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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/106483] undefined reference to function implemented in
 shared library if putting main.cpp after options, but non of any error when
 putting before options
Date: Sat, 30 Jul 2022 13:20:56 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106483

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Firstly, this is the linker doing this, not GCC. GCC just passes the argume=
nts
to the linker in the order you specify them.

Secondly, this is the correct behaviour. Your linker is set up to default to
--as-needed which means that shared libraries on the command line will only=
 get
used if they satisfy a non-weak undefined reference from a regular object f=
ile
that has already been processed by the linker. If you put -ladd before main=
.cpp
then there are no undefined symbols yet, so the library is just ignored.

https://web.archive.org/web/20210609020437/c-faq.com/lib/libsearch.html

Either link with -Wl,--no-as-needed to change the linker's behaviour so that
shared libraries are always used, or put the libraries in the right order.=