Merge pull request #49501 from CyrusNajmabadi/preserveFormattingAnnot…

…ation Preserve annotation on comment trivia when performing formatting.
dotnet · Nov 19, 2020 · c8d646a · c8d646a
2 parents 449aba9 + 2609575
commit c8d646a
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Showing 2 changed files with 52 additions and 23 deletions.
diff --git a/src/EditorFeatures/CSharpTest/Formatting/FormattingEngineTests.cs b/src/EditorFeatures/CSharpTest/Formatting/FormattingEngineTests.cs
@@ -2234,6 +2234,34 @@ public void SeparateGroups_GroupIfSorted_RecognizeSystemNotFirst()
             AssertFormatWithView(expected, code, (GenerationOptions.SeparateImportDirectiveGroups, true));
         }
 
+        [Fact, WorkItem(49492, "https://github.com/dotnet/roslyn/issues/49492")]
+        public void PreserveAnnotationsOnMultiLineTrivia()
+        {
+            var text = @"
+namespace TestApp
+{
+    class Test
+    {
+    /* __marker__ */
+    }
+}
+";
+
+            var position = text.IndexOf("/* __marker__ */");
+            var syntaxTree = CSharpSyntaxTree.ParseText(text);
+            var root = syntaxTree.GetRoot();
+
+            var annotation = new SyntaxAnnotation("marker");
+            var markerTrivia = root.FindTrivia(position, findInsideTrivia: true);
+            var annotatedMarkerTrivia = markerTrivia.WithAdditionalAnnotations(annotation);
+            root = root.ReplaceTrivia(markerTrivia, annotatedMarkerTrivia);
+
+            var formattedRoot = Formatter.Format(root, new AdhocWorkspace());
+            var annotatedTrivia = formattedRoot.GetAnnotatedTrivia("marker");
+
+            Assert.Single(annotatedTrivia);
+        }
+
         private static void AssertFormatAfterTypeChar(string code, string expected, Dictionary<OptionKey2, object> changedOptionSet = null)
         {
             using var workspace = TestWorkspace.CreateCSharp(code);

diff --git a/...dUtilitiesAndExtensions/Compiler/CSharp/Formatting/Engine/Trivia/CSharpTriviaFormatter.cs b/...dUtilitiesAndExtensions/Compiler/CSharp/Formatting/Engine/Trivia/CSharpTriviaFormatter.cs
@@ -180,32 +180,33 @@ private static bool IsMultilineComment(SyntaxTrivia trivia1)
 
         private bool TryFormatMultiLineCommentTrivia(LineColumn lineColumn, SyntaxTrivia trivia, out SyntaxTrivia result)
         {
-            result = default;
-
-            if (trivia.Kind() != SyntaxKind.MultiLineCommentTrivia)
-            {
-                return false;
-            }
-
-            var indentation = lineColumn.Column;
-            var indentationDelta = indentation - GetExistingIndentation(trivia);
-            if (indentationDelta != 0)
+            if (trivia.Kind() == SyntaxKind.MultiLineCommentTrivia)
             {
-                var multiLineComment = trivia.ToFullString().ReindentStartOfXmlDocumentationComment(
-                    false /* forceIndentation */,
-                    indentation,
-                    indentationDelta,
-                    this.Options.GetOption(FormattingOptions2.UseTabs),
-                    this.Options.GetOption(FormattingOptions2.TabSize),
-                    this.Options.GetOption(FormattingOptions2.NewLine));
-
-                var multilineCommentTrivia = SyntaxFactory.ParseLeadingTrivia(multiLineComment);
-                Contract.ThrowIfFalse(multilineCommentTrivia.Count == 1);
-
-                result = multilineCommentTrivia.ElementAt(0);
-                return true;
+                var indentation = lineColumn.Column;
+                var indentationDelta = indentation - GetExistingIndentation(trivia);
+                if (indentationDelta != 0)
+                {
+                    var multiLineComment = trivia.ToFullString().ReindentStartOfXmlDocumentationComment(
+                        false /* forceIndentation */,
+                        indentation,
+                        indentationDelta,
+                        this.Options.GetOption(FormattingOptions2.UseTabs),
+                        this.Options.GetOption(FormattingOptions2.TabSize),
+                        this.Options.GetOption(FormattingOptions2.NewLine));
+
+                    var multilineCommentTrivia = SyntaxFactory.ParseLeadingTrivia(multiLineComment);
+                    Contract.ThrowIfFalse(multilineCommentTrivia.Count == 1);
+
+                    // Preserve annotations on this comment as the formatter is only supposed to touch whitespace, and
+                    // thus should make it appear as if the original comment trivia (with annotations) is still there in
+                    // the resultant formatted tree.
+                    var firstTrivia = multilineCommentTrivia.First();
+                    result = trivia.CopyAnnotationsTo(firstTrivia);
+                    return true;
+                }
             }
 
+            result = default;
             return false;
         }