2005-01-19 Sureshkumar T <tsureshkumar@novell.com>
[mono.git] / mcs / gmcs / convert.cs
index 52dfd88c8a506f6cc841c03197cc945a78c6c81e..e6bdf4674c0c7a0c35c58e5000ac1e8785e4e066 100644 (file)
@@ -19,7 +19,17 @@ namespace Mono.CSharp {
        // A container class for all the conversion operations
        //
        public class Convert {
-               static void Error_CannotConvertType (Location loc, Type source, Type target)
+               //
+               // This is used to prettify the code: a null argument is allowed
+               // for ImplicitStandardConversion as long as it is known that
+               // no anonymous method will play a role.
+               //
+               // FIXME: renamed from `const' to `static' to allow bootstraping from older
+               // versions of the compiler that could not cope with this construct.
+               //
+               public static EmitContext ConstantEC = null;
+               
+               static public void Error_CannotConvertType (Location loc, Type source, Type target)
                {
                        Report.Error (30, loc, "Cannot convert type '" +
                                      TypeManager.CSharpName (source) + "' to '" +
@@ -42,16 +52,93 @@ namespace Mono.CSharp {
 
                static bool TypeParameter_to_Null (Type target_type)
                {
-                       if ((target_type.BaseType == null) ||
-                           (target_type.BaseType == TypeManager.value_type) ||
-                           target_type.BaseType.IsValueType)
+                       GenericConstraints gc = TypeManager.GetTypeParameterConstraints (target_type);
+                       if (gc == null)
                                return false;
 
-                       return true;
+                       if (gc.HasReferenceTypeConstraint)
+                               return true;
+                       if (gc.HasClassConstraint && !TypeManager.IsValueType (gc.ClassConstraint))
+                               return true;
+
+                       return false;
+               }
+
+               static Type TypeParam_EffectiveBaseType (EmitContext ec, Type t)
+               {
+                       GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
+                       if (gc == null)
+                               return TypeManager.object_type;
+
+                       return TypeParam_EffectiveBaseType (ec, gc);
+               }
+
+               static Type TypeParam_EffectiveBaseType (EmitContext ec, GenericConstraints gc)
+               {
+                       ArrayList list = new ArrayList ();
+                       list.Add (gc.EffectiveBaseClass);
+                       foreach (Type t in gc.InterfaceConstraints) {
+                               if (!t.IsGenericParameter)
+                                       continue;
+
+                               GenericConstraints new_gc = TypeManager.GetTypeParameterConstraints (t);
+                               if (new_gc != null)
+                                       list.Add (TypeParam_EffectiveBaseType (ec, new_gc));
+                       }
+                       return FindMostEncompassedType (ec, list);
+               }
+
+               static Expression TypeParameterConversion (Expression expr, bool is_reference, Type target_type)
+               {
+                       if (is_reference)
+                               return new EmptyCast (expr, target_type);
+                       else
+                               return new BoxedCast (expr, target_type);
+               }
+
+               static Expression ImplicitTypeParameterConversion (EmitContext ec, Expression expr,
+                                                                  Type target_type)
+               {
+                       Type expr_type = expr.Type;
+
+                       GenericConstraints gc = TypeManager.GetTypeParameterConstraints (expr_type);
+
+                       if (gc == null) {
+                               if (target_type == TypeManager.object_type)
+                                       return new BoxedCast (expr);
+
+                               return null;
+                       }
+
+                       // We're converting from a type parameter which is known to be a reference type.
+                       bool is_reference = gc.IsReferenceType;
+                       Type base_type = TypeParam_EffectiveBaseType (ec, gc);
+
+                       if (TypeManager.IsSubclassOf (base_type, target_type))
+                               return TypeParameterConversion (expr, is_reference, target_type);
+
+                       if (target_type.IsInterface) {
+                               if (TypeManager.ImplementsInterface (base_type, target_type))
+                                       return TypeParameterConversion (expr, is_reference, target_type);
+
+                               foreach (Type t in gc.InterfaceConstraints) {
+                                       if (TypeManager.IsSubclassOf (t, target_type))
+                                               return TypeParameterConversion (expr, is_reference, target_type);
+                               }
+                       }
+
+                       foreach (Type t in gc.InterfaceConstraints) {
+                               if (!t.IsGenericParameter)
+                                       continue;
+                               if (TypeManager.IsSubclassOf (t, target_type))
+                                       return TypeParameterConversion (expr, is_reference, target_type);
+                       }
+
+                       return null;
                }
 
                static EmptyExpression MyEmptyExpr;
-               static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
+               static public Expression ImplicitReferenceConversion (EmitContext ec, Expression expr, Type target_type)
                {
                        Type expr_type = expr.Type;
 
