Avoid chopping single trailing lambda

Src/CSharpier.Core/CSharp/SyntaxPrinter/ArgumentListLikeSyntax.cs

@@ -2,6 +2,7 @@
 using CSharpier.Core.DocTypes;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
 
 namespace CSharpier.Core.CSharp.SyntaxPrinter;
 
@@ -78,6 +79,21 @@ lambda.Block is not null
         {
             args = SeparatedSyntaxList.Print(arguments, Argument.Print, Doc.Line, context);
         }
+        else if (
+            arguments.Count > 1
+            && arguments[^1].Expression is LambdaExpressionSyntax lastLambda
+            && !arguments
+                .Take(arguments.Count - 1)
+                .Any(o => o.Expression is AnonymousFunctionExpressionSyntax)
+            && !openParenToken
+                .Parent!.DescendantTrivia(
+                    TextSpan.FromBounds(openParenToken.SpanStart, lastLambda.ArrowToken.SpanStart)
+                )
+                .Any(o => o.IsComment() || o.IsDirective)
+        )
+        {
+            args = ArgumentListWithTrailingLambda.Print(arguments, lastLambda, context);
+        }
         else if (arguments.Count > 0)
         {
             args = Doc.Concat(

Src/CSharpier.Core/CSharp/SyntaxPrinter/ArgumentListWithTrailingLambda.cs

@@ -0,0 +1,75 @@
+using CSharpier.Core.CSharp.SyntaxPrinter.SyntaxNodePrinters;
+using CSharpier.Core.DocTypes;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace CSharpier.Core.CSharp.SyntaxPrinter;
+
+internal static class ArgumentListWithTrailingLambda
+{
+    public static Doc Print(
+        SeparatedSyntaxList<ArgumentSyntax> arguments,
+        LambdaExpressionSyntax lastLambda,
+        PrintingContext context
+    )
+    {
+        var chop = Doc.Concat(
+            Doc.Indent(
+                Doc.SoftLine,
+                SeparatedSyntaxList.Print(arguments, Argument.Print, Doc.Line, context)
+            ),
+            Doc.SoftLine
+        );
+
+        Doc lambdaHead;
+        Doc lambdaBody;
+        bool bodyIsBraced;
+        if (lastLambda is SimpleLambdaExpressionSyntax simpleLambda)
+        {
+            bodyIsBraced =
+                simpleLambda.Body
+                    is BlockSyntax
+                        or ObjectCreationExpressionSyntax
+                        or AnonymousObjectCreationExpressionSyntax;
+
+            lambdaHead = SimpleLambdaExpression.PrintHead(simpleLambda, context);
+            lambdaBody = SimpleLambdaExpression.PrintBody(simpleLambda, context);
+        }
+        else if (lastLambda is ParenthesizedLambdaExpressionSyntax parenthesizedLambda)
+        {
+            bodyIsBraced = parenthesizedLambda.Block is not null;
+            lambdaHead = ParenthesizedLambdaExpression.PrintHead(parenthesizedLambda, context);
+            lambdaBody = bodyIsBraced
+                ? ParenthesizedLambdaExpression.PrintBody(parenthesizedLambda, context)
+                : Doc.Indent(Doc.Line, Node.Print(parenthesizedLambda.Body, context));
+        }
+        else
+        {
+            return chop;
+        }
+
+        var flatParts = new List<Doc>((arguments.Count - 1) * 3 + 2);
+        for (var x = 0; x < arguments.Count - 1; x++)
+        {
+            flatParts.Add(Argument.Print(arguments[x], context));
+            flatParts.Add(Token.Print(arguments.GetSeparator(x), context));
+            flatParts.Add(" ");
+        }
+
+        flatParts.Add(Argument.PrintModifiers(arguments[^1], context));
+        flatParts.Add(lambdaHead);
+
+        if (flatParts.Any(DocUtilities.ContainsBreak))
+        {
+            return chop;
+        }
+
+        var wrap = Doc.Concat(
+            Doc.ForceFlat(flatParts),
+            lambdaBody,
+            bodyIsBraced ? Doc.Null : Doc.SoftLine
+        );
+
+        return Doc.ConditionalGroup(wrap, wrap, chop);
+    }
+}

Src/CSharpier.Tests/FormattingTests/TestFiles/cs/ObnoxiousEdgeCases.test

@@ -9,9 +9,8 @@ class ClassName
     internal StackObjectPool<
         Dictionary<object, KeyedItemInfo>
     > KeyedItemInfoDictionaryPool { get; } =
-        new StackObjectPool<Dictionary<object, KeyedItemInfo>>(
-            maxPreservedItems: 10,
-            () => new Dictionary<object, KeyedItemInfo>()
+        new StackObjectPool<Dictionary<object, KeyedItemInfo>>(maxPreservedItems: 10, () =>
+            new Dictionary<object, KeyedItemInfo>()
         );
 
     RenderFragment<AuthenticationState> customNotAuthorized = state =>

Src/CSharpier.Tests/FormattingTests/TestFiles/cs/ParenthesizedLambdaExpressions.test

@@ -104,8 +104,26 @@ public class ClassName
             CallAnotherMethod______________________________________________________123()
         );
 
+        CallMethod(CallAnotherMethod_________________(), () =>
+            CallAnotherMethod_________________()
+        );
+
+        CallMethod(
+            CallAnotherMethod_________________(),
+            // Comment
+            () => CallAnotherMethod_________________()
+        );
+
+        CallMethod(
+#if DEBUG
+            CallAnotherMethod_________________(),
+#endif
+            () => CallAnotherMethod_________________()
+        );
+
         CallMethod(
             CallAnotherMethod_________________(),
+            () => CallAnotherMethod_________________(),
             () => CallAnotherMethod_________________()
         );
     }