Currently, empty sequences in gather rules make the conditional for
gather rules fail as empty sequences evaluate as "False". We need to
explicitly check for "None" (the failure condition) to avoid false
negatives.
This is for the C generator:
- Disallow rule and variable names starting with `_`
- Rename most local variable names generated by the parser to start with `_`
Exceptions:
- Renaming `p` to `_p` will be a separate PR
- There are still some names that might clash, e.g.
- anything starting with `Py`
- C reserved words (`if` etc.)
- Macros like `EXTRA` and `CHECK`
Pablo Galindo Salgado
Batuhan Taskaya
Lysandros Nikolaou