New tests.
[mono.git] / mcs / mcs / nullable.cs
index d8a1d4b82f21f97fa16c648d26715fb0d29c9f66..8e2dc682bbc0fbbfc2403f8ed3842c0c87c11dd4 100644 (file)
 using System;
 using System.Reflection;
 using System.Reflection.Emit;
-using System.Collections;
        
 namespace Mono.CSharp.Nullable
 {
        public class NullableType : TypeExpr
        {
-               Expression underlying;
+               TypeExpr underlying;
 
-               public NullableType (Expression underlying, Location l)
+               public NullableType (TypeExpr underlying, Location l)
                {
                        this.underlying = underlying;
                        loc = l;
@@ -30,120 +29,121 @@ namespace Mono.CSharp.Nullable
                        eclass = ExprClass.Type;
                }
 
-               public NullableType (Type type, Location loc)
+               public NullableType (TypeSpec type, Location loc)
                        : this (new TypeExpression (type, loc), loc)
                { }
 
-               protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
+               protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
                {
-                       TypeArguments args = new TypeArguments (loc);
-                       args.Add (underlying);
-
                        if (TypeManager.generic_nullable_type == null) {
-                               TypeManager.generic_nullable_type = TypeManager.CoreLookupType (
-                                       "System", "Nullable`1", Kind.Struct, true);
+                               TypeManager.generic_nullable_type = TypeManager.CoreLookupType (ec.Compiler,
+                                       "System", "Nullable", 1, MemberKind.Struct, true);
                        }
 
+                       TypeArguments args = new TypeArguments (underlying);
                        GenericTypeExpr ctype = new GenericTypeExpr (TypeManager.generic_nullable_type, args, loc);
                        return ctype.ResolveAsTypeTerminal (ec, false);
                }
-
-               public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
-               {
-                       return ResolveAsBaseTerminal (ec, silent);
-               }               
        }
 
-       public sealed class NullableInfo
+       static class NullableInfo
        {
-               public readonly Type Type;
-               public readonly Type UnderlyingType;
-               public MethodInfo HasValue;
-               public MethodInfo Value;
-               public MethodInfo GetValueOrDefault;
-               public ConstructorInfo Constructor;
-
-               public NullableInfo (Type type)
-               {
-                       Type = type;
-                       UnderlyingType = TypeManager.GetTypeArguments (type) [0];
-
-                       PropertyInfo has_value_pi = TypeManager.GetPredefinedProperty (type, "HasValue", Location.Null, Type.EmptyTypes);
-                       PropertyInfo value_pi = TypeManager.GetPredefinedProperty (type, "Value", Location.Null, Type.EmptyTypes);
-                       GetValueOrDefault = TypeManager.GetPredefinedMethod (type, "GetValueOrDefault", Location.Null, Type.EmptyTypes);
-
-                       HasValue = has_value_pi.GetGetMethod (false);
-                       Value = value_pi.GetGetMethod (false);
-#if MS_COMPATIBLE
-                       if (UnderlyingType.Module == CodeGen.Module.Builder) {
-                               Type o_type = TypeManager.DropGenericTypeArguments (type);
-                               Constructor = TypeBuilder.GetConstructor (type,
-                                       TypeManager.GetPredefinedConstructor (o_type, Location.Null, o_type.GetGenericArguments ()));
-                               return;
-                       }
-#endif
-                       Constructor = type.GetConstructor (new Type[] { UnderlyingType });
+               public static MethodSpec GetConstructor (TypeSpec nullableType)
+               {
+                       return TypeManager.GetPredefinedConstructor (nullableType, Location.Null, GetUnderlyingType (nullableType));
+               }
+
+               public static MethodSpec GetHasValue (TypeSpec nullableType)
+               {
+                       return (MethodSpec) MemberCache.FindMember (nullableType,
+                               MemberFilter.Method ("get_HasValue", 0, ParametersCompiled.EmptyReadOnlyParameters, null), BindingRestriction.None);
+               }
+
+               public static MethodSpec GetGetValueOrDefault (TypeSpec nullableType)
+               {
+                       return (MethodSpec) MemberCache.FindMember (nullableType,
+                               MemberFilter.Method ("GetValueOrDefault", 0, ParametersCompiled.EmptyReadOnlyParameters, null), BindingRestriction.None);
+               }
+
+               public static MethodSpec GetValue (TypeSpec nullableType)
+               {
+                       return (MethodSpec) MemberCache.FindMember (nullableType,
+                               MemberFilter.Method ("get_Value", 0, ParametersCompiled.EmptyReadOnlyParameters, null), BindingRestriction.None);
+               }
+
+               public static TypeSpec GetUnderlyingType (TypeSpec nullableType)
+               {
+                       return ((InflatedTypeSpec) nullableType).TypeArguments[0];
+               }
+
+               public static bool IsNullableType (TypeSpec type)
+               {
+                       throw new NotImplementedException ("net");
                }
        }
 
        public class Unwrap : Expression, IMemoryLocation, IAssignMethod
        {
                Expression expr;
-               NullableInfo info;
 
                LocalTemporary temp;
+               readonly bool useDefaultValue;
 
-               protected Unwrap (Expression expr)
+               Unwrap (Expression expr, bool useDefaultValue)
                {
                        this.expr = expr;
                        this.loc = expr.Location;
+                       this.useDefaultValue = useDefaultValue;
+
+                       type = NullableInfo.GetUnderlyingType (expr.Type);
+                       eclass = expr.eclass;
                }
 
-               public static Unwrap Create (Expression expr, EmitContext ec)
+               public static Expression Create (Expression expr)
                {
-                       return new Unwrap (expr).Resolve (ec) as Unwrap;
+                       //
+                       // Avoid unwraping and wraping of same type
+                       //
+                       Wrap wrap = expr as Wrap;
+                       if (wrap != null)
+                               return wrap.Child;
+
+                       return Create (expr, false);
+               }
+
+               public static Unwrap Create (Expression expr, bool useDefaultValue)
+               {
+                       return new Unwrap (expr, useDefaultValue);
                }
                
