From eb1a5750fe483e766e90b7a6fef3a1ddd969b069 Mon Sep 17 00:00:00 2001
From: Mattia Di Eleuterio <madiele92@gmail.com>
Date: Sat, 17 Feb 2024 20:13:25 +0100
Subject: [PATCH] fix #2550 inlay hints lambdas parameter type null reference
 exception

---
 .../Handlers/OmniSharpInlayHintHandler.cs     |  2 +-
 .../OmniSharpInlayHintHandlerFacts.cs         | 37 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/OmniSharp.LanguageServerProtocol/Handlers/OmniSharpInlayHintHandler.cs b/src/OmniSharp.LanguageServerProtocol/Handlers/OmniSharpInlayHintHandler.cs
index c3c831e61e..ce16575d73 100644
--- a/src/OmniSharp.LanguageServerProtocol/Handlers/OmniSharpInlayHintHandler.cs
+++ b/src/OmniSharp.LanguageServerProtocol/Handlers/OmniSharpInlayHintHandler.cs
@@ -82,7 +82,7 @@ private static LSPInlayHint ToLSPInlayHint(OmniSharpInlayHint hint)
                     ? new MarkupContent() { Kind = MarkupKind.Markdown, Value = hint.Tooltip }
                     : null,
                 Position = ToPosition(hint.Position),
-                TextEdits = new(ToTextEdits(hint.TextEdits)),
+                TextEdits = hint.TextEdits is not null ? new(ToTextEdits(hint.TextEdits)) : null,
                 PaddingLeft = hint.Label.Length > trimmedStartLabel.Length,
                 PaddingRight = trimmedStartLabel.Length > trimmedLabel.Length,
                 Data = JToken.FromObject(hint.Data),
diff --git a/tests/OmniSharp.Lsp.Tests/OmniSharpInlayHintHandlerFacts.cs b/tests/OmniSharp.Lsp.Tests/OmniSharpInlayHintHandlerFacts.cs
index 904992d23d..ba5a3a6a44 100644
--- a/tests/OmniSharp.Lsp.Tests/OmniSharpInlayHintHandlerFacts.cs
+++ b/tests/OmniSharp.Lsp.Tests/OmniSharpInlayHintHandlerFacts.cs
@@ -156,6 +156,43 @@ public async Task InlayHintsForVarTypes(string fileName)
         }
     }
 
+    [Theory]
+    [InlineData("dummy.cs")]
+    [InlineData("dummy.csx")]
+    public async Task InlayHintsForLambdaParameterTypeNearFunctionParameterName(string fileName)
+    {
+        var code = @"
+using System;
+void fun(Func<int, bool> lambda) {}
+{|ihRegion:fun(b => true);|}
+";
+
+        var options = InlayHintsOptions.AllOn with { ForLambdaParameterTypes = false };
+
+        {
+            await SetInlayHintOptionsAsync(options);
+            var response = await GetInlayHints(fileName, code);
+            AssertEx.Equal(new[]
+                {
+                    new InlayHint { Position = new Position { Line = 3, Character = 4 }, Label = "lambda:", Kind = InlayHintKind.Parameter, Tooltip = null, TextEdits = new[] { new TextEdit { Range = new Range() { Start = new Position() { Line = 3, Character = 4 }, End = new Position() { Line = 3, Character = 4 } }, NewText = "lambda: " } }, PaddingLeft = false, PaddingRight = true },
+                },
+                response,
+                ignoreDataComparer);
+        }
+
+        {
+            await SetInlayHintOptionsAsync(options with { ForLambdaParameterTypes = true });
+            var response = await GetInlayHints(fileName, code);
+            AssertEx.Equal(new[]
+                {
+                    new InlayHint { Position = new Position { Line = 3, Character = 4 }, Label = "lambda:", Kind = InlayHintKind.Parameter, Tooltip = null, TextEdits = new[] { new TextEdit { Range = new Range() { Start = new Position() { Line = 3, Character = 4 }, End = new Position() { Line = 3, Character = 4 } }, NewText = "lambda: " } }, PaddingLeft = false, PaddingRight = true },
+                    new InlayHint { Position = new Position { Line = 3, Character = 4 }, Label = "int", Kind = InlayHintKind.Type, Tooltip = null, TextEdits = null, PaddingLeft = false, PaddingRight = true },
+                },
+                response,
+                ignoreDataComparer);
+        }
+    }
+
     [Theory]
     [InlineData("dummy.cs")]
     [InlineData("dummy.csx")]