Why is std::move undefined although compiler invoked with -std=c++11?

Question

I want to compile kenlm on OSX but I am getting the error:

error: no member named 'move' in namespace 'std'

Other posts suggest to compile with

'-std=c++11'

but I am still getting the same error. How can I resolve this?

g++ --version outputs:

Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 8.1.0 (clang-802.0.38)
Target: x86_64-apple-darwin16.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

---

The build script of kenlm looks like this:

from setuptools import setup, Extension
import glob
import platform
import os

#Does gcc compile with this header and library?
def compile_test(header, library):
    dummy_path = os.path.join(os.path.dirname(__file__), "dummy")
    command = "bash -c \"g++ -include " + header + " -l" + library + " -x c++ - <<<'int main() {}' -o " + dummy_path + " >/dev/null 2>/dev/null && rm " + dummy_path + " 2>/dev/null\""
    return os.system(command) == 0
...

#We don't need -std=c++11 but python seems to be compiled with it now.  https://github.com/kpu/kenlm/issues/86
ARGS = ['-O3', '-DNDEBUG', '-DKENLM_MAX_ORDER=6', '-std=c++11']
ext_modules = [
    Extension(name='kenlm',
        sources=FILES + ['python/kenlm.cpp'],
        language='C++', 
        include_dirs=['.'],
        libraries=LIBS, 
        extra_compile_args=ARGS)
]
...

Code using std::move:

#ifndef UTIL_FILE_STREAM_H
#define UTIL_FILE_STREAM_H
#include <utility>
#include "util/fake_ostream.hh"
#include "util/file.hh"
#include "util/scoped.hh"

#include <cassert>
#include <cstring>

#include <stdint.h>

namespace util {

class FileStream : public FakeOStream<FileStream> {
  public:
    explicit FileStream(int out = -1, std::size_t buffer_size = 8192)
      : buf_(util::MallocOrThrow(std::max<std::size_t>(buffer_size, kToStringMaxBytes))),
        current_(static_cast<char*>(buf_.get())),
        end_(current_ + std::max<std::size_t>(buffer_size, kToStringMaxBytes)),
        fd_(out) {}

#if __cplusplus >= 201103L
    FileStream(FileStream &&from) noexcept : buf_(std::move(from.buf_)), current_(from.current_), end_(from.end_), fd_(from.fd_) {
      from.end_ = reinterpret_cast<char*>(from.buf_.get());
      from.current_ = from.end_;
    }
#endif

Answer 1

According to the GNU CC Standard Library feature matrix, std::move (N2812) §"Impact on the Standard Library" was only added in version 4.5 and revised in version 4.6.

You should update you Standard Library version to version 4.5 (at least). Yours is 4.2.1.