-               public override Expression CreateExpressionTree (EmitContext ec)
+               public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        return expr.CreateExpressionTree (ec);
-               }                       
+               }
 
-               public override Expression DoResolve (EmitContext ec)
+               protected override Expression DoResolve (ResolveContext ec)
                {
-                       if (expr == null)
-                               return null;
-
-                       info = new NullableInfo (expr.Type);
-                       type = info.UnderlyingType;
-                       eclass = expr.eclass;
                        return this;
                }
-               
-               public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
+
+               public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
                {
                        return DoResolve (ec);
-               }                       
+               }
 
                public override void Emit (EmitContext ec)
                {
                        Store (ec);
-                       AddressOf (ec, AddressOp.LoadStore);
-                       ec.ig.EmitCall (OpCodes.Call, info.Value, null);
+                       if (useDefaultValue)
+                               Invocation.EmitCall (ec, false, this, NullableInfo.GetGetValueOrDefault (expr.Type), null, loc);
+                       else
+                               Invocation.EmitCall (ec, false, this, NullableInfo.GetValue (expr.Type), null, loc);
                }
 
                public void EmitCheck (EmitContext ec)
                {
                        Store (ec);
-                       AddressOf (ec, AddressOp.LoadStore);
-                       ec.ig.EmitCall (OpCodes.Call, info.HasValue, null);
-               }
-
-               public void EmitGetValueOrDefault (EmitContext ec)
-               {
-                       Store (ec);
-                       AddressOf (ec, AddressOp.LoadStore);
-                       ec.ig.EmitCall (OpCodes.Call, info.GetValueOrDefault, null);
+                       Invocation.EmitCall (ec, false, this, NullableInfo.GetHasValue (expr.Type), null, loc);
                }
 
                public override bool Equals (object obj)
@@ -189,13 +189,9 @@ namespace Mono.CSharp.Nullable
                                LocalVariable.Emit (ec);
                }
 
-               public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
+               public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
                {
-                       type = storey.MutateType (type);
-                       info.Constructor = storey.MutateConstructor (info.Constructor);
-                       info.HasValue = storey.MutateGenericMethod (info.HasValue);
-                       info.GetValueOrDefault = storey.MutateGenericMethod (info.GetValueOrDefault);
-                       info.Value = storey.MutateGenericMethod (info.Value);
+                       return expr.MakeExpression (ctx);
                }
 
                public void AddressOf (EmitContext ec, AddressOp mode)
@@ -213,7 +209,7 @@ namespace Mono.CSharp.Nullable
                LocalTemporary LocalVariable {
                        get {
                                if (temp == null)
-                                       temp = new LocalTemporary (info.Type);
+                                       temp = new LocalTemporary (expr.Type);
                                return temp;
                        }
                }
@@ -229,31 +225,29 @@ namespace Mono.CSharp.Nullable
                public void EmitAssign (EmitContext ec, Expression source,
                                        bool leave_copy, bool prepare_for_load)
                {
-                       InternalWrap wrap = new InternalWrap (source, info, loc);
+                       InternalWrap wrap = new InternalWrap (source, expr.Type, loc);
                        ((IAssignMethod) expr).EmitAssign (ec, wrap, leave_copy, false);
                }
 
-               protected class InternalWrap : Expression
+               class InternalWrap : Expression
                {
                        public Expression expr;
-                       public NullableInfo info;
 
-                       public InternalWrap (Expression expr, NullableInfo info, Location loc)
+                       public InternalWrap (Expression expr, TypeSpec type, Location loc)
                        {
                                this.expr = expr;
-                               this.info = info;
                                this.loc = loc;
+                               this.type = type;
 
-                               type = info.Type;
                                eclass = ExprClass.Value;
                        }
 
-                       public override Expression CreateExpressionTree (EmitContext ec)
+                       public override Expression CreateExpressionTree (ResolveContext ec)
                        {
                                throw new NotSupportedException ("ET");
                        }
 
-                       public override Expression DoResolve (EmitContext ec)
+                       protected override Expression DoResolve (ResolveContext ec)
                        {
                                return this;
                        }
@@ -261,29 +255,37 @@ namespace Mono.CSharp.Nullable
                        public override void Emit (EmitContext ec)
                        {
                                expr.Emit (ec);
-                               ec.ig.Emit (OpCodes.Newobj, info.Constructor);
+                               ec.Emit (OpCodes.Newobj, NullableInfo.GetConstructor (type));
                        }
                }
        }
 
        public class Wrap : TypeCast
        {
-               readonly NullableInfo info;
-
-               protected Wrap (Expression expr, Type type)
+               private Wrap (Expression expr, TypeSpec type)
                        : base (expr, type)
                {
-                       info = new NullableInfo (type);
                        eclass = ExprClass.Value;
                }
 
-               public static Expression Create (Expression expr, Type type)
+               public override Expression CreateExpressionTree (ResolveContext ec)
+               {
+                       TypeCast child_cast = child as TypeCast;
+                       if (child_cast != null) {
+                               child.Type = type;
+                               return child_cast.CreateExpressionTree (ec);
+                       }
+
+                       return base.CreateExpressionTree (ec);
+               }
+
+               public static Expression Create (Expression expr, TypeSpec type)
                {
                        //
                        // Avoid unwraping and wraping of the same type
                        //
                        Unwrap unwrap = expr as Unwrap;
-                       if (unwrap != null && TypeManager.IsEqual (expr.Type, TypeManager.GetTypeArguments (type) [0]))
+                       if (unwrap != null && TypeManager.IsEqual (expr.Type, NullableInfo.GetUnderlyingType (type)))
                                return unwrap.Original;
                
