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Re: Crash occurs when catching std::exception in Objective-C++ code comp

From: Lobron, David
Subject: Re: Crash occurs when catching std::exception in Objective-C++ code compiled with clang on Linux and using libobjc2
Date: Thu, 30 Nov 2017 20:23:19 +0000

>>> The -fgnu-runtime is for using the runtime that comes with the GNU compiler 
>>> (gcc).
>> More specifically, it is for telling GCC to use the runtime that comes with 
>> GCC.  If you wish to use the GCC runtime with clang, the correct flag is 
>> -fobjc-runtime=gcc (optionally with a version, though clang currently 
>> ignores the version because it doesn’t know of any changes to the GCC 
>> runtime ABI since clang shipped - I don’t think there are any). 
> That's interesting ...I don't think gnustep-make really knows about/supports 
> the option of using clang with the gcc runtime.
> If you use gnu-gnu-gnu as the library combo, it's expecting gcc and the gnu 
> runtime
> If you use ng-gnu-gnu as the library combo, it's expecting clang and the 
> gnustep/objc2 runtime
> If someone is really determined they can override compiler/flags, but I don't 
> trust my ability to get wierd combination right, so I never try that.
> Perhaps gnustep-make should try to detect those sorts of override and protect 
> us from our own mistakes, but there's a limit to how far that can be taken 
> and we should probably just trust that if people override cimpiler and flags 
> specifications they know what they are doing.

Many thanks for your help, guys.

I updated gnustep-make to set the library combo to ng-gnu-gnu.  This is picked 
up by the configure script in gnustep-base:

checking the Objective-C runtime... Next Gen

However, the next few lines in the configure output of gnustep-base are 

checking for custom shared objc library... NONE
checking objc/runtime.h usability... yes
checking objc/runtime.h presence... no
configure: WARNING: objc/runtime.h: accepted by the compiler, rejected by the 
configure: WARNING: objc/runtime.h: proceeding with the compiler's result

The configure tool fails a few lines later, stating that it can't use clang to 
compile an ObjC program:

checking whether objc really works... no
I don't seem to be able to use your Objective-C compiler to produce
working binaries!  Please check your Objective-C compiler installation.

My clang compiler has not changed, so I know the compiler is in fact able to 
compile ObjC.

Are there additional flags needed for clang to work with gnustep-base when 
gnustep-make is using ng-gnu-gnu as the library combo?  My current configure 
flags for gnustep-base are:

CFLAGS="-m64 -march=opteron -mno-3dnow -ggdb -O2 -Wall -fPIC -fPIC -I 
/home/dlobron/build/clangport/akamai/common/include" CXXFLAGS="-m64 
-march=opteron -mno-3dnow -ggdb -O2 -fPIC -fPIC -I 
/home/dlobron/build/clangport/akamai/common/include" LDFLAGS="-m64  -rdynamic 
LD_LIBRARY_PATH=/home/dlobron/build/clangport/akamai/common/lib OBJC2RUNTIME=1 
                --target=x86_64-unknown-linux-gnu \
                --with-config-file=/usr/local/akamai/GNUstep/GNUstep.conf \
--with-ffi-include=/home/dlobron/build/clangport/akamai/common/include \
--with-ffi-library=/home/dlobron/build/clangport/akamai/common/lib \
                --enable-icu \
                --disable-tls \
                --disable-xml \
                --disable-zeroconf \


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