Use default for primitives and reference types instead of Unsafe.SkipInit.

Author: timcassell

src/BenchmarkDotNet/Code/DeclarationsProvider.cs

@@ -90,7 +90,8 @@ public override string OverheadImplementation
             get
             {
                 var type = WorkloadMethodReturnType;
-                if (type.IsByRefLike())
+                bool isByRefLike = type.IsByRefLike();
+                if (isByRefLike || (Consumer.IsConsumable(type) && !isByRefLike))
                 {
                     return $"return default({type.GetCorrectCSharpTypeName()});";
                 }

src/BenchmarkDotNet/Engines/Consumer.cs

@@ -12,6 +12,13 @@ namespace BenchmarkDotNet.Engines
 {
     public class Consumer
     {
+        private static readonly HashSet<Type> SupportedTypes
+            = new HashSet<Type>(
+                typeof(Consumer).GetTypeInfo()
+                                .DeclaredFields
+                                .Where(field => !field.IsStatic) // exclude this HashSet itself
+                                .Select(field => field.FieldType));
+
 #pragma warning disable IDE0052 // Remove unread private members
         private volatile byte byteHolder;
         private volatile sbyte sbyteHolder;
@@ -123,7 +130,8 @@ public void Consume<T>(in T value)
             // This also works for empty structs, because the runtime enforces a minimum size of 1 byte.
             => byteHolder = Unsafe.As<T, byte>(ref Unsafe.AsRef(in value));
 
-        internal static bool IsConsumable(Type type) => !type.IsByRefLike();
+        internal static bool IsConsumable(Type type)
+            => SupportedTypes.Contains(type) || type.GetTypeInfo().IsClass || type.GetTypeInfo().IsInterface || !type.IsByRefLike();
 
         internal static bool HasConsumableField(Type type, out FieldInfo consumableField)
         {

src/BenchmarkDotNet/Toolchains/InProcess/Emit/Implementation/Emitters/ConsumableConsumeEmitter.cs

@@ -80,7 +80,8 @@ protected override void OnEmitCtorBodyOverride(ConstructorBuilder constructorBui
 
         public override void EmitOverheadImplementation(ILGenerator ilBuilder, Type returnType)
         {
-            if (returnType.IsByRefLike())
+            bool isByRefLike = returnType.IsByRefLike();
+            if (isByRefLike || (Consumer.IsConsumable(returnType) && !isByRefLike))
             {
                 /*
                     // return default;