                        return new Wrap (expr, type);
@@ -292,50 +294,41 @@ namespace Mono.CSharp.Nullable
                public override void Emit (EmitContext ec)
                {
                        child.Emit (ec);
-                       ec.ig.Emit (OpCodes.Newobj, info.Constructor);
+                       ec.Emit (OpCodes.Newobj, NullableInfo.GetConstructor (type));
                }
        }
 
        //
        // Represents null literal lifted to nullable type
        //
-       public class LiftedNull : EmptyConstantCast, IMemoryLocation
+       public class LiftedNull : NullConstant, IMemoryLocation
        {
-               private LiftedNull (Type nullable_type, Location loc)
-                       : base (new NullLiteral (loc), nullable_type)
+               private LiftedNull (TypeSpec nullable_type, Location loc)
+                       : base (nullable_type, loc)
                {
                        eclass = ExprClass.Value;
                }
 
-               public static Constant Create (Type nullable, Location loc)
+               public static Constant Create (TypeSpec nullable, Location loc)
                {
                        return new LiftedNull (nullable, loc);
                }
 
-               public static Expression CreateFromExpression (Expression e)
+               public static Expression CreateFromExpression (ResolveContext ec, Expression e)
                {
-                       Report.Warning (458, 2, e.Location, "The result of the expression is always `null' of type `{0}'",
+                       ec.Report.Warning (458, 2, e.Location, "The result of the expression is always `null' of type `{0}'",
                                TypeManager.CSharpName (e.Type));
 
                        return ReducedExpression.Create (Create (e.Type, e.Location), e);
                }
 
-               public override Expression CreateExpressionTree (EmitContext ec)
-               {
-                       ArrayList args = new ArrayList (2);
-                       args.Add (new Argument (this));
-                       args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
-
-                       return CreateExpressionFactoryCall ("Constant", args);
-               }
-
                public override void Emit (EmitContext ec)
                {
                        // TODO: generate less temporary variables
                        LocalTemporary value_target = new LocalTemporary (type);
 
                        value_target.AddressOf (ec, AddressOp.Store);
-                       ec.ig.Emit (OpCodes.Initobj, type);
+                       ec.Emit (OpCodes.Initobj, type);
                        value_target.Emit (ec);
                }
 
@@ -344,78 +337,81 @@ namespace Mono.CSharp.Nullable
                        LocalTemporary value_target = new LocalTemporary (type);
                                
                        value_target.AddressOf (ec, AddressOp.Store);
-                       ec.ig.Emit (OpCodes.Initobj, type);
+                       ec.Emit (OpCodes.Initobj, type);
                        ((IMemoryLocation) value_target).AddressOf (ec, Mode);
                }
        }
 
-       public abstract class Lifted : Expression, IMemoryLocation
+       //
+       // Generic lifting expression, supports all S/S? -> T/T? cases
+       //
+       public class Lifted : Expression, IMemoryLocation
        {
-               Expression expr, underlying, wrap, null_value;
+               Expression expr, null_value;
                Unwrap unwrap;
 
-               protected Lifted (Expression expr, Location loc)
+               public Lifted (Expression expr, Unwrap unwrap, TypeSpec type)
                {
                        this.expr = expr;
-                       this.loc = loc;
+                       this.unwrap = unwrap;
+                       this.loc = expr.Location;
+                       this.type = type;
+               }
+
+               public Lifted (Expression expr, Expression unwrap, TypeSpec type)
+                       : this (expr, unwrap as Unwrap, type)
+               {
                }
                
-               public override Expression CreateExpressionTree (EmitContext ec)
+               public override Expression CreateExpressionTree (ResolveContext ec)
                {
-                       ArrayList args = new ArrayList (2);
-                       args.Add (new Argument (expr.CreateExpressionTree (ec)));
-                       args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
-                       return CreateExpressionFactoryCall ("Convert", args);
+                       return expr.CreateExpressionTree (ec);
                }                       
 
-               public override Expression DoResolve (EmitContext ec)
+               protected override Expression DoResolve (ResolveContext ec)
                {
-                       expr = expr.Resolve (ec);
-                       if (expr == null)
-                               return null;
-
-                       unwrap = Unwrap.Create (expr, ec);
-                       if (unwrap == null)
-                               return null;
-
-                       underlying = ResolveUnderlying (unwrap, ec);
-                       if (underlying == null)
-                               return null;
+                       //
+                       // It's null when lifting non-nullable type
+                       //
+                       if (unwrap == null) {
+                               // S -> T? is wrap only
+                               if (TypeManager.IsNullableType (type))
+                                       return Wrap.Create (expr, type);
 
-                       TypeExpr target_type = new NullableType (underlying.Type, loc);
-                       target_type = target_type.ResolveAsTypeTerminal (ec, false);
-                       if (target_type == null)
-                               return null;
+                               // S -> T can be simplified
+                               return expr;
+                       }
 
-                       wrap = Wrap.Create (underlying, target_type.Type);
-                       if (wrap == null)
-                               return null;
+                       // Wrap target for T?
+                       if (TypeManager.IsNullableType (type)) {
+                               expr = Wrap.Create (expr, type);
+                               if (expr == null)
+                                       return null;
 
-                       null_value = LiftedNull.Create (wrap.Type, loc);
+                               null_value = LiftedNull.Create (type, loc);
+                       } else {
+                               null_value = new NullConstant (type, loc);
+                       }
 
-                       type = wrap.Type;
                        eclass = ExprClass.Value;
                        return this;
                }
 
-               protected abstract Expression ResolveUnderlying (Expression unwrap, EmitContext ec);
-
                public override void Emit (EmitContext ec)
                {
-                       ILGenerator ig = ec.ig;
-                       Label is_null_label = ig.DefineLabel ();
-                       Label end_label = ig.DefineLabel ();
+                       Label is_null_label = ec.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
                        unwrap.EmitCheck (ec);
-                       ig.Emit (OpCodes.Brfalse, is_null_label);
+                       ec.Emit (OpCodes.Brfalse, is_null_label);
+
+                       expr.Emit (ec);
 
