dlib示例，测试生成失败。

Question

运行ubuntu12.04，我下载了源代码并按指示编译了它(参见https://github.com/davisking/dlib)。下面是显示的错误消息。

cmake --build . --config Release
[ 1%] Building CXX object dlib_build/CMakeFiles/dlib.dir/bsp/bsp.cpp.o
In file included from /home/andreif/downlib/dlib-19.2/dlib/bsp/../sockets/../threads/parallel_for_extension.h:9:0,
from /home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads.h:24,
from /home/my_path/dlib-19.2/dlib/bsp/../sockets/sockets_kernel_2.h:33,
from /home/my_path/dlib-19.2/dlib/bsp/../sockets/posix.h:4,
from /home/my_path/dlib-19.2/dlib/bsp/../sockets.h:14,
from /home/my_path/dlib-19.2/dlib/bsp/bsp.h:7,
from /home/my_path/dlib-19.2/dlib/bsp/bsp.cpp:6:
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h: In function ‘std::future<typename std::result_of<_Functor(_ArgTypes="" ...)="">::type> dlib::async(dlib::thread_pool&, Function&&, Args&& ...)’:
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:63:15: error: expected nested-name-specifier before ‘bind_t’
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:63:15: error: ‘bind_t’ has not been declared
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:63:22: error: expected ‘;’ before ‘=’ token
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:63:22: error: expected primary-expression before ‘=’ token
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:63:24: error: expected primary-expression before ‘decltype’
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:63:24: error: expected ‘;’ before ‘decltype’
/home/my_path/dlib-19.2/dlib/bsp/../sockets/../threads/async.h:64:37: error: ‘bind_t’ was not declared in this scope
make[2]: [dlib_build/CMakeFiles/dlib.dir/bsp/bsp.cpp.o] Error 1
make[1]: [dlib_build/CMakeFiles/dlib.dir/all] Error 2
make: *** [all] Error 2

Answer 1

问题在于我的c++编译器:ubuntu12.04中默认的gcc 4.6支持c++11，但是在调用它时必须在命令行中启用它。我试着编辑/.bashrc来自动完成这个操作，但是它没有工作。我的解决方案是安装gcc/g++ 4.8 (并使用更新选项来保持旧安装的可用性)，如下所述。

http://mortenvp.com/installing-a-newer-gccg-on-ubuntu-12-04-lts/