Building GCC on OS X 10.11

Question

Building GCC (latest revision) on OS X 10.11.1 here, using the command line:

../gccx/configure --with-gmp=\"/opt/local\" --with-mpfr=\"/opt/local\" \\
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Answer 1

First, see Jonathan Leffler's very complete answer. I have a few more suggestions here.

The gcc configuration and build process needs to find your system's native header files and C run-time libraries. Newer, clang-based versions of Xcode hide these pretty deeply, and older versions of gcc don't seem to know how to find them. To get gcc 4.6 to build at all, I had to create these symlinks:

ln -s /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk/usr/include /usr
ln -s /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/lib/dylib1.10.5.o /usr/local/lib
ln -s /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/lib/crt1.10.5.o /usr/local/lib
ln -s /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/lib/bundle1.o /usr/local/lib

Your mileage will likely vary slightly: note that those pathnames underneath /Applications/Xcode.app/Contents have various version numbers baked in to them, which are likely to be different on your system.

(If, as Jonathan describes, the newest versions of MacOS don't allow you to put anything in /usr, you might have to create the /usr/include symlink in /usr/local/include, instead, and I suspect that would work, too.)

Also, this is mentioned elsewhere, but it's an unusual requirement, and easy to overlook: do not try to build gcc within its own source tree. Always create a build directory which is a parallel sibling, not a child underneath, of the directory into which you've extracted the gcc sources. That is, do not do this:

tar xzf gcc-x.y.z.tar.bz2
cd gcc-x.y.z       # WRONG
mkdir build
cd build
../configure       # WRONG
make

Instead, do this:

tar xzf gcc-x.y.z.tar.bz2
mkdir build
cd build
../gcc-x.y.z/configure
make

This is counterintuitive, I know, and it's not the way a lot of other packages work, but it definitely does work for gcc, and it's the recommended way to do it.

Another point: if you discover that your build is failing because you configured it improperly, such that you have to rerun configure with different options, it's safer to delete your entire build directory and start from scratch. The configure and build system sometimes, but it seems not 100% reliably, detects what might need rebuilding in that case. (Deleting and starting over is frustrating, I agree, but again, it can really save time in the long run.)

Finally, if you're trying to build a cross-compiler, see some additional suggestions and commentary at install gcc 4.6.1 on OS X 10.11 .