Suppress expansion of void* rows

...because they would have type ```void```, which can't be instantiated.

src/ExpressionEvaluator/CSharp/Test/ResultProvider/ExpansionTests.cs

@@ -710,11 +710,54 @@ internal C(long p)
                     EvalResult(fullName, "{4}", "System.IntPtr", fullName, DkmEvaluationResultFlags.Expandable));
                 children = GetChildren(children[0]);
                 Verify(children,
-                    EvalResult("m_value", PointerToString(new IntPtr(i)), "void*", string.Format("({0}).m_value", fullName), DkmEvaluationResultFlags.Expandable),
+                    EvalResult("m_value", PointerToString(new IntPtr(i)), "void*", string.Format("({0}).m_value", fullName)),
                     EvalResult("Static members", null, "", "System.IntPtr", DkmEvaluationResultFlags.Expandable | DkmEvaluationResultFlags.ReadOnly, DkmEvaluationResultCategory.Class));
             }
         }
 
+        [WorkItem(1154608)]
+        [Fact]
+        public void VoidPointer()
+        {
+            var source = @"
+using System;
+
+unsafe class C
+{
+    internal C(long p)
+    {
+        this.v = (void*)p;
+        this.vv = (void**)p;
+    }
+    void* v;
+    void** vv;
+}";
+            var assembly = GetUnsafeAssembly(source);
+            unsafe
+            {
+                // NOTE: We're depending on endian-ness to put
+                // the interesting bytes first when we run this
+                // test as 32-bit.
+                long i = 4;
+                long p = (long)&i;
+                long pp = (long)&p;
+                var type = assembly.GetType("C");
+                var rootExpr = $"new C({pp})";
+                var value = CreateDkmClrValue(type.Instantiate(pp));
+                var evalResult = FormatResult(rootExpr, value);
+                Verify(evalResult,
+                    EvalResult(rootExpr, "{C}", "C", rootExpr, DkmEvaluationResultFlags.Expandable));
+                var children = GetChildren(evalResult);
+                Verify(children,
+                    EvalResult("v", PointerToString(new IntPtr(pp)), "void*", $"({rootExpr}).v"),
+                    EvalResult("vv", PointerToString(new IntPtr(pp)), "void**", $"({rootExpr}).vv", DkmEvaluationResultFlags.Expandable));
+                string fullName = $"*({rootExpr}).vv";
+                children = GetChildren(children[1]);
+                Verify(children,
+                    EvalResult(fullName, PointerToString(new IntPtr(p)), "void*", fullName));
+            }
+        }
+
         [WorkItem(1064176)]
         [Fact]
         public void NullPointer()

src/ExpressionEvaluator/Core/Source/ResultProvider/ResultProvider.cs

@@ -819,7 +819,10 @@ private void GetEvaluationResultsAndContinue(ArrayBuilder<EvalResultDataItem> ro
             {
                 // If this ever happens, the element type info is just .SkipOne().
                 Debug.Assert(!new DynamicFlagsCustomTypeInfo(declaredTypeAndInfo.Info).Any());
-                return !value.IsNull ? new PointerDereferenceExpansion(new TypeAndCustomInfo(declaredType.GetElementType())) : null;
+                var elementType = declaredType.GetElementType();
+                return value.IsNull || elementType.IsVoid()
+                    ? null
+                    : new PointerDereferenceExpansion(new TypeAndCustomInfo(elementType));
             }
 
             if (value.EvalFlags.Includes(DkmEvaluationResultFlags.ExceptionThrown) &&

src/ExpressionEvaluator/Core/Test/ResultProvider/Debugger/Engine/DkmClrValue.cs

@@ -98,7 +98,7 @@ public DkmClrValue Dereference(DkmInspectionContext inspectionContext)
                 value = e;
                 evalFlags |= DkmEvaluationResultFlags.ExceptionThrown;
             }
-            var valueType = new DkmClrType(this.Type.RuntimeInstance, (value == null) ? elementType : (TypeImpl)value.GetType());
+            var valueType = new DkmClrType(this.Type.RuntimeInstance, (value == null || elementType.IsPointer) ? elementType : (TypeImpl)value.GetType());
             return new DkmClrValue(
                 value,
                 value,
@@ -489,13 +489,13 @@ public DkmClrValue GetMemberValue(string MemberName, int MemberType, string Pare
             {
                 unsafe
                 {
-                    if (Marshal.SizeOf(typeof(void*)) == 4)
+                    if (Environment.Is64BitProcess)
                     {
-                        value = (int)System.Reflection.Pointer.Unbox(value);
+                        value = (long)System.Reflection.Pointer.Unbox(value);
                     }
                     else
                     {
-                        value = (long)System.Reflection.Pointer.Unbox(value);
+                        value = (int)System.Reflection.Pointer.Unbox(value);
                     }
                 }
                 type = declaredType;
@@ -711,7 +711,10 @@ private unsafe static object Dereference(IntPtr ptr, Type elementType)
                     {
                         throw new InvalidOperationException("Dereferencing null");
                     }
-                    return Marshal.PtrToStructure(ptr, ((TypeImpl)elementType).Type);
+                    var destinationType = elementType.IsPointer
+                        ? (Environment.Is64BitProcess ? typeof(long) : typeof(int))
+                        : ((TypeImpl)elementType).Type;
+                    return Marshal.PtrToStructure(ptr, destinationType);
                 default:
                     throw new InvalidOperationException();
             }