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Date: Fri, 16 Sep 2005 17:36:30 +1200
From: Danny Smith <dannysmith AT clear DOT net DOT nz>
Subject: Re: Bug in gcc and/or binutils?
To: Cygwin <cygwin AT cygwin DOT com>
Reply-to: Danny Smith <dannysmith AT users DOT sourceforge DOT net>
Message-id: <000701c5ba80$abb3ba70$e04861cb@DANNY>
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References: <http://sources.redhat.com/ml/cygwin/2005-09/msg00471.html>
<http://sources.redhat.com/ml/cygwin/2005-09/msg00519.html>

Charles Wilson <cygwin at cwilson dot fastmail dot fm>  wrote:

>
> Using .def files turns off the auto-EXport logic (which it should,
> because if you specify a specific set of exports you don't want binutils
> adding a few more on its own).

There seems to be a common misconception that auto-export logic and
explicit designation of exports are incompatible.
You can still use --export-all  (to get the auto-export of all defined
symbols) with a .def file or with __declspec(dllexport).

eg
gcc -shared -ofoo.dll foo.def foo.c -Wl,--export-all

The use of a def file (with --export-all) is useful when you want to
export all symbols but want special handling of some, say an alias or
marking a symbol as PRIVATE (exclude from import lib) or NONAME (exclude
the name of the symbol from the dll's export table), (almost like
__attribute__((hidden)) Or you may want to add a symbol that is just
forwarded to another dll. Or you have a function foo() but only want
the indirect ref __imp__foo visible in the import lib, and not the label:

foo:
  jmp * __imp__foo

so you only export the pointer  by marking as DATA in the def file

Danny


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