Re: Crash occurs when catching std::exception in Objective-C++ code compiled with clang on Linux and using libobjc2

[Lobron, David]

Hi David,

> I think the best option is probably to give up trying to avoid the libstdc++ 
> dependency and just build a single libobjc.so that links against libstdc++.so 
> if lib{supc++,cxxrt,c++abi}.so is not available.  

I added the following to CMakeLists.txt:

target_link_libraries(objc stdc++)
target_link_libraries(objc objcxx)

All unit tests now pass for me.  However, my test program still crashes when I 
try to catch a std::exception in ObjC++.

Looking at the tests more closely, it appears that the CXXExceptions tests are 
compiled as pure ObjC and C++ (i.e., with .m and .cc suffixes, respectively).  
I don't see a test with a .mm suffix, so I'm not sure if the tests really cover 
the bug that's biting me.

I tried making a .mm version of CXXExceptions.cc.  The test compiled, but I've 
been having trouble linking it (I've copied my link error below- I'm linking 
explicitly with libobjcxx.so and libobjc.o, but the linker isn't finding 
objc_autorelease or throw_int).

Do you think I'm barking up the wrong tree here?  Do the existing tests 
actually cover the case of ObjC++, and I'm just not seeing it?  

Thank you,

David

Linker error when trying to add a .mm version of CXXException to the tests:

(ALSI8)dlobron@bos-lps80:~/build/clangport/akamai/libobjc2/libobjc2-1.8.1/build/Test$
 /home/dlobron/build/clangport/akamai/llvm/llvm-5.0.0.install/bin/clang 
-std=gnu99  -fexceptions  -rdynamic 
CMakeFiles/CXXException.dir/CXXException.mm.o  -o CXXException 
-Wl,-rpath,/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/build 
../libobjc.so.4.6 -lstdc++ ../libobjcxx.so.4.6 
-L/home/dlobron/build/clangport/akamai/common/lib -lobjcxx -lobjc 
CMakeFiles/CXXException.dir/CXXException.mm.o: In function 
`_i_Test__autorelease':
/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/Test/CXXException.mm:(.text+0x98):
 undefined reference to `objc_autorelease(objc_object*)'
CMakeFiles/CXXException.dir/CXXException.mm.o: In function `_i_Test__retain':
/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/Test/CXXException.mm:(.text+0xc8):
 undefined reference to `objc_retain(objc_object*)'
CMakeFiles/CXXException.dir/CXXException.mm.o: In function `_i_Test__release':
/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/Test/CXXException.mm:(.text+0xf8):
 undefined reference to `objc_release(objc_object*)'
CMakeFiles/CXXException.dir/CXXException.mm.o: In function 
`_c_NSAutoreleasePool__addObject_':
/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/Test/CXXException.mm:(.text+0x149):
 undefined reference to `objc_autorelease(objc_object*)'
CMakeFiles/CXXException.dir/CXXException.mm.o: In function `finally()':
/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/Test/CXXException.mm:(.text+0x18d):
 undefined reference to `throw_int()'
CMakeFiles/CXXException.dir/CXXException.mm.o: In function `main':
/home/dlobron/build/clangport/akamai/libobjc2/libobjc2-1.8.1/Test/CXXException.mm:(.text+0x3a2):
 undefined reference to `catchall()'