-                       wrap.Emit (ec);
-                       ig.Emit (OpCodes.Br, end_label);
+                       ec.Emit (OpCodes.Br, end_label);
+                       ec.MarkLabel (is_null_label);
 
-                       ig.MarkLabel (is_null_label);
                        null_value.Emit (ec);
-
-                       ig.MarkLabel (end_label);
+                       ec.MarkLabel (end_label);
                }
 
                public void AddressOf (EmitContext ec, AddressOp mode)
@@ -424,46 +420,13 @@ namespace Mono.CSharp.Nullable
                }
        }
 
-       public class LiftedConversion : Lifted
-       {
-               public readonly bool IsUser;
-               public readonly bool IsExplicit;
-               public readonly Type TargetType;
-
-               public LiftedConversion (Expression expr, Type target_type, bool is_user,
-                                        bool is_explicit, Location loc)
-                       : base (expr, loc)
-               {
-                       this.IsUser = is_user;
-                       this.IsExplicit = is_explicit;
-                       this.TargetType = target_type;
-               }
-
-               protected override Expression ResolveUnderlying (Expression unwrap, EmitContext ec)
-               {
-                       Type type = TypeManager.GetTypeArguments (TargetType) [0];
-
-                       if (IsUser) {
-                               if (IsExplicit)
-                                       return Convert.ExplicitUserConversion (ec, unwrap, type, loc);
-                               else
-                                       return Convert.ImplicitUserConversion (ec, unwrap, type, loc);
-                       } else {
-                               if (IsExplicit)
-                                       return Convert.ExplicitConversion (ec, unwrap, type, loc);
-                               else
-                                       return Convert.ImplicitConversion (ec, unwrap, type, loc);
-                       }
-               }
-       }
-
        public class LiftedUnaryOperator : Unary, IMemoryLocation
        {
                Unwrap unwrap;
                Expression user_operator;
 
-               public LiftedUnaryOperator (Unary.Operator op, Expression expr)
-                       : base (op, expr)
+               public LiftedUnaryOperator (Unary.Operator op, Expression expr, Location loc)
+                       : base (op, expr, loc)
                {
                }
 
@@ -472,7 +435,7 @@ namespace Mono.CSharp.Nullable
                        unwrap.AddressOf (ec, mode);
                }
 
-               public override Expression CreateExpressionTree (EmitContext ec)
+               public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        if (user_operator != null)
                                return user_operator.CreateExpressionTree (ec);
@@ -483,12 +446,9 @@ namespace Mono.CSharp.Nullable
                        return base.CreateExpressionTree (ec);
                }
 
-               public override Expression DoResolve (EmitContext ec)
+               protected override Expression DoResolve (ResolveContext ec)
                {
-                       if (eclass != ExprClass.Invalid)
-                               return this;
-
-                       unwrap = Unwrap.Create (Expr, ec);
+                       unwrap = Unwrap.Create (Expr, false);
                        if (unwrap == null)
                                return null;
 
@@ -510,31 +470,28 @@ namespace Mono.CSharp.Nullable
 
                public override void Emit (EmitContext ec)
                {
-                       ILGenerator ig = ec.ig;
-                       Label is_null_label = ig.DefineLabel ();
-                       Label end_label = ig.DefineLabel ();
+                       Label is_null_label = ec.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
                        unwrap.EmitCheck (ec);
-                       ig.Emit (OpCodes.Brfalse, is_null_label);
-
-                       NullableInfo ni = new NullableInfo (type);
+                       ec.Emit (OpCodes.Brfalse, is_null_label);
 
                        if (user_operator != null) {
                                user_operator.Emit (ec);
                        } else {
-                               EmitOperator (ec, ni.UnderlyingType);
+                               EmitOperator (ec, NullableInfo.GetUnderlyingType (type));
                        }
 
-                       ig.Emit (OpCodes.Newobj, ni.Constructor);
-                       ig.Emit (OpCodes.Br_S, end_label);
+                       ec.Emit (OpCodes.Newobj, NullableInfo.GetConstructor (type));
+                       ec.Emit (OpCodes.Br_S, end_label);
 
-                       ig.MarkLabel (is_null_label);
+                       ec.MarkLabel (is_null_label);
                        LiftedNull.Create (type, loc).Emit (ec);
 
-                       ig.MarkLabel (end_label);
+                       ec.MarkLabel (end_label);
                }
 
-               Expression LiftExpression (EmitContext ec, Expression expr)
+               Expression LiftExpression (ResolveContext ec, Expression expr)
                {
                        TypeExpr lifted_type = new NullableType (expr.Type, expr.Location);
                        lifted_type = lifted_type.ResolveAsTypeTerminal (ec, false);
@@ -545,7 +502,7 @@ namespace Mono.CSharp.Nullable
                        return expr;
                }
 
-               protected override Expression ResolveEnumOperator (EmitContext ec, Expression expr)
+               protected override Expression ResolveEnumOperator (ResolveContext ec, Expression expr)
                {
                        expr = base.ResolveEnumOperator (ec, expr);
                        if (expr == null)
@@ -555,7 +512,7 @@ namespace Mono.CSharp.Nullable
                        return LiftExpression (ec, expr);
                }
 
-               protected override Expression ResolveUserOperator (EmitContext ec, Expression expr)
+               protected override Expression ResolveUserOperator (ResolveContext ec, Expression expr)
                {
                        expr = base.ResolveUserOperator (ec, expr);
                        if (expr == null)
@@ -579,16 +536,14 @@ namespace Mono.CSharp.Nullable
                bool left_null_lifted, right_null_lifted;
                Expression left_orig, right_orig;
                Expression user_operator;
-               ConstructorInfo wrap_ctor;
+               MethodSpec wrap_ctor;
 
