A libinfixed Qt which was configured with "-usedeffiles" crashes on Symbian^3 phones, if that phone already has a stock Qt installed (as part of the UDA package).
For my Qt with infix "_QTBUG_6611", I get the following stack trace:

PC          804cd14c    L.L.                
LR          804bc40d    ..K.                
00435ad0    7ef5c6bc    ...~                
00435f54    0040a380    ..@.    0038    newallocator_hook.o(.text)    UserHeap::SetupThreadHeap(int, SStdEpocThreadCreateInfo&)
00435f74    00408000    ..@.            uc_exe_.o(.emb_text)    _E32Startup
00435f7c    0040a154    T.@.    0010    uc_exe.o(.text)    RunThread
00435f98    00408000    ..@.            uc_exe_.o(.emb_text)    _E32Startup

...and see the attached screenshot for "Code segments". Apparently qtcore.dll (the not infixed one) is somehow already loaded!

How I can reproduce the crash

• Symbian SDK: Symbian^3 v0.8 SDK with patches. The one that is easy to "install" from our git repo
• Phone: N8, and E7
• Firmware Images: wk47/48 prd (not RnD). Once also mcl wk48.
• configure line: -xplatform symbian-sbsv2 -opensource -confirm-license -openvg -script -no-scripttools -no-webkit -graphicssystem
  openvg -no-phonon-backend -usedeffiles -nomake examples -nomake demos -nomake tools
• armv5_urel (I do not use armv6_urel anymore, since that is not supported, according to QTBUG-16008)
• built apps from command line and Creator. No difference, both crash
• tested with own 2-3 minimal test apps. All crash.

Apps run fine with -qtlibinfix + -usedeffiles Qt if I flash my Symbian^3 phone without UDA (udaerase). If I remove -usedeffiles and use -nokia-developer instead, everything is fine.