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Out of the blue "Entry Point Not Found" error with QT5

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Out of the blue "Entry Point Not Found" error with QT5

Postby chriscalef » Mon Aug 03, 2020 5:06 am

So, a few months ago I was happily coding away on my FG build and everything was going great... and then Covid happened, and as a side effect of all that I found myself sucked into a months long project that took me away from the FlightGear build. I don't think I installed anything crazy or made any deep system changes, but somewhere along the way I thought I should check in on my FG, and I was met with this unfriendly message:

Image

After clicking on it I get a few more of the same, referencing Qt5Quick, fgfs.exe, and then Qt5Qml again.

The first time this happened I had not rebuilt my fgfs.exe, everything should have been exactly the way I left it. After rebuilding, just to see, nothing changed.

Anybody have any idea what could have caused this, and what I should do to fix it?
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby wkitty42 » Mon Aug 03, 2020 1:06 pm

noting the use of "D:" and "msvc" i guess this is a windows system... my first thought was that a system update has updated your Qt which will cause this problem... generally reconfigureing and recompiling should fix it... you might need to clear build caches to get a full rebuild... i don't know anything about using msvc so...

you might also check on the dev mailing list about this, too... if you haven't already, that is ;)
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby chriscalef » Mon Aug 03, 2020 7:24 pm

Thanks for the response! Yeah, sorry, should have mentioned my OS: running win10 64 with MSVC, building the fg_from_scratch package. I have Qt 5.14 installed and that is in my path, perhaps the fg_from_scratch build wanted to use its own version of Qt? Out of time for this morning but I'll hit it again soon. Did do a full rebuild but that didn't fix it.

I got a PM directing me to this thread, which might also be useful, if anyone happens along with the same problem here are more possible clues:

https://forum.qt.io/topic/115438/windep ... anslated/5
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby chriscalef » Tue Aug 04, 2020 4:48 am

Welp. I upgraded my Qt to 5.15, MSVC2019_64, switched over my path to point to that, changed my include and link directories in Visual Studio, rebuilt everything... and have pretty much the same messages.

Curious as to why Qt is even involved at all, I had thought it was only used for the launcher? I am starting fgfs directly, not going through the launcher. But anyway... I also need to update my FG repo, trying that next.
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby FlugHund » Tue Aug 04, 2020 11:28 am

In that case the cmake option ENABLE_QT=OFF might be a solution (if that still works as it did two years ago).
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby wkitty42 » Tue Aug 04, 2020 2:04 pm

yeah, unless you explicitly disable the launcher code, it is still built...

something else is that the launcher code is also used as the in-sim aircraft selector... if you disable the launcher, you'll also need to make a code adjustment to use the old in-sim aircraft selector...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby Hooray » Tue Aug 04, 2020 2:32 pm

Curious as to why Qt is even involved at all, I had thought it was only used for the launcher? I am starting fgfs directly, not going through the launcher.


It might be worth checking $FG_SRC/Main - If I remember correctly, someone reported on the devel list that a Qt-enabled binary (regardless of whether the launcher is explicitly used/started or not), will by default create a Qt-based OpenGL window/context (if that's the case, see if a non-Qt build works any better for you): https://sourceforge.net/p/flightgear/fl ... n.cxx#l551

In fact, a number of senior contributors have repeatedly reported various Qt related issues in Qt-enabled binaries over the years, including window manager issues identified by i4dnf, threading issues, OpenGL conflicts and segfaults in atexit() handlers mentioned by bugman and others, and obviously "dependency hell" (DSOs).
However, since then, the situation should actually have massively improved over the years.

Background:
https://sourceforge.net/p/flightgear/ma ... /33245028/
A heads-up announcement - I’m prototyping (at the suggestion / encouragement of Curt, Torsten D & others) a GUI integration for FlightGear based on Qt 5. [...]

The goal is to make an *optional* Qt dependency to replace PLIB PUI. Except of course PUI will have to remain for some awkward use cases in the short term (aircraft dialogs, potentially). When compiled without Qt support, you’ll get a fully functional FG (i.e, Qt will never be a requirement to build FG), but without the GUI functions - which is indeed what some people want anyway, e.g. some home cockpit setups.

https://sourceforge.net/p/flightgear/ma ... /35633931/
The launcher UI is built using Qt, which is also my day job so I know it quite extensively.


https://sourceforge.net/p/flightgear/ma ... /34536197/
One concern I have though, from the discussions over the last year, is
that the PUI->Qt migration plan is not a direct one-to-one migration.
I.e. to have a main Qt window providing the main FlightGear window by
containing a top menu bar followed by a QtWindow GL widget underneath,
in which the FG main execution loop is run as a thread from within the
Qt main loop. My impression was that the GUI will be a secondary
window or dialog that you have to switch to. But one problem I see
with this design is that all modern GUI toolkits (Qt, GTK, metro,
Cacoa, Carbon, etc.) suffer from racing and segfaulting issues if the
GUI main thread or main loop/event handler is not thread number 1.


https://sourceforge.net/p/flightgear/ma ... /34431801/
Note that as the QtLauncher transitions into a full GUI to replace the PUI GUI, many of
these issues will disappear, and new ones will appear. In any case,
debugging a modern GUI is much harder than debugging the non-GUI
parts. A basic knowledge of threading, locks, and racing is quite
useful for understanding and catching these bugs.



http://wiki.flightgear.org/Integrated_Qt5_Launcher
Details: https://sourceforge.net/p/flightgear/ma ... l_list=all
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Re: Out of the blue "Entry Point Not Found" error with QT5

Postby zakalawe » Wed Aug 05, 2020 6:05 pm

Something is messed up in your build I think: QNetworkReply lives in in Qt5Network.dll, not Qt5Qml.dll. So of course it's not found in there :) Can you post some more of the errors you get?

I'm assuming when you upgraded compilers you wiped your build dir completely?

When you switched to the new Qt version and compiler, did the paths in the error message change to point to the expected ones? I guess something like D:\Qt\5.15.0\msvc2019_64 ?

Also, you could try using thisL https://github.com/lucasg/Dependencies on fgfs.exe to see what it reports: if you set PATH to be whatever PATH you use when running fgfs.exe, it will do the DLL symbol resolution process and hopefully give some clearer idea what's going on.
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