Based on original documentation by OpenTTD team.

With these files you may build odcctools and GCC 4.2.1 targetting Darwin/macOS.

This has been tested in the following environments:

x86_64-pc-linux-gnu with GCC 4.5.3

The following targets have been tested:

i686-apple-darwin11
x86_64-apple-darwin11
arm-apple-darwin (requires iOS SDK)

These might work:

ppc-apple-darwin11
ppc64-apple-darwin11

Decide your target, and export:

export TARGET=i686-apple-darwin11

11 denotes Lion, 10 for Snow Leopard, and 9 for Leopard. These are mostly superficial. All code will run on 10.5 and greater.

Decide your prefix directory and set it to a variable.

export PREFIX=/usr/$TARGET
mkdir $PREFIX
cd $PREFIX

In ~/.bashrc or similar you may want:

export DARWIN_PREFIX=<prefix you chose>

Prepare your prefix

If you don't have a Mac, skip this and read Prepare your prefix (no Mac). Even if you have a Mac, the no-Mac method is cleaner than using scp but not as easy.

You will need a copy of an SDK directory to begin. You can choose any version past 10.4u really but I suppose only if you need new things in Lion would copy Lion's SDK (and that requires Lion itself of course). I expect that you are doing most development on the Mac anyway so therefore your compiler settings in Xcode will decide support level.

mkdir $PREFIX/SDKs
cd $PREFIX/SDKs

If you have Snow Leopard:

export SDK=MacOSX10.6.sdk
scp -r myname@mymac:/Developer/SDKs/$SDK .

If you have Lion (and want latest headers):

export SDK=MacOSX10.7.sdk
scp -r myname@mymac:/Developer/SDKs/$SDK .

Prepare your prefix (no Mac)

If you are copying from Mac with scp, skip to 'Continue with scp'.

Download the DMG from Apple for Xcode, any version. You need to have the following:

Linux kernel built with HFS+ file system driver
Catacombae DMGExtractor (requires Java) http://sourceforge.net/projects/catacombae/
- Gentoo users: I have an ebuild and prefix: https://github.com/tatsh/tatsh-overlay and once installed, simply run: emerge app-arch/dmgextractor to get this
p7zip
xar
cpio

Use mount and umount as root or with sudo (probably easier with sudo). Example here is with Xcode 4.2. Replace /mnt/tmp with your own mount point.

cd where-my-xcode-dmg-lives
java -jar path/to/dmgextractor.jar xcode_4.2_and_ios_5_sdk_for_snow_leopard.dmg my.iso (click OK on any prompts)
# if on Gentoo, you can use `dmgextractor xcode_4.2_and_ios_5_sdk_for_snow_leopard.dmg` my.iso
7z x my.iso
mount -t hfsplus disk\ image.hfs /mnt/tmp
xar -f /mnt/tmp/Packages/MacOSX10.6.pkg Payload
cpio -i < Payload
umount /mnt/tmp

You will now have an SDKs directory, but it needs fixing.

cd SDKs/MacOSX10.6.sdk
rm Library/Frameworks
ln -s System/Library/Frameworks Library
mv Developer/usr/llvm-gcc-4.2 usr
rm -r Developer/usr
ln -s usr Developer

Copy the prefix:

cd ../..
cp -r SDKs $PREFIX

cd $PREFIX

Note that we are going to put stuff in this .sdk directory. Anything we build from here will be placed inside. So we are going to create symlinks to its directories in $PREFIX.

ln -s SDKs/$SDK/Developer
ln -s SDKs/$SDK/Library
ln -s SDKs/$SDK/System
ln -s SDKs/$SDK/usr

If you used the no-Mac method, skip to Building cctools'.

Continue with scp

Delete any of YOUR frameworks (these are all from 3rd parties, not Apple). None of these are necessary.

rm -R Library/Frameworks

Create a symlink to the Apple Frameworks directory.

cd Library
ln -s ../System/Library/Frameworks
cd ..

Later on, you can copy the 3rd party frameworks from your Mac to $PREFIX/Library/Frameworks:

scp -r /Developer/SDKs/MacOSX10.6.sdk/Library/Frameworks/* $PREFIX/Library/Frameworks

usr is of great importantance to us in the next steps. It's where cctools and GCC will go. So yes, this usr directory (and possibly Library) will eventually be 'dirty' and non-equivalent to the one in macOS (and in the next steps we will overwrite files in the directory).

Never copy the SDK directory back to macOS for any reason.

Building cctools

You really should only apply the patch if you are not on macOS/Darwin, because I have not tested any of this on OS X/Darwin yet.

wget http://opensource.apple.com/tarballs/cctools/cctools-806.tar.gz
tar xvf cctools-806.tar.gz
patch -p0 < patches/cctools-806-nondarwin.patch
cd cctools-806
chmod +x configure
CFLAGS="-m32" LDFLAGS="-m32" ./configure --prefix=$PREFIX/usr --target=$TARGET --with-sysroot=$PREFIX
make
make install
cd ..

Note -m32. Everything will be 32-bit. Building for 64-bit is not supported (but using 32-bit to build 64-bit binaries is). Do not try optimisation flags. ranlib is especially sensitive.

Ignore ALL warnings. There will be many (or you can use -w for a CFLAG).

Building ld64

To build GCC we cannot use what's known as 'classic' ld. We have to use ld64 (even though we are not going to build it in 64-bit mode). For the moment, use odcctools-9.2 from the iphone-dev project (the version in this repository is patched for GCC 4.5):

cd odcctools-9.2-ld
CFLAGS="-m32" LDFLAGS="-m32" ./configure \
    --prefix=$PREFIX/usr \
    --target=$TARGET \
    --with-sysroot=$PREFIX \
    --enable-ld64
make
cd ld64
make install
cd ../..

