C++ BOOST undefined reference to `boost::filesystem::detail::copy_file

Question

I have no clue why boost::filesystem::copy_file is making trouble for me.

undefined reference to `boost::filesystem::detail::copy_file

Answer 1

In older boost versions it is BOOST_NO_SCOPED_ENUMS, not BOOST_NO_CXX11_SCOPED_ENUMS

see boost::filesystem::copy_file() missing symbol in c++11

Answer 2

There is a workaround for this problem, replace

#include <boost/filesystem.hpp>

with

#define BOOST_NO_CXX11_SCOPED_ENUMS
#include <boost/filesystem.hpp>
#undef BOOST_NO_CXX11_SCOPED_ENUMS

Or, preferably, add -DBOOST_NO_CXX11_SCOPED_ENUMS to your compiler flags

Answer 3

I could not compile a file that included the header boost/filesystem.hpp either. This is how I solved it: I commented out the line boost/filesystem.hpp and all the lines that were using Boost, and then compiled the file. I then uncommented all the lines in the files and compiled again, and then it worked. I was compiling with the flag -lboost_system both times!

Answer 4

If you run into this problem make sure to include both -lboost_system and -lboost_filesystem in your call to g++

Example working Makefile

BINARY = output
FILE_OBJECTS = main.o fileLoader.o
BOOST = -lboost_system -lboost_filesystem
GCC = g++ -std=c++17
FLAGS = -Wall -pedantic -Wextra

build: $(FILE_OBJECTS)
    $(GCC) $(FLAGS) $(FILE_OBJECTS) -o $(BINARY) $(BOOST)

main.o: main.cpp fileLoader.o
    $(GCC) $(FLAGS) -c main.cpp

fileLoader.o: fileLoader.cpp
    $(GCC) $(FLAGS) -c fileLoader.cpp

clean:
    rm -rf *.o $(BINARY)

Example working code

#include <boost/filesystem.hpp>

void create_data_file(std::string file_path)
{
    boost::filesystem::path p(file_path);
    boost::filesystem::create_directory(p);
}