Re: Flex 2.5.31 m4 bug

[Bruce Lilly]

John wrote:

> Currently, it is invalid to have the sequences [[ or ]] anywhere
> within the flex input, as they are the quote sequences for the m4
> processing phase. This is documented in the manual under the appendix
> `m4 dependency'.
>
> One obvious solution is for flex to completely parse the C code in the
> input actions. A less obvious solution escapes me at the moment!

How about using a character or character sequence that doesn't appear
in the input?  Of course, that means a pre-pass over the input to find
an appropriate character or sequence, but that's better than a failure
with cryptic error messages on valid lex input.  Chances are good that
for any reasonable input file, there is some (8-bit) character that
doesn't appear, and there will always be some sequence that doesn't
appear.