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Date: Sat, 18 Feb 2006 11:52:36 -0700
From: Eric Blake <ebb9 AT byu DOT net>
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To: skaller <skaller AT users DOT sourceforge DOT net>
CC: cygwin AT cygwin DOT com
Subject: Re: Linux vs Cygwin linkage
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According to skaller on 2/18/2006 11:39 AM:
> I have found some unexpected differences between Cygwin
> and Linux. FYI I think Cygwin is right, and Linux is wrong.

No, they are both right, in their own way.  Windows .dlls cannot use
undefined symbols, whereas Linux shared objects can (the dynamic loader
resolves them lazily, failing only at execution time if the symbol was not
ultimately provided).  Libtool has a -no-undefined switch to force
platforms like Linux with lazy linking to have a link failure if the
symbol is undefined, whereas on Windows, you have no choice.  For
development, it is sometimes easier to rely on lazy linkage (or linux
wouldn't provide it), but for portability, you are right that cygwin is
stricter thanks to the underlying windows dll semantics.

> Can I fix that with
> 
> 	-Wl,--no-allow-shlib-undefined
> 
> switch to gcc, so Linux and Cygwin behave the same?

Why not look at what the -no-undefined switch to libtool uses?

- --
Life is short - so eat dessert first!

Eric Blake             ebb9 AT byu DOT net
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