----- Original Message -----
From: "Ken Williams" <[EMAIL PROTECTED]>
To: "Sisyphus" <[EMAIL PROTECTED]>
Cc: "inline" <inline@perl.org>
Sent: Monday, April 10, 2006 2:55 AM
Subject: Re: #ifdef and Inline::C
>
> On Apr 7, 2006, at 9:24 PM, Sisyphus wrote:
>
> > Hi,
> >
> > The following code builds and runs fine on linux (perl 5.8.8), but
> > won't
> > compile on Win32 (perl 5.8.8):
> >
> > use warnings;
> > use Inline C => Config =>
> > BUILD_NOISY => 1;
> >
> > use Inline C => <<'EOC';
> >
> > #ifdef RUBBISH
> >
> > void greet1() {
> > printf("Hello 1\n");
> >
> > //#else
> >
> > //void greet1(){}
> >
> > #endif
> >
> > void greet2() {
> > printf("Hello 2\n");
> > }
> >
> > EOC
> >
> > greet2();
> >
> > __END__
> >
> > 'RUBBISH' is not defined on either box.
> >
> > Here's the error I get on Win32:
> >
> > try_pl_7b60.o(.text+0x7e):try_pl_7b60.c: undefined reference to
> > `greet1'
> > collect2: ld returned 1 exit status
> > dmake: Error code 129, while making
> > 'blib\arch\auto\try_pl_7b60\try_pl_7b60.dll
>
> I don't get it, where is there any reference to greet1() when RUBBISH
> is not defined?
>
Yes - I didn't explain it very well.
When RUBBISH is not defined greet1() will never be called (note that the
script never calls greet1), so there's no need for any reference to
greet1().
Linux seems quite happy with that, but Windows doesn't - an unexpected
situation.
I've decided to do it along these lines:
#ifdef PERL58
SV * foo(SV * arg) {
// do its stuff and return an SV
}
#else
SV * foo(SV * arg) {
croak("This function should not have been called");
}
#endif
It's probably the correct thing to do - at least it looks like the
*thorough* thing to do.
It still seems a little odd to me because the module will *never* call foo()
if PERL58 is not defined. But I guess it would always be possible
to call foo() by it's fully-qualified name, and if that was ever done when
PERL58 was not defined then it would be better to see a croak() message
rather than some sort of segfault.
The other thing that strikes me as odd about the '#else' version of foo() is
that it is never going to return anything, though the prototype specifies
that it will return an SV*. None of the compilers that I have used seem
bothered by that, so it's not going to bother me too much, either :-)
Thanks Ken.
Cheers,
Rob
