.Contracts\ref\System.Diagnostics.Contracts.csproj" />
     <ProjectReference Include="..\..\System.Runtime\ref\System.Runtime.csproj" />
     <ProjectReference Include="..\..\System.Runtime.InteropServices\ref\System.Runtime.InteropServices.csproj" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard1.0'">
     <Reference Include="System.Runtime" />
     <Reference Include="System.Collections" />
-    <Reference Include="System.Diagnostics.Contracts" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard1.3'">
     <Reference Include="System.Runtime" />
     <Reference Include="System.Collections" />
-    <Reference Include="System.Diagnostics.Contracts" />
     <Reference Include="System.Runtime.InteropServices" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard1.3' or '$(TargetFramework)' == 'netstandard2.0'">

src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/IImmutableDictionary.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Diagnostics.Contracts;
 
 namespace System.Collections.Immutable
 {
@@ -18,7 +17,6 @@ public interface IImmutableDictionary<TKey, TValue> : IReadOnlyDictionary<TKey,
         /// <summary>
         /// Gets an empty dictionary with equivalent ordering and key/value comparison rules.
         /// </summary>
-        [Pure]
         IImmutableDictionary<TKey, TValue> Clear();
 
         /// <summary>
@@ -31,7 +29,6 @@ public interface IImmutableDictionary<TKey, TValue> : IReadOnlyDictionary<TKey,
         /// <remarks>
         /// If the given key-value pair are already in the dictionary, the existing instance is returned.
         /// </remarks>
-        [Pure]
         IImmutableDictionary<TKey, TValue> Add(TKey key, TValue value);
 
         /// <summary>
@@ -40,7 +37,6 @@ public interface IImmutableDictionary<TKey, TValue> : IReadOnlyDictionary<TKey,
         /// <param name="pairs">The pairs.</param>
         /// <returns>The new dictionary containing the additional key-value pairs.</returns>
         /// <exception cref="ArgumentException">Thrown when one of the given keys already exists in the dictionary but has a different value.</exception>
-        [Pure]
         IImmutableDictionary<TKey, TValue> AddRange(IEnumerable<KeyValuePair<TKey, TValue>> pairs);
 
         /// <summary>
@@ -53,31 +49,27 @@ public interface IImmutableDictionary<TKey, TValue> : IReadOnlyDictionary<TKey,
         /// If the given key-value pair are already in the dictionary, the existing instance is returned.
         /// If the key already exists but with a different value, a new instance with the overwritten value will be returned.
         /// </remarks>
-        [Pure]
         IImmutableDictionary<TKey, TValue> SetItem(TKey key, TValue value);
 
         /// <summary>
         /// Applies a given set of key=value pairs to an immutable dictionary, replacing any conflicting keys in the resulting dictionary.
         /// </summary>
         /// <param name="items">The key=value pairs to set on the dictionary.  Any keys that conflict with existing keys will overwrite the previous values.</param>
         /// <returns>An immutable dictionary.</returns>
-        [Pure]
         IImmutableDictionary<TKey, TValue> SetItems(IEnumerable<KeyValuePair<TKey, TValue>> items);
 
         /// <summary>
         /// Removes the specified keys from the dictionary with their associated values.
         /// </summary>
         /// <param name="keys">The keys to remove.</param>
         /// <returns>A new dictionary with those keys removed; or this instance if those keys are not in the dictionary.</returns>
-        [Pure]
         IImmutableDictionary<TKey, TValue> RemoveRange(IEnumerable<TKey> keys);
 
         /// <summary>
         /// Removes the specified key from the dictionary with its associated value.
         /// </summary>
         /// <param name="key">The key to remove.</param>
         /// <returns>A new dictionary with the matching entry removed; or this instance if the key is not in the dictionary.</returns>
-        [Pure]
         IImmutableDictionary<TKey, TValue> Remove(TKey key);
 
         /// <summary>
@@ -87,7 +79,6 @@ public interface IImmutableDictionary<TKey, TValue> : IReadOnlyDictionary<TKey,
         /// <returns>
         ///   <c>true</c> if this dictionary contains the key-value pair; otherwise, <c>false</c>.
         /// </returns>
-        [Pure]
         bool Contains(KeyValuePair<TKey, TValue> pair);
 
         /// <summary>
@@ -102,7 +93,6 @@ public interface IImmutableDictionary<TKey, TValue> : IReadOnlyDictionary<TKey,
         /// the canonical value, or a value that has more complete data than the value you currently have,
         /// although their comparer functions indicate they are equal.
         /// </remarks>
-        [Pure]
         bool TryGetKey(TKey equalKey, out TKey actualKey);
     }
 }

src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/IImmutableList.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Diagnostics.Contracts;
 
 namespace System.Collections.Immutable
 {
@@ -21,7 +20,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <summary>
         /// Gets an empty list that retains the same sort semantics that this instance has.
         /// </summary>
-        [Pure]
         IImmutableList<T> Clear();
 
         /// <summary>
@@ -49,7 +47,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// elements in the <see cref="ImmutableList{T}"/> that starts at index and
         /// contains count number of elements, if found; otherwise, -1.
         /// </returns>
-        [Pure]
         int IndexOf(T item, int index, int count, IEqualityComparer<T>? equalityComparer);
 