@@ -64,6 +151,9 @@ namespace Mono.CSharp {
                        if (expr_type == TypeManager.void_type)
                                return null;
 
+                       if (expr_type.IsGenericParameter)
+                               return ImplicitTypeParameterConversion (ec, expr, target_type);
+                               
                        //
                        // notice that it is possible to write "ValueType v = 1", the ValueType here
                        // is an abstract class, and not really a value type, so we apply the same rules.
@@ -77,13 +167,20 @@ namespace Mono.CSharp {
 
                                if (TypeManager.IsValueType (expr_type))
                                        return new BoxedCast (expr);
-                               if (expr_type.IsClass || expr_type.IsInterface || expr_type == TypeManager.enum_type)
+                               if (expr_type.IsClass || expr_type.IsInterface || expr_type == TypeManager.enum_type){
+                                       if (expr_type == TypeManager.anonymous_method_type)
+                                               return null;
                                        return new EmptyCast (expr, target_type);
+                               }
+
+                               return null;
                        } else if (target_type == TypeManager.value_type) {
                                if (TypeManager.IsValueType (expr_type))
                                        return new BoxedCast (expr);
-                               if (expr is NullLiteral)
+                               if (expr_type == TypeManager.null_type)
                                        return new NullCast (expr, target_type);
+
+                               return null;
                        } else if (TypeManager.IsSubclassOf (expr_type, target_type)) {
                                //
                                // Special case: enumeration to System.Enum.
@@ -94,90 +191,88 @@ namespace Mono.CSharp {
                                        return new BoxedCast (expr);
 
                                return new EmptyCast (expr, target_type);
-                       } else {
+                       }
 
-                               // This code is kind of mirrored inside ImplicitStandardConversionExists
-                               // with the small distinction that we only probe there
-                               //
-                               // Always ensure that the code here and there is in sync
+                       // This code is kind of mirrored inside ImplicitStandardConversionExists
+                       // with the small distinction that we only probe there
+                       //
+                       // Always ensure that the code here and there is in sync
 
-                               // from the null type to any reference-type.
-                               if (expr is NullLiteral){
-                                       if (target_type.IsPointer)
-                                               return NullPointer.Null;
+                       // from the null type to any reference-type.
+                       if (expr_type == TypeManager.null_type){
+                               if (target_type.IsPointer)
+                                       return new EmptyCast (expr, target_type);
                                        
-                                       if (!target_type.IsValueType)
-                                               return new NullCast (expr, target_type);
-                               }
+                               if (!target_type.IsValueType)
+                                       return new NullCast (expr, target_type);
+                       }
 
-                               // from any class-type S to any interface-type T.
-                               if (target_type.IsInterface) {
-                                       if (TypeManager.ImplementsInterface (expr_type, target_type)){
-                                               if (expr_type.IsGenericParameter)
-                                                       return new BoxedCast (expr, target_type);
-                                               else if (expr_type.IsClass)
-                                                       return new EmptyCast (expr, target_type);
-                                               else if (TypeManager.IsValueType (expr_type) ||
-                                                        TypeManager.IsEnumType (expr_type))
-                                                       return new BoxedCast (expr, target_type);
-                                               else
-                                                       return new EmptyCast (expr, target_type);
-                                       }
+                       // from any class-type S to any interface-type T.
+                       if (target_type.IsInterface) {
+                               if (target_type != TypeManager.iconvertible_type &&
+                                   expr_type.IsValueType && (expr is Constant) &&
+                                   !(expr is IntLiteral || expr is BoolLiteral ||
+                                     expr is FloatLiteral || expr is DoubleLiteral ||
+                                     expr is LongLiteral || expr is CharLiteral ||
+                                     expr is StringLiteral || expr is DecimalLiteral ||
+                                     expr is UIntLiteral || expr is ULongLiteral)) {
+                                       return null;
                                }
 
-                               // from any interface type S to interface-type T.
-                               if (expr_type.IsInterface && target_type.IsInterface) {
-                                       if (TypeManager.ImplementsInterface (expr_type, target_type))
-                                               return new EmptyCast (expr, target_type);
+                               if (TypeManager.ImplementsInterface (expr_type, target_type)){
+                                       if (expr_type.IsGenericParameter || TypeManager.IsValueType (expr_type))
+                                               return new BoxedCast (expr, target_type);
                                        else
-                                               return null;
+                                               return new EmptyCast (expr, target_type);
                                }
+                       }
+
+                       // from any interface type S to interface-type T.
+                       if (expr_type.IsInterface && target_type.IsInterface) {
+                               if (TypeManager.ImplementsInterface (expr_type, target_type))
+                                       return new EmptyCast (expr, target_type);
+                               else
+                                       return null;
+                       }
                                
