# ============================================================================ # www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html # ============================================================================ # # SYNOPSIS # # AX_CXX_COMPILE_STDCXX_11(,[mandatory|optional]) # # DESCRIPTION # # Check for baseline language coverage in the compiler for the C++11 # standard; if necessary, add switches to CXXFLAGS to enable support. # # The first argument, if specified, indicates whether you insist on an # extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g. # -std=c++11). If neither is specified, you get whatever works, with # preference for an extended mode. # # The second argument, if specified 'mandatory' or if left unspecified, # indicates that baseline C++11 support is required and that the macro # should error out if no mode with that support is found. If specified # 'optional', then configuration proceeds regardless, after defining # HAVE_CXX11 if and only if a supporting mode is found. # # LICENSE # # Copyright © 2008 Benjamin Kosnik <bkoz@redhat.com> # Copyright © 2012 Zack Weinberg <zackw@panix.com> # Copyright © 2013 Roy Stogner <roystgnr@ices.utexas.edu> # Copyright © 2014 Alexey Sokolov <sokolov@google.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 4

m4_define(, [[

template <typename T>
  struct check
  {
    static_assert(sizeof(int) <= sizeof(T), "not big enough");
  };

  struct Base {
  virtual void f() {}
  };
  struct Child : public Base {
  virtual void f() override {}
  };

  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);

  auto d = a;
  auto l = [](){};

]])

AC_DEFUN(, [dnl

m4_if([$1], [], [],
      [$1], [ext], [],
      [$1], [noext], [],
      [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl
m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
      [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
      [$2], [optional], [ax_cxx_compile_cxx11_required=false],
      [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])
AC_LANG_PUSH([C++])dnl
ac_success=no
AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
ax_cv_cxx_compile_cxx11,
[AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
  [ax_cv_cxx_compile_cxx11=yes],
  [ax_cv_cxx_compile_cxx11=no])])
if test x$ax_cv_cxx_compile_cxx11 = xyes; then
  ac_success=yes
fi

m4_if([$1], [noext], [], [dnl
if test x$ac_success = xno; then
  for switch in -std=gnu++11 -std=gnu++0x; do
    cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
    AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
                   $cachevar,
      [ac_save_CXXFLAGS="$CXXFLAGS"
       CXXFLAGS="$CXXFLAGS $switch"
       AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
        [eval $cachevar=yes],
        [eval $cachevar=no])
       CXXFLAGS="$ac_save_CXXFLAGS"])
    if eval test x\$$cachevar = xyes; then
      CXXFLAGS="$CXXFLAGS $switch"
      ac_success=yes
      break
    fi
  done
fi])

m4_if([$1], [ext], [], [dnl
if test x$ac_success = xno; then
  for switch in -std=c++11 -std=c++0x; do
    cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
    AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
                   $cachevar,
      [ac_save_CXXFLAGS="$CXXFLAGS"
       CXXFLAGS="$CXXFLAGS $switch"
       AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
        [eval $cachevar=yes],
        [eval $cachevar=no])
       CXXFLAGS="$ac_save_CXXFLAGS"])
    if eval test x\$$cachevar = xyes; then
      CXXFLAGS="$CXXFLAGS $switch"
      ac_success=yes
      break
    fi
  done
fi])
AC_LANG_POP([C++])
if test x$ax_cxx_compile_cxx11_required = xtrue; then
  if test x$ac_success = xno; then
    AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
  fi
else
  if test x$ac_success = xno; then
    HAVE_CXX11=0
    AC_MSG_NOTICE([No compiler with C++11 support was found])
  else
    HAVE_CXX11=1
    AC_DEFINE(HAVE_CXX11,1,
              [define if the compiler supports basic C++11 syntax])
  fi

  AC_SUBST(HAVE_CXX11)
fi

])