Merge pull request #3882 from Evangelink/CA1812-vbnet

Update CA1812 to not report on vbnet static-like holder type

src/NetAnalyzers/Core/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/StaticHolderTypes.cs

@@ -27,7 +27,7 @@ namespace Microsoft.CodeQuality.Analyzers.ApiDesignGuidelines
     /// even though the title of CA1053 is "Static holder types should not have constructors".
     /// Like FxCop, this analyzer does emit a diagnostic when the type has a private default
     /// constructor, even though the documentation of CA1053 says it should only trigger for public
-    /// or protected default constructor. Like FxCop, this analyzer does not emit a diagnostic when 
+    /// or protected default constructor. Like FxCop, this analyzer does not emit a diagnostic when
     /// class has a base class, however the diagnostic is emitted if class supports empty interface.
     /// </para>
     /// <para>
@@ -73,13 +73,18 @@ public override void Initialize(AnalysisContext context)
         private static void AnalyzeSymbol(SymbolAnalysisContext context)
         {
             var symbol = (INamedTypeSymbol)context.Symbol;
+
             if (!symbol.IsStatic &&
-                symbol.MatchesConfiguredVisibility(context.Options, Rule, context.Compilation, context.CancellationToken) &&
+                !symbol.IsAbstract &&
+                !IsSealedAndVisualBasic(symbol) &&
                 symbol.IsStaticHolderType() &&
-                !symbol.IsAbstract)
+                symbol.MatchesConfiguredVisibility(context.Options, Rule, context.Compilation, context.CancellationToken))
             {
                 context.ReportDiagnostic(symbol.CreateDiagnostic(Rule, symbol.Name));
             }
+
+            static bool IsSealedAndVisualBasic(INamedTypeSymbol symbol)
+                => symbol.IsSealed && symbol.Language == LanguageNames.VisualBasic;
         }
     }
 }

src/NetAnalyzers/UnitTests/Microsoft.CodeQuality.Analyzers/Maintainability/AvoidUninstantiatedInternalClassesTests.cs

@@ -1511,6 +1511,87 @@ public void M()
             }.RunAsync();
         }
 
+        [Fact, WorkItem(1878, "https://github.com/dotnet/roslyn-analyzers/issues/1878")]
+        public async Task CA1812_VisualBasic_StaticLikeClass_NoDiagnostic()
+        {
+            await VerifyVB.VerifyAnalyzerAsync(@"
+Imports System
+Friend NotInheritable Class C1
+
+    Private Sub New()
+    End Sub
+
+    Public Shared Function GetSomething(o As Object) As String
+        Return o.ToString()
+    End Function
+End Class
+
+Public Class Helpers
+    Private NotInheritable Class C2
+
+        Private Sub New()
+        End Sub
+
+        Public Shared Function GetSomething(o As Object) As String
+            Return o.ToString()
+        End Function
+    End Class
+End Class
+
+Friend NotInheritable Class C3
+
+    Private Const SomeConstant As String = ""Value""
+    Private Shared f As Integer
+
+    Private Sub New()
+    End Sub
+
+    Public Shared Sub M()
+    End Sub
+
+    Public Shared Property P As Integer
+
+    Public Shared Event ThresholdReached As EventHandler
+End Class
+
+Friend Class C4
+
+    Private Sub New()
+    End Sub
+
+    Public Shared Function GetSomething(o As Object) As String
+        Return o.ToString()
+    End Function
+End Class
+
+Friend NotInheritable Class C5
+
+    Public Sub New()
+    End Sub
+
+    Public Shared Function GetSomething(o As Object) As String
+        Return o.ToString()
+    End Function
+End Class");
+        }
+
+        [Fact, WorkItem(1878, "https://github.com/dotnet/roslyn-analyzers/issues/1878")]
+        public async Task CA1812_VisualBasic_NotStaticLikeClass_Diagnostic()
+        {
+            await VerifyVB.VerifyAnalyzerAsync(@"
+Imports System
+
+Friend NotInheritable Class [|C1|]
+
+    Private Sub New()
+    End Sub
+
+    Public Function GetSomething(o As Object) As String
+        Return o.ToString()
+    End Function
+End Class");
+        }
+
         private static DiagnosticResult GetCSharpResultAt(int line, int column, string className)
             => VerifyCS.Diagnostic()
                 .WithLocation(line, column)

src/Utilities/Compiler/Extensions/INamedTypeSymbolExtensions.cs

@@ -36,7 +36,7 @@ public static IEnumerable<INamedTypeSymbol> GetBaseTypesAndThis(this INamedTypeS
         /// <see cref="Stack{T}"/>.
         /// </para>
         /// <para>
-        /// Similarly, if <paramref name="parentType"/> is the interface <see cref="IList{T}"/>, 
+        /// Similarly, if <paramref name="parentType"/> is the interface <see cref="IList{T}"/>,
         /// then this method will return <see langword="true"/> for <c>List&gt;int></c>
         /// or any other class that extends <see cref="IList{T}"/> or an class that implements it,
         /// because <c>IList&gt;int></c> is constructed from <see cref="IList{T}"/>.
@@ -139,8 +139,10 @@ public static bool IsStaticHolderType(this INamedTypeSymbol symbol)
                 return false;
             }
 
-            // Sealed objects are presumed to be non-static holder types
-            if (symbol.IsSealed)
+            // Sealed objects are presumed to be non-static holder types for C#.
+            // In VB.NET the type cannot be static and guidelines favor having a sealed (NotInheritable) type
+            //  to act as static holder type.
+            if (symbol.IsSealed && symbol.Language == LanguageNames.CSharp)
             {
                 return false;
             }