Building GCC-4.9.2 on OS X Yosemite - macos

Question

Ok, I'm having trouble building gcc-4.9.2 on Apple's new OS X Yosemite. I'm not sure if I need to be building a gnu-gcc compiler on OS X, as most other software has compiled fine, apart from tesseract-3.0.1 and some of my own wxWidgets applications. Are there certain programs/code features that clang can't compile?
My build steps are as follows:
cd build-gcc
../gcc-4.9.1/configure --program-prefix="gnu-" --prefix="/usr/local/gcc-4.9.1" --with-gmp="/usr/local" --with-mpfr="/usr/local" --with-mpc="/usr/local" CC=clang CXX=clang++
make
My build path and gcc source paths do not contain any whitespace, and I have installed GMP, MPFR and MPC in /usr/local.
My build outputs are:
clang++ -g -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wno-format -Wmissing-format-attribute -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -fno-common -DHAVE_CONFIG_H -Wl,-no_pie -o cc1 c/c-lang.o c-family/stub-objc.o attribs.o c/c-errors.o c/c-decl.o c/c-typeck.o c/c-convert.o c/c-aux-info.o c/c-objc-common.o c/c-parser.o c/c-array-notation.o c-family/c-common.o c-family/c-cppbuiltin.o c-family/c-dump.o c-family/c-format.o c-family/c-gimplify.o c-family/c-lex.o c-family/c-omp.o c-family/c-opts.o c-family/c-pch.o c-family/c-ppoutput.o c-family/c-pragma.o c-family/c-pretty-print.o c-family/c-semantics.o c-family/c-ada-spec.o c-family/c-cilkplus.o c-family/array-notation-common.o c-family/cilk.o c-family/c-ubsan.o i386-c.o darwin-c.o \
cc1-checksum.o libbackend.a main.o tree-browser.o libcommon-target.a libcommon.a ../libcpp/libcpp.a ../libdecnumber/libdecnumber.a libcommon.a ../libcpp/libcpp.a ./../intl/libintl.a -liconv ../libbacktrace/.libs/libbacktrace.a ../libiberty/libiberty.a ../libdecnumber/libdecnumber.a -L/usr/local/lib -L/usr/local/lib -L/usr/local/lib -lmpc -lmpfr -lgmp -L../zlib -lz
ld: warning: ld: warning: ld: warning: ignoring file libbackend.a, file was built for archive which is not the architecture being linked (x86_64): libbackend.aignoring file libcommon-target.a, file was built for archive which is not the architecture being linked (x86_64): libcommon-target.aignoring file ../libdecnumber/libdecnumber.a, file was built for archive which is not the architecture being linked (x86_64): ../libdecnumber/libdecnumber.a
ld: warning: ignoring file ../zlib/libz.a, file was built for archive which is not the architecture being linked (x86_64): ../zlib/libz.a
Undefined symbols for architecture x86_64:
... (Lots of symbols)
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]: *** [cc1] Error 1
make[2]: *** [all-stage1-gcc] Error 2
make[1]: *** [stage1-bubble] Error 2
make: *** [all] Error 2
Configure outputs the build type as: x86_64-apple-darwin14.0.0, so I don't understand why this is happening.
Thank You in advance for any help.

Answer 1

Turns out that I had a broken ranlib in /usr/local/bin - maybe GNU Binutils don't work on OS X? All I needed to do to fix the problem was to:
sudo mv /usr/local/bin/ranlib /usr/local/ranlib_old
and then make, and now I have a working GCC!