Linker errors when using boost::filesystem?

Question

I have the following code:

#include <iostream>
#include <boost\filesystem.hpp>

int main(){
    const char* file_path = "my_path";
    std::cout << boost::filesystem::file_size(file_path) << std::endl;
}

and when I build I get the following errors:

1>Main.obj : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::system_category(void)" (?system_category@system@boost@@YAAEBVerror_category@12@XZ) referenced in function "void __cdecl boost::system::`dynamic initializer for 'native_ecat''(void)" (??__Enative_ecat@system@boost@@YAXXZ)
1>Main.obj : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::generic_category(void)" (?generic_category@system@boost@@YAAEBVerror_category@12@XZ) referenced in function "void __cdecl boost::system::`dynamic initializer for 'errno_ecat''(void)" (??__Eerrno_ecat@system@boost@@YAXXZ)
1>Main.obj : error LNK2019: unresolved external symbol "void __cdecl boost::filesystem::path_traits::convert(char const *,char const *,class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > &,class std::codecvt<wchar_t,char,int> const &)" (?convert@path_traits@filesystem@boost@@YAXPEBD0AEAV?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@AEBV?$codecvt@_WDH@5@@Z) referenced in function "void __cdecl boost::filesystem::path_traits::dispatch<class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > &,class std::codecvt<wchar_t,char,int> const &)" (??$dispatch@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@path_traits@filesystem@boost@@YAXAEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@AEAV?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@4@AEBV?$codecvt@_WDH@4@@Z)
1>Main.obj : error LNK2019: unresolved external symbol "public: static class std::codecvt<wchar_t,char,int> const & __cdecl boost::filesystem::path::codecvt(void)" (?codecvt@path@filesystem@boost@@SAAEBV?$codecvt@_WDH@std@@XZ) referenced in function "public: __cdecl boost::filesystem::path::path<char const [1]>(char const (&)[1],void *)" (??$?0$$BY00$$CBD@path@filesystem@boost@@QEAA@AEAY00$$CBDPEAX@Z)
1>Main.obj : error LNK2019: unresolved external symbol "unsigned __int64 __cdecl boost::filesystem::detail::file_size(class boost::filesystem::path const &,class boost::system::error_code *)" (?file_size@detail@filesystem@boost@@YA_KAEBVpath@23@PEAVerror_code@system@3@@Z) referenced in function "unsigned __int64 __cdecl boost::filesystem::file_size(class boost::filesystem::path const &)" (?file_size@filesystem@boost@@YA_KAEBVpath@12@@Z)

I am using Visual Studio and I have set the additional library path for my linker to include "C:\Program Files\Boost\boost_1_54_0\stage\lib;". I also have set the include path to look at C:\Program Files\Boost\boost_1_54_0;

Can anyone please help? My code builds fine when I use boost::algorithm, boost::string and boost::interprocess.

EDIT: this is what my linking if done on the command-line looks like:

/OUT:"my_file_path" /MANIFEST /NXCOMPAT /PDB:"my_file_path" /DYNAMICBASE "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib" /DEBUG /MACHINE:X64 /INCREMENTAL /PGD:"my_file_path" /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /ManifestFile:"my_file_path" /ERRORREPORT:PROMPT /NOLOGO /LIBPATH:"C:\Program Files\Boost\boost_1_54_0\stage\lib" /TLBID:1

Answer 1

I had similar unresolved externals building in Visual Studio.
The solution was to set use wchar_t to be treated as built-in.

Answer 2

You have the same issue as in How do I resolve LNK1104 error with Boost Filesystem Library in MSCV? and the answer is the same: Boost.Filesystem depends upon Boost.System and you need to link additionally with the latter library.

Answer 3

Set the linker's /VERBOSE flag ("Linker | General | Show Progress" = "Display all progress messages (/VERBOSE)" in the IDE). Then look at the output; in the IDE it'll be in the build output directory in a file called <project-name>.log.

If there's a boost filesystem library being looked for, make sure it exists; if there isn't one being looked for then you'll have to add the appropriate one explicitly in the linker inputs as Dietmar Kühl mentioned in a now-deleted post.

Also, since it looks like you're building for an x64 target, make sure you're not trying link against 32-bit boost libraries.