-                               // from an array-type S to an array-type of type T
-                               if (expr_type.IsArray && target_type.IsArray) {
-                                       if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
+                       // from an array-type S to an array-type of type T
+                       if (expr_type.IsArray && target_type.IsArray) {
+                               if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 
-                                               Type expr_element_type = TypeManager.GetElementType (expr_type);
+                                       Type expr_element_type = TypeManager.GetElementType (expr_type);
 
-                                               if (MyEmptyExpr == null)
-                                                       MyEmptyExpr = new EmptyExpression ();
+                                       if (MyEmptyExpr == null)
+                                               MyEmptyExpr = new EmptyExpression ();
                                                
-                                               MyEmptyExpr.SetType (expr_element_type);
-                                               Type target_element_type = TypeManager.GetElementType (target_type);
+                                       MyEmptyExpr.SetType (expr_element_type);
+                                       Type target_element_type = TypeManager.GetElementType (target_type);
 
-                                               if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
-                                                       if (ImplicitStandardConversionExists (MyEmptyExpr,
+                                       if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
+                                               if (ImplicitStandardConversionExists (ConstantEC, MyEmptyExpr,
                                                                                      target_element_type))
-                                                               return new EmptyCast (expr, target_type);
-                                       }
+                                                       return new EmptyCast (expr, target_type);
                                }
+                       }
                                
+                       // from an array-type to System.Array
+                       if (expr_type.IsArray && target_type == TypeManager.array_type)
+                               return new EmptyCast (expr, target_type);
                                
-                               // from an array-type to System.Array
-                               if (expr_type.IsArray && target_type == TypeManager.array_type)
-                                       return new EmptyCast (expr, target_type);
-                               
-                               // from any delegate type to System.Delegate
-                               if ((expr_type == TypeManager.delegate_type || 
-                                    TypeManager.IsDelegateType (expr_type)) &&
-                                   target_type == TypeManager.delegate_type)
-                                       return new EmptyCast (expr, target_type);
+                       // from any delegate type to System.Delegate
+                       if ((expr_type == TypeManager.delegate_type || TypeManager.IsDelegateType (expr_type)) &&
+                           target_type == TypeManager.delegate_type)
+                               return new EmptyCast (expr, target_type);
                                        
-                               // from any array-type or delegate type into System.ICloneable.
-                               if (expr_type.IsArray ||
-                                   expr_type == TypeManager.delegate_type ||
-                                   TypeManager.IsDelegateType (expr_type))
-                                       if (target_type == TypeManager.icloneable_type)
-                                               return new EmptyCast (expr, target_type);
-
-                               // from a generic type definition to a generic instance.
-                               if (TypeManager.IsEqualGenericType (expr_type, target_type))
+                       // from any array-type or delegate type into System.ICloneable.
+                       if (expr_type.IsArray ||
+                           expr_type == TypeManager.delegate_type || TypeManager.IsDelegateType (expr_type))
+                               if (target_type == TypeManager.icloneable_type)
                                        return new EmptyCast (expr, target_type);
-                               
-                               return null;
 
-                       }
-                       
+                       // from a generic type definition to a generic instance.
+                       if (TypeManager.IsEqual (expr_type, target_type))
+                               return new EmptyCast (expr, target_type);
+
                        return null;
                }
 
@@ -185,80 +280,98 @@ namespace Mono.CSharp {
                // Tests whether an implicit reference conversion exists between expr_type
                // and target_type
                //
-               public static bool ImplicitReferenceConversionExists (Expression expr, Type target_type)
+               public static bool ImplicitReferenceConversionExists (EmitContext ec, Expression expr, Type target_type)
                {
                        Type expr_type = expr.Type;
 
+                       if (expr_type.IsGenericParameter)
+                               return ImplicitTypeParameterConversion (ec, expr, target_type) != null;
+
                        //
                        // This is the boxed case.
                        //
                        if (target_type == TypeManager.object_type) {
                                if (expr_type.IsClass || TypeManager.IsValueType (expr_type) ||
                                    expr_type.IsInterface || expr_type == TypeManager.enum_type)
+                                       if (target_type != TypeManager.anonymous_method_type)
                                        return true;
+
+                               return false;
                        } else if (TypeManager.IsSubclassOf (expr_type, target_type))
                                return true;
-                       else {
-                               // Please remember that all code below actually comes
-                               // from ImplicitReferenceConversion so make sure code remains in sync
+
+                       // Please remember that all code below actually comes
+                       // from ImplicitReferenceConversion so make sure code remains in sync
                                
