Remove WellKnownType.Last

src/Compilers/CSharp/Portable/Symbols/Compilation_WellKnownMembers.cs

@@ -77,7 +77,7 @@ internal Symbol GetWellKnownTypeMember(WellKnownMember member)
 
         internal NamedTypeSymbol GetWellKnownType(WellKnownType type)
         {
-            Debug.Assert(type >= WellKnownType.First && type <= WellKnownType.Last && type != WellKnownType.ExtSentinel);
+            Debug.Assert(type.IsValid());
 
             int index = (int)type - (int)WellKnownType.First;
             if (_lazyWellKnownTypes == null || (object)_lazyWellKnownTypes[index] == null)
@@ -778,7 +778,7 @@ public WellKnownMembersSignatureComparer(CSharpCompilation compilation)
             protected override bool MatchTypeToTypeId(TypeSymbol type, int typeId)
             {
                 WellKnownType wellKnownId = (WellKnownType)typeId;
-                if (wellKnownId >= WellKnownType.First && wellKnownId <= WellKnownType.Last)
+                if (wellKnownId.IsWellKnownType())
                 {
                     return (type == _compilation.GetWellKnownType(wellKnownId));
                 }

src/Compilers/CSharp/Test/Symbol/Symbols/MissingSpecialMember.cs

@@ -548,7 +548,7 @@ public void AllWellKnownTypes()
             }.Concat(WinRtRefs).ToArray();
             var comp = CreateCompilation("", refs);
 
-            for (var wkt = WellKnownType.First; wkt <= WellKnownType.Last; wkt++)
+            for (var wkt = WellKnownType.First; wkt < WellKnownType.NextAvailable; wkt++)
             {
                 switch (wkt)
                 {
@@ -572,7 +572,7 @@ public void AllWellKnownTypes()
         }
 
         [Fact]
-        public void AllWellKnowTypesBeforeCSharp7()
+        public void AllWellKnownTypesBeforeCSharp7()
         {
             foreach (var type in new[] {
                             WellKnownType.System_Math,

src/Compilers/Core/Portable/WellKnownTypes.cs

@@ -260,8 +260,7 @@ internal enum WellKnownType
         System_ValueTuple_T7,
         System_ValueTuple_TRest,
 
-        Available,
-        Last = Available - 1,
+        NextAvailable,
     }
 
     internal static class WellKnownTypes
@@ -269,7 +268,7 @@ internal static class WellKnownTypes
         /// <summary>
         /// Number of well known types in WellKnownType enum
         /// </summary>
-        internal const int Count = WellKnownType.Last - WellKnownType.First + 1;
+        internal const int Count = WellKnownType.NextAvailable - WellKnownType.First;
 
         /// <summary>
         /// Array of names for types.
@@ -537,31 +536,49 @@ private static void AssertEnumAndTableInSync()
                 var typeId = (WellKnownType)(i + WellKnownType.First);
 
                 string typeIdName;
-                if (typeId == WellKnownType.First)
+                switch (typeId)
                 {
-                    typeIdName = "System.Math";
+                    case WellKnownType.First:
+                        typeIdName = "System.Math";
+                        break;
+                    case WellKnownType.Microsoft_VisualBasic_CompilerServices_ObjectFlowControl_ForLoopControl:
+                        typeIdName = "Microsoft.VisualBasic.CompilerServices.ObjectFlowControl+ForLoopControl";
+                        break;
+                    case WellKnownType.CSharp7Sentinel:
+                        typeIdName = "System.IFormatProvider";
+                        break;
+                    case WellKnownType.ExtSentinel:
+                        typeIdName = "";
+                        continue;
+                    default:
+                        typeIdName = typeId.ToString().Replace("__", "+").Replace('_', '.');
+                        break;
                 }
-                else if (typeId == WellKnownType.Last)
-                {
-                    typeIdName = "System.ValueTuple`8";
-                }
-                else if (typeId == WellKnownType.ExtSentinel)
-                {
-                    Debug.Assert(name == "");
-                    continue;
-                }
-                else
+
+                int separator = name.IndexOf('`');
+                if (separator >= 0)
                 {
-                    typeIdName = typeId.ToString().Replace("__", "+").Replace('_', '.');
+                    // Ignore type parameter qualifier for generic types.
+                    name = name.Substring(0, separator);
+                    typeIdName = typeIdName.Substring(0, separator);
                 }
 
