From ea2872fd2a889cd8d4a8802c2401874f8b9f7a86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Amaury=20Lev=C3=A9?= <amaury.leve@sonarsource.com>
Date: Wed, 6 Mar 2019 15:18:37 +0100
Subject: [PATCH] Fix S1144: False Positive when private member is only used in
 a generated file

---
 .../Rules/UnusedPrivateMember.cs                  | 13 +++++++++----
 .../Rules/UnusedPrivateMemberTest.cs              | 13 +++++++++++++
 .../UnusedPrivateMember.CalledFromGenerated.cs    | 15 +++++++++++++++
 .../TestCases/UnusedPrivateMember.Generated.cs    | 14 ++++++++++++++
 4 files changed, 51 insertions(+), 4 deletions(-)
 create mode 100644 sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.CalledFromGenerated.cs
 create mode 100644 sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.Generated.cs

diff --git a/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/UnusedPrivateMember.cs b/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/UnusedPrivateMember.cs
index 19593ffe156..b4417469019 100644
--- a/sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/UnusedPrivateMember.cs
+++ b/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()))
                 {
diff --git a/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/Rules/UnusedPrivateMemberTest.cs b/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/Rules/UnusedPrivateMemberTest.cs
index 1bdf624b6d1..2dd748a4f0c 100644
--- a/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/Rules/UnusedPrivateMemberTest.cs
+++ b/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());
+        }
     }
 }
diff --git a/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.CalledFromGenerated.cs b/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.CalledFromGenerated.cs
new file mode 100644
index 00000000000..9dd17999920
--- /dev/null
+++ b/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()
+        {
+        }
+    }
+}
diff --git a/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.Generated.cs b/sonaranalyzer-dotnet/tests/SonarAnalyzer.UnitTest/TestCases/UnusedPrivateMember.Generated.cs
new file mode 100644
index 00000000000..fea3a692cdf
--- /dev/null
+++ b/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();
+        }
+    }
+}