qt 4.7.4 linking error, missing --enable-auto-import

[lvdong]

I compiled qwt 6.0.1 dynamic library with qt 4.7.4, and added it to my qt project,
but there is a linking warning saying missing --enable-auto-import option,
I checked the qmake.conf file in mkspecs/win32-g++, QMAKE_LFLAGS is empty,
QMAKE_LFLAGS =
but in qt 4.7.3, QMAKE_LFLAGS = -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc
so I added the -Wl,-enable-auto-import to qt 4.7.4, it worked.
I am confused.

env: win7 32bit, qt 4.7.4, qtcreator 2.3.0
log:

g++ -mthreads -Wl,-subsystem,windows -o debug\mpbs.exe object_script.mpbs.Debug -L"c:\Qt\4.7.4\lib" -lmingw32 -lqtmaind debug\mpbs_res.o -Ld:/qwt-6.0.1/lib -lqwtd -lQAxContainerd -lole32 -loleaut32 -luser32 -lgdi32 -ladvapi32 -luuid -lQtGuid4 -lQtCored4

Info: resolving QwtPlot::staticMetaObject by linking to __imp___ZN7QwtPlot16staticMetaObjectE (auto-import)

c:/qt/qtcreator-2.3.0/mingw/bin/../lib/gcc/mingw32/4.4.0/../../../../mingw32/bin/ld.exe: warning: auto-importing has been activated without --enable-auto-import specified on the command line.
This should work unless it involves constant data structures referencing symbols from auto-imported DLLs.

[Niels Holst]

I have the exact same problem after upgrading from Qt 4.7.3 to 4.7.4 in same environment as you. Projects with a DLL target now produces those infos and warnings I never saw before.
And now my program (using those DLLs) crashes when I try to execute it! It goes "The application was unable to start correctly (0xc0000005)."

I am impressed you managed to spot that change in the default flag setting for the linker. But how do we proceed?

1. Why was the option changed? If it was for a good reason, I would not like to change it back. Beside I am managing an open source project and I do not want to instruct all contributors to hack that flag inside the Qt distribution.
2. What is the correct way to set the linker flags in my own .pro file? In Help it says that we should not change QMAKE_LFLAGS.
3. What about the other flags that were dropped in Qt 4.7.4? Under what circumstances should we worry about them?

[Uwe]

Better ask, where Qt developers are listing - or add bug report to their task tracker.

When Qt 4.7.3 and 4.7.4 are incompatible it should qualify as a bug.

Uwe

[Niels Holst]

Thanks, Uwe, just added this issue as a bug.