-                Debug.Assert(name == "Microsoft.VisualBasic.CompilerServices.ObjectFlowControl+ForLoopControl"
-                          || name.IndexOf('`') > 0 // a generic type
-                          || name == typeIdName);
+                Debug.Assert(name == typeIdName);
             }
 
             Debug.Assert((int)WellKnownType.ExtSentinel == 255);
-            Debug.Assert((int)WellKnownType.Last < 512);
+            Debug.Assert((int)WellKnownType.NextAvailable <= 512);
+        }
+
+        public static bool IsWellKnownType(this WellKnownType typeId)
+        {
+            Debug.Assert(typeId != WellKnownType.ExtSentinel);
+            return typeId >= WellKnownType.First && typeId < WellKnownType.NextAvailable;
+        }
+
+        public static bool IsValid(this WellKnownType typeId)
+        {
+            return typeId >= WellKnownType.First && typeId < WellKnownType.NextAvailable && typeId != WellKnownType.ExtSentinel;
         }
 
         public static string GetMetadataName(this WellKnownType id)

src/Compilers/VisualBasic/Portable/Symbols/WellKnownMembers.vb

@@ -341,7 +341,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         End Function
 
         Friend Function GetWellKnownType(type As WellKnownType) As NamedTypeSymbol
-            Debug.Assert(type >= WellKnownType.First AndAlso type <= WellKnownType.Last AndAlso type <> WellKnownType.ExtSentinel)
+            Debug.Assert(type.IsWellKnownType())
             Dim index As Integer = type - WellKnownType.First
 
             If _lazyWellKnownTypes Is Nothing OrElse _lazyWellKnownTypes(index) Is Nothing Then
@@ -639,15 +639,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End Sub
 
             Protected Overrides Function MatchTypeToTypeId(type As TypeSymbol, typeId As Integer) As Boolean
-                Dim result As Boolean = False
-
-                If typeId >= WellKnownType.First AndAlso typeId <= WellKnownType.Last Then
-                    result = (type Is _compilation.GetWellKnownType(CType(typeId, WellKnownType)))
-                Else
-                    result = MyBase.MatchTypeToTypeId(type, typeId)
+                Dim wellKnownId = CType(typeId, WellKnownType)
+                If wellKnownId.IsWellKnownType() Then
+                    Return type Is _compilation.GetWellKnownType(wellKnownId)
                 End If
 
-                Return result
+                Return MyBase.MatchTypeToTypeId(type, typeId)
             End Function
         End Class
     End Class

src/Compilers/VisualBasic/Test/Symbol/SymbolsTests/WellKnownTypeValidationTests.vb

@@ -493,8 +493,9 @@ End Namespace
                 ValueTupleRef
             }.Concat(WinRtRefs).ToArray()
 
+            Dim lastType = CType(WellKnownType.NextAvailable - 1, WellKnownType)
             Dim comp = CreateCompilationWithReferences((<compilation/>), refs.Concat(MsvbRef_v4_0_30319_17929).ToArray())
-            For wkt = WellKnownType.First To WellKnownType.Last
+            For wkt = WellKnownType.First To lastType
                 Select Case wkt
                     Case WellKnownType.Microsoft_VisualBasic_CompilerServices_EmbeddedOperators
                         ' Only present when embedding VB Core.
@@ -514,7 +515,7 @@ End Namespace
             Next
 
             comp = CreateCompilationWithReferences(<compilation/>, refs, TestOptions.ReleaseDll.WithEmbedVbCoreRuntime(True))
-            For wkt = WellKnownType.First To WellKnownType.Last
+            For wkt = WellKnownType.First To lastType
                 Select Case wkt
                     Case WellKnownType.Microsoft_VisualBasic_CallType,
                          WellKnownType.Microsoft_VisualBasic_CompilerServices_Operators,