556839 - STL: How to use it on android?

Status: RESOLVED FIXED

(Core :: XPCOM, enhancement)

Description

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

According to mwu, the native android apps are built with gcc 4.4, but only the bare minimum standard C++ headers are provided to compile C++ code (no STL).  The problem is that android uses bionic instead of glibc (does it use libstdc++ at all?  Guessing not.).  I would hate it if android kept mozilla code perpetually in C+ idiom land, so ideally we'd like to figure out a way to use the STL on android.  I think we have two choices

 (1) Import the gcc STL headers we need and sort out missing runtime functions in bionic.  I'm pretty sure that with the patch in bug 551254, the STL containers (<vector> et al.) don't require any symbols from glibc or libstdc++.  However, I know that <string> and <wstring> (used by chromium/ code) do.  We could list these dependencies and implement them as hidden libxul symbols, like we do for the __throw_[exception]() symbols.  (In fact, chromium/ already implemented some of these for a related reason.)
 (2) Import a cross-platform STL library such as STLport.  This has other potential benefits, but it's also a potentially large-ish maintenance burden.

I'd like to figure out what's needed for (1) before we decide.

Also, everyone agrees that sorting this out shouldn't block android v1 release, but at the same time we can't use multi-process code in android until it is sorted.

Comment 1

[Stuart Parmenter]

Chris:  Having e10s for Android will be a blocker for our first alpha (not for our first public builds though)

Comment 2

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

At one point we looked at using uclibcxx for android; I actually got things building that way.  But Gecko's usage of STL was so minimal it wasn't worth it.  For e10s though, that might be the way to go; importing the headers/etc. is going to be a big pain, I'd rather just pull in a full complete implementation, especially if we can stick it in our own private namespace.

Comment 3

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

Update: uClibc++ is out because of licensing issues.  SGI's is out because it's ancient and depends on the compiler providing headers that android-g++ doesn't.  Apache STL is out because of licensing issues (until MPL.next).  Waiting to hear back about STLport's license.

Comment 4

[Zack Weinberg (:zwol)]

Can't we just LART the Android people until they start shipping a complete C++ standard library?

Comment 5

[Mark Finkle (:mfinkle) (use needinfo?)]

Still blocking?

Comment 6

[Brad Lassey [:blassey] (use needinfo?)]

we're using the stl from our custom ndk

Comment 7

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Did legal decide that was ok for final ship?  I thought that decision got punted...