-               public LiftedBinaryOperator (Binary.Operator op, Expression left, Expression right,
-                                            Location loc)
-                       : base (op, left, right)
+               public LiftedBinaryOperator (Binary.Operator op, Expression left, Expression right, Location loc)
+                       : base (op, left, right, loc)
                {
-                       this.loc = loc;
                }
 
-               public override Expression CreateExpressionTree (EmitContext ec)
+               public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        if (user_operator != null)
                                return user_operator.CreateExpressionTree (ec);
@@ -601,42 +556,40 @@ namespace Mono.CSharp.Nullable
                // with the null literal *outside* of a generics context and
                // inlines that as true or false.
                //
-               Expression CreateNullConstant (Expression expr)
+               Expression CreateNullConstant (ResolveContext ec, Expression expr)
                {
                        // FIXME: Handle side effect constants
-                       Constant c = new BoolConstant (Oper == Operator.Inequality, loc);
+                       Constant c = new BoolConstant (Oper == Operator.Inequality, loc).Resolve (ec);
 
                        if ((Oper & Operator.EqualityMask) != 0) {
-                               Report.Warning (472, 2, loc, "The result of comparing value type `{0}' with null is `{1}'",
-                                               expr.GetSignatureForError (), c.AsString ());
+                               ec.Report.Warning (472, 2, loc, "The result of comparing value type `{0}' with null is `{1}'",
+                                       TypeManager.CSharpName (expr.Type), c.AsString ());
                        } else {
-                               Report.Warning (464, 2, loc, "The result of comparing type `{0}' with null is always `{1}'",
-                                               expr.GetSignatureForError (), c.AsString ());
+                               ec.Report.Warning (464, 2, loc, "The result of comparing type `{0}' with null is always `{1}'",
+                                       TypeManager.CSharpName (expr.Type), c.AsString ());
                        }
 
                        return ReducedExpression.Create (c, this);
                }
 
-               public override Expression DoResolve (EmitContext ec)
+               protected override Expression DoResolve (ResolveContext ec)
                {
-                       if (eclass != ExprClass.Invalid)
-                               return this;
-
                        if ((Oper & Operator.LogicalMask) != 0) {
-                               Error_OperatorCannotBeApplied (left, right);
+                               Error_OperatorCannotBeApplied (ec, left, right);
                                return null;
                        }
 
+                       bool use_default_call = (Oper & (Operator.BitwiseMask | Operator.EqualityMask)) != 0;
                        left_orig = left;
                        if (TypeManager.IsNullableType (left.Type)) {
-                               left = left_unwrap = Unwrap.Create (left, ec);
+                               left = left_unwrap = Unwrap.Create (left, use_default_call);
                                if (left == null)
                                        return null;
                        }
 
                        right_orig = right;
                        if (TypeManager.IsNullableType (right.Type)) {
-                               right = right_unwrap = Unwrap.Create (right, ec);
+                               right = right_unwrap = Unwrap.Create (right, use_default_call);
                                if (right == null)
                                        return null;
                        }
@@ -646,13 +599,13 @@ namespace Mono.CSharp.Nullable
                        // Arguments can be lifted for equal operators when the return type is bool and both
                        // arguments are of same type
                        //      
-                       if (left is NullLiteral) {
+                       if (left_orig.IsNull) {
                                left = right;
                                left_null_lifted = true;
                                type = TypeManager.bool_type;
                        }
 
-                       if (right is NullLiteral) {
+                       if (right_orig.IsNull) {
                                right = left;
                                right_null_lifted = true;
                                type = TypeManager.bool_type;
@@ -664,23 +617,21 @@ namespace Mono.CSharp.Nullable
 
                void EmitBitwiseBoolean (EmitContext ec)
                {
-                       ILGenerator ig = ec.ig;
+                       Label load_left = ec.DefineLabel ();
+                       Label load_right = ec.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
-                       Label load_left = ig.DefineLabel ();
-                       Label load_right = ig.DefineLabel ();
-                       Label end_label = ig.DefineLabel ();
+                       left_unwrap.Emit (ec);
+                       ec.Emit (OpCodes.Brtrue_S, load_right);
 
-                       left_unwrap.EmitGetValueOrDefault (ec);
-                       ig.Emit (OpCodes.Brtrue_S, load_right);
-
-                       right_unwrap.EmitGetValueOrDefault (ec);
-                       ig.Emit (OpCodes.Brtrue_S, load_left);
+                       right_unwrap.Emit (ec);
+                       ec.Emit (OpCodes.Brtrue_S, load_left);
 
                        left_unwrap.EmitCheck (ec);
-                       ig.Emit (OpCodes.Brfalse_S, load_right);
+                       ec.Emit (OpCodes.Brfalse_S, load_right);
 
                        // load left
-                       ig.MarkLabel (load_left);
+                       ec.MarkLabel (load_left);
 
                        if (Oper == Operator.BitwiseAnd) {
                                left_unwrap.Load (ec);
@@ -688,94 +639,87 @@ namespace Mono.CSharp.Nullable
                                right_unwrap.Load (ec);
                                right_unwrap = left_unwrap;
                        }
-                       ig.Emit (OpCodes.Br_S, end_label);
+                       ec.Emit (OpCodes.Br_S, end_label);
 
                        // load right
-                       ig.MarkLabel (load_right);
+                       ec.MarkLabel (load_right);
                        right_unwrap.Load (ec);
 
-                       ig.MarkLabel (end_label);
+                       ec.MarkLabel (end_label);
                }
 
                //
                // Emits optimized equality or inequality operator when possible
                //
-               bool EmitEquality (EmitContext ec)
+               void EmitEquality (EmitContext ec)
                {
-                       ILGenerator ig = ec.ig;
-
                        //
                        // Either left or right is null
                        //
                        if (left_unwrap != null && (right_null_lifted || right.IsNull)) {
                                left_unwrap.EmitCheck (ec);
                                if (Oper == Binary.Operator.Equality) {
-                                       ig.Emit (OpCodes.Ldc_I4_0);
-                                       ig.Emit (OpCodes.Ceq);
+                                       ec.Emit (OpCodes.Ldc_I4_0);
+                                       ec.Emit (OpCodes.Ceq);
                                }
-                               return true;
+                               return;
                        }
 
