Question

The problem

I am trying to build SRI’s Language Modeling tool, srilm version 1.6.0 on my mac, and coming across some fairly strange compilation problems (“strange” in that a few hours of Google-fu did not help), so I am turning to you to see if anyone sees how I can fix this.

I have already checked that I have the required dependencies and followed the install instructions as well as gone through the build troubleshooting section of the FAQ.

System Specifications

I have a pretty vanilla install of OS X, with some packages installed through homebrew. XCode 4.3.2 (latest version) is installed. Here are the other relevant system details.

OS version

Mac OS X 10.7.4

gcc -v printout

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-apple-darwin11.0.0/4.6.1/lto-wrapper
Target: x86_64-apple-darwin11.0.0
Configured with: ../gcc-4.6.1/configure --enable-languages=fortran,c++
Thread model: posix
gcc version 4.6.1 (GCC)

g++ -v printout

$ gcc -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-apple-darwin11.0.0/4.6.1/lto-wrapper
Target: x86_64-apple-darwin11.0.0
Configured with: ../gcc-4.6.1/configure --enable-languages=fortran,c++
Thread model: posix
gcc version 4.6.1 (GCC) 

uname -a printout

$ uname -a
Darwin MacBook-Air.local 11.4.0 Darwin Kernel Version 11.4.0: Mon Apr  9 19:32:15 PDT 2012; root:xnu-1699.26.8~1/RELEASE_X86_64 x86_64

The error itself

The following is the end of the output produced by running make World from the srlim top-level directory. Everything up until this point compiles fine in any of the following circumstances:

• I run make World on its own.
• I run make World MACHINE_TYPE=macosx
• I run make World MACHINE_TYPE=macosx-m64 (specific makefile for 64bit processors)
• I run make World MACHINE_TYPE=macosx-m32 (specific makefile for 32bit processors)

And the error that pops up is always the same (shown below).

stderr printout

$ make World

(...) # a bunch of stuff compiles with no errors or warnings

c++ -Wreturn-type -Wimplicit -DINSTANTIATE_TEMPLATES -DHAVE_ZOPEN  -I/usr/include -I. -I../../include -DHAVE_ZOPEN   -c -g -O2 -fno-common -o ../obj/macosx/LatticeIndex.o LatticeIndex.cc
LatticeIndex.cc:78:6: error: variable length array of non-POD element type
      'NBestWordInfo'
            makeArray(NBestWordInfo, roundedNgram, len + 1);
            ^
../../include/Array.h:93:33: note: expanded from macro 'makeArray'
# define makeArray(T, A, n)             T A[n]
                                           ^
LatticeIndex.cc:126:4: warning: data argument not used by format string
      [-Wformat-extra-args]
                        (float)ngram[0].start);
                        ^
LatticeIndex.cc:128:4: warning: data argument not used by format string
      [-Wformat-extra-args]
                        (float)(ngram[len-1].start + ngram[len-1].duration));
                        ^
2 warnings and 1 error generated.
make[2]: *** [../obj/macosx/LatticeIndex.o] Error 1
make[1]: *** [release-libraries] Error 1
make: *** [World] Error 2

Any idea what could be going wrong? It seems to compile fine on some other people’s macs in my department, and I’ve checked their makefiles for differences, but nothing popped up. No one here has any idea why the build fails, but we’d really appreciate it if you can help us out. Thanks in advance for any help you can provide me with! 🙂

Answer 1

The problem is due to Apple using llvm-gcc/clang, which does not support variable length arrays. This problem can actually be addressed by modifying $SRILM/dstruct/src/Array.h, and has been noted and addressed in the upcoming release of srilm.

For the time being, on a mac, build srilm using g++ 4.2 instead, using the following command:

$ make MACHINE_TYPE=macosx-m64 CXX=g++-4.2 World

This builds srilm without problem on all my macs.