问题描述
目前,我的项目有以下简单的树:
Currently my project has the following simple tree:
./Makefile.am
./configure.ac
./README
./src/main.cpp
./src/Makefile.am
./bin
我正在尝试遵循以下教程:
I'm trying to following the following tutorial:
http://www.gnu.org/software/automake/manual/automake.html#Hello-World
如何指示configure.ac使用C ++ 0x扩展?特别是,如果main.cpp文件中的hello-world行如下所示:
How can I instruct configure.ac to use the C++0x extensions? In particular, what if the hello-world line in main.cpp file is as follows:
cout << ([] () {return "Hello, World!";}) () << endl;
发出"make"会导致错误.
Issuing "make" results in an error.
推荐答案
如果您正在使用gcc(看起来像您一样),则可以从 libstdc ++手册,其中有用于检查c ++基本语言功能的autoconf示例:
If you're using gcc (looks like you are) then from the libstdc++ manual they have autoconf examples for checking c++ base language features:
# AC_COMPILE_STDCXX_OX
AC_DEFUN([AC_COMPILE_STDCXX_0X], [
AC_CACHE_CHECK(if g++ supports C++0x features without additional flags,
ac_cv_cxx_compile_cxx0x_native,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_TRY_COMPILE([
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), "not big enough");
};
typedef check<check<bool>> right_angle_brackets;
int a;
decltype(a) b;
typedef check<int> check_type;
check_type c;
check_type&& cr = c;],,
ac_cv_cxx_compile_cxx0x_native=yes, ac_cv_cxx_compile_cxx0x_native=no)
AC_LANG_RESTORE
])
AC_CACHE_CHECK(if g++ supports C++0x features with -std=c++0x,
ac_cv_cxx_compile_cxx0x_cxx,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
ac_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -std=c++0x"
AC_TRY_COMPILE([
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), "not big enough");
};
typedef check<check<bool>> right_angle_brackets;
int a;
decltype(a) b;
typedef check<int> check_type;
check_type c;
check_type&& cr = c;],,
ac_cv_cxx_compile_cxx0x_cxx=yes, ac_cv_cxx_compile_cxx0x_cxx=no)
CXXFLAGS="$ac_save_CXXFLAGS"
AC_LANG_RESTORE
])
AC_CACHE_CHECK(if g++ supports C++0x features with -std=gnu++0x,
ac_cv_cxx_compile_cxx0x_gxx,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
ac_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -std=gnu++0x"
AC_TRY_COMPILE([
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), "not big enough");
};
typedef check<check<bool>> right_angle_brackets;
int a;
decltype(a) b;
typedef check<int> check_type;
check_type c;
check_type&& cr = c;],,
ac_cv_cxx_compile_cxx0x_gxx=yes, ac_cv_cxx_compile_cxx0x_gxx=no)
CXXFLAGS="$ac_save_CXXFLAGS"
AC_LANG_RESTORE
])
if test "$ac_cv_cxx_compile_cxx0x_native" = yes ||
test "$ac_cv_cxx_compile_cxx0x_cxx" = yes ||
test "$ac_cv_cxx_compile_cxx0x_gxx" = yes; then
AC_DEFINE(HAVE_STDCXX_0X,,[Define if g++ supports C++0x features. ])
fi
])
如果愿意,您可以尝试在其中放一个lambda.然后,在手握HAVE_STDCXX_0X的情况下,可以适当地设置--std = c ++ 0x.
You could probably try to put a lambda in there if you wanted. Then with HAVE_STDCXX_0X in hand you could set --std=c++0x appropriately.
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