Merge pull request #2074 from Hosch250/Issue2010

Ignore Len and LenB in UnassignedVariableUsage inspection

Author: Hosch250

RetailCoder.VBE/Inspections/UnassignedVariableUsageInspection.cs

@@ -1,5 +1,7 @@
 using System.Collections.Generic;
 using System.Linq;
+using Antlr4.Runtime;
+using Rubberduck.Parsing;
 using Rubberduck.Parsing.Symbols;
 using Rubberduck.Parsing.VBA;
 
@@ -27,10 +29,46 @@ public override IEnumerable<InspectionResultBase> GetInspectionResults()
                 .SelectMany(declaration => declaration.References)
                 .Where(usage => !usage.IsInspectionDisabled(AnnotationName));
 
+            var lenFunction = BuiltInDeclarations.SingleOrDefault(s => s.Scope == "VBE7.DLL;VBA.Strings.Len");
+            var lenbFunction = BuiltInDeclarations.SingleOrDefault(s => s.Scope == "VBE7.DLL;VBA.Strings.LenB");
+
             foreach (var issue in usages)
             {
-                yield return new UnassignedVariableUsageInspectionResult(this, issue.Context, issue.QualifiedModuleName, issue.Declaration);
+                if (DeclarationReferencesContainsReference(lenFunction, issue) ||
+                    DeclarationReferencesContainsReference(lenbFunction, issue))
+                {
+                    continue;
+                }
+
+                yield return
+                    new UnassignedVariableUsageInspectionResult(this, issue.Context, issue.QualifiedModuleName,
+                        issue.Declaration);
+            }
+        }
+
+        private bool DeclarationReferencesContainsReference(Declaration parentDeclaration, IdentifierReference issue)
+        {
+            if (parentDeclaration == null)
+            {
+                return false;
+            }
+
+            var lenUsesIssue = false;
+            foreach (var reference in parentDeclaration.References)
+            {
+                var context = (ParserRuleContext) reference.Context.Parent;
+                if (context.GetSelection().Contains(issue.Selection))
+                {
+                    lenUsesIssue = true;
+                    break;
+                }
+            }
+
+            if (lenUsesIssue)
+            {
+                return true;
             }
+            return false;
         }
     }
 }