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.

functor F(M : sig end) = struct
    fun f () = f ()

    functor G(M : sig end) = struct
        fun g () = f ()
    end
end

structure M1 = F(struct end)
structure M2 = F(struct end)

structure N1 = M1.G(struct end)
structure N2 = M2.G(struct end)

fun main () : transaction page =
    return (N1.g ());
    return (N2.g ());
    return <xml/>