Fix XML indentation in Emacs mode The return value of MATCH-STRING is a string. At least on Emacs 25, the comparisons between string and character with EQUAL could never succeed, and so the cases for matching braces were never triggered. GET-TEXT-PROPERTY may return a list rather than an atom (for example, on long lines with whitespace-mode turned on), and this broke the heuristic of looking for the tag face in previous text.

datatype foo = A | B of bar
and bar = C | D of foo

val q = B (D A)

fun main () = return <xml>
  {case q of
       B (D A) => <xml>Good</xml>
     | _ => <xml>Bad</xml>}
</xml>