Re: [Discuss-gnuradio] Configure question / Qt libraries

[Eric Blossom]

On Fri, Jan 10, 2003 at 11:04:56PM -0600, Jim Smith wrote:
> To start, yes, I've read the README and the INSTALL files.
>
> I'm building gnuradio 0.6 on a FreeBSD 4.7 system.  This system was
> originally built with gcc 2.95.4.  and that is the current version of
> gcc/g++ on this system.  Unlike the example in the README file, I'm not
> building gnuradio with gcc 3.x, while having built my system with
> 2.95.4.  
> 
> What isn't clear from the above two files is:  does gnuradio0.6 *need*
> to be build with gcc > 3.0?

Nope.  We routinely build it with 2.96, 3.0*, 3.1* and 3.2


Q. Configure is bombing, because it can't find the Qt libraries, but they
are there.

A. There are two known causes for configure not finding Qt libraries
when you're sure they're installed.  The most common one is a problem
where the Qt and GNU Radio are compiled with different versions of
g++.  Note that g++ 2.96, 3.0, 3.1 and 3.2 all have different ABI's
for C++ code.  3.2 is supposed to be the "final multi-vendor agreed"
ABI.  Take a look at config.log.  If what you're seeing are messages
from the linker indicating "unable to find symbol blah blah blah" or
something like this, more than likely, Qt and GNU Radio are compiled
with different versions.

The fix is to download and build a copy of Qt using the same compiler
as you're building GNU Radio with.

The second failure has been observed only relatively recently, and has
to do with distributions that have Qt 3.0 installed and called
something like /usr/lib/qt3/lib/libqt.so.  The CVS version of GNU
Radio has been patched to work around this.  Also, I've seen some
systems (e.g., Mandrake 9.0) that install Qt in /usr/lib/qt3/lib, but
only install the multi-threaded version of libraries.  Look at
config.log and see if it's completely failing to find the library.  If
it can't find libqt.so, and there's a libqt-mt.so installed, then
adding the --enable-mt flag to ./configure will fix the problem.
[This should be fixed in the configure script.  If any one's up for
it, the fix goes in gnuradio/config/lf_qt.m4.  Please fix and submit a
patch.]

Eric