[re2c-general] flex syntax and parsing ambiguity

[Ulya F. <skv...@gm...>]

Hello everyone,

in short:

  * Partial flex syntax support (enabled with '-F' option) causes
    ambiguity in re2c grammar and introduces parsing conflicts.
  * These conflicts are mitigated in '-c' mode, so the one major user of
    '-F' that I know of (PHP team) didn't notice them until now.
    However, they lead to severe parsing failures in normal mode.
  * There's a couple of ways to fix the problem, but all of them have
    major downsides (mostly backwards compatibility breaks).

Please read the full analyses 
<https://github.com/skvadrik/re2c/issues/115>and tell what you think.

Ulya