Fix one formatting bug, and prevent another from crashing the formatter (#12786)

From
https://developercommunity.visualstudio.com/t/Razor-Formatting-Feature-internal-error/11041869#T-ND11043454

First commit is a fix for formatting when there are two markup elements
in the same line, inside a C# block.
Second commit is ensuring we don't crash when the document generation
produces bad data. The bad data comes from us not handling block bodied
lambdas in attributes properly, for which I've logged
#12785 to fix at some point.
Thought it was worth at least unblocking users for now though.

Author: davidwengier

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/FormattingUtilities.cs

@@ -407,7 +407,11 @@ public static void GetOriginalDocumentChangesFromLineInfo(FormattingContext cont
                         ? originalLine.End - originalStart
                         : lineInfo.FormattedLength;
                     var formattedStart = formattedLine.Start + formattedIndentation + lineInfo.FormattedOffset;
-                    formattingChanges.Add(new TextChange(new TextSpan(originalStart, length), formattedText.ToString(TextSpan.FromBounds(formattedStart, formattedLine.End - lineInfo.FormattedOffsetFromEndOfLine))));
+                    var formattedEnd = formattedLine.End - lineInfo.FormattedOffsetFromEndOfLine;
+                    if (formattedEnd > formattedStart)
+                    {
+                        formattingChanges.Add(new TextChange(new TextSpan(originalStart, length), formattedText.ToString(TextSpan.FromBounds(formattedStart, formattedEnd))));
+                    }
 
                     if (lineInfo.CheckForNewLines)
                     {

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/RazorFormattingPass.cs

@@ -380,6 +380,13 @@ private static bool FormatBlock(FormattingContext context, RazorSourceDocument s
             return didFormat;
         }
 
+        // When there are multiple sibling markup blocks in a C# code block (e.g., "<text>:</text> <InputFile />"),
+        // the open/close brace nodes passed to this method may actually be sibling markup blocks rather than
+        // actual braces. We should not try to format between sibling markup blocks as they should remain on the
+        // same line.
+        var openBraceIsMarkupBlock = openBraceNode is MarkupBlockSyntax && openBraceNode != codeNode;
+        var closeBraceIsMarkupBlock = closeBraceNode is MarkupBlockSyntax && closeBraceNode != codeNode;
+
         var additionalIndentation = "";
 
         // It's important with the new formatting engine that we maintain the indentation that the Html formatter would have applied,
@@ -401,7 +408,8 @@ private static bool FormatBlock(FormattingContext context, RazorSourceDocument s
             additionalIndentation = openBraceLine.GetLeadingWhitespace();
         }
 
-        if (openBraceNode.TryGetLinePositionSpanWithoutWhitespace(source, out var openBraceRange) &&
+        if (!openBraceIsMarkupBlock &&
+            openBraceNode.TryGetLinePositionSpanWithoutWhitespace(source, out var openBraceRange) &&
             openBraceRange.End.Line == codeRange.Start.Line &&
             !RangeHasBeenModified(ref changes, source.Text, codeRange))
         {
@@ -411,7 +419,8 @@ private static bool FormatBlock(FormattingContext context, RazorSourceDocument s
             didFormat = true;
         }
 
-        if (closeBraceNode.Span.Length > 0 &&
+        if (!closeBraceIsMarkupBlock &&
+            closeBraceNode.Span.Length > 0 &&
             closeBraceNode.TryGetLinePositionSpanWithoutWhitespace(source, out var closeBraceRange) &&
             !RangeHasBeenModified(ref changes, source.Text, codeRange))
         {

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Formatting/DocumentFormattingTest.cs

@@ -18,6 +18,56 @@ namespace Microsoft.AspNetCore.Razor.LanguageServer.Formatting;
 
 public class DocumentFormattingTest(ITestOutputHelper testOutput) : DocumentFormattingTestBase(testOutput)
 {
+    [Fact]
+    [WorkItem("https://developercommunity.visualstudio.com/t/Razor-Formatting-Feature-internal-error/11041869")]
+    public async Task TextAndTagOnSameLine()
+    {
+        await RunFormattingTestAsync(
+            input: """
+                 <div>
+                 	@if (b)
+                 	{
+                 		<text>:</text> <InputFile OnChange="StateHasChanged" />
+                 	}
+                 </div>
+
+                 @code
+                 {
+                 	bool b;
+                 }
+                 
+                 """,
+            htmlFormatted: """
+                 <div>
+                 	@if (b)
+                 	{
+                 	<text>:</text> <InputFile OnChange="StateHasChanged" />
+                 	}
+                 </div>
+                 
+                 @code
+                 {
+                 	bool b;
+                 }
+                 
+                 """,
+            expected: """
+                 <div>
+                 	@if (b)
+                 	{
+                 		<text>:</text> <InputFile OnChange="StateHasChanged" />
+                 	}
+                 </div>
+                 
+                 @code
+                 {
+                 	bool b;
+                 }
+                 
+                 """,
+            insertSpaces: false);
+    }
+
     [Fact]
     [WorkItem("https://github.com/microsoft/vscode-dotnettools/issues/2766")]
     public async Task DifferentAttributeWrappingPoint1()

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/Cohost/Formatting/FormattingLogTest.cs

@@ -88,6 +88,22 @@ public async Task RanOutOfOriginalLines()
         await GetFormattingEditsAsync(contents, htmlChangesFile);
     }
 
+    [Fact]
+    [WorkItem("https://developercommunity.visualstudio.com/t/Razor-Formatting-Feature-internal-error/11041869#T-ND11043454")]
+    public async Task MultiLineLambda()
+    {
+        var contents = GetResource("InitialDocument.txt");
+
+        var document = CreateProjectAndRazorDocument(contents);
+
+        var options = new RazorFormattingOptions();
+
+        var formattingService = (RazorFormattingService)OOPExportProvider.GetExportedValue<IRazorFormattingService>();
+        formattingService.GetTestAccessor().SetFormattingLoggerFactory(new TestFormattingLoggerFactory(TestOutputHelper));
+
+        await GetFormattingEditsAsync(document, [], span: default, options.CodeBlockBraceOnNextLine, options.AttributeIndentStyle, options.InsertSpaces, options.TabSize, RazorCSharpSyntaxFormattingOptions.Default);
+    }
+
     private async Task<TextEdit[]?> GetFormattingEditsAsync(string contents, string htmlChangesFile)
     {
         var document = CreateProjectAndRazorDocument(contents);

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/TestFiles/FormattingLog/MultiLineLambda/InitialDocument.txt

@@ -0,0 +1,3 @@
+<button @onclick="()=>{
+StateHasChanged();}">
+</button>