[mcs] Emit field initializer with expression tree in all user constru…

…ctors. Fixes #18308

mcs/mcs/anonymous.cs

@@ -1267,7 +1267,7 @@ public Expression Compatible (ResolveContext ec, TypeSpec type)
 				throw new InternalErrorException (e, loc);
 			}
 
-			if (!ec.IsInProbingMode) {
+			if (!ec.IsInProbingMode && !etree_conversion) {
 				compatibles.Add (type, am ?? EmptyExpression.Null);
 			}
 

mcs/mcs/assign.cs

@@ -334,7 +334,7 @@ protected override Expression DoResolve (ResolveContext ec)
 
 			if (source == null) {
 				ok = false;
-				source = EmptyExpression.Null;
+				source = ErrorExpression.Instance;
 			}
 
 			target = target.ResolveLValue (ec, source);
@@ -589,6 +589,12 @@ public FieldInitializer (FieldBase mc, Expression expression, Location loc)
 
 		public int AssignmentOffset { get; private set; }
 
+		public FieldBase Field {
+			get {
+				return mc;
+			}
+		}
+
 		public override Location StartLocation {
 			get {
 				return loc;
@@ -601,8 +607,8 @@ protected override Expression DoResolve (ResolveContext rc)
 			if (source == null)
 				return null;
 
-			var bc = (BlockContext) rc;
 			if (resolved == null) {
+				var bc = (BlockContext) rc;
 				var ctx = new FieldInitializerContext (mc, bc);
 				resolved = base.DoResolve (ctx) as ExpressionStatement;
 				AssignmentOffset = ctx.AssignmentInfoOffset - bc.AssignmentInfoOffset;

mcs/mcs/class.cs

@@ -1010,9 +1010,20 @@ public void ResolveFieldInitializers (BlockContext ec)
 
 			for (int i = 0; i < initialized_fields.Count; ++i) {
 				FieldInitializer fi = initialized_fields [i];
+
+				//
+				// Clone before resolving otherwise when field initializer is needed
+				// in more than 1 constructor any resolve after the initial one would
+				// only took the resolved expression which is problem for expressions
+				// that generate extra expressions or code during Resolve phase
+				//
+				var cloned = fi.Clone (new CloneContext ());
+
 				ExpressionStatement s = fi.ResolveStatement (ec);
-				if (s == null)
+				if (s == null) {
+					initialized_fields [i] = new FieldInitializer (fi.Field, ErrorExpression.Instance, Location.Null);
 					continue;
+				}
 
 				//
 				// Field is re-initialized to its default value => removed
@@ -1022,6 +1033,7 @@ public void ResolveFieldInitializers (BlockContext ec)
 
 				ec.AssignmentInfoOffset += fi.AssignmentOffset;
 				ec.CurrentBlock.AddScopeStatement (new StatementExpression (s));
+				initialized_fields [i] = (FieldInitializer) cloned;
 			}
 		}
 

mcs/mcs/convert.cs

@@ -1467,6 +1467,7 @@ static Expression ImplicitConversionStandard (ResolveContext ec, Expression expr
 				return e;
 
 			source.Error_ValueCannotBeConverted (ec, target_type, false);
+
 			return null;
 		}
 

mcs/mcs/ecore.cs

@@ -5792,6 +5792,14 @@ public void SetHasAddressTaken ()
 			}
 		}
 
+		protected override void CloneTo (CloneContext clonectx, Expression target)
+		{
+			var t = (FieldExpr) target;
+
+			if (InstanceExpression != null)
+				t.InstanceExpression = InstanceExpression.Clone (clonectx);
+		}
+
 		public override Expression CreateExpressionTree (ResolveContext ec)
 		{
 			return CreateExpressionTree (ec, true);

mcs/mcs/expression.cs

@@ -9999,6 +9999,10 @@ public EmptyExpression (TypeSpec t)
 			loc = Location.Null;
 		}
 
+		protected override void CloneTo (CloneContext clonectx, Expression target)
+		{
+		}
+
 		public override bool ContainsEmitWithAwait ()
 		{
 			return false;

mcs/tests/gtest-etree-30.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Linq.Expressions;
+
+public sealed class C
+{
+	public C ()
+	{
+	}
+
+	public C (Action<object, object> tappedCallback)
+	{
+	}
+
+	public readonly string TappedCallbackProperty = Create<C, Action<object, object>> (o => o.TappedCallback);
+
+	public Action<object, object> TappedCallback {
+		get;
+		set;
+	}
+
+	public static string Create<T1, T2> (Expression<Func<T1, T2>> getter)
+	{
+		return null;
+	}
+
+	public static void Main ()
+	{
+		new C (null);
+	}
+}