There are a few issues at play here which you need to overcome to get this compiling on OSX. My instructions below assume that you are running on El Capitan (10.11.1 in my instance), but you may get some milage out of them for different versions.
Firstly, Xcode currently uses Apple's LLVM Compiler as the default C++ compiler. However, this doesn't support some of GCC's extensions, such as support for non-POD variable length arrays.
To get around this, I installed and compile with GCC: if you haven't already, install Homebrew, and then install the latest GCC compiler with:
$ brew install gcc
At the time of writing, this will install GCC v5.2.0.
That should fix your initial problem, but you will instantly hit others!
The next issue is that the included libqc.a will need recompiling for x86_64. So you will need to modify the file <base_dir>/qc/Makefile
with the following changes:
...
# Add:
CXX = /usr/local/Cellar/gcc/5.2.0/bin/g++-5
CXXFLAGS = $(ARCHOPT) -c -pedantic -Wall $(DEBUG) $(PRGOPT)
...
Then rebuild libqc.a
:
$ cd qc; make clean; make
If all goes well, you should have a shiny new libqc.a
.
Finally, modify the main Makefile <base_dir>/Makefile
with the following changes:
...
# Comment out:
#PLOPT = -DQCL_PLOT
#PLLIB = -L/usr/X11/lib -lplotter
...
# Comment out:
#RLOPT = -DQCL_USE_READLINE
#RLLIB = -lreadline
#RLLIB = -lreadline -lncurses
...
# Comment out:
#CXX = g++
#CPP = $(CC) -E
#CXXFLAGS = -c $(ARCHOPT) $(DEBUG) $(PLOPT) $(RLOPT) $(IRQOPT) $(ENCOPT) -I$(QCDIR) -DDEF_INCLUDE_PATH="\"$(QCLDIR)\""
#LDFLAGS = $(ARCHOPT) -L$(QCDIR) $(DEBUG) $(PLLIB) -lm -lfl -lqc $(RLLIB)
# Add:
CXX = /usr/local/Cellar/gcc/5.2.0/bin/g++-5
CPP = $(CC) -E
CXXFLAGS = -c $(ARCHOPT) $(DEBUG) $(PLOPT) $(RLOPT) $(IRQOPT) $(ENCOPT) -I$(QCDIR) -DDEF_INCLUDE_PATH="\"$(QCLDIR)\""
LDFLAGS = $(ARCHOPT) -L$(QCDIR) $(DEBUG) $(PLLIB) -lm -ll -lqc $(RLLIB) -lc++
...
This should now allow you to build the main application as per the instructions:
$ make clean; make; make install