DevDiv #1019283: Part 2 - Consuming the attributes field on local debug info

On its own, this change seems kind of silly - instead of consuming a mangled name from the PDB, we set the name to null.  The main benefit is that other PDB producers have a way to communicate to the EE that certain locals should not be consumed, regardless of how they are named. (changeset 1332108)

Src/Test/PdbUtilities/Shared/ISymUnmanagedVariable.cs

@@ -12,7 +12,7 @@ namespace Roslyn.Utilities.Pdb
     internal interface ISymUnmanagedVariable
     {
         void GetName(int cchName, out int pcchName, [In, Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 0)] char[] name);
-        void GetAttributes(out int pRetVal);
+        void GetAttributes(out uint pRetVal);
         void GetSignature(int cSig, out int pcSig, [In, Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 0)] byte[] sig);
 
         // the following methods are useless (not implemented, or returning a constant):

Src/Test/PdbUtilities/Shared/SymUnmanagedReaderExtensions.cs

@@ -31,7 +31,7 @@ internal static ISymUnmanagedMethod GetBaselineMethod(this ISymUnmanagedReader r
         /// <summary>
         /// Returns local names indexed by slot.
         /// </summary>
-        internal static ImmutableArray<string> GetLocalNames(this ISymUnmanagedReader symReader, int methodToken, int ilOffset, bool isScopeEndInclusive)
+        internal static ImmutableArray<string> GetLocalNames(this ISymUnmanagedReader symReader, int methodToken, int ilOffset, bool isScopeEndInclusive, uint? attributesToIgnore)
         {
             if (symReader == null)
             {
@@ -39,15 +39,15 @@ internal static ImmutableArray<string> GetLocalNames(this ISymUnmanagedReader sy
             }
             
             var symMethod = symReader.GetBaselineMethod(methodToken);
-            return symMethod.GetLocalVariableSlots(ilOffset, isScopeEndInclusive);
+            return symMethod.GetLocalVariableSlots(ilOffset, isScopeEndInclusive, attributesToIgnore);
         }
 
         internal static ImmutableArray<string> GetLocalVariableSlots(this ISymUnmanagedMethod method)
         {
-            return GetLocalVariableSlots(method, offset: -1, isScopeEndInclusive: false);
+            return GetLocalVariableSlots(method, offset: -1, isScopeEndInclusive: false, attributesToIgnoreOpt: null);
         }
 
-        internal static ImmutableArray<string> GetLocalVariableSlots(this ISymUnmanagedMethod method, int offset, bool isScopeEndInclusive)
+        internal static ImmutableArray<string> GetLocalVariableSlots(this ISymUnmanagedMethod method, int offset, bool isScopeEndInclusive, uint? attributesToIgnoreOpt)
         {
             char[] nameBuffer = null;
             string[] result = null;
@@ -57,8 +57,21 @@ internal static ImmutableArray<string> GetLocalVariableSlots(this ISymUnmanagedM
 
             ISymUnmanagedVariable[] localsBuffer = null;
 
+            bool haveAttributesToIgnore = attributesToIgnoreOpt.HasValue;
+            uint attributesToIgnore = attributesToIgnoreOpt.GetValueOrDefault();
+
             ForEachLocalVariableRecursive(rootScope, offset, isScopeEndInclusive, ref localsBuffer, local =>
             {
+                if (haveAttributesToIgnore)
+                {
+                    uint attributes;
+                    local.GetAttributes(out attributes);
+                    if (attributes == attributesToIgnore)
+                    {
+                        return;
+                    }
+                }
+
                 int nameLength;
                 local.GetName(0, out nameLength, null);
 
@@ -77,7 +90,7 @@ internal static ImmutableArray<string> GetLocalVariableSlots(this ISymUnmanagedM
 
                     EnsureBufferSize(ref result, slot + 1);
 
-                    // nameLength is NUL-terminated
+                    // nameBuffer is NUL-terminated
                     Debug.Assert(nameBuffer[nameLength - 1] == '\0');
                     result[slot] = new string(nameBuffer, 0, nameLength - 1);
                 }