Allow <code> in DocComments to render as a block in Hover response

src/LanguageServer/Protocol/Extensions/ProtocolConversions.cs

@@ -19,7 +19,6 @@
 using Microsoft.CodeAnalysis.Internal.Log;
 using Microsoft.CodeAnalysis.LanguageServer.Handler;
 using Microsoft.CodeAnalysis.NavigateTo;
-using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.PooledObjects;
 using Microsoft.CodeAnalysis.SpellCheck;
 using Microsoft.CodeAnalysis.Tags;
@@ -936,12 +935,23 @@ public static LSP.MarkupContent GetDocumentationMarkupContent(ImmutableArray<Tag
 
                         codeFence = null;
 
+                        break;
+                    case TextTags.Text when taggedText.Style == (TaggedTextStyle.Code | TaggedTextStyle.PreserveWhitespace):
+                        // This represents a block of code (`<code></code>`) in doc comments.
+                        // Since code elements optionally support a `lang` attribute and we do not have access to the
+                        // language which was specified at this point, we tell the client to render it as plain text.
+
+                        if (!markdownBuilder.IsLineEmpty())
+                            AppendLineBreak(markdownBuilder);
+
+                        // The current line is empty, we can append a code block.
+                        markdownBuilder.AppendLine($"{BlockCodeFence}text");
+                        markdownBuilder.AppendLine(taggedText.Text);
+                        markdownBuilder.AppendLine(BlockCodeFence);
+
                         break;
                     case TextTags.LineBreak:
-                        // A line ending with double space and a new line indicates to markdown
-                        // to render a single-spaced line break.
-                        markdownBuilder.Append("  ");
-                        markdownBuilder.AppendLine();
+                        AppendLineBreak(markdownBuilder);
                         break;
                     default:
                         var styledText = GetStyledText(taggedText, codeFence != null);
@@ -958,6 +968,14 @@ public static LSP.MarkupContent GetDocumentationMarkupContent(ImmutableArray<Tag
                 Value = content,
             };
 
+            static void AppendLineBreak(MarkdownContentBuilder markdownBuilder)
+            {
+                // A line ending with double space and a new line indicates to markdown
+                // to render a single-spaced line break.
+                markdownBuilder.Append("  ");
+                markdownBuilder.AppendLine();
+            }
+
             static string GetCodeBlockLanguageName(string language)
             {
                 return language switch

src/LanguageServer/ProtocolUnitTests/Hover/HoverTests.cs

@@ -424,6 +424,48 @@ void A.AMethod(int i)
             Assert.Equal(expectedMarkdown, results.Contents.Fourth.Value);
         }
 
+        [Theory, CombinatorialData]
+        public async Task TestGetHoverAsync_UsingMarkupContentDoesNotEscapeCodeBlock(bool mutatingLspWorkspace)
+        {
+            var markup =
+@"class A
+{
+    /// <summary>
+    /// <code>
+    /// if (true) {
+    ///     Console.WriteLine(""hello"");
+    /// }
+    /// </code>
+    /// </summary>
+    void {|caret:AMethod|}(int i)
+    {
+    }
+}";
+            var clientCapabilities = new LSP.ClientCapabilities
+            {
+                TextDocument = new LSP.TextDocumentClientCapabilities { Hover = new LSP.HoverSetting { ContentFormat = [LSP.MarkupKind.Markdown] } }
+            };
+            await using var testLspServer = await CreateTestLspServerAsync(markup, mutatingLspWorkspace, clientCapabilities);
+            var expectedLocation = testLspServer.GetLocations("caret").Single();
+
+            var expectedMarkdown = @"```csharp
+void A.AMethod(int i)
+```
+
+
+```text
+if (true) {
+    Console.WriteLine(""hello"");
+}
+```  
+";
+
+            var results = await RunGetHoverAsync(
+                testLspServer,
+                expectedLocation).ConfigureAwait(false);
+            Assert.Equal(expectedMarkdown, results.Contents.Fourth.Value);
+        }
+
         [Theory, CombinatorialData, WorkItem("https://github.com/dotnet/vscode-csharp/issues/6577")]
         public async Task TestGetHoverAsync_UsesInlineCodeFencesInAwaitReturn(bool mutatingLspWorkspace)
         {