Date: Fri, 02 May 2008 13:43:55 -0700 From: Bakul Shah <bakul@bitblocks.com> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: freebsd-ports@freebsd.org Subject: Re: Using stderr in an initialization? Message-ID: <20080502204355.6349B5B3B@mail.bitblocks.com> In-Reply-To: Your message of "Fri, 02 May 2008 13:23:56 PDT." <20080502202356.GA67129@troutmask.apl.washington.edu>
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On Fri, 02 May 2008 13:23:56 PDT Steve Kargl <sgk@troutmask.apl.washington.edu> wrote:
> I'm porting a piece of code to FreeBSD, and I've run into
> a problem that I currently don't know how to solve. I scanned
> both the Porter's Handbook and the Developer's Handbook, but
> came up empty.
>
> A reduce testcase is
>
> #include <stdio.h>
>
> typedef FILE *FILEP;
>
> static FILEP outfile = {stderr};
>
...
> GCC gives
>
> troutmask:sgk[204] cc -o z a.c
> a.c:5: error: initializer element is not constant
> a.c:5: error: (near initialization for 'outfile')
>
> So, anyone have a
> suggestion on how to change line 5 to satisfy gcc?
It *used* to be the case that stderr was a macro referring to
something like &_iob[2] which is a link time constant
expression. As per section 7.19.1 in the C standard, the
stderr macro is an expression of type `pointer to file' but
not a constant. You wouldn't expect the following to work,
would you?
FILE* f;
FILE* outfile = f;
It is the exact same thing. But you can do
static FILE** _outfile = &stderr;
#define outfile (*_outfile)
to achive the effect you want.
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