Do not try optimisation flags here either.

Set $PATH to have your new tools. You may want to add this to your ~/.bashrc or similar.

export PATH="$PATH:/usr/$TARGET/usr/bin"

Building GCC

Now you can proceed to build GCC, but it must be patched first. Patches are located in patches.

wget http://opensource.apple.com/tarballs/gcc/gcc-5666.3.tar.gz
tar xvf gcc-5666.3.tar.gz
cd gcc-5666.3
patch -p1 < ../patches/gcc-5666.3-cflags.patch

Apply if you are annoyed by the default directory structure:

patch -p1 < ../patches/gcc-5666.3-tooldir.patch

After patching, I recommend building outside of the source of GCC.

cd ..
mkdir gcc-build
cd gcc-build

CFLAGS="-m32" CXXFLAGS="$CFLAGS" LDFLAGS="-m32" \
    ../gcc-5666.3/configure --prefix=$PREFIX/usr \
    --disable-checking \
    --enable-languages=c,objc,c++,obj-c++ \
    --with-as=$PREFIX/usr/bin/$TARGET-as \
    --with-ld=$PREFIX/usr/bin/$TARGET-ld64 \
    --target=$TARGET \
    --with-sysroot=$PREFIX \
    --enable-static \
    --enable-shared \
    --enable-nls \
    --disable-multilib \
    --disable-werror \
    --enable-libgomp \
    --with-gxx-include-dir=$PREFIX/usr/include/c++/4.2.1 \
    --with-ranlib=$PREFIX/usr/bin/$TARGET-ranlib \
    --with-lipo=$PREFIX/usr/bin/$TARGET-lipo

Optimisations do work here (most of the time). You can try to configure with:

CFLAGS="-m32 -O2 -msse2"

No, there is no Java (GCJ) or Fortran.

Make and install like normal.

make
make install

Sometimes you may get an issue about ranlib not working or lipo, which is why --with-ranlib and --with-lipo are appended to ./configure. However, you may have to run make again or not use a -j flag. I would recommend not using the -j flag anyway just to ease debugging of any issues. Seriously, try doing make over and over until it does work.

If ranlib has a buffer overflow during build, it is probably because you enabled optimisation flags.

Hack to fix include path

export LAST=$PWD
cd $PREFIX/usr/local
ln -s ../lib/gcc/$TARGET/4.2.1/include
cd $LAST

Test GCC

From the cloned source:

$TARGET-gcc -o msg msg.m \
    -fconstant-string-class=NSConstantString \
    -lobjc -framework Foundation

Test C++:

$TARGET-g++ -o msgcpp msg.cpp -I$PREFIX/usr/include/c++/4.2.1

I know, that's a weird -I flag. For now, just use an alias for $TARGET-g++ with it. You can safely alias $TARGET-gcc as well with -fconstant-string-class=NSConstantString even if you are compiling C.

file msg

Output:

msg: Mach-O executable i386

Copying to Mac and executing with ssh:

scp msg myname@mymac:
ssh myname@mymac ./msg
scp msgcpp myname@mymac:
ssh myname@mymac ./msgcpp

Output:

2011-09-03 03:51:52.887 msg[31266:1007] Are you John smith?
2011-09-03 03:51:52.889 msg[31266:1007] My message
This was compiled on a non-Mac!

Optional: Building LLVM-GCC

Because LLVM is the future right?

First, force the use of ld64 everywhere (yes you can keep this as permanent):

export LAST=$PWD
cd $PREFIX/usr/bin
mv $TARGET-ld $TARGET-ld.classic
ln -s $TARGET-ld64 $TARGET-ld
cd $LAST

You need to build Apple's LLVM first.

wget http://opensource.apple.com/tarballs/llvmgcc42/llvmgcc42-2335.15.tar.gz
tar xvf llvmgcc42-2335.15.tar.gz
mkdir llvm-obj
cd llvm-obj
CFLAGS="-m32" CXXFLAGS="$CFLAGS" LDFLAGS="-m32" \
    ../llvmgcc42-2335.15/llvmCore/configure \
    --prefix=$PREFIX/usr \
    --enable-optimized \
    --disable-assertions \
    --target=$TARGET
make
make install # optional
cd ..

This is somewhat intensive (lots of C++) so if you don't have a powerful PC do not use -j flag with make.

Next, proceed to build GCC itself, but you need to patch one thing (at least needed GCC 4.5):

cd llvmgcc42-2335.15
patch -p0 < ../patches/llvmgcc42-2335.15-redundant.patch
patch -p0 < ../patches/llvmgcc42-2335.15-mempcpy.patch
cd ..

Build outside the directory.

mkdir llvmgcc-build
cd llvmgcc-build
CFLAGS="-m32" CXXFLAGS="$CFLAGS" LDFLAGS="-m32" \
    ../llvmgcc42-2335.15/configure \
    --target=$TARGET \
    --with-sysroot=$PREFIX \
    --prefix=$PREFIX/usr \
    --enable-languages=objc,c++,obj-c++ \
    --disable-bootstrap \
    --enable--checking \
    --enable-llvm=$PWD/../llvm-obj \
    --enable-shared \
    --enable-static \
    --enable-libgomp \
    --disable-werror \
    --disable-multilib \
    --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ \
    -

Xchain

Install / Use

README