                        if (right_unwrap != null && (left_null_lifted || left.IsNull)) {
                                right_unwrap.EmitCheck (ec);
                                if (Oper == Binary.Operator.Equality) {
-                                       ig.Emit (OpCodes.Ldc_I4_0);
-                                       ig.Emit (OpCodes.Ceq);
+                                       ec.Emit (OpCodes.Ldc_I4_0);
+                                       ec.Emit (OpCodes.Ceq);
                                }
-                               return true;
+                               return;
                        }
 
-                       if (user_operator != null)
-                               return false;
-
-                       Label dissimilar_label = ig.DefineLabel ();
-                       Label end_label = ig.DefineLabel ();
+                       Label dissimilar_label = ec.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
-                       if (left_unwrap != null)
-                               left_unwrap.EmitGetValueOrDefault (ec);
-                       else
+                       if (user_operator != null) {
+                               user_operator.Emit (ec);
+                               ec.Emit (Oper == Operator.Equality ? OpCodes.Brfalse_S : OpCodes.Brtrue_S, dissimilar_label);
+                       } else {
                                left.Emit (ec);
-
-                       if (right_unwrap != null)
-                               right_unwrap.EmitGetValueOrDefault (ec);
-                       else
                                right.Emit (ec);
 
-                       ig.Emit (OpCodes.Bne_Un_S, dissimilar_label);
+                               ec.Emit (OpCodes.Bne_Un_S, dissimilar_label);
+                       }
 
                        if (left_unwrap != null)
                                left_unwrap.EmitCheck (ec);
+
                        if (right_unwrap != null)
                                right_unwrap.EmitCheck (ec);
 
                        if (left_unwrap != null && right_unwrap != null) {
                                if (Oper == Operator.Inequality)
-                                       ig.Emit (OpCodes.Xor);
+                                       ec.Emit (OpCodes.Xor);
                                else
-                                       ig.Emit (OpCodes.Ceq);
+                                       ec.Emit (OpCodes.Ceq);
                        } else {
                                if (Oper == Operator.Inequality) {
-                                       ig.Emit (OpCodes.Ldc_I4_0);
-                                       ig.Emit (OpCodes.Ceq);
+                                       ec.Emit (OpCodes.Ldc_I4_0);
+                                       ec.Emit (OpCodes.Ceq);
                                }
                        }
 
-                       ig.Emit (OpCodes.Br_S, end_label);
+                       ec.Emit (OpCodes.Br_S, end_label);
 
-                       ig.MarkLabel (dissimilar_label);
+                       ec.MarkLabel (dissimilar_label);
                        if (Oper == Operator.Inequality)
-                               ig.Emit (OpCodes.Ldc_I4_1);
+                               ec.Emit (OpCodes.Ldc_I4_1);
                        else
-                               ig.Emit (OpCodes.Ldc_I4_0);
+                               ec.Emit (OpCodes.Ldc_I4_0);
 
-                       ig.MarkLabel (end_label);
-                       return true;
+                       ec.MarkLabel (end_label);
                }
                
                public override void EmitBranchable (EmitContext ec, Label target, bool onTrue)
                {
                        Emit (ec);
-                       ec.ig.Emit (onTrue ? OpCodes.Brtrue : OpCodes.Brfalse, target);
+                       ec.Emit (onTrue ? OpCodes.Brtrue : OpCodes.Brfalse, target);
                }                       
 
                public override void Emit (EmitContext ec)
@@ -792,18 +736,16 @@ namespace Mono.CSharp.Nullable
                        }
 
                        if ((Oper & Operator.EqualityMask) != 0) {
-                               if (EmitEquality (ec))
-                                       return;
+                               EmitEquality (ec);
+                               return;
                        }
 
-                       ILGenerator ig = ec.ig;
-
-                       Label is_null_label = ig.DefineLabel ();
-                       Label end_label = ig.DefineLabel ();
+                       Label is_null_label = ec.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
                        if (left_unwrap != null) {
                                left_unwrap.EmitCheck (ec);
-                               ig.Emit (OpCodes.Brfalse, is_null_label);
+                               ec.Emit (OpCodes.Brfalse, is_null_label);
                        }
 
                        //
@@ -811,35 +753,27 @@ namespace Mono.CSharp.Nullable
                        //
                        if (right_unwrap != null && !left.Equals (right)) {
                                right_unwrap.EmitCheck (ec);
-                               ig.Emit (OpCodes.Brfalse, is_null_label);
+                               ec.Emit (OpCodes.Brfalse, is_null_label);
                        }
 
                        EmitOperator (ec, left.Type);
 
                        if (wrap_ctor != null)
-                               ig.Emit (OpCodes.Newobj, wrap_ctor);
+                               ec.Emit (OpCodes.Newobj, wrap_ctor);
 
-                       ig.Emit (OpCodes.Br_S, end_label);
-                       ig.MarkLabel (is_null_label);
+                       ec.Emit (OpCodes.Br_S, end_label);
+                       ec.MarkLabel (is_null_label);
 
                        if ((Oper & Operator.ComparisonMask) != 0) {
-                               //
-                               // Emit true when equality operator both operands are null
-                               // or inequality operator operands has only one null
-                               //
-                               if ((Oper == Operator.Equality && left_unwrap != null && right_unwrap != null) ||
-                                       (Oper == Operator.Inequality && left_unwrap != right_unwrap))
-                                       ig.Emit (OpCodes.Ldc_I4_1);
-                               else
-                                       ig.Emit (OpCodes.Ldc_I4_0);
+                               ec.Emit (OpCodes.Ldc_I4_0);
                        } else {
                                LiftedNull.Create (type, loc).Emit (ec);
                        }
 
