[kde-linux] JPEG 7 vs KDE-4.4 (DLL HELL comes to Linux?)

[Duncan]

James Tyrer posted on Sat, 13 Mar 2010 07:48:44 -0700 as excerpted:

> James Tyrer wrote:
> 
>> I appear to have found the problem.  Qt did not properly relink the
>> JPEG plugin.  So, a: "make clean", "make", & "make install" appears to
>> have fixed the problem.  II(now)RC, I read somewhere that one shouldn't
>> depend on the Qt build system of properly rebuilding when library
>> versions are updated.
>> 
> One final note to anyone that comes across this later.  KDE-4.4 stuff
> also calls: "libjpeg.so.*" directly without going through Qt which I did
> not consider and which was the cause of a great deal of confusion.  So,
> what I needed to do after upgrading JPEG was to see that both Qt and my
> KDE-4.4 BRANCH tree rebuilt correctly.  Obviously although I did the
> rebuilds, it didn't work automatically.

That'd be why jpeg itself was complaining about the version.  The kde 
program linked qt, which was linked against one version (apparently the 
ond one in this case), while the "KDE-4.4 stuff" linked against another 
(the new).  Having the two versions installed wasn't the problem, but 
trying to load them both in the same program... that's about as bad as 
trying to load a 32-bit library in a 64-bit process, it's not going to 
work! =:^(

So in that list of jpeg dependencies I posted earlier, it would have been 
qt-gui (qt is split on gentoo, that's the only module of it that depends 
on jpeg) that hadn't been rebuild against the new jpeg.

That's why it's nice, if you compile from source as I do on Gentoo and as 
you do on LFS, to have an automated rev-dep scanner and rebuilder, much 
like the gentoolkit revdep-rebuild, and why I run it faithfully after 
every update.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman