Necessitas alpha4 delays

Wed Aug 22 05:32:10 UTC 2012

Hello everyone,

We've faced some big problems which prevent us to release alpha4 SDK,
so, I think we own you some explanations why we delay it that much.

  First problem we've encountered it was the changes done in QtCreator
(by Nokia guys), which delayed the release with more than 2-3 weeks,
then we had to wait for ssl certificates for Ministro to arrive, then
we've discovered that the official Android NDK had to be rebuilt for
all platforms, then, again, we've found problems in QtCreator, then
the SDK installer keep me busy for a couple of days, then we've face
even more problems with Ministro [1] and now we've found the biggest
one, which might break some apps.
The problem is the C++ support on Android. The default libstdc++
library is useless, it contains only "new", "delete", "type_info"
implementations, so we had to use something else which also comes with
stl support, so I choose to use the static gnu libstdc++.
Shortly after we release alpha3 I found that is not very wise to use
static libstdc++ on more than one library,
android-ndk/docs/STANDALONE-TOOLCHAIN.html says that:

[quote]
The standalone toolchain also comes with a copy of the GNU libstdc++
library, which provides an implementation of the C++ Standard Template
Library. To use it, you however need to link with the proper library:

  * Use -lstdc++ to link against the _static_ library version. This ensures
    that all required C++ STL code is included into your final binary. This
    is ideal if you are only generating a single shared library or executable.

    This is the recommended way to do it.

  * Use -lgnustl_shared to link against the _shared_ library version. This
    is required if you have several related shared libraries or executables
    that need to run in the same address space at runtime (some global variables
    need to be defined uniquely, which is not possible if you link the static
    libstdc++ against each one of your executables).
[/quote]

Now the question is, how to fix this problem without breaking the ABI?
The answer it seemed to be easy, theoretically just adding the whole
libstdc++ to QtCore should do the job [2], I loved myself for that
idea, but ... not for a long time, because hey, in real life nothing
is that simple, after we shipped the second testing SDK, Marco post an
alarming message [3] on necessitas-devel mailing list. The problem
seems to be easy to fix, because I removed the STL library from the
mkspecs file, the STL test didn't  compile anymore and that it seemed
it  was the reason for the problems, but again, "la vie en rose"
doesn't apply to me, because soon I discover that the --whole-archive
[2] flag is not working as it should, basically it doesn't export all
the symbols from libstdc++ and you can not use only QtCore to link
your STL apps. We (mostly Ray)  tried a lot of different paths but all
of them ended badly, then Ray reported this issue to Google
http://code.google.com/p/android/issues/detail?id=36472,  we really
hopped that we did something stupid but ... it seems we didn't.

Now we must decide what we do next, we see the following solutions:
1 - Release the SDK in a few days, but we must keep it as it is, try
to embed the whole libstdc++ library into QtCore, even it is not
exported all of it,but it seems it fixes the "static libstdc++"
problem described above, but we are not 100% sure.
2 - Delay the release, and fix the bloody linker, make it export
everything it should from libstdc++. The "static libstdc++" problem
will be 100% fixed (at least theoretically).
3 - Delay the release, switch to shared libstdc++ library, but this
move it will break the ABI, because all existing apps will search for
stl and c++ symbols into QtCore not in the shared libstdc++. Of course
we can not afford to break all existing apps, so we Ministro will need
more love to handle multiple ABI versions.
4. Is a combination between first and the seconds solution: we ship
the SDK now (1), but we (actually Ray is doing this tremendous job,
I'm just  the assistant)  keep working on (2).

Please let us know your opinions on this matter.

Any help with (2) will be very appreciated.

Cheers,
BogDan.

[1] http://www.omat.nl/2012/08/11/how-necessitas-grew-to-be-a-20tb-of-traffic-a-month-project/
[2] http://quickgit.kde.org/index.php?p=android-qt.git&a=blobdiff&h=348a33a421017d7fd77426dec24736cadec83d1f&hp=d7306e05aca22ba519b7b4d3332197649619779f&hb=8c4c862ee26283d1f4cd698071d002577aff72df&f=src/corelib/corelib.pro
[3] http://mail.kde.org/pipermail/necessitas-devel/2012-August/001123.html