-                               // from any class-type S to any interface-type T.
-                               if (target_type.IsInterface) {
-                                       if (TypeManager.ImplementsInterface (expr_type, target_type))
-                                               return true;
+                       // from any class-type S to any interface-type T.
+                       if (target_type.IsInterface) {
+                               if (target_type != TypeManager.iconvertible_type &&
+                                   expr_type.IsValueType && (expr is Constant) &&
+                                   !(expr is IntLiteral || expr is BoolLiteral ||
+                                     expr is FloatLiteral || expr is DoubleLiteral ||
+                                     expr is LongLiteral || expr is CharLiteral ||
+                                     expr is StringLiteral || expr is DecimalLiteral ||
+                                     expr is UIntLiteral || expr is ULongLiteral)) {
+                                       return false;
                                }
                                
-                               // from any interface type S to interface-type T.
-                               if (expr_type.IsInterface && target_type.IsInterface)
-                                       if (TypeManager.ImplementsInterface (expr_type, target_type))
-                                               return true;
+                               if (TypeManager.ImplementsInterface (expr_type, target_type))
+                                       return true;
+                       }
+                               
+                       // from any interface type S to interface-type T.
+                       if (expr_type.IsInterface && target_type.IsInterface)
+                               if (TypeManager.ImplementsInterface (expr_type, target_type))
+                                       return true;
                                
-                               // from an array-type S to an array-type of type T
-                               if (expr_type.IsArray && target_type.IsArray) {
-                                       if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
+                       // from an array-type S to an array-type of type T
+                       if (expr_type.IsArray && target_type.IsArray) {
+                               if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
                                                
-                                               Type expr_element_type = expr_type.GetElementType ();
+                                       Type expr_element_type = expr_type.GetElementType ();
 
-                                               if (MyEmptyExpr == null)
-                                                       MyEmptyExpr = new EmptyExpression ();
+                                       if (MyEmptyExpr == null)
+                                               MyEmptyExpr = new EmptyExpression ();
                                                
-                                               MyEmptyExpr.SetType (expr_element_type);
-                                               Type target_element_type = TypeManager.GetElementType (target_type);
+                                       MyEmptyExpr.SetType (expr_element_type);
+                                       Type target_element_type = TypeManager.GetElementType (target_type);
                                                
-                                               if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
-                                                       if (ImplicitStandardConversionExists (MyEmptyExpr,
+                                       if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
+                                               if (ImplicitStandardConversionExists (ConstantEC, MyEmptyExpr,
                                                                                      target_element_type))
-                                                               return true;
-                                       }
+                                                       return true;
                                }
+                       }
                                
-                               // from an array-type to System.Array
-                               if (expr_type.IsArray && (target_type == TypeManager.array_type))
-                                       return true;
+                       // from an array-type to System.Array
+                       if (expr_type.IsArray && (target_type == TypeManager.array_type))
+                               return true;
                                
-                               // from any delegate type to System.Delegate
-                               if ((expr_type == TypeManager.delegate_type ||
-                                    TypeManager.IsDelegateType (expr_type)) &&
-                                   target_type == TypeManager.delegate_type)
-                                       if (target_type.IsAssignableFrom (expr_type))
-                                               return true;
+                       // from any delegate type to System.Delegate
+                       if ((expr_type == TypeManager.delegate_type || TypeManager.IsDelegateType (expr_type)) &&
+                           target_type == TypeManager.delegate_type)
+                               if (target_type.IsAssignableFrom (expr_type))
+                                       return true;
                                        
-                               // from any array-type or delegate type into System.ICloneable.
-                               if (expr_type.IsArray ||
-                                   expr_type == TypeManager.delegate_type ||
-                                   TypeManager.IsDelegateType (expr_type))
-                                       if (target_type == TypeManager.icloneable_type)
-                                               return true;
+                       // from any array-type or delegate type into System.ICloneable.
+                       if (expr_type.IsArray ||
+                           expr_type == TypeManager.delegate_type || TypeManager.IsDelegateType (expr_type))
+                               if (target_type == TypeManager.icloneable_type)
+                                       return true;
                                
-                               // from the null type to any reference-type.
-                               if (expr is NullLiteral && !target_type.IsValueType &&
-                                   !TypeManager.IsEnumType (target_type))
+                       // from the null type to any reference-type.
+                       if (expr_type == TypeManager.null_type){
+                               if (target_type.IsPointer)
                                        return true;
-
-                               // from a generic type definition to a generic instance.
-                               if (TypeManager.IsEqualGenericType (expr_type, target_type))
+                       
+                               if (!target_type.IsValueType)
                                        return true;
                        }
+
+                       // from a generic type definition to a generic instance.
+                       if (TypeManager.IsEqual (expr_type, target_type))
+                               return true;
+
                        return false;
                }
 
