ax_loc_cxx_compile_stdcxx_0x.m4

# ============================================================================
#
# SYNOPSIS
#
#   AX_LOC_CXX_COMPILE_STDCXX_0X
#
# DESCRIPTION
#
#   Check for baseline language coverage in the compiler for the C++0x
#   standard.
#

# Frank Liu, May 2014,
# Frank Liu, Sept 2014: watch out when the c++0x is not set 
# 
# Modified to define a variable CXX_STDCXX_0X_FLAG, 
# based on AX_CXX_COMPILE_STDCXX_0X written by B. Kosnik
# 
# honor the same license - free as in beer, as far as the copyright notice is displayed

# LICENSE
#
#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
#
#   Copying and distribution of this file, with or without modification, are
#   permitted in any medium without royalty provided the copyright notice
#   and this notice are preserved. This file is offered as-is, without any
#   warranty.

# 
#
#serial 7

AU_ALIAS([AC_LOC_CXX_COMPILE_STDCXX_0X], [AX_LOC_CXX_COMPILE_STDCXX_0X])
AC_DEFUN([AX_LOC_CXX_COMPILE_STDCXX_0X], [
  AC_CACHE_CHECK(if g++ supports C++0x features without additional flags,
  ax_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 = static_cast<check_type&&>(c);],,
  ax_cv_cxx_compile_cxx0x_native=yes, ax_cv_cxx_compile_cxx0x_native=no)
  AC_LANG_RESTORE
  ])

  AC_CACHE_CHECK(if g++ supports C++0x features with -std=c++0x,
  ax_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 = static_cast<check_type&&>(c);],,
  ax_cv_cxx_compile_cxx0x_cxx=yes, ax_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,
  ax_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 = static_cast<check_type&&>(c);],,
  ax_cv_cxx_compile_cxx0x_gxx=yes, ax_cv_cxx_compile_cxx0x_gxx=no)
  CXXFLAGS="$ac_save_CXXFLAGS"
  AC_LANG_RESTORE
  ])

  if test "$ax_cv_cxx_compile_cxx0x_native" = yes ||
     test "$ax_cv_cxx_compile_cxx0x_cxx" = yes ||
     test "$ax_cv_cxx_compile_cxx0x_gxx" = yes; then
    AC_DEFINE(HAVE_STDCXX_0X,,[Define if g++ supports C++0x features. ])
    CXX_STDCXX_0X_FLAG="-std=c++0x"
  else
    CXX_STDCXX_0X_FLAG=""
  fi
  AC_SUBST([CXX_STDCXX_0X_FLAG])
])