Building GCC on OS X 10.11 - macos

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" \
--with-mpc="/opt/local" --with-libiconv-prefix="/opt/local" --with-pkgversion="GCCX" \
--program-transform-name='s/^gcc$/gccx/; s/^g++$/g++x/' --enable-languages=c
Followed build instructions exactly, and getting this error:
g++ -std=gnu++98 -g -DIN_GCC -fno-strict-aliasing
-fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wno-format -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -fno-common -DHAVE_CONFIG_H -DGENERATOR_FILE -fno-PIE -Wl,-no_pie -o build/genmatch \
build/genmatch.o ../build-x86_64-apple-darwin15.0.0/libcpp/libcpp.a build/errors.o build/vec.o build/hash-table.o ../build-x86_64-apple-darwin15.0.0/libiberty/libiberty.a Undefined symbols for architecture x86_64: "_iconv", referenced from:
convert_using_iconv(void*, unsigned char const*, unsigned long, _cpp_strbuf*) in libcpp.a(charset.o)
(maybe you meant: __Z14cpp_init_iconvP10cpp_reader, __cpp_destroy_iconv ) "_iconv_close", referenced from:
__cpp_destroy_iconv in libcpp.a(charset.o)
__cpp_convert_input in libcpp.a(charset.o) "_iconv_open", referenced from:
init_iconv_desc(cpp_reader*, char const*, char const*) in libcpp.a(charset.o) ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) make[3]: *** [build/genmatch] Error 1 make[2]: *** [all-stage1-gcc] Error 2 make[1]: *** [stage1-bubble] Error 2 make:
*** [all] Error 2
(A complete log is available at https://gist.github.com/3cb5d044533e657f4add.)
After investigating gcc/Makefile, it seems that the BUILD_CPPLIB variable does not include $(LIBICONV), since it is in a stage1 bootstrap at the time of the error. The relevant section is preceded by
# For stage1 and when cross-compiling use the build libcpp which is
# built with NLS disabled. For stage2+ use the host library and
# its dependencies.
Yet clearly the stage1 build of build/genmatch is referencing libcpp, which uses symbols from libiconv. So something is amiss here.
How can I fix it?