@@ -277,7 +390,6 @@ namespace Mono.CSharp {
                        // Attempt to do the implicit constant expression conversions
 
                        if (expr is Constant){
-                               
                                if (expr is IntConstant){
                                        Expression e;
                                        
@@ -292,7 +404,7 @@ namespace Mono.CSharp {
                                        // we just inline it
                                        //
                                        long v = ((LongConstant) expr).Value;
-                                       if (v > 0)
+                                       if (v >= 0)
                                                return new ULongConstant ((ulong) v);
                                } 
                        }
@@ -439,7 +551,7 @@ namespace Mono.CSharp {
                        if ((expr is NullLiteral) && target_type.IsGenericParameter)
                                return TypeParameter_to_Null (target_type);
 
-                       if (ImplicitStandardConversionExists (expr, target_type))
+                       if (ImplicitStandardConversionExists (ec, expr, target_type))
                                return true;
 
                        Expression dummy = ImplicitUserConversion (ec, expr, target_type, Location.Null);
@@ -460,8 +572,10 @@ namespace Mono.CSharp {
                /// <summary>
                ///  Determines if a standard implicit conversion exists from
                ///  expr_type to target_type
+               ///
+               ///  ec should point to a real EmitContext if expr.Type is TypeManager.anonymous_method_type.
                /// </summary>
-               public static bool ImplicitStandardConversionExists (Expression expr, Type target_type)
+               public static bool ImplicitStandardConversionExists (EmitContext ec, Expression expr, Type target_type)
                {
                        Type expr_type = expr.Type;
 
@@ -579,7 +693,7 @@ namespace Mono.CSharp {
                                        return true;
                        }       
                        
-                       if (ImplicitReferenceConversionExists (expr, target_type))
+                       if (ImplicitReferenceConversionExists (ec, expr, target_type))
                                return true;
 
                        //
@@ -640,6 +754,18 @@ namespace Mono.CSharp {
                        if (target_type == TypeManager.void_ptr_type && expr_type.IsPointer)
                                return true;
 
+                       if (expr_type == TypeManager.anonymous_method_type){
+                               if (!TypeManager.IsDelegateType (target_type))
+                                       return false;
+
+                               AnonymousMethod am = (AnonymousMethod) expr;
+                               int errors = Report.Errors;
+
+                               Expression conv = am.Compatible (ec, target_type, true);
+                               if (conv != null)
+                                       return true;
+                       }
+                       
                        return false;
                }
 
@@ -654,7 +780,7 @@ namespace Mono.CSharp {
                ///  Finds "most encompassed type" according to the spec (13.4.2)
                ///  amongst the methods in the MethodGroupExpr
                /// </summary>
-               static Type FindMostEncompassedType (ArrayList types)
+               static Type FindMostEncompassedType (EmitContext ec, ArrayList types)
                {
                        Type best = null;
 
@@ -669,7 +795,7 @@ namespace Mono.CSharp {
                                        continue;
                                }
                                
-                               if (ImplicitStandardConversionExists (priv_fmet_param, best))
+                               if (ImplicitStandardConversionExists (ec, priv_fmet_param, best))
                                        best = t;
                        }
 
@@ -687,7 +813,7 @@ namespace Mono.CSharp {
                ///  Finds "most encompassing type" according to the spec (13.4.2)
                ///  amongst the types in the given set
                /// </summary>
-               static Type FindMostEncompassingType (ArrayList types)
+               static Type FindMostEncompassingType (EmitContext ec, ArrayList types)
                {
                        Type best = null;
 
@@ -702,7 +828,7 @@ namespace Mono.CSharp {
                                        continue;
                                }
 
-                               if (ImplicitStandardConversionExists (priv_fmee_ret, t))
+                               if (ImplicitStandardConversionExists (ec, priv_fmee_ret, t))
                                        best = t;
                        }
                        
