Some rewritings diverge instead of stopping on a recursion limit

[LPTK]

See:

scala> ir"val x = 42; println(x.toDouble)" fix_rewrite { case ir"($n:Int).toDouble" => ir"$n.toDouble+1" }
java.lang.StackOverflowError

on the other hand, this one does not exhibit the problem:

scala> ir"val x = 42; println(x.toDouble)" fix_rewrite { case ir"($n:Int).toDouble" => ir"$n.toDouble" }
Rewrite rules did not converge after 8 iterations.
ir"""{
  val x_0 = 42;
  scala.Predef.println(x_0.toDouble)
}"""

[LPTK]

Note: the problem also appears when rewrite is used instead of fix_rewrite.
This is because the term grows in size and thus the top-down transformation never finishes.

[LPTK]

A good fix would be to make rewrite use a bottom-up traversal by default, which does not have this problem. Top-down transformations are either more dangerous (if they are allowed to recurse into freshly-rewritten terms) or less powerful in term of expressiveness (if they are not).