Do not Let coerce on Property Let regardless of type

Author: MDoerner

Rubberduck.Parsing/Binding/Bindings/LetCoercionDefaultBinding.cs

@@ -63,7 +63,8 @@ private static IBoundExpression Resolve(IBoundExpression wrappedExpression, Pars
                 || !wrappedDeclaration.IsObject 
                     && !(wrappedDeclaration.IsObjectArray 
                         && wrappedExpression is IndexExpression indexExpression 
-                        && indexExpression.IsArrayAccess))
+                        && indexExpression.IsArrayAccess)
+                || wrappedDeclaration.DeclarationType == DeclarationType.PropertyLet)
             {
                 return wrappedExpression;
             }

RubberduckTests/Grammar/ResolverTests.cs

@@ -4632,6 +4632,56 @@ End Sub
             }
         }
 
+        [Test]
+        [Category("Grammar")]
+        [Category("Resolver")]
+        [TestCase("    cls.Baz = fooBar", 5, 12)]
+        [TestCase("    Let cls.Baz = fooBar", 9, 16)]
+        //This prevents problems with some types in libraries like OLE_COLOR, which are not really classes.
+        public void LetCoercionOnPropertyLetNeverDoesAnything(string statement, int selectionStartColumn, int selectionEndColumn)
+        {
+            var class1Code = @"
+Public Function Foo() As Long
+Attribute Foo.VB_UserMemId = 0
+End Function
+";
+
+            var class2Code = @"
+Public Property Let Baz(RHS As Class1)
+End Property
+
+Public Property Get Baz() As Class1
+Attribute Baz.VB_UserMemId = 0
+End Property
+";
+
+            var moduleCode = $@"
+Private Function Foo() As Variant 
+    Dim cls As New Class2
+    Dim fooBar As New Class1
+{statement}
+End Function
+";
+
+            var vbe = MockVbeBuilder.BuildFromModules(
+                ("Class1", class1Code, ComponentType.ClassModule),
+                ("Class2", class2Code, ComponentType.ClassModule),
+                ("Module1", moduleCode, ComponentType.StandardModule));
+
+            var selection = new Selection(5, selectionStartColumn, 5, selectionEndColumn);
+
+            using (var state = Resolve(vbe.Object))
+            {
+                var module = state.DeclarationFinder.AllModules.First(qmn => qmn.ComponentName == "Module1");
+                var qualifiedSelection = new QualifiedSelection(module, selection);
+                var defaultMemberReferences = state.DeclarationFinder.IdentifierReferences(qualifiedSelection);
+                var failedLetCoercionReferences = state.DeclarationFinder.FailedLetCoercions(module);
+
+                Assert.IsFalse(defaultMemberReferences.Any());
+                Assert.IsFalse(failedLetCoercionReferences.Any());
+            }
+        }
+
         [Test]
         [Category("Grammar")]
         [Category("Resolver")]

RubberduckTests/Inspections/ObjectVariableNotSetInspectionTests.cs

@@ -1,10 +1,10 @@
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using NUnit.Framework;
 using Rubberduck.Inspections.Concrete;
 using Rubberduck.Parsing.Inspections.Abstract;
+using Rubberduck.Parsing.Symbols;
 using Rubberduck.Parsing.VBA;
 using Rubberduck.VBEditor;
 using Rubberduck.VBEditor.SafeComWrappers;
@@ -1378,6 +1378,48 @@ End Sub
             Assert.AreEqual(expectedSelection, actualSelection);
         }
 
+        [Test]
+        [Category("Grammar")]
+        [Category("Resolver")]
+        [TestCase("    cls.Baz = fooBar")]
+        [TestCase("    Let cls.Baz = fooBar")]
+        //This prevents problems with some types in libraries like OLE_COLOR, which are not really classes.
+        //See issue #4997 at https://github.com/rubberduck-vba/Rubberduck/issues/4997
+        public void PropertyLetOnLHS_NoResult(string statement)
+        {
+            var class1Code = @"
+Public Function Foo() As Long
+Attribute Foo.VB_UserMemId = 0
+End Function
+";
+
+            var class2Code = @"
+Public Property Let Baz(RHS As Class1)
+End Property
+
+Public Property Get Baz() As Class1
+Attribute Baz.VB_UserMemId = 0
+End Property
+";
+
+            var moduleCode = $@"
+Private Function Foo() As Variant 
+    Dim cls As New Class2
+    Dim fooBar As New Class1
+{statement}
+End Function
+";
+
+            var vbe = MockVbeBuilder.BuildFromModules(
+                ("Class1", class1Code, ComponentType.ClassModule),
+                ("Class2", class2Code, ComponentType.ClassModule),
+                ("Module1", moduleCode, ComponentType.StandardModule));
+
+            var inspectionResults = InspectionResults(vbe.Object);
+
+            Assert.IsFalse(inspectionResults.Any());
+        }
+
         protected override IInspection InspectionUnderTest(RubberduckParserState state)
         {
             return new ObjectVariableNotSetInspection(state);