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Date: Mon, 25 Nov 2002 16:33:39 -0800 (PST)
From: "Peter A. Castro" <doctor AT fruitbat DOT org>
To: Andrew DeFaria <ADeFaria AT Salira DOT com>
cc: cygwin AT cygwin DOT com
Subject: Re: impure_ptr/Mingw and Cygwin
In-Reply-To: <3DE29314.8040102@Salira.com>
Message-ID: <Pine.LNX.4.21.0211251615350.7231-100000@gremlin.fruitbat.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Mon, 25 Nov 2002, Andrew DeFaria wrote:

> Peter A. Castro wrote:
> > On Sun, 24 Nov 2002, Andrew DeFaria wrote:
> >> Peter A. Castro wrote:
> >>
> >>> What you show below is only linking. I believe you need to 
> >>> re-compile all of your source with -mno-cygwin -mwindows as well to 
> >>> make the _impure_ptr references go away.
> >>
> >> But I did re-compile all my sources with -mno-cygwin -mwindows! Still 
> >>  have the error.
> >
> > Suggest you run nm against all your objects and libraries and find which
> > has the _impure_ptr references, then recompile just those.
> 
> But I did recompile everything already! The _impure_ptr keeps getting 
> generated:
>
> $ nm mksf.o | grep impure
>          U __impure_ptr
> $ rm mksf.o
> $ make mksf.o
> /bin/gcc -c -g -mno-cygwin -mwindows -I. -I../../include -I/usr/include 
> -DCYGWIN mksf.c
> $ nm mksf.o | grep impure
>          U __impure_ptr
> $

You're getting stdio.h from /usr/include, that's why.

> As you can see the _impure_ptr reference gets regenerated. But wait! 
> There's more!
> 
> I can cause these _impure_ptr even with the little foo.c merely by 
> including -I/usr/include on the command line. Why am I referencing 
> /usr/include? Because in my larger application I need it for getopt.h. 
> The mere inclusion of -I/usr/include causes_impure_ptr's to be emitted. 
> So the question now is: How do I satisfy my need for getopt and still 
> produce objects without _impure_ptr's?

libiberty.a in /usr/lib/mingw has getopt(), so link with -liberty

> Ah ha!
> 
> $ grep impure /usr/include/*.h
> /usr/include/stdio.h:#define    stdin   (_impure_ptr->_stdin)
> /usr/include/stdio.h:#define    stdout  (_impure_ptr->_stdout)
> /usr/include/stdio.h:#define    stderr  (_impure_ptr->_stderr)
> 
> Hmmm... Changed options to:
> 
> /bin/gcc -c -g -mno-cygwin -I. -I../../include -I/usr/include/mingw 
> -I/usr/include -DCYGWIN mksf.c
> cc1: warning: changing search order for system directory 
> "/usr/include/mingw"
> cc1: warning:   as it has already been specified as a non-system directory
> 
> This works but why am I getting this warning?

Because -mno-cygwin specifies /usr/include/mingw as a system dir and
you're specifying it again on the command line with -I, which makes it a
User dir too.  gcc is a bit puzzled about why you're doing that. 

If you add the "-v" flag to you compile flags, gcc will dump the list of
directories it searches for include files.  In this case it would be:

 ../../include
 /usr/include/mingw
 /usr/include
 /usr/lib/gcc-lib/i686-pc-cygwin/2.95.3-5/include
 /usr/include/mingw
 /usr/include/w32api
     
-- 
Peter A. Castro <doctor AT fruitbat DOT org> or <Peter DOT Castro AT oracle DOT com>
	"Cats are just autistic Dogs" -- Dr. Tony Attwood


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