Fix #2120: An expression tree may not contain a base access

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -2061,7 +2061,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			// If references are missing member.IsStatic might not be set correctly.
 			// Additionally check target for null, in order to avoid a crash.
 			if (!memberStatic && target != null) {
-				if (nonVirtualInvocation && MatchLdThis(target) && memberDeclaringType.GetDefinition() != resolver.CurrentTypeDefinition) {
+				if (ShouldUseBaseReference()) {
 					return new BaseReferenceExpression()
 						.WithILInstruction(target)
 						.WithRR(new ThisResolveResult(memberDeclaringType, nonVirtualInvocation));
@@ -2097,6 +2097,17 @@ namespace ICSharpCode.Decompiler.CSharp
 					.WithRR(new TypeResolveResult(memberDeclaringType));
 			}
 
+			bool ShouldUseBaseReference()
+			{
+				if (!nonVirtualInvocation)
+					return false;
+				if (!MatchLdThis(target))
+					return false;
+				if (memberDeclaringType.GetDefinition() == resolver.CurrentTypeDefinition)
+					return false;
+				return true;
+			}
+
 			bool MatchLdThis(ILInstruction inst)
 			{
 				// ldloc this

ICSharpCode.Decompiler/IL/Transforms/TransformExpressionTrees.cs

@@ -512,7 +512,10 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			}
 			switch (member) {
 				case IMethod method:
-					return (targetVariable => new Call(method) { Arguments = { new LdLoc(targetVariable), value() } }, method.ReturnType);
+					if (method.IsStatic)
+						return (targetVariable => new Call(method) { Arguments = { new LdLoc(targetVariable), value() } }, method.ReturnType);
+					else	
+						return (targetVariable => new CallVirt(method) { Arguments = { new LdLoc(targetVariable), value() } }, method.ReturnType);
 				case IField field:
 					return (targetVariable => new StObj(new LdFlda(new LdLoc(targetVariable), (IField)member) { DelayExceptions = true }, value(), member.ReturnType), field.ReturnType);
 			}
@@ -560,10 +563,10 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			CallInstruction BuildCall()
 			{
 				CallInstruction call;
-				if (method.IsAbstract || method.IsVirtual || method.IsOverride) {
-					call = new CallVirt(method);
-				} else {
+				if (method.IsStatic) {
 					call = new Call(method);
+				} else {
+					call = new CallVirt(method);
 				}
 				if (targetConverter != null) {
 					call.Arguments.Add(PrepareCallTarget(method.DeclaringType, targetConverter(), targetType));
@@ -749,7 +752,9 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 
 			ILInstruction BuildCall()
 			{
-				CallInstruction call = new Call((IMethod)member);
+				CallInstruction call = member.IsStatic
+					? (CallInstruction)new Call((IMethod)member)
+					: new CallVirt((IMethod)member);
 				call.Arguments.AddRange(args.Select(f => f()));
 				return call;
 			}
@@ -1123,10 +1128,10 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			ILInstruction BuildProperty()
 			{
 				CallInstruction call;
-				if (member.IsAbstract || member.IsVirtual || member.IsOverride) {
-					call = new CallVirt((IMethod)member);
-				} else {
+				if (member.IsStatic) {
 					call = new Call((IMethod)member);
+				} else {
+					call = new CallVirt((IMethod)member);
 				}
 				if (targetConverter != null) {
 					call.Arguments.Add(PrepareCallTarget(member.DeclaringType, targetConverter(), targetType));