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Re: Warning for trigraphs in comment?
Paul Koning <pkoning@equallogic.com> writes:
> >> Would it make sense to have the lexer ignore trigraphs (i.e., just
> >> treat ??/ as three characters) unless specifically enabled with
> >> -fenable-trigraphs? In the unlikely case that anyone actually
> >> uses trigraphs, this would enable them to continue doing so.
>
> Zack> GCC has done this for decades. See the documentation of the
> Zack> -trigraphs option.
>
> Oh. So it looks like what's needed is to have -ansi NOT imply
> -trigraphs.
We can't do that. It would violate user expectations that -ansi
puts GCC in fully conforming mode. I should point out here that
GCC's default ignoring of trigraphs is controversial in some circles;
suggest you read through some back issues of comp.std.c.
Gabriel Dos Reis <gdr@integrable-solutions.net> writes:
> What is happening with current GCC in production use is that GCC
> choosed NOT to warn for trigraphs in comment even if -Wtrigraph.
Correct, because the common case of such trigraphs is
/* some text (???) */
which obviously cannot affect the meaning of the program. You're
right that ??/\n can change a comment boundary; Neil and I knew that
this was a potential issue but we decided not to worry about it until
it came up, which has now happened, and we've addressed it.
zw