Merge pull request #47552 from Youssef1313/patch-7

Signature help should use SymbolDisplayMiscellaneousOptions.AllowDefaultLiteral

src/EditorFeatures/CSharpTest/SignatureHelp/InvocationExpressionSignatureHelpProviderTests.cs

@@ -962,6 +962,30 @@ void Goo(int someParameter, bool something)
 
         #region "Trigger tests"
 
+        [Fact, Trait(Traits.Feature, Traits.Features.SignatureHelp)]
+        [WorkItem(47364, "https://github.com/dotnet/roslyn/issues/47364")]
+        public async Task TestInvocationOnTriggerParens_OptionalDefaultStruct()
+        {
+            var markup = @"
+using System;
+using System.Threading;
+
+class Program
+{
+   static void SomeMethod(CancellationToken token = default) => throw new NotImplementedException();
+
+    static void Main(string[] args)
+    {
+        [|SomeMethod($$|]);
+    }
+}";
+
+            var expectedOrderedItems = new List<SignatureHelpTestItem>();
+            expectedOrderedItems.Add(new SignatureHelpTestItem("void Program.SomeMethod([CancellationToken token = default])", string.Empty, null, currentParameterIndex: 0));
+
+            await TestAsync(markup, expectedOrderedItems, usePreviousCharAsTrigger: true);
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.SignatureHelp)]
         public async Task TestInvocationOnTriggerParens()
         {

src/Features/CSharp/Portable/SignatureHelp/AbstractCSharpSignatureHelpProvider.cs

@@ -13,6 +13,9 @@ namespace Microsoft.CodeAnalysis.CSharp.SignatureHelp
 {
     internal abstract class AbstractCSharpSignatureHelpProvider : AbstractSignatureHelpProvider
     {
+        private static readonly SymbolDisplayFormat s_allowDefaultLiteralFormat = SymbolDisplayFormat.MinimallyQualifiedFormat
+            .AddMiscellaneousOptions(SymbolDisplayMiscellaneousOptions.AllowDefaultLiteral);
+
         protected AbstractCSharpSignatureHelpProvider()
         {
         }
@@ -53,7 +56,7 @@ protected static SymbolDisplayPart NewLine()
                 parameter.Name,
                 parameter.IsOptional,
                 parameter.GetDocumentationPartsFactory(semanticModel, position, formatter),
-                parameter.ToMinimalDisplayParts(semanticModel, position));
+                parameter.ToMinimalDisplayParts(semanticModel, position, s_allowDefaultLiteralFormat));
         }
 
         /// <summary>