Error Building Giraffe (Chess Program): /opt/local/bin/as: assembler (/opt/local/bin/clang) not installed - g++

Question

I'm trying to build the Giraffe Deep Belief Chess Playing program which I downloaded from Mercurial.
From README.md:
Tested on Linux (GCC 4.9), OS X (GCC 4.9), Windows (MinGW-W64 GCC 5.1). GCC versions earlier than 4.8 are definitely NOT supported, due to broken regex implementation in libstdc++.
Here's the error:
David-Laxers-MacBook-Pro:giraffe davidlaxer$ make
g++ -Wall -Wextra -Wno-unused-function -std=gnu++11 -mtune=native -Wa,-q -ffast-math -pthread -fopenmp -DHGVERSION="\"efceca80bf74\"" -O3 -march=native -Wa,-q -I. -c backend.cpp -o obj/backend.o
/opt/local/bin/as: assembler (/opt/local/bin/clang) not installed
make: *** [obj/backend.o] Error 1
I'm on OS X 10.10.5.
port select --list clang
Available versions for clang:
mp-clang-3.5
mp-clang-3.7
none (active)
David-Laxers-MacBook-Pro:giraffe davidlaxer$ ls -l /opt/local/bin/as
-r-xr-xr-x 1 root admin 28012 Feb 15 2015 /opt/local/bin/as
David-Laxers-MacBook-Pro:giraffe davidlaxer$ /opt/local/bin/as -v
Apple Inc version cctools-862, GNU assembler version 1.38
David-Laxers-MacBook-Pro:giraffe davidlaxer$ file /opt/local/bin/as
/opt/local/bin/as: Mach-O 64-bit executable x86_64
David-Laxers-MacBook-Pro:giraffe davidlaxer$ g++ --version
g++ (MacPorts gcc49 4.9.3_0) 4.9.3
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
From Makefile:
#CXX=g++-4.9 # I changed this - dbl
CXX=g++
# this is used to build gtb only
CC=gcc-4.9
HGVERSION:= $(shell hg parents --template '{node|short}')
CXXFLAGS_BASE = \
-Wall -Wextra -Wno-unused-function -std=gnu++11 -mtune=native -Wa,-q -ffast-math \
-pthread -fopenmp -DHGVERSION="\"${HGVERSION}\""

Answer 1

Here is what I did to solve this issue using Brew,
$ clang
zsh: no such file or directory: clang
$ brew install llvm --with-clang --with-asan
==> Downloading http://llvm.org/releases/3.5.0/llvm-3.5.0.src.tar.xz
######################################################################## 100.0%
🍺 /usr/local/Cellar/llvm/3.5.0: 1235 files, 171M, built in 16.8 minutes
$ clang -v
Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix