[Development] Qt 4.8.7 built with linux-clang-64

[Thiago Macieira]

On Wednesday 22 July 2015 10:23:20 René J.V. Bertin wrote:
> Hi,
> 
> I've spent some time the other day configuring an Ubuntu PPA I've been using
> to build my "system" Qt 4.8.7 to use clang 3.5.1 instead of gcc-4.9. It was
> rather straightforward to get things to build (I had to modify 1 Kubuntu
> patch). The experiment wasn't very conclusive though: my KDE environment no
> longer worked correctly as if Qt no longer recognised all KDE plugins it
> ought to. FWIW, I've been keeping my base KDE packages up to date
> (following git/master) via PPAs of my own, and those are built with clang
> 3.5 too.

Make sure it even searched those plugins in the first place. Try setting 
QT_PLUGIN_PATH to `kde4-config --path qtplugins`.

Anyway, linux-clang isn't supported in Qt 4.8. There's barely any testing done 
with that. In Qt 5, both Olivier and I are maintaining it.

> Does this ring any bells? It's going to be more than a bit cumbersome to try
> to figure out what's going on with the resources I have (just preparing the
> stuff to upload to the PPA takes a good 40 minutes), but what would I be
> looking for?

What is the build key with Clang? Does it list "gcc-4" or not? Can you check 
if the plugins have a .qtplugin section (objdump -h).

Actually, just run this on a plugin that won't load:
	objdump -sj.qtplugin /path/to/plugin

You should get something like:
Contents of section .qtplugin:
 31380 70617474 65726e3d 51545f50 4c554749  pattern=QT_PLUGI
 31390 4e5f5645 52494649 43415449 4f4e5f44  N_VERIFICATION_D
 313a0 4154410a 76657273 696f6e3d 342e382e  ATA.version=4.8.
 313b0 360a6465 6275673d 66616c73 650a6275  6.debug=false.bu
 313c0 696c646b 65793d69 33383620 6c696e75  ildkey=i386 linu
 313d0 7820672b 2b2d3420 66756c6c 2d636f6e  x g++-4 full-con
 313e0 66696700                             fig.            

We're looking for a version number that is not higher than the Qt version you 
compiled and a build key that is the same as the Qt you compiled.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center