Merge pull request #32908 from sharwell/hands-off

Avoid touching files that didn't actually change

src/Tools/dotnet-format/CodeFormatter.cs

@@ -159,7 +159,14 @@ private static async Task<Solution> FormatFilesInProjectAsync(ILogger logger, Pr
                     }
 
                     var formattedDocument = await Formatter.FormatAsync(document, documentOptions, cancellationToken).ConfigureAwait(false);
-                    return await formattedDocument.GetTextAsync(cancellationToken).ConfigureAwait(false);
+                    var formattedSourceText = await formattedDocument.GetTextAsync(cancellationToken).ConfigureAwait(false);
+                    if (formattedSourceText.ContentEquals(await document.GetTextAsync(cancellationToken).ConfigureAwait(false)))
+                    {
+                        // Avoid touching files that didn't actually change
+                        return null;
+                    }
+
+                     return formattedSourceText;
                 }, cancellationToken);
 
                 formattedDocuments.Add((documentId, formatTask));