Re: building GNUstep from scratch

[Andreas Fink]

I had good success with libojbc/clang under debian9 (stretch). I wouldn't want to go back to gcc due to non support of certain stuff I use every day (the stuff which apple introduced in what they called objc2.0). Part is working in recent gcc's though but I like clangs error reporting and better support for objc.

For clang, the debian shipped clang 3.8 was long my standard compiler. With newer versions of clang and latest libobjc2 I've run into an incompatibility with very weird side effects.

I had cases where something like this:

-(void)somemethod

{

_intProperty = 123;

NSLog(@"%d", _intProperty);

was printing out a value of 0 instead of 123, and of course this makes very strange things much later in your code.

According to David Chisnall this is fixed in clang after r339128 and was due to how the compiler aligns structs/object properties in memory (compilers tend to optimize this in some way and all compilers used for individual parts have to use the same optimisation to come to the same order which wasn't the case if I understood correctly).

this is how I build the latest clang8 from source

git clone https://git.llvm.org/git/llvm.git/

cd llvm/tools

git clone https://git.llvm.org/git/clang.git/

cd ../projects

git clone https://git.llvm.org/git/compiler-rt.git/

git clone https://git.llvm.org/git/openmp.git/

git clone https://git.llvm.org/git/libcxx.git/

git clone https://git.llvm.org/git/libcxxabi.git/

git clone https://git.llvm.org/git/test-suite.git/

cmake .. -DCMAKE_BUILD_TYPE=Release

make -j8 install

This takes quite some time and lots of memory. If you forget -DCMAKE_BUILD_TYPE=Release you end up with 32 gigabytes of RAM not being sufficient (constantly swapping) and compile times of hours to days. On 32bit machines its even worse due to the 4GB memory limit.

Then I install gnustep like this:

Setting some defaults

------------------------------------------------

    export CC=clang

    export CXX=clang++

    export PATH=/usr/local/bin:$PATH

    export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/

Download the sourcecode of gnustep and dependencies

---------------------------------------------------

    

    mkdir gnustep

    cd gnustep

    wget http://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.15.tar.gz

    git clone https://github.com/apple/swift-corelibs-libdispatch

    git clone https://github.com/gnustep/scripts

    git clone https://github.com/gnustep/make

    git clone https://github.com/gnustep/libobjc2

    git clone https://github.com/gnustep/base

    git clone https://github.com/gnustep/corebase

    git clone https://github.com/gnustep/gui

    git clone https://github.com/gnustep/back

    ./scripts/install-dependencies

Build dependencies

---------------------------------------------------

    tar -xvzf libiconv-1.15.tar.gz

    cd libiconv-1.15

    ./configure

    make CFLAGS=-g

    make CFLAGS=-g install

    cd ..

    cd swift-corelibs-libdispatch

    mkdir build

    cd build

    cmake .. -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_CXX_FLAGS=-g -DCMAKE_C_FLAGS=-g

    make

    make install

    

Install gnustep-make

---------------------------------------------------

    cd make

    export CC=/usr/bin/clang

    export CXX=/usr/bin/clang++

    export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/

    export OBJCFLAGS="-DEXPOSE_classname_IVARS=1"

    ./configure --with-layout=fhs \

            --disable-importing-config-file \

            --enable-native-objc-exceptions \

            --enable-objc-arc \

            --enable-install-ld-so-conf \

            --with-library-combo=ng-gnu-gnu

     make install

     source /usr/local/etc/GNUstep/GNUstep.conf

     cd ..

     

Install libobjc2 runtime

---------------------------------------------------

    cd libobjc2

    mkdir Build

    cd Build

    cmake .. -DBUILD_STATIC_LIBOBJC=1  -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_CXX_FLAGS=-g -DCMAKE_C_FLAGS=-g

    make

    make install

    cd ..

    ldconfig

install gnustep-base

---------------------------------------------------

    cd base

    ./configure CFLAGS="-DEXPOSE_classname_IVARS=1 -g " --with-config-file=/usr/local/etc/GNUstep/GNUstep.conf --disable-libdispatch

    make -j8

    make install

    cd ../..

    ldconfig

(for debug version use "make debug=yes" instead of "make")

and then the other gnustep libraries with simple ./configure; make;make install

On 22 Aug 2018, at 06:47, Riccardo Mottola <riccardo.mottola@libero.it> wrote:

Hi,

On 08/22/18 00:34, Scott Christley wrote:

Honestly, I'm not sure if I need the modern runtime or not. I do use NSInvocation stuff quite a bit but I don't think this code base needs the runtime introspection stuff...

you need he modern runtime if you need modern features like blocks. Also properties are better supported.
The modern runtime gives you also the modern @try @catch exception handling.

Performance wise it may be better or worse, depending on your code. If your code "compiles" with gcc, it should also run - barren bugs.

In theory libobjc2 supports both "gnu" and "ng" runtimes and did so for a long time, but latest release are buggy for me, either they crash the code or they fail to catch exceptions

I did get further and was able to compile libobjc2 completely after setting cc and c++ to clang. However, two tests failed so maybe that's the recent difficulties you were mentioning.

The following tests FAILED:

25 - PropertyIntrospectionTest2 (OTHER_FAULT)

26 - PropertyIntrospectionTest2_optimised (OTHER_FAULT)

No that's different, I hope others will help you or maybe David himself.

Riccardo

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