Boost 1.53 and 1.58 difference - c++

Question

Following is a small and simple piece of code I wrote :
#include<iostream>
#include<boost/filesystem.hpp>
using namespace std;
namespace fs = boost::filesystem;
int main(int argc, char** argv)
{
fs::directory_iterator it((fs::path(argv[1])));
fs::directory_iterator endit;
while(it != endit)
{
cout<<it->path().string()<<endl;
++it;
}
}
I then wrote a very simple CMakeLists.txt file as follows :
cmake_minimum_required(VERSION 2.8)
project(test)
find_package(Boost COMPONENTS filesystem system REQUIRED)
include_directories(${Boost_INCLUDE_DIR})
add_executable(test test.cpp)
target_link_libraries(test ${Boost_LIBRARIES})
When I compile this code on OS X Yosemite, it runs perfectly.
The compiler details are as follows :
$ g++ -v
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)
Target: x86_64-apple-darwin14.3.0
Thread model: posix
I then ran it on a Fedora 19 system and it did produce errors during compilation. The error message is very long. My project involves a number of source files, but for this problem, a part of the error message is sufficient to understand the problem :
/user/uujjwal/home/code/pom-final/test/abc.cpp: In function 'int main(int, char**)':
/user/uujjwal/home/code/pom-final/test/abc.cpp:13:10: error: no match for 'operator!=' (operand types are 'boost::filesystem::directory_iterator(boost::filesystem::path*)' and 'boost::filesystem::directory_iterator')
while(it!=endit)
Thus it shows that the operator != is invalid.
The compiler details on Fedora system are :
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.2/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto --enable-plugin --enable-initfini-array --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-isl=/builddir/build/BUILD/gcc-4.8.2-20131017/obj-x86_64-redhat-linux/isl-install --with-cloog=/builddir/build/BUILD/gcc-4.8.2-20131017/obj-x86_64-redhat-linux/cloog-install --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.2 20131017 (Red Hat 4.8.2-1) (GCC)
Boost version on OS X - 1.58
Boost version on Fedora System - 1.53
I want to know that is this owing to a fundamental difference between the two versions ? Is the reason something else ? If I have to make some changes in the code, to make it portable, what is the right way ?
****PS :-I also noticed out of experimentation that on Fedora if , do the following**
fs::path root_path(argv[1]);
fs::directory_iterator it(root_path);
it then compiles. So where is the difference coming and why ?**

Answer 1

The LHS operand type in your error message is boost::filesystem::directory_iterator(boost::filesystem::path*). This indicates that you're experiencing a most vexing parse error; the declaration of it is being parsed as a function declaration rather than a local variable declaration-instantiation:
fs::directory_iterator it(fs::path(argv[1]));
This is parsed as the declaration of an extern function named it, taking one argument (named argv) of type fs::path[1] (fs::path* after decay) and returning fs::directory_iterator.
What's odd is that your extra parentheses should have prevented the MVP error. Either your version of gcc is buggy and ignored them, or something changed between the code you're presenting and what was passed to the compiler.
fs::directory_iterator it((fs::path(argv[1])));
// extra parentheses ^ ^ to prevent MVP