-                       ig.MarkLabel (end_label);
+                       ec.MarkLabel (end_label);
                }
 
-               protected override void EmitOperator (EmitContext ec, Type l)
+               protected override void EmitOperator (EmitContext ec, TypeSpec l)
                {
                        if (user_operator != null) {
                                user_operator.Emit (ec);
@@ -859,7 +793,7 @@ namespace Mono.CSharp.Nullable
                        }
                }
 
-               Expression LiftResult (EmitContext ec, Expression res_expr)
+               Expression LiftResult (ResolveContext ec, Expression res_expr)
                {
                        TypeExpr lifted_type;
 
@@ -896,40 +830,40 @@ namespace Mono.CSharp.Nullable
                                if (lifted_type == null)
                                        return null;
 
-                               wrap_ctor = new NullableInfo (lifted_type.Type).Constructor;
+                               wrap_ctor = NullableInfo.GetConstructor (lifted_type.Type);
                                type = res_expr.Type = lifted_type.Type;
                        }
 
                        if (left_null_lifted) {
                                left = LiftedNull.Create (right.Type, left.Location);
 
-                               if ((Oper & (Operator.ArithmeticMask | Operator.ShiftMask)) != 0)
-                                       return LiftedNull.CreateFromExpression (res_expr);
+                               if ((Oper & (Operator.ArithmeticMask | Operator.ShiftMask | Operator.BitwiseMask)) != 0)
+                                       return LiftedNull.CreateFromExpression (ec, res_expr);
 
                                //
                                // Value types and null comparison
                                //
                                if (right_unwrap == null || (Oper & Operator.RelationalMask) != 0)
-                                       return CreateNullConstant (right_orig).Resolve (ec);
+                                       return CreateNullConstant (ec, right_orig).Resolve (ec);
                        }
 
                        if (right_null_lifted) {
                                right = LiftedNull.Create (left.Type, right.Location);
 
-                               if ((Oper & (Operator.ArithmeticMask | Operator.ShiftMask)) != 0)
-                                       return LiftedNull.CreateFromExpression (res_expr);
+                               if ((Oper & (Operator.ArithmeticMask | Operator.ShiftMask | Operator.BitwiseMask)) != 0)
+                                       return LiftedNull.CreateFromExpression (ec, res_expr);
 
                                //
                                // Value types and null comparison
                                //
                                if (left_unwrap == null || (Oper & Operator.RelationalMask) != 0)
-                                       return CreateNullConstant (left_orig).Resolve (ec);
+                                       return CreateNullConstant (ec, left_orig);
                        }
 
                        return res_expr;
                }
 
-               protected override Expression ResolveOperatorPredefined (EmitContext ec, Binary.PredefinedOperator [] operators, bool primitives_only, Type enum_type)
+               protected override Expression ResolveOperatorPredefined (ResolveContext ec, Binary.PredefinedOperator [] operators, bool primitives_only, TypeSpec enum_type)
                {
                        Expression e = base.ResolveOperatorPredefined (ec, operators, primitives_only, enum_type);
 
@@ -951,7 +885,7 @@ namespace Mono.CSharp.Nullable
                        return e;
                }
 
-               protected override Expression ResolveUserOperator (EmitContext ec, Type l, Type r)
+               protected override Expression ResolveUserOperator (ResolveContext ec, TypeSpec l, TypeSpec r)
                {
                        Expression expr = base.ResolveUserOperator (ec, l, r);
                        if (expr == null)
@@ -979,45 +913,45 @@ namespace Mono.CSharp.Nullable
                        this.loc = loc;
                }
                
-               public override Expression CreateExpressionTree (EmitContext ec)
+               public override Expression CreateExpressionTree (ResolveContext ec)
                {
-                       if (left is NullLiteral)
-                               Report.Error (845, loc, "An expression tree cannot contain a coalescing operator with null left side");
+                       if (left.Type == TypeManager.null_type)
+                               ec.Report.Error (845, loc, "An expression tree cannot contain a coalescing operator with null left side");
 
                        UserCast uc = left as UserCast;
                        Expression conversion = null;
                        if (uc != null) {
                                left = uc.Source;
 
-                               ArrayList c_args = new ArrayList (2);
+                               Arguments c_args = new Arguments (2);
                                c_args.Add (new Argument (uc.CreateExpressionTree (ec)));
                                c_args.Add (new Argument (left.CreateExpressionTree (ec)));
-                               conversion = CreateExpressionFactoryCall ("Lambda", c_args);
+                               conversion = CreateExpressionFactoryCall (ec, "Lambda", c_args);
                        }
 
-                       ArrayList args = new ArrayList (3);
+                       Arguments args = new Arguments (3);
                        args.Add (new Argument (left.CreateExpressionTree (ec)));
                        args.Add (new Argument (right.CreateExpressionTree (ec)));
                        if (conversion != null)
                                args.Add (new Argument (conversion));
                        
-                       return CreateExpressionFactoryCall ("Coalesce", args);
+                       return CreateExpressionFactoryCall (ec, "Coalesce", args);
                }
 
-               Expression ConvertExpression (EmitContext ec)
+               Expression ConvertExpression (ResolveContext ec)
                {
                        // TODO: ImplicitConversionExists should take care of this
                        if (left.eclass == ExprClass.MethodGroup)
                                return null;
 
-                       Type ltype = left.Type;
+                       TypeSpec ltype = left.Type;
 
                        //
                        // If left is a nullable type and an implicit conversion exists from right to underlying type of left,
                        // the result is underlying type of left
                        //
                        if (TypeManager.IsNullableType (ltype)) {
-                               unwrap = Unwrap.Create (left, ec);
+                               unwrap = Unwrap.Create (left, false);
                                if (unwrap == null)
                                        return null;
 
