Fix S1144: False Positive when private member is only used in a gener…

sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/UnusedPrivateMember.cs

@@ -85,7 +85,7 @@ protected override void Initialize(SonarAnalysisContext context)
                             // Collect symbols of private members that could potentially be removed
                             var removableSymbolsCollector = new CSharpRemovableSymbolWalker(c.Compilation.GetSemanticModel);
 
-                            if (!VisitDeclaringReferences(namedType, removableSymbolsCollector, c.Compilation))
+                            if (!VisitDeclaringReferences(namedType, removableSymbolsCollector, c.Compilation, includeGeneratedFile: false))
                             {
                                 return;
                             }
@@ -100,7 +100,7 @@ protected override void Initialize(SonarAnalysisContext context)
                                 c.Compilation.GetSemanticModel,
                                 removableSymbolsCollector.PrivateSymbols.Select(s => s.Name).ToHashSet());
 
-                            if (!VisitDeclaringReferences(namedType, usageCollector, c.Compilation))
+                            if (!VisitDeclaringReferences(namedType, usageCollector, c.Compilation, includeGeneratedFile: true))
                             {
                                 return;
                             }
@@ -286,9 +286,14 @@ private static string GetMemberType(ISymbol symbol)
             }
         }
 
-        private static bool VisitDeclaringReferences(INamedTypeSymbol namedType, CSharpSyntaxWalker visitor, Compilation compilation)
+        private static bool VisitDeclaringReferences(INamedTypeSymbol namedType, CSharpSyntaxWalker visitor, Compilation compilation,
+            bool includeGeneratedFile)
         {
-            foreach (var reference in namedType.DeclaringSyntaxReferences.Where(r => !IsGenerated(r)))
+            var syntaxReferencesToVisit = includeGeneratedFile
+                ? namedType.DeclaringSyntaxReferences
+                : namedType.DeclaringSyntaxReferences.Where(r => !IsGenerated(r));
+
+            foreach (var reference in syntaxReferencesToVisit)
             {
                 if (!visitor.SafeVisit(reference.GetSyntax()))
                 {

sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/Rules/UnusedPrivateMemberTest.cs

@@ -190,5 +190,18 @@ public void UnusedPrivateMember_CodeFix()
                 new CS.UnusedPrivateMember(),
                 new CS.UnusedPrivateMemberCodeFixProvider());
         }
+
+        [TestMethod]
+        [TestCategory("Rule")]
+        public void UnusedPrivateMember_UsedInGeneratedFile()
+        {
+            Verifier.VerifyAnalyzer(
+                new[]
+                {
+                    @"TestCases\UnusedPrivateMember.CalledFromGenerated.cs",
+                    @"TestCases\UnusedPrivateMember.Generated.cs"
+                },
+                new CS.UnusedPrivateMember());
+        }
     }
 }

sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.CalledFromGenerated.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace Tests.Diagnostics
+{
+    public partial class MyClass
+    {
+        private void PrivateMethodOnlyCalledFromGenerated()
+        {
+        }
+
+        internal void InternalMethodOnlyCalledFromGenerated()
+        {
+        }
+    }
+}

sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.Generated.cs

@@ -0,0 +1,14 @@
+// <AUTO-GENERATED>
+using System;
+
+namespace Tests.Diagnostics
+{
+    public partial class MyClass
+    {
+        public void Foo()
+        {
+            PrivateMethodOnlyCalledFromGenerated();
+            InternalMethodOnlyCalledFromGenerated();
+        }
+    }
+}