Re: Gcc 3.0, printf() and exim-3.30

[Neil Booth <neil at daikokuya dot demon dot co dot uk>]

Nix wrote:-

> >> pcretest.c:474:1: directives may not be used inside a macro argument
>
> Correct, but not relevant to this situation, I think.

No, it is - trust the messages!
 
> > The code in question reads:
> > 
> >       printf("  -d   debug: show compiled code; implies -i\n"
> >              "  -i   show information about compiled pattern\n"
> >   #if !defined NOPOSIX
> >              "  -p   use POSIX interface\n"
> >   #endif
> >              "  -s   output store information\n"
> >              "  -t   time compilation and execution\n");
> > 
> > It looks as if gcc 3.0 has printf defined as a macro. IMHO this is
> > lunacy.
> 
> Nope; printf is not a macro, and GCC does not define printf :)

No, it is - trust the diagnostics! (I agree about the lunacy, but it's
in glibc).

> I think your #if itself is triggering a bug in GCC; a workaround may be
> to say
> 
> #if !defined(NOPOSIX)
> 
> instead.

No.

> The error you're getting is meant to be triggered by code like
> 
> #if #else
> 
> which is obvious nonsense; but it doesn't seem to me that this should be
> triggered here.

No - I don't see a macro nor an argument here, so how can this be what
the message is about?

In fact, your line

#if #else

is a valid GNU C line, though it may not mean what you think it does.
It is a #if that tests for whether or not an assertion called "else"
has been asserted.

> It looks to me like gcc/cppexp.c:parse_defined() and/or the tokenizer is
> fubared, and it doesn't realize that the #if has finished, and
> interprets the #endif as part of the #if expression.

No.

> Zack/Neil, is my guess correct, or is this something to do with string
> literal concatenation and macro expansion getting tangled up or
> something (I seem to recall that causing problems in the past), or is
> that code actually invalid, or is this something completely different?

No - it's just what the error message says.  Glibc defines printf as a
macro when you compile with optimisation on.  So you cannot have
directives inside a printf call.  I don't know if / why this works
with GCC 2.95.2.

The error message should probably be changed to

pcretest.c:474:1: directives may not be used inside the macro "printf"

so that users are more inclined to believe the message the compiler
gives them :-)

Neil.