[Bug modula2/121354] ICE when attempting to fold HIGH from an unbounded array in a nested procedure

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121354

--- Comment #3 from Gaius Mulley <gaius at gcc dot gnu.org> ---
The problem is that it is attempting to fold HIGH for an unbounded array.
FoldHigh needs to ignore such cases.