@@ -719,8 +845,8 @@ namespace Mono.CSharp {
                ///   by making use of FindMostEncomp* methods. Applies the correct rules separately
                ///   for explicit and implicit conversion operators.
                /// </summary>
-               static public Type FindMostSpecificSource (MethodGroupExpr me, Expression source,
-                                                          bool apply_explicit_conv_rules,
+               static public Type FindMostSpecificSource (EmitContext ec, MethodGroupExpr me,
+                                                          Expression source, bool apply_explicit_conv_rules,
                                                           Location loc)
                {
                        ArrayList src_types_set = new ArrayList ();
@@ -749,17 +875,17 @@ namespace Mono.CSharp {
                                        // or encompassed by S to a type encompassing or encompassed by T
                                        //
                                        priv_fms_expr.SetType (param_type);
-                                       if (ImplicitStandardConversionExists (priv_fms_expr, source_type))
+                                       if (ImplicitStandardConversionExists (ec, priv_fms_expr, source_type))
                                                src_types_set.Add (param_type);
                                        else {
-                                               if (ImplicitStandardConversionExists (source, param_type))
+                                               if (ImplicitStandardConversionExists (ec, source, param_type))
                                                        src_types_set.Add (param_type);
                                        }
                                } else {
                                        //
                                        // Only if S is encompassed by param_type
                                        //
-                                       if (ImplicitStandardConversionExists (source, param_type))
+                                       if (ImplicitStandardConversionExists (ec, source, param_type))
                                                src_types_set.Add (param_type);
                                }
                        }
@@ -771,21 +897,21 @@ namespace Mono.CSharp {
                                ArrayList candidate_set = new ArrayList ();
 
                                foreach (Type param_type in src_types_set){
-                                       if (ImplicitStandardConversionExists (source, param_type))
+                                       if (ImplicitStandardConversionExists (ec, source, param_type))
                                                candidate_set.Add (param_type);
                                }
 
                                if (candidate_set.Count != 0)
-                                       return FindMostEncompassedType (candidate_set);
+                                       return FindMostEncompassedType (ec, candidate_set);
                        }
 
                        //
                        // Final case
                        //
                        if (apply_explicit_conv_rules)
-                               return FindMostEncompassingType (src_types_set);
+                               return FindMostEncompassingType (ec, src_types_set);
                        else
-                               return FindMostEncompassedType (src_types_set);
+                               return FindMostEncompassedType (ec, src_types_set);
                }
 
                //
@@ -796,8 +922,8 @@ namespace Mono.CSharp {
                /// <summary>
                ///  Finds the most specific target Tx according to section 13.4.4
                /// </summary>
-               static public Type FindMostSpecificTarget (MethodGroupExpr me, Type target,
-                                                          bool apply_explicit_conv_rules,
+               static public Type FindMostSpecificTarget (EmitContext ec, MethodGroupExpr me,
+                                                          Type target, bool apply_explicit_conv_rules,
                                                           Location loc)
                {
                        ArrayList tgt_types_set = new ArrayList ();
@@ -825,11 +951,11 @@ namespace Mono.CSharp {
                                        // or encompassed by S to a type encompassing or encompassed by T
                                        //
                                        priv_fms_expr.SetType (ret_type);
-                                       if (ImplicitStandardConversionExists (priv_fms_expr, target))
+                                       if (ImplicitStandardConversionExists (ec, priv_fms_expr, target))
                                                tgt_types_set.Add (ret_type);
                                        else {
                                                priv_fms_expr.SetType (target);
-                                               if (ImplicitStandardConversionExists (priv_fms_expr, ret_type))
+                                               if (ImplicitStandardConversionExists (ec, priv_fms_expr, ret_type))
                                                        tgt_types_set.Add (ret_type);
                                        }
                                } else {
@@ -837,7 +963,7 @@ namespace Mono.CSharp {
                                        // Only if T is encompassed by param_type
                                        //
                                        priv_fms_expr.SetType (ret_type);
-                                       if (ImplicitStandardConversionExists (priv_fms_expr, target))
+                                       if (ImplicitStandardConversionExists (ec, priv_fms_expr, target))
                                                tgt_types_set.Add (ret_type);
                                }
                        }
@@ -851,21 +977,21 @@ namespace Mono.CSharp {
                                foreach (Type ret_type in tgt_types_set){
                                        priv_fmt_expr.SetType (ret_type);
                                        
-                                       if (ImplicitStandardConversionExists (priv_fmt_expr, target))
+                                       if (ImplicitStandardConversionExists (ec, priv_fmt_expr, target))
                                                candidate_set.Add (ret_type);
                                }
 
                                if (candidate_set.Count != 0)
-                                       return FindMostEncompassingType (candidate_set);
+                                       return FindMostEncompassingType (ec, candidate_set);
                        }
                        
                        //
                        // Okay, final case !
                        //
                        if (apply_explicit_conv_rules)
-                               return FindMostEncompassedType (tgt_types_set);
+                               return FindMostEncompassedType (ec, tgt_types_set);
                        else 
-                               return FindMostEncompassingType (tgt_types_set);
+                               return FindMostEncompassingType (ec, tgt_types_set);
                }
                