         /// <summary>
@@ -73,23 +70,20 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// in the <see cref="ImmutableList{T}"/> that contains <paramref name="count"/> number of elements
         /// and ends at <paramref name="index"/>, if found; otherwise, -1.
         /// </returns>
-        [Pure]
         int LastIndexOf(T item, int index, int count, IEqualityComparer<T>? equalityComparer);
 
         /// <summary>
         /// Adds the specified value to this list.
         /// </summary>
         /// <param name="value">The value to add.</param>
         /// <returns>A new list with the element added.</returns>
-        [Pure]
         IImmutableList<T> Add(T value);
 
         /// <summary>
         /// Adds the specified values to this list.
         /// </summary>
         /// <param name="items">The values to add.</param>
         /// <returns>A new list with the elements added.</returns>
-        [Pure]
         IImmutableList<T> AddRange(IEnumerable<T> items);
 
         /// <summary>
@@ -98,7 +92,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <param name="index">The index at which to insert the value.</param>
         /// <param name="element">The element to insert.</param>
         /// <returns>The new immutable list.</returns>
-        [Pure]
         IImmutableList<T> Insert(int index, T element);
 
         /// <summary>
@@ -107,7 +100,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <param name="index">The index at which to insert the value.</param>
         /// <param name="items">The elements to insert.</param>
         /// <returns>The new immutable list.</returns>
-        [Pure]
         IImmutableList<T> InsertRange(int index, IEnumerable<T> items);
 
         /// <summary>
@@ -119,7 +111,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// If <c>null</c>, <see cref="EqualityComparer{T}.Default"/> is used.
         /// </param>
         /// <returns>A new list with the element removed, or this list if the element is not in this list.</returns>
-        [Pure]
         IImmutableList<T> Remove(T value, IEqualityComparer<T>? equalityComparer);
 
         /// <summary>
@@ -133,7 +124,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <returns>
         /// The new list.
         /// </returns>
-        [Pure]
         IImmutableList<T> RemoveAll(Predicate<T> match);
 
         /// <summary>
@@ -147,7 +137,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <returns>
         /// A new list with the elements removed.
         /// </returns>
-        [Pure]
         IImmutableList<T> RemoveRange(IEnumerable<T> items, IEqualityComparer<T>? equalityComparer);
 
         /// <summary>
@@ -158,15 +147,13 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <returns>
         /// A new list with the elements removed.
         /// </returns>
-        [Pure]
         IImmutableList<T> RemoveRange(int index, int count);
 
         /// <summary>
         /// Removes the element at the specified index.
         /// </summary>
         /// <param name="index">The index.</param>
         /// <returns>A new list with the elements removed.</returns>
-        [Pure]
         IImmutableList<T> RemoveAt(int index);
 
         /// <summary>
@@ -175,7 +162,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// <param name="index">The position in the list of the element to replace.</param>
         /// <param name="value">The element to replace the old element with.</param>
         /// <returns>The new list -- even if the value being replaced is equal to the new value for that position.</returns>
-        [Pure]
         IImmutableList<T> SetItem(int index, T value);
 
         /// <summary>
@@ -189,7 +175,6 @@ public interface IImmutableList<T> : IReadOnlyList<T>
         /// </param>
         /// <returns>The new list -- even if the value being replaced is equal to the new value for that position.</returns>
         /// <exception cref="ArgumentException">Thrown when the old value does not exist in the list.</exception>
-        [Pure]
         IImmutableList<T> Replace(T oldValue, T newValue, IEqualityComparer<T>? equalityComparer);
     }
 }

src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/IImmutableQueue.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Diagnostics.Contracts;
 
 namespace System.Collections.Immutable
 {
@@ -20,13 +19,11 @@ public interface IImmutableQueue<T> : IEnumerable<T>
         /// <value>
         ///   <c>true</c> if this queue is empty; otherwise, <c>false</c>.
         /// </value>
-        [Pure]
         bool IsEmpty { get; }
 
         /// <summary>
         /// Gets an empty queue.
         /// </summary>
-        [Pure]
         IImmutableQueue<T> Clear();
 
         /// <summary>
@@ -36,7 +33,6 @@ public interface IImmutableQueue<T> : IEnumerable<T>
         /// The element at the front of the queue.
         /// </returns>
         /// <exception cref="InvalidOperationException">Thrown when the queue is empty.</exception>
-        [Pure]
         T Peek();
 
         /// <summary>
@@ -46,15 +42,13 @@ public interface IImmutableQueue<T> : IEnumerable<T>
         /// <returns>
         /// The new queue.
         /// </returns>
-        [Pure]
         IImmutableQueue<T> Enqueue(T value);
 
         /// <summary>
         /// Returns a queue that is missing the front element.
         /// </summary>
         /// <returns>A queue; never <c>null</c>.</returns>
         /// <exception cref="InvalidOperationException">Thrown when the queue is empty.</exception>
-        [Pure]
         IImmutableQueue<T> Dequeue();
     }
 }