@@ -1040,7 +974,7 @@ namespace Mono.CSharp.Nullable
                                        // Reduce (left ?? null) to left OR (null-constant ?? right) to right
                                        //
                                        if (right.IsNull || lc != null)
-                                               return ReducedExpression.Create (lc != null ? right : left, this).Resolve (ec);
+                                               return ReducedExpression.Create (lc != null ? right : left, this);
 
                                        right = Convert.ImplicitConversion (ec, right, ltype, loc);
                                        type = left.Type;
@@ -1050,7 +984,7 @@ namespace Mono.CSharp.Nullable
                                return null;
                        }
 
-                       Type rtype = right.Type;
+                       TypeSpec rtype = right.Type;
                        if (!Convert.ImplicitConversionExists (ec, unwrap != null ? unwrap : left, rtype) || right.eclass == ExprClass.MethodGroup)
                                return null;
 
@@ -1058,18 +992,15 @@ namespace Mono.CSharp.Nullable
                        // Reduce (null ?? right) to right
                        //
                        if (left.IsNull)
-                               return ReducedExpression.Create (right, this).Resolve (ec);
+                               return ReducedExpression.Create (right, this);
 
                        left = Convert.ImplicitConversion (ec, unwrap != null ? unwrap : left, rtype, loc);
                        type = rtype;
                        return this;
                }
 
-               public override Expression DoResolve (EmitContext ec)
+               protected override Expression DoResolve (ResolveContext ec)
                {
-                       if (eclass != ExprClass.Invalid)
-                               return this;
-
                        left = left.Resolve (ec);
                        right = right.Resolve (ec);
 
@@ -1080,7 +1011,7 @@ namespace Mono.CSharp.Nullable
 
                        Expression e = ConvertExpression (ec);
                        if (e == null) {
-                               Binary.Error_OperatorCannotBeApplied (left, right, "??", loc);
+                               Binary.Error_OperatorCannotBeApplied (ec, left, right, "??", loc);
                                return null;
                        }
 
@@ -1089,42 +1020,33 @@ namespace Mono.CSharp.Nullable
 
                public override void Emit (EmitContext ec)
                {
-                       ILGenerator ig = ec.ig;
-
-                       Label end_label = ig.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
                        if (unwrap != null) {
-                               Label is_null_label = ig.DefineLabel ();
+                               Label is_null_label = ec.DefineLabel ();
 
                                unwrap.EmitCheck (ec);
-                               ig.Emit (OpCodes.Brfalse, is_null_label);
+                               ec.Emit (OpCodes.Brfalse, is_null_label);
 
                                left.Emit (ec);
-                               ig.Emit (OpCodes.Br, end_label);
+                               ec.Emit (OpCodes.Br, end_label);
 
-                               ig.MarkLabel (is_null_label);
+                               ec.MarkLabel (is_null_label);
                                right.Emit (ec);
 
-                               ig.MarkLabel (end_label);
+                               ec.MarkLabel (end_label);
                                return;
                        }
 
                        left.Emit (ec);
 
-                       ig.Emit (OpCodes.Dup);
-                       ig.Emit (OpCodes.Brtrue, end_label);
+                       ec.Emit (OpCodes.Dup);
+                       ec.Emit (OpCodes.Brtrue, end_label);
 
-                       ig.Emit (OpCodes.Pop);
+                       ec.Emit (OpCodes.Pop);
                        right.Emit (ec);
 
-                       ig.MarkLabel (end_label);
-               }
-
-               public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
-               {
-                       left.MutateHoistedGenericType (storey);
-                       right.MutateHoistedGenericType (storey);
-                       type = storey.MutateType (type);
+                       ec.MarkLabel (end_label);
                }
 
                protected override void CloneTo (CloneContext clonectx, Expression t)
@@ -1148,54 +1070,53 @@ namespace Mono.CSharp.Nullable
                        this.expr = expr;
                        this.Mode = mode;
                        this.loc = loc;
-
-                       eclass = ExprClass.Value;
                }
 
-               public override Expression CreateExpressionTree (EmitContext ec)
+               public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        return new SimpleAssign (this, this).CreateExpressionTree (ec);
                }
 
-               public override Expression DoResolve (EmitContext ec)
+               protected override Expression DoResolve (ResolveContext ec)
                {
                        expr = expr.Resolve (ec);
                        if (expr == null)
                                return null;
 
-                       unwrap = Unwrap.Create (expr, ec);
+                       unwrap = Unwrap.Create (expr, false);
                        if (unwrap == null)
                                return null;
 
-                       underlying = (UnaryMutator) new UnaryMutator (Mode, unwrap).Resolve (ec);
+                       underlying = (UnaryMutator) new UnaryMutator (Mode, unwrap, loc).Resolve (ec);
                        if (underlying == null)
                                return null;
 
+
+                       eclass = ExprClass.Value;
                        type = expr.Type;
                        return this;
                }
 
                void DoEmit (EmitContext ec, bool is_expr)
                {
-                       ILGenerator ig = ec.ig;
-                       Label is_null_label = ig.DefineLabel ();
-                       Label end_label = ig.DefineLabel ();
+                       Label is_null_label = ec.DefineLabel ();
+                       Label end_label = ec.DefineLabel ();
 
                        unwrap.EmitCheck (ec);
-                       ig.Emit (OpCodes.Brfalse, is_null_label);
+                       ec.Emit (OpCodes.Brfalse, is_null_label);
 
                        if (is_expr) {
                                underlying.Emit (ec);
-                               ig.Emit (OpCodes.Br_S, end_label);
+                               ec.Emit (OpCodes.Br_S, end_label);
                        } else {
                                underlying.EmitStatement (ec);
                        }
 
-                       ig.MarkLabel (is_null_label);
+                       ec.MarkLabel (is_null_label);
                        if (is_expr)
                                LiftedNull.Create (type, loc).Emit (ec);
 
-                       ig.MarkLabel (end_label);
+                       ec.MarkLabel (end_label);
                }
 
                public override void Emit (EmitContext ec)