                /// <summary>
@@ -886,6 +1012,8 @@ namespace Mono.CSharp {
                        return UserDefinedConversion (ec, source, target, loc, true);
                }
 
+               static DoubleHash explicit_conv = new DoubleHash (100);
+               static DoubleHash implicit_conv = new DoubleHash (100);
                /// <summary>
                ///   Computes the MethodGroup for the user-defined conversion
                ///   operators from source_type to target_type.  `look_for_explicit'
@@ -903,6 +1031,9 @@ namespace Mono.CSharp {
                        op_name = "op_Implicit";
 
                        MethodGroupExpr union3;
+                       object r;
+                       if ((look_for_explicit ? explicit_conv : implicit_conv).Lookup (source_type, target_type, out r))
+                               return (MethodGroupExpr) r;
 
                        mg1 = Expression.MethodLookup (ec, source_type, op_name, loc);
                        if (source_type.BaseType != null)
@@ -952,7 +1083,9 @@ namespace Mono.CSharp {
                                union4 = Invocation.MakeUnionSet (union5, union6, loc);
                        }
                        
-                       return Invocation.MakeUnionSet (union3, union4, loc);
+                       MethodGroupExpr ret = Invocation.MakeUnionSet (union3, union4, loc);
+                       (look_for_explicit ? explicit_conv : implicit_conv).Insert (source_type, target_type, ret);
+                       return ret;
                }
                
                /// <summary>
@@ -972,11 +1105,11 @@ namespace Mono.CSharp {
                        
                        Type most_specific_source, most_specific_target;
 
-                       most_specific_source = FindMostSpecificSource (union, source, look_for_explicit, loc);
+                       most_specific_source = FindMostSpecificSource (ec, union, source, look_for_explicit, loc);
                        if (most_specific_source == null)
                                return null;
 
-                       most_specific_target = FindMostSpecificTarget (union, target, look_for_explicit, loc);
+                       most_specific_target = FindMostSpecificTarget (ec, union, target, look_for_explicit, loc);
                        if (most_specific_target == null) 
                                return null;
 
@@ -1070,24 +1203,27 @@ namespace Mono.CSharp {
 
                        if (expr.eclass == ExprClass.MethodGroup){
                                if (!TypeManager.IsDelegateType (target_type)){
-                                       Report.Error (428, loc,
-                                                     String.Format (
-                                                          "Cannot convert method group to `{0}', since it is not a delegate",
-                                                          TypeManager.CSharpName (target_type)));
                                        return null;
                                }
 
-                               return ImplicitDelegateCreation.Create (ec, (MethodGroupExpr) expr, target_type, loc);
+                               //
+                               // Only allow anonymous method conversions on post ISO_1
+                               //
+                               if (RootContext.Version != LanguageVersion.ISO_1){
+                                       MethodGroupExpr mg = expr as MethodGroupExpr;
+                                       if (mg != null)
+                                               return ImplicitDelegateCreation.Create (ec, mg, target_type, loc);
+                               }
                        }
 
-                       if (expr_type.Equals (target_type) && !(expr is NullLiteral))
+                       if (expr_type.Equals (target_type) && !TypeManager.IsNullType (expr_type))
                                return expr;
 
                        e = ImplicitNumericConversion (ec, expr, target_type, loc);
                        if (e != null)
                                return e;
 
-                       e = ImplicitReferenceConversion (expr, target_type);
+                       e = ImplicitReferenceConversion (ec, expr, target_type);
                        if (e != null)
                                return e;
                        
@@ -1116,7 +1252,7 @@ namespace Mono.CSharp {
                                }
                                
                                if (target_type.IsPointer) {
-                                       if (expr is NullLiteral)
+                                       if (expr_type == TypeManager.null_type)
                                                return new EmptyCast (expr, target_type);
 
                                        if (expr_type == TypeManager.void_ptr_type)
@@ -1124,6 +1260,30 @@ namespace Mono.CSharp {
                                }
                        }
 
+                       if (expr_type == TypeManager.anonymous_method_type){
+                               if (!TypeManager.IsDelegateType (target_type)){
+                                       Report.Error (1660, loc,
+                                                             "Cannot convert anonymous method to `{0}', since it is not a delegate",
+                                                             TypeManager.CSharpName (target_type));
+                                       return null;
+                               }
+
+                               AnonymousMethod am = (AnonymousMethod) expr;
+                               int errors = Report.Errors;
+
+                               Expression conv = am.Compatible (ec, target_type, false);
+                               if (conv != null)
+                                       return conv;
+                               
+                               //
+                               // We return something instead of null, to avoid
+                               // the duplicate error, since am.Compatible would have
+                               // reported that already
+                               //
+                               if (errors != Report.Errors)
+                                       return new EmptyCast (expr, target_type);
+                       }
+                       
                        return null;
                }
 
