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Date: Sat, 1 Dec 2007 13:00:32 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: Failure in building GFortran on Cygwin
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On Dec  1 03:14, Brian Dessent wrote:
> Corinna Vinschen wrote:
> 
> > Unfortunately it doesn't work for variables.  We can hide the timezone
> > function, but how do we alias timezone to _timezone in libcygwin.a?
> 
> Why does the variable need to be renamed?  Can't we continue to call it
> _timezone internally and then "#define timezone _timezone" in a public
> header?  It looks like this is already what we get in <cygwin/time.h> if
> we simply stop defining __timezonefunc__.

That's the default case starting with 1.5.25.  You get timezone
by this #define in cygwin/time.h.

The problem right now is that this clashes with the previous definition
of `struct timezone'.  What happens is this:

  struct timezone { int foo; };    // by including sys/time.h
  [...]
  #define timezone _timezone       // sys/time.h includes cygwin/time.h
  [...]
  struct timezone tzp;             // the application defines this tzp var

So `struct timezone tzp' becomes `struct _timezone tzp' which is
an unknown structure type.

I have a simple patch for this which just reorders sys/time.h slightly.
The effect is that the #define is pulled in front of the structure
definition so all timezone gets _timezone and that's it.

> Or is pulluting the namespace with a macro called "timezone" too
> hideous?  In that case we could try declaring it "extern long timezone
> asm("_timezone");" in the header.

Erm... sorry if my lack of assembler inlining shows, but that really
works?  If so, it looks like a rather elegant solution to me.  I'll give
it a try.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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