Roslyn patch to add syntactic sugar to C# replacing IEnumerable<T> with T~

roslyn-enumerable-of-t.diff

diff --git a/Src/Compilers/CSharp/Source/Binder/Binder_Symbols.cs b/Src/Compilers/CSharp/Source/Binder/Binder_Symbols.cs
index ce0a903..b34b498 100644
--- a/Src/Compilers/CSharp/Source/Binder/Binder_Symbols.cs
+++ b/Src/Compilers/CSharp/Source/Binder/Binder_Symbols.cs
@@ -379,6 +379,20 @@ namespace Microsoft.CodeAnalysis.CSharp
                         return new PointerTypeSymbol(elementType);
                     }
 
+                case SyntaxKind.EnumerableType:
+                {
+                    NamedTypeSymbol enumerableOfT = GetSpecialType(SpecialType.System_Collections_Generic_IEnumerable_T, diagnostics, syntax);
+                    TypeSyntax typeArgumentSyntax = ((EnumerableTypeSyntax)syntax).ElementType;
+                    TypeSymbol typeArgument = BindType(typeArgumentSyntax, diagnostics, basesBeingResolved);
+                    NamedTypeSymbol constructedType = enumerableOfT.Construct(typeArgument);
+                    if (ShouldCheckConstraints)
+                    {
+                        constructedType.CheckConstraints(this.Compilation, this.Conversions, syntax.Location, diagnostics);
+                    }
+                    return constructedType;
+
+                }
+
                 case SyntaxKind.OmittedTypeArgument:
                     {
                         return BindTypeArgument((TypeSyntax)syntax, diagnostics, basesBeingResolved);
diff --git a/Src/Compilers/CSharp/Source/Parser/LanguageParser.cs b/Src/Compilers/CSharp/Source/Parser/LanguageParser.cs
index e87bc2c..bdffb2c 100644
--- a/Src/Compilers/CSharp/Source/Parser/LanguageParser.cs
+++ b/Src/Compilers/CSharp/Source/Parser/LanguageParser.cs
@@ -5574,6 +5574,11 @@ namespace Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax
             /// Might be a pointer type or a multiplication.
             /// </summary>
             PointerOrMultiplication,
+
+            /// <summary>
+            /// Enumerable type (ending with ~).
+            /// </summary>
+            EnumerableType,
         }
 
         private bool IsPossibleType()
@@ -5714,6 +5719,12 @@ namespace Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax
                 result = ScanTypeFlags.NullableType;
             }
 
+            if (this.CurrentToken.Kind == SyntaxKind.TildeToken)
+            {
+                this.EatToken();
+                result = ScanTypeFlags.EnumerableType;
+            }
+
             // Now check for pointer type(s)
             while (this.CurrentToken.Kind == SyntaxKind.AsteriskToken)
             {
@@ -5819,6 +5830,12 @@ namespace Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax
                 }
             }
 
+            if (this.CurrentToken.Kind == SyntaxKind.TildeToken)
+            {
+                var tilde = this.EatToken();
+                type = syntaxFactory.EnumerableType(type, tilde);
+            }
+
             // Check for pointer types (only if pType is NOT an array type)
             type = this.ParsePointerTypeMods(type);
 
@@ -8655,8 +8672,10 @@ namespace Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax
             // 2) (Foo?)bar;
             // 3) "(int)bar" or "(int[])bar"
             // 4) (G::Foo)bar
+            // 5) (Foo~)bar;
             if (type == ScanTypeFlags.PointerOrMultiplication ||
                 type == ScanTypeFlags.NullableType ||
                 type == ScanTypeFlags.MustBeType ||
-                type == ScanTypeFlags.AliasQualifiedName)
+                type == ScanTypeFlags.AliasQualifiedName ||
+                type == ScanTypeFlags.EnumerableType)
             {
diff --git a/Src/Compilers/CSharp/Source/Syntax/Syntax.xml b/Src/Compilers/CSharp/Source/Syntax/Syntax.xml
index 67ea757..6d87274 100644
--- a/Src/Compilers/CSharp/Source/Syntax/Syntax.xml
+++ b/Src/Compilers/CSharp/Source/Syntax/Syntax.xml
@@ -236,7 +236,27 @@
       <summary>Class which represents the syntax node for a nullable type.</summary>
     </TypeComment>
     <FactoryComment>
-      <summary>Creates an NullableTypeSyntax node.</summary>
+      <summary>Creates a NullableTypeSyntax node.</summary>
+    </FactoryComment>
+  </Node>
+  <Node Name="EnumerableTypeSyntax" Base="TypeSyntax">
+    <Kind Name="EnumerableType"/>
+    <Field Name="ElementType" Type="TypeSyntax">
+      <PropertyComment>
+        <summary>TypeSyntax node representing the type of the element.</summary>
+      </PropertyComment>
+    </Field>
+    <Field Name="TildeToken" Type="SyntaxToken">
+      <Kind Name="TildeToken"/>
+      <PropertyComment>
+        <summary>SyntaxToken representing the tilde.</summary>
+      </PropertyComment>
+    </Field>
+    <TypeComment>
+      <summary>Class which represents the syntax node for an enumerable type.</summary>
+    </TypeComment>
+    <FactoryComment>
+      <summary>Creates an EnumerableTypeSyntax node.</summary>
     </FactoryComment>
   </Node>
   <Node Name="OmittedTypeArgumentSyntax" Base="TypeSyntax">
diff --git a/Src/Compilers/CSharp/Source/Syntax/SyntaxKind.cs b/Src/Compilers/CSharp/Source/Syntax/SyntaxKind.cs
index 997af9f..8d8bc8d 100644
--- a/Src/Compilers/CSharp/Source/Syntax/SyntaxKind.cs
+++ b/Src/Compilers/CSharp/Source/Syntax/SyntaxKind.cs
@@ -288,6 +288,7 @@ namespace Microsoft.CodeAnalysis.CSharp
         ArrayRankSpecifier,
         PointerType,
         NullableType,
+        EnumerableType,
         OmittedTypeArgument,
 
         // expressions