@@ -1171,7 +1331,7 @@ namespace Mono.CSharp {
                                //
                                // Possibly, we need to create a different 0 literal before passing
                                // to EnumConstant
-                               //n
+                               //
                                if (underlying == TypeManager.int64_type)
                                        e = new LongLiteral (0);
                                else if (underlying == TypeManager.uint64_type)
@@ -1184,11 +1344,17 @@ namespace Mono.CSharp {
 
                static public void Error_CannotImplicitConversion (Location loc, Type source, Type target)
                {
-                       string msg = "Cannot convert implicitly from `"+
-                               TypeManager.CSharpName (source) + "' to `" +
-                               TypeManager.CSharpName (target) + "'";
-
-                       Report.Error (29, loc, msg);
+                       if (source.Name == target.Name){
+                               Report.ExtraInformation (loc,
+                                        String.Format (
+                                               "The type {0} has two conflicting definitons, one comes from {0} and the other from {1}",
+                                               source.Assembly.FullName, target.Assembly.FullName));
+                                                        
+                       }
+                       Report.Error (29, loc, "Cannot convert implicitly from {0} to `{1}'",
+                                     source == TypeManager.anonymous_method_type ?
+                                     "anonymous method" : "`" + TypeManager.CSharpName (source) + "'",
+                                     TypeManager.CSharpName (target));
                }
 
                /// <summary>
@@ -1208,10 +1374,15 @@ namespace Mono.CSharp {
                        if (e != null)
                                return e;
 
-                       if (source is DoubleLiteral && target_type == TypeManager.float_type){
-                               Report.Error (664, loc,
-                                             "Double literal cannot be implicitly converted to " +
-                                             "float type, use F suffix to create a float literal");
+                       if (source is DoubleLiteral) {
+                               if (target_type == TypeManager.float_type) {
+                                       Error_664 (loc, "float", "f");
+                                       return null;
+                               }
+                               if (target_type == TypeManager.decimal_type) {
+                                       Error_664 (loc, "decimal", "m");
+                                       return null;
+                               }
                        }
 
                        if (source is Constant){
@@ -1226,6 +1397,12 @@ namespace Mono.CSharp {
                        return null;
                }
 
+               static void Error_664 (Location loc, string type, string suffix) {
+                       Report.Error (664, loc,
+                               "Literal of type double cannot be implicitly converted to type '{0}'. Add suffix '{1}' to create a literal of this type",
+                               type, suffix);
+               }
+
                /// <summary>
                ///   Performs the explicit numeric conversions
                /// </summary>
@@ -1243,7 +1420,7 @@ namespace Mono.CSharp {
                        if (TypeManager.IsEnumType (real_target_type))
                                real_target_type = TypeManager.EnumToUnderlying (real_target_type);
 
-                       if (ImplicitStandardConversionExists (expr, real_target_type)){
+                       if (ImplicitStandardConversionExists (ec, expr, real_target_type)){
                                Expression ce = ImplicitConversionStandard (ec, expr, real_target_type, loc);
 
                                if (real_target_type != target_type)
@@ -1706,23 +1883,20 @@ namespace Mono.CSharp {
                        //
                        // Unboxing conversion.
                        //
-                       if (expr_type == TypeManager.object_type && target_type.IsValueType){
-                               if (expr is NullLiteral){
-                                       //
-                                       // Skip the ExplicitReferenceConversion because we can not convert
-                                       // from Null to a ValueType, and ExplicitReference wont check against
-                                       // null literal explicitly
-                                       //
-                                       goto skip_explicit;
-                               }
+                       if (expr_type == TypeManager.object_type && target_type.IsValueType)
                                return new UnboxCast (expr, target_type);
 
+                       //
+                       // Skip the ExplicitReferenceConversion because we can not convert
+                       // from Null to a ValueType, and ExplicitReference wont check against
+                       // null literal explicitly
+                       //
+                       if (expr_type != TypeManager.null_type){
+                               ne = ExplicitReferenceConversion (expr, target_type);
+                               if (ne != null)
+                                       return ne;
                        }
 
-                       ne = ExplicitReferenceConversion (expr, target_type);
-                       if (ne != null)
-                               return ne;
-
                skip_explicit:
                        if (ec.InUnsafe){
                                if (target_type.IsPointer){