https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110246
--- Comment #1 from Thorsten Otto <ad...@tho-otto.de> --- Edit: the problem seems to be caused by using a FOR loop. Changing it to a similar WHILE loop: ch := 'A'; WHILE ch <= 'Z' DO arr[ch] := 0; INC(ch); END; does work without problems.