Stop using Compilationoptions.Features to enable test-only code paths. (changeset 1211317)

Src/Compilers/CSharp/Source/Compilation/CSharpCompilation.cs

@@ -57,6 +57,11 @@ public sealed partial class CSharpCompilation : Compilation
         // NOTE: Presently, we do not cache the per-tree diagnostics.
         private ImmutableArray<Diagnostic> lazyClsComplianceDiagnostics;
 
+        /// <summary>
+        /// Used for test purposes only to immulate missing members.
+        /// </summary>
+        private SmallDictionary<int, bool> lazyMakeMemberMissingMap;
+
         private Conversions conversions;
         internal Conversions Conversions
         {
@@ -3035,5 +3040,40 @@ internal override int CompareSourceLocations(Location loc1, Location loc2)
         }
 
         #endregion
+
+        internal void MakeMemberMissing(WellKnownMember member)
+        {
+            MakeMemberMissing((int)member);
+        }
+
+        internal void MakeMemberMissing(SpecialMember member)
+        {
+            MakeMemberMissing(-(int)member - 1);
+        }
+
+        internal bool IsMemberMissing(WellKnownMember member)
+        {
+            return IsMemberMissing((int)member);
+        }
+
+        internal bool IsMemberMissing(SpecialMember member)
+        {
+            return IsMemberMissing(-(int)member - 1);
+        }
+
+        private void MakeMemberMissing(int member)
+        {
+            if (lazyMakeMemberMissingMap == null)
+            {
+                lazyMakeMemberMissingMap = new SmallDictionary<int, bool>(); 
+            }
+
+            lazyMakeMemberMissingMap[member] = true;
+        }
+
+        private bool IsMemberMissing(int member)
+        {
+            return lazyMakeMemberMissingMap != null && lazyMakeMemberMissingMap.ContainsKey(member);
+        }
     }
 }

Src/Compilers/CSharp/Source/Symbols/Compilation_WellKnownMembers.cs

@@ -44,8 +44,7 @@ internal Symbol GetWellKnownTypeMember(WellKnownMember member)
             Debug.Assert(member >= 0 && member < WellKnownMember.Count);
 
             // if this member is to be forced "missing", return null
-            var makeMissingMember = this.Feature("MakeMissingMember");
-            if (makeMissingMember != null && makeMissingMember == member.ToString()) return null;
+            if (IsMemberMissing(member)) return null;
 
             if (lazyWellKnownTypeMembers == null || ReferenceEquals(lazyWellKnownTypeMembers[(int)member], ErrorTypeSymbol.UnknownResultType))
             {

Src/Compilers/CSharp/Source/Symbols/Source/SourceAssemblySymbol.cs

@@ -185,8 +185,7 @@ public override AssemblyIdentity Identity
 
         internal override Symbol GetSpecialTypeMember(SpecialMember member)
         {
-            var makeMissingMember = compilation.Feature("MakeMissingMember");
-            return makeMissingMember != null && makeMissingMember == member.ToString() ? null : base.GetSpecialTypeMember(member);
+            return compilation.IsMemberMissing(member) ? null : base.GetSpecialTypeMember(member);
         }
 
         private string GetWellKnownAttributeDataStringField(Func<CommonAssemblyWellKnownAttributeData, string> fieldGetter, string missingValue = null)

