Re: Win32 libltdl issue

[Howard Chu]

Bob Friesenhahn wrote:

> > I see that more recent versions of cygwin/mingw appear to have made 
> > using declspec unnecessary:
> >
> > http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/gnu-linker/win32.html 

> > I don't know how others would feel about it, but perhaps you could 
> > just say "version >= XX of cygwin/mingw binutils are required" and 
> > forget about all of these issues.

> This assumes that libtool should only support the GCC compiler under 
> Windows.  Microsoft, Borland, and others, need not apply.  Is there a 
> good reason to rule out all compilers except for GCC?

Sorry, I wasn't aware that anyone used those other compilers with Cygwin 
or MinGW. No, I'm not recommending that support for those be dropped if 
they are indeed supported right now.

But there are a number of features in the new binutils that will make 
supporting gcc easier on Cygwin/MinGW, so for environments where the GNU 
toolchain is in use, I would still suggest placing minimum version 
requirements in.

One other annoying gotcha when building with libtool and Win32 is that 
libtool (at least in the 1.x line) assumed that any lib*.a was a static 
library, and refused to link it into a DLL. It didn't account for the 
possibility that the library was actually a DLL import library. Now that 
the linker can automatically Do The Right thing regardless of what type 
of library is fed to it, libtool could just use pass_all here. So again, 
it simplifies the Win32 support if you can assume a recent toolchain.

Right now (1.x), when libtool sees that you're trying to link against a 
DLL, it calls dlltool to generate a new import library on the fly, and 
then deletes it when that step completes. It does this each time the DLL 
is referenced in a build procedure, which is a ton of wasted effort and 
makes builds much slower than they should be. With a new toolchain you 
could delete all of the commands for these cases and just let ld link 
the thing.

Failing that, libtool should include the import library in the install 
step, and the .la file should list
library_names='libfoo.dll libfoo.dll.a'
so that libtool will use the import library when linking libtool 
libraries together.

--
  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support