Re: pthread linking issue

[Bob Friesenhahn]

On Tue, 19 Oct 2004, Chris Coleman wrote:
> I have a question about the libtool package and automake...
>
> In my configure.in I have AC_PROG_LIBTOOL to set up the necessary bits n 
> bobs. I also have the macro ACX_PTHREAD to determine which threading 
> libraries are needed in order to link my app.
>
> However on the final stage of make (and only since I added libtool to the 
> project) it now fails with the errors below. Now I guess its not linking with 
> the pthread library for some reason.  -pthread is what the ACX_PTHREAD macro 
> chooses both on solaris and linux, however if I copy and past the libtool 
> link line at the bottom and change -pthread to -lpthread the final 
> excecutable compiles with no problem. Any clues as to why this is, whats the 
> difference and how to solve it?

Released libtool provides no special handling for -pthread so it is 
not passed to the compiler.  Libtool 2.0 (in the throes of final 
bug-fixing and testing) will pass -pthread to the compiler.

As a work-around you can avoid using -pthread and pass the necessary 
pre-processor option (e.g. -D_REENTRANT) and library (e.g. -lpthread) 
via CPPFLAGS and LIBS.

For the package I support, I was not happy with ACX_PTHREAD so I use a 
modified version which provides the CPPFLAGS and LIBS info I need. 
The ACX_PTHREAD macro actually knows all of this internally, but 
requires some modifications to extract it.

Bob
======================================
Bob Friesenhahn
address@hidden
http://www.simplesystems.org/users/bfriesen