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Subject: Re: Build Success 20.3b7 "Oslo" - with one problem
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From: Steven L Baur <steve@xemacs.org>
In-Reply-To: Andreas Jaeger's message of "19 Jun 1997 08:15:10 +0200"
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Date: 19 Jun 1997 10:43:51 -0700
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Andreas Jaeger <aj@arthur.rhein-neckar.de> writes:

> Btw. since the definition in the last two betas of _BSD_SOURCE was
> totally useless (defined at the wrong place), following your argument
> everybody should have problems under Linux because of jmp_buf - but
> nobody AFAIK reported a problem so far.

I don't know (I've hardcoded -D_BSD_SOURCE in `--cflags' until configure
gets fixed).

Here is the problem demonstrated with libc-5.4.33 -- the latest libc-5
distributed AFAIK.

#include <setjmp.h>

main()
{
	jmp_buf j;

	printf("Sizeof jmp_buf = %d\n", sizeof j);
}

$ gcc -o jj jj.c 
$ ./jj
Sizeof jmp_buf = 24
$ gcc -D_BSD_SOURCE -o jj jj.c 
$ ./jj                        
Sizeof jmp_buf = 32
$ 

Having two sizes for jmp_buf is bound to cause difficulties.

> [1] libc5 always favors BSD if _BSD_SOURCE is set, but glibc
> doesn't. Defining all three flags is AFAIK the only portable solution
> to support both libc5 and glibc2.

O.K.
-- 
steve@calag.com baur
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