Re: GNU Libtool 2.2.8 released (stable)

[Bob Friesenhahn]

On Tue, 8 Jun 2010, Charles Wilson wrote:
> > If it doesn't, then that's a bug.  Libltdl is supposed to keep track
> > of everything it loads,
>
> But the point here is that Bob is advocating that (in the first half of
> the example above) *libltdl* does NOT explicitly load the libjpeg
> dependency.  However, the Windows *will* load it "behind the scenes" and
> automatically, when libltdl does a LoadLibrary(libtiff) because libtiff
> depends on libjpeg.
>
> Once Windows has done so, and THEN libltdl attempts to do a
> LoadLibrary(libjpeg) -- when libjpeg has already been "privately"
> loaded, unbeknownst to libltdl -- what happens?

As a useful data point, when GraphicsMagick gets built using Visual 
Studio, libltdl is not used.  Instead a more simple loader based on 
LoadLibrary() is used and Windows automatically loads any 
dependendencies.  This has not caused any problems that I can recall. 
In the MinGW and Cygwin builds of GraphicsMagick, libldtl does get 
used so libltdl's redundant dependency loading is active.  I assume 
that in this case, libltdl's loader ends up taking precedence over 
Windows similar features since it is invoked first.  Windows surely 
still loads some implicit DLLs that libltdl is not aware of.

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/