Is it possible to display whitespace in output?

I'm working on creating some sample code that is heavily commented (as a teaching tool) and rustfmt was unhappy with trailing whitespace when I was using // on a line by itself to break up long blocks of text. the output showed

         // Payload: The response from the function, or an error object.
-        // 
+        //
         // For our example, we are just going to interact with the payload
         // portion of the response
         Ok(resp) => {

Which is rather confusing until you copy/paste the response and examine that one contains a space and the other doesn't. Would it be possible for rustfmt to identify this whitespace in some way? maybe like with the little dots that some IDEs use?

Start by reproducing the shown rustfmt output with the commented lines containing and omitting trailing whitespace. Read the relevant rustfmt output behavior and determine how whitespace could be made distinguishable without changing the formatted code; done means the difference is clear in the output and covered by a regression test.