Distribute j2objc libraries with Bitcode enabled (only jre libs were built with Bitcode)

[brunobowden]

It appears that Bitcode support in the j2objc libraries is limited to jre_emul and jre_emul_core and not supported in other libraries. Running the standard Bitcode marker test:

$ otool -l libjre_emul.a | grep __LLVM | head -1
segname __LLVM
$ otool -l libjre_emul_core.a | grep __LLVM | head -1
segname __LLVM

All the other libraries come up negative. This request is to add support to all those libraries to enable support of watchOS apps. I don't believe it's needed for junit or mockito but is necessary for the others.

[tomball]

All libraries are built with the -fembed-bitcode-marker flag. To verify this, be sure and specify otool's -arch flag (only the armv7 and arm64 should set this flag):

$ otool -l libguava.a -arch armv7 | grep __LLVM | head -1
segname __LLVM
$ otool -l libguava.a -arch arm64 | grep __LLVM | head -1
segname __LLVM

I don't know why otool will find the segment in some fat libraries, like libjre_emul.a, but not others.

[gianlucabertani]

Actually if you try to Build & Archive an app that uses jre_emul.a, you get an error saying the library was built without full bitcode:

ld: bitcode bundle could not be generated because '[...]/lib/libjre_emul.a(IosHttpHandler.o)'
was built without full bitcode. All object files and libraries for bitcode must be generated
from Xcode Archive or Install build for architecture armv7

Redistributable binaries should be built with _-fembed-bitcode_, not -fembed-bitcode-marker flag. The difference between these two flags is explained well here:

• How do I xcodebuild a static library with Bitcode enabled?

[tomball]

Has anyone successfully rebuilt j2objc with -fembed-bitcode? Only the jre_emul/environment.mk and make/fat_lib_macros.mk files need to be updated.

[gianlucabertani]

Successfully rebuild just now, my environment is:

Xcode 7.1.1 Build version 7B1005
Apple LLVM version 7.0.0 (clang-700.1.76)

The resulting libjre_emul.a contains full bitcode segments (and in fact it is > 250 MB, way greater than the ~120 MB of currently released version) and links correctly against a test app.

[lukhnos]

I have also successfully built, archived, and validated an app of mine with the latest libjre_emul.a (current master at 0eb1680).

[yurevich1]

lukhnos, do you mean what the file at path j2objc-1.1/lib/libjre_emul.a works for watchOS? I'm getting this warning:

#780