Answer 1

General discussion
Building GCC on Mac OS X is an occasionally fraught process. I've had various issues with various versions of GCC and various versions of Mac OS X over the years. You can see an earlier explanation of what I did in Install GCC on Mac OS X — that was for building GCC 4.8.x on Mavericks 10.9.x (or possibly Mountain Lion 10.8.x); it also reports success building GCC 4.9.0 on Mavericks 10.9.x, but failure to do so on Yosemite 10.10.x.
This is an updated recipe for building GCC 5.2.0 on Mac OS X 10.11.1 El Capitan.
It starts off using XCode 7.1.1 — I don't know which other versions of XCode are OK.
Note that El Capitan has a feature SIP (System Integrity Protection) that was not in Yosemite and earlier versions. This means you cannot create arbitrary directories under /usr any more. I used to install in /usr/gcc/vX.Y.Z; that is no longer permitted in El Capitan. One major change, therefore, is that I now install in /opt/gcc/v.X.Y.Z.
I've found that having DYLD_LIBRARY_PATH set is problematic — especially on El Capitan. In a major break from the past, I'm now not setting that at all. Note that the scripts unset it. Note too that the script explicitly sets the phase 1 compilers CC and CXX to /usr/bin/clang and /usr/bin/clang++ respectively (the XCode compilers). The current versions of GCC require a capable C++ compiler instead of (or as well as) a C compiler.
I have occasionally had problems with libiconv, but at the moment I've evaded them by not having my own version installed. Similarly, I've occasionally had problems with some awk scripts in the GCC source. I had to hack it/them to get it to work OK. However, with release copy of GCC 5.2.0 source, I seem to be able to build directly out of the box.
If you've only got a single disk partition, this next point isn't crucial. If you have multiple disks, either make sure the target directory does not exist or ensure that its name is exactly what you want. On the machines at work (not Macs but Linux machines, etc), I still use /usr/gcc/vX.Y.Z as the 'official' install location, but the software ends up in some arbitrary file system where there's enough space, such as /work4/gcc, and eventually there is a symlink such that /usr/gcc/vX.Y.Z gets to /work4/gcc/vX.Y.Z. However, it is crucial that /work4/gcc/vX.Y.Z does not exist while GCC is being compiled because it will resolve the name via realpath() or its equivalent and embed /work4/gcc/vX.Y.Z into the binaries, rather than the neutral name /usr/gcc/vX.Y.Z. This limits the portability of the installation; any other machine that it is moved to has to have a directory /work4/gcc/vX.Y.Z, even though you asked to install it in /usr/gcc/vX.Y.Z.
Compiling GCC 5.2.0 on Mac OS X 10.11.1 with XCode 7.1.1
I had to work with down-versions of both GMP (5.1.3 instead of 6.0.0a) and ISL (0.14 instead of 0.15). The builds for the later versions both caused me trouble.
Note that I put the library code for GMP, MPC, MPFR, ISL and Cloog (see the GCC pre-requisites) in the GCC source directory so that GCC builds its own versions of these libraries. I've found that its the simplest way to ensure that GCC locates these libraries correctly.
Target directory: /opt/gcc/v5.2.0
Build time was about 2h 15m on a 17" MacBook Pro (early 2011) running Intel Core i7 at 2.3 GHz, with 16 GiB 1333 MHz DDR3 main memory, and a 750 GB 5400 rpm hard disk drive. The source occupies about 850 MiB; the build tree ends up at about 4.6 GiB — you need plenty of disk space. The installed code ends up at about 420 MiB.
Script used — extract-gcc-5.2.0.sh
#!/bin/bash
unset DYLD_LIBRARY_PATH
TAR=tar
VER_NUM=5.2.0
GCC_VER=gcc-${VER_NUM}
TGT_BASE=/opt/gcc
TGT_DIR=${TGT_BASE}/v${VER_NUM}
CC=/usr/bin/clang
CXX=/usr/bin/clang++
extract() {
echo "Extract $1"
$TAR -xf $1
}
if [ ! -d "$GCC_VER" ]
then extract ${GCC_VER}.tar.bz2 || exit 1
fi
(
cd ${GCC_VER} || exit
nbncl <<EOF |
cloog 0.18.1 tar.gz
gmp 5.1.3 tar.xz
# gmp 6.0.0 tar.lz
isl 0.14 tar.bz2
# isl 0.15 tar.bz2
mpc 1.0.3 tar.gz
mpfr 3.1.3 tar.xz
EOF
while read file vrsn extn
do
tarfile="../$file-$vrsn.$extn"
if [ ! -f "$tarfile" ]
then echo "Cannot find $tarfile" >&2; exit 1;
fi
if [ ! -d "$file-$vrsn" ]
then
(
set -x
extract "$tarfile" &&
ln -s "$file-$vrsn" "$file"
) || exit 1
fi
done
)
if [ $? = 0 ]
then
mkdir ${GCC_VER}-obj
cd ${GCC_VER}-obj
../${GCC_VER}/configure --prefix="${TGT_DIR}" \
CC="${CC}" \
CXX="${CXX}"
make -j8 bootstrap
fi
Script nbncl — non-blank, non-comment lines
#!/usr/bin/env perl
#
# Non-blank, non-comment lines only
use warnings;
use strict;
while (<>)
{
chomp;
s/\s+$//;
s/\s*#.*$//;
print "$_\n" unless /^$/;
}

Answer 2

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 .

Answer 3

For what it's worth, MacPorts has ports for all recent versions that should be sufficiently easy for everyone (who knows how to code!) to read who doesn't want to install MacPorts but prefers to install the various dependencies mentioned here some other way.
A slightly tweaked personal version of the port for gcc 6.3.0:
https://github.com/RJVB/macstrop/blob/master/lang/gcc6/Portfile
The reason I mention that one (and post this answer) is that this tweaked version shows how to get G++ to use libc++ instead of libstdc++. That's a prerogative for being able to use G++ as a real replacement for clang++ that can be used without worrying about C++ runtime incompatibilities. This patch has allowed me to use g++ to build KDE (KF5) code and run it against Qt5 and the KF5 frameworks built with various clang compiler versions. (The patch files are in .../gcc6/files .)
Some explanation that might help interpreting the Tcl code of the linked file:
Ignore anything that's specific to $subport == "libgcc".
As you can see, you need gmp, mpc, mpfr and isl (the other dependencies should be of no interest if you're installing on your own).
The configure.args expressions construct the argument list to the configure script, configure.env and build.env add environmental variables for the configure and build (make) commands. Many of the configure options here are to ensure that the build uses dependencies from MacPorts but they'd probably be required too if you want or have to use a location not controlled by SIP and that isn't included in standard PATH definitions (the compiler still ought to work when invoked through a process that resets the path).
The configure and build are done in a build directory that sits next to the source directory, which makes it very easy to start over or just clean up without throwing away the sources.
After the configure step the build is done with "make bootstrap-lean" - which still creates about 1.7Gb of data in that build directory.