Re: Link Problem on Windows

[Ralf Wildenhues]

Hi Martyn,

* Martyn Russell wrote on Tue, Jun 07, 2005 at 12:52:44PM CEST:
> On Thu, 2005-06-02 at 16:13 +0100, Martyn Russell wrote:
> > 
> > I am currently having problems linking in libpq (Postgres client front
> > end) from PostgreSQL 8.0.2.  I downloaded the source and installed it
> > under MSYS/MinGW (to /usr/local).  The .dll and the .a are
> > in /usr/local/pgsql/lib.
> > 
> > I have tried using 
> > 
> >     -L/usr/local/pgsql/lib -lpq 
> > 
> > but it fails miserably, I get the following:
> > 
> > *** Warning: linker path does not have real file for library -lpq.
*snip*
> > *** using a file magic. Last file checked: 
> > C:/msys/1.0/local/pgsql/lib/libpq.dll
*snip*
> 
> OK, just thought I would post my progress on this.

Great!

> Basically, the reason it didn't work is because I needed the
> AC_LIBTOOL_DLOPEN macro defined.  With this added, all seems to work
> well.  Is this right/wrong? If right, why?

Docs state that you need this (for 1.5.18).  Does that suffice for an
answer?  For newer branches you should add the `dlopen' option to
LT_INIT:
  LT_INIT([dlopen])

> > I saw this when trying to link with the Winsock2 library (-lws2_32)
> > before now and decided to try and update libtool from 1.4.x to 1.5.18.
> > It worked perfectly especially now I make use of the automatic
> > import/export feature in gcc, however, this doesn't work for libpq?
> 
> This was a problem with environment and different versions of libtool,
> etc.  My mistake :)

So that works now?

> > The only other detail I have noticed about libpq.dll is that the file
> > format is pe-i386 and my libraries and the Winsock2 library is of format
> > pei-i386.  Does this have an impact on my problem?
> 
> I am interested in the differences between a pe-i386 format and a pei-
> i386 are, plus if there are any issues mixing and matching libraries and
> executables of different types?

Should be documented with GNU ld.  I haven't had the chance to dive in
there yet, though.

> So basically, I have got it all running.  The only other issue I had was
> using libltdl within a library.  For some reason, the symbols were not
> exported properly so I couldn't link with it.  The symbols that were in
> the library were specifically libltdl functions?

Using libltdl from within a library is supported only starting with
branch-2-0, not with branch-1-5.  There are known problems that manifest
themselves (at least) on MinGW, though (less on cygwin).  The recent
archives of this and the libtool-patches mailing list have details.
Work on this is always welcome.  :)

Cheers,
Ralf