Compiling with `cobc -A -Wa,-O0` passes `-Wa,-O0` to the gcc frontend, which will pass `-O0` to the assembler. Compiling with `cobcd -A -Wa,-O0` passes `-A -Wa -O0` to cobc, which will then "eat" -O0 (adding it later again) and passing -Wa to the gcc frontend, which will then complain that this is invalid. The issue in in cobcd.py with the combination and splitting of the command line options. I _think_ that could be done differently, at least by switching to a different, less used separator, possibly a `~` (which we use in the symbol table, if I remember correctly) or a `|`/`#`.. but much less likely are possibly `^` or `°`. (`-Wa` is only an example, that can be problematic in other cases as well)