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

@@ -11,25 +11,6 @@ namespace Microsoft.CodeAnalysis.CSharp.UnitTests
 {
     public class MissingSpecialMember : CSharpTestBase
     {
-        private CSharpCompilationOptions WithMissingMember(WellKnownMember wm)
-        {
-            return WithMissingMember(wm.ToString());
-        }
-        private CSharpCompilationOptions WithMissingMember(SpecialMember sm)
-        {
-            return WithMissingMember(sm.ToString());
-        }
-        private CSharpCompilationOptions WithMissingMember(string memberKey)
-        {
-            var compOptions = TestOptions.Dll.WithOptimizations(true).WithFeatures(new[] { "MakeMissingMember:" + memberKey });
-            if (System.Diagnostics.Debugger.IsAttached)
-            {
-                // Using single-threaded build if debugger attached, to simplify debugging.
-                compOptions = compOptions.WithConcurrentBuild(false);
-            }
-            return compOptions;
-        }
-
         [Fact]
         public void Missing_System_Collections_Generic_IEnumerable_T__GetEnumerator()
         {
@@ -48,7 +29,11 @@ public IEnumerable<int> M()
         yield return 1;
     }
 }";
-            CreateCompilationWithMscorlib(source, compOptions: WithMissingMember(SpecialMember.System_Collections_Generic_IEnumerable_T__GetEnumerator)).VerifyEmitDiagnostics(
+            var comp = CreateCompilationWithMscorlib(source, compOptions: TestOptions.Dll.WithOptimizations(true));
+
+            comp.MakeMemberMissing(SpecialMember.System_Collections_Generic_IEnumerable_T__GetEnumerator);
+            
+            comp.VerifyEmitDiagnostics(
     // (10,5): error CS0656: Missing compiler required member 'System.Collections.Generic.IEnumerable`1.GetEnumerator'
     //     {
     Diagnostic(ErrorCode.ERR_MissingPredefinedMember, @"{
@@ -76,7 +61,11 @@ public IEnumerable<int> M()
         yield return 1;
     }
 }";
-            CreateCompilationWithMscorlib(source, compOptions: WithMissingMember(SpecialMember.System_IDisposable__Dispose)).VerifyEmitDiagnostics(
+            var comp = CreateCompilationWithMscorlib(source, compOptions: TestOptions.Dll.WithOptimizations(true));
+
+            comp.MakeMemberMissing(SpecialMember.System_IDisposable__Dispose);
+
+            comp.VerifyEmitDiagnostics(
     // (10,5): error CS0656: Missing compiler required member 'System.IDisposable.Dispose'
     //     {
     Diagnostic(ErrorCode.ERR_MissingPredefinedMember, @"{
@@ -104,7 +93,11 @@ public IEnumerable<int> M()
         yield return 1;
     }
 }";
-            CreateCompilationWithMscorlib(source, compOptions: WithMissingMember(WellKnownMember.System_Diagnostics_DebuggerHiddenAttribute__ctor)).VerifyEmitDiagnostics(
+            var comp = CreateCompilationWithMscorlib(source, compOptions: TestOptions.Dll.WithOptimizations(true));
+
+            comp.MakeMemberMissing(WellKnownMember.System_Diagnostics_DebuggerHiddenAttribute__ctor);
+
+            comp.VerifyEmitDiagnostics(
                 // the DebuggerHidden attribute is optional.
                 );
         }
@@ -123,7 +116,11 @@ public static void Main(string[] args)
 
     public static void Extension(this string x) {}
 }";
-            CreateCompilationWithMscorlib(source, compOptions: WithMissingMember(WellKnownMember.System_Diagnostics_DebuggerHiddenAttribute__ctor)).VerifyEmitDiagnostics(
+            var comp = CreateCompilationWithMscorlib(source, compOptions: TestOptions.Dll.WithOptimizations(true));
+
+            comp.MakeMemberMissing(WellKnownMember.System_Diagnostics_DebuggerHiddenAttribute__ctor);
+
+            comp.VerifyEmitDiagnostics(
                 // (9,34): error CS1110: Cannot define a new extension method because the compiler required type 'System.Runtime.CompilerServices.ExtensionAttribute' cannot be found. Are you missing a reference to System.Core.dll?
                 //     public static void Extension(this string x) {}
                 Diagnostic(ErrorCode.ERR_ExtensionAttrNotFound, "this").WithArguments("System.Runtime.CompilerServices.ExtensionAttribute").WithLocation(9, 34)