Support removing unused exception variables.

src/EditorFeatures/CSharpTest/RemoveUnusedVariable/RemoveUnusedVariableTest.cs

@@ -172,6 +172,37 @@ void Method()
     void Method()
     {
     }
+}");
+        }
+
+        [WorkItem(20466, "https://github.com/dotnet/roslyn/issues/20466")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnusedVariable)]
+        public async Task RemoveUnusedCatchVariable()
+        {
+            await TestInRegularAndScriptAsync(
+@"class Class
+{
+    void Method()
+    {
+        try
+        {
+        }
+        catch (System.Exception [|e|])
+        {
+        }
+    }
+}",
+@"class Class
+{
+    void Method()
+    {
+        try
+        {
+        }
+        catch (System.Exception)
+        {
+        }
+    }
 }");
         }
     }

src/Features/CSharp/Portable/RemoveUnusedVariable/CSharpRemoveUnusedVariableCodeFixProvider.cs

@@ -17,5 +17,8 @@ internal partial class CSharpRemoveUnusedVariableCodeFixProvider : AbstractRemov
 
         public sealed override ImmutableArray<string> FixableDiagnosticIds 
             => ImmutableArray.Create(CS0168, CS0219);
+
+        protected override bool IsCatchDeclarationIdentifier(SyntaxToken token)
+            => token.Parent is CatchDeclarationSyntax catchDeclaration && catchDeclaration.Identifier == token;
     }
-}
+}
\ No newline at end of file

src/Features/Core/Portable/RemoveUnusedVariable/AbstractRemoveUnusedVariableCodeFixProvider.cs

@@ -8,27 +8,33 @@
 using Microsoft.CodeAnalysis.CodeActions;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.Editing;
+using Microsoft.CodeAnalysis.Formatting;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.RemoveUnusedVariable
 {
     internal abstract class AbstractRemoveUnusedVariableCodeFixProvider<TLocalDeclarationStatement, TVariableDeclarator, TVariableDeclaration> : SyntaxEditorBasedCodeFixProvider
-        where TLocalDeclarationStatement: SyntaxNode
-        where TVariableDeclarator: SyntaxNode
-        where TVariableDeclaration: SyntaxNode
+        where TLocalDeclarationStatement : SyntaxNode
+        where TVariableDeclarator : SyntaxNode
+        where TVariableDeclaration : SyntaxNode
     {
+        protected abstract bool IsCatchDeclarationIdentifier(SyntaxToken token);
+
         public async override Task RegisterCodeFixesAsync(CodeFixContext context)
         {
             foreach (var diagnostic in context.Diagnostics)
             {
                 var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
                 var token = root.FindToken(diagnostic.Location.SourceSpan.Start);
-                var ancestor = token.GetAncestor<TLocalDeclarationStatement>();
-
-                if (ancestor == null)
+                if (!IsCatchDeclarationIdentifier(token))
                 {
-                    return;
+                    var ancestor = token.GetAncestor<TLocalDeclarationStatement>();
+
+                    if (ancestor == null)
+                    {
+                        return;
+                    }
                 }
             }
 
@@ -42,18 +48,27 @@ protected override Task FixAllAsync(Document document, ImmutableArray<Diagnostic
             var root = editor.OriginalRoot;
             foreach (var diagnostic in diagnostics)
             {
-                var token = root.FindToken(diagnostic.Location.SourceSpan.Start);
-                var variableDeclarator = token.GetAncestor<TVariableDeclarator>();
-
-                var variableDeclarators = token.GetAncestor<TVariableDeclaration>().ChildNodes().Where(x => x is TVariableDeclarator);
-
-                if (variableDeclarators.Count() == 1)
+                var token = diagnostic.Location.FindToken(cancellationToken);
+                if (IsCatchDeclarationIdentifier(token))
                 {
-                    editor.RemoveNode(token.GetAncestor<TLocalDeclarationStatement>());
+                    editor.ReplaceNode(
+                        token.Parent,
+                        token.Parent.ReplaceToken(token, default(SyntaxToken)).WithAdditionalAnnotations(Formatter.Annotation));
                 }
-                else if (variableDeclarators.Count() > 1)
+                else
                 {
-                    editor.RemoveNode(variableDeclarator);
+                    var variableDeclarator = token.GetAncestor<TVariableDeclarator>();
+
+                    var variableDeclarators = token.GetAncestor<TVariableDeclaration>().ChildNodes().Where(x => x is TVariableDeclarator);
+
+                    if (variableDeclarators.Count() == 1)
+                    {
+                        editor.RemoveNode(token.GetAncestor<TLocalDeclarationStatement>());
+                    }
+                    else if (variableDeclarators.Count() > 1)
+                    {
+                        editor.RemoveNode(variableDeclarator);
+                    }
                 }
             }
 
@@ -68,4 +83,4 @@ private class MyCodeAction : CodeAction.DocumentChangeAction
             }
         }
     }
-}
+}
\ No newline at end of file

src/Features/VisualBasic/Portable/RemoveUnusedVariable/VisualBasicRemoveUnusedVariableCodeFixProvider.vb

@@ -7,16 +7,20 @@ Imports Microsoft.CodeAnalysis.RemoveUnusedVariable
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.RemoveUnusedVariable
-
-    <ExportCodeFixProviderAttribute(LanguageNames.VisualBasic, Name:=PredefinedCodeFixProviderNames.RemoveUnusedVariable), [Shared]>
+    <ExportCodeFixProvider(LanguageNames.VisualBasic, Name:=PredefinedCodeFixProviderNames.RemoveUnusedVariable), [Shared]>
     <ExtensionOrder(After:=PredefinedCodeFixProviderNames.AddImport)>
     Friend Class VisualBasicRemoveUnusedVariableCodeFixProvider
         Inherits AbstractRemoveUnusedVariableCodeFixProvider(Of
             LocalDeclarationStatementSyntax, ModifiedIdentifierSyntax, VariableDeclaratorSyntax)
 
-        Private Const BC42024 As String = "BC42024"
+        Private Const BC42024 As String = NameOf(BC42024)
 
         Public Overrides ReadOnly Property FixableDiagnosticIds As ImmutableArray(Of String) =
             ImmutableArray.Create(BC42024)
+
+        Protected Overrides Function IsCatchDeclarationIdentifier(token As SyntaxToken) As Boolean
+            ' VB does not support catch declarations without an identifier in them
+            Return False
+        End Function
     End Class
 End Namespace
\ No newline at end of file