Fix ObjectVariableNotSet around default members

Author: MDoerner

Rubberduck.CodeAnalysis/Inspections/Concrete/VariableRequiresSetAssignmentEvaluator.cs

@@ -53,13 +53,7 @@ public static bool RequiresSetAssignment(IdentifierReference reference, IDeclara
             {
                 // get the members of the returning type, a default member could make us lie otherwise
                 var classModule = declaration.AsTypeDeclaration as ClassModuleDeclaration;
-                if (classModule?.DefaultMember == null)
-                {
-                    return true;
-                }
-                var parameters = (classModule.DefaultMember as IParameterizedDeclaration)?.Parameters;
-                // assign declaration is an object without a default parameterless (or with all parameters optional) member - LHS needs a 'Set' keyword.
-                return parameters != null && parameters.Any(p => !p.IsOptional);
+                return !HasPotentiallyNonObjectParameterlessDefaultMember(classModule);
             }
 
             // assigned declaration is a variant. we need to know about the RHS of the assignment.           
@@ -76,9 +70,30 @@ public static bool RequiresSetAssignment(IdentifierReference reference, IDeclara
                 return false;
             }
 
-            if (expression is VBAParser.NewExprContext)
+
+            var module = Declaration.GetModuleParent(reference.ParentScoping);
+
+            if (expression is VBAParser.NewExprContext newExpr)
             {
-                // RHS expression is newing up an object reference - LHS needs a 'Set' keyword:
+                var newTypeExpression = newExpr.expression();
+                
+                // todo resolve expression type
+
+                //Covers the case of a single type on the RHS of the assignment.
+                var simpleTypeName = newTypeExpression.GetDescendent<VBAParser.SimpleNameExprContext>();
+                if (simpleTypeName != null && simpleTypeName.GetText() == newTypeExpression.GetText())
+                {
+                    var qualifiedIdentifierSelection = new QualifiedSelection(module.QualifiedModuleName,
+                        simpleTypeName.identifier().GetSelection());
+                    var identifierText = simpleTypeName.identifier().GetText();
+                    return declarationFinderProvider.DeclarationFinder.IdentifierReferences(qualifiedIdentifierSelection)
+                        .Select(identifierReference => identifierReference.Declaration)
+                        .Where(decl => identifierText == decl.IdentifierName)
+                        .OfType<ClassModuleDeclaration>()
+                        .Any(typeDecl => !HasPotentiallyNonObjectParameterlessDefaultMember(typeDecl));
+                }
+                //Here, we err on the side of false-positives, but that seems more appropriate than not to treat qualified type expressions incorrectly.
+                //Whether there is a legitimate use here for default members is questionable anyway.
                 return true;
             }
 
@@ -94,8 +109,6 @@ public static bool RequiresSetAssignment(IdentifierReference reference, IDeclara
             }
 
             // todo resolve expression return type
-            var project = Declaration.GetProjectParent(reference.ParentScoping);
-            var module = Declaration.GetModuleParent(reference.ParentScoping);
 
             //Covers the case of a single variable on the RHS of the assignment.
             var simpleName = expression.GetDescendent<VBAParser.SimpleNameExprContext>();
@@ -104,15 +117,40 @@ public static bool RequiresSetAssignment(IdentifierReference reference, IDeclara
                 var qualifiedIdentifierSelection = new QualifiedSelection(module.QualifiedModuleName,
                     simpleName.identifier().GetSelection());
                 return declarationFinderProvider.DeclarationFinder.IdentifierReferences(qualifiedIdentifierSelection)
-                    .Any(identifierReference => identifierReference.Declaration.IsObject 
-                                                && simpleName.identifier().GetText() == identifierReference.Declaration.IdentifierName);
+                    .Select(identifierReference => identifierReference.Declaration)
+                    .Where(decl => decl.IsObject
+                                   && simpleName.identifier().GetText() == decl.IdentifierName)
+                    .Select(typeDeclaration => typeDeclaration.AsTypeDeclaration as ClassModuleDeclaration)
+                    .Any(typeDecl => !HasPotentiallyNonObjectParameterlessDefaultMember(typeDecl));
             }
 
+            var project = Declaration.GetProjectParent(reference.ParentScoping);
+
             //todo: Use code path analysis to ensure that we are really picking up the last assignment to the RHS.
             // is the reference referring to something else in scope that's a object?
             return declarationFinderProvider.DeclarationFinder.MatchName(expression.GetText())
                 .Any(decl => (decl.DeclarationType.HasFlag(DeclarationType.ClassModule) || Tokens.Object.Equals(decl.AsTypeName))
                 && AccessibilityCheck.IsAccessible(project, module, reference.ParentScoping, decl));
         }
+
+        private static bool HasPotentiallyNonObjectParameterlessDefaultMember(ClassModuleDeclaration classModule)
+        {
+            var defaultMember = classModule?.DefaultMember;
+
+            if (defaultMember == null)
+            {
+                return false;
+            }
+
+            var parameters = (defaultMember as IParameterizedDeclaration)?.Parameters;
+            // assign declaration is an object without a default parameterless (or with all parameters optional) member - LHS needs a 'Set' keyword.
+            if (parameters != null && parameters.Any(p => !p.IsOptional))
+            {
+                return false;
+            }
+
+            var defaultMemberType = defaultMember.AsTypeDeclaration as ClassModuleDeclaration;
+            return defaultMemberType == null || HasPotentiallyNonObjectParameterlessDefaultMember(defaultMemberType);
+        }
     }
 }