Segmentation fault with boost::filesystem

Question

I just installed boost on my mac. (Installed MacPorts, sudo port install boost) In XCode I added Header Search Path (/opt/local/include) and Library Search Path (/opt/local/lib) and added libraries into Build Phases - Link Binary With Libraries (libboost_filesystem-mt.a, libboost_filesystem-mt.dylib, libboost_system-mt.a, libboost_system-mt.dylib). Now I trying to build and run this code

#include <iostream>
#include <string>
#include <boost/filesystem.hpp>

int main() {
    std::string filename;
    std::cin >> filename;
    std::cout << boost::filesystem::exists(filename);

    return 0;
}

And with any path typed I got Segmentation Fault: 11 when calling exists().

What i did wrong? Is any mistakes when installing boost?

Answer 1

I've run in to similar problems in the past when boost isn't built with the same CXXFLAGS as your program. Here's a pseudo-complete set of bootstrap instructions.

# Configure, build, and install boost
./bootstrap.sh \
  --prefix=${PWD}/.local \
  --with-libraries=...,filesystem,...
./b2 \
  -q \
  -d2 \
  -j4 \
  --debug-configuration \
  --disable-filesystem2 \
  --layout=tagged \
  --build-dir=${PWD}/obj \
  cxxflags="-v -std=c++11 -stdlib=libc++" \
  linkflags="-stdlib=libc++" \
  link=shared \
  threading=multi \
  install

The important part there is the cxxflags and linkflags. In my experience, it's most often because macports compiles without using -stdlib=libc++ but that's required when using compiling C++11 code using -std=c++11. Common symptoms include random backtraces in gdb that indicate something is a problem with a pointer inside of a particular struct buried deep within a boost library/template.

As you can tell from the above, I build a local copy of boost in to a per-project directory (e.g. ${PWD}/.local) and then link against the local version during development until it's time to package (at which point I statically link or do something else).

# In a GNUmakefile
LOCAL_DIR=${PWD}/.local
INC_DIR=${LOCAL_DIR}/include
LIB_DIR=${LOCAL_DIR}/lib

CPPFLAGS=-I"${INC_DIR}"
CXXFLAGS=-std=c++11 -stdlib=libc++
LDFLAGS=-stdlib=libc++ -L"${LIB_DIR}"

MYPROG_SRCS=myprog.cpp
MYPROG_OBJS=$(MYPROG_SRCS:.cpp=.o)

%.o : %.cpp %.hpp
        ${CXX} ${CXXFLAGS} ${CPPFLAGS} -c -o $@ $<

myprog: ${MYPROG_OBJS}
        ${CXX} ${LDFLAGS} -o $@ $^ ${LIBS}

Bottom line: your CPPFLAGS and LDFLAGS need to match between boost and your program.