Chris@526: 
Chris@526: # From autoconf archive:
Chris@526: 
Chris@526: # ============================================================================
Chris@526: #  http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
Chris@526: # ============================================================================
Chris@526: #
Chris@526: # SYNOPSIS
Chris@526: #
Chris@526: #   AX_CXX_COMPILE_STDCXX_11([ext|noext],[mandatory|optional])
Chris@526: #
Chris@526: # DESCRIPTION
Chris@526: #
Chris@526: #   Check for baseline language coverage in the compiler for the C++11
Chris@526: #   standard; if necessary, add switches to CXXFLAGS to enable support.
Chris@526: #
Chris@526: #   The first argument, if specified, indicates whether you insist on an
Chris@526: #   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
Chris@526: #   -std=c++11).  If neither is specified, you get whatever works, with
Chris@526: #   preference for an extended mode.
Chris@526: #
Chris@526: #   The second argument, if specified 'mandatory' or if left unspecified,
Chris@526: #   indicates that baseline C++11 support is required and that the macro
Chris@526: #   should error out if no mode with that support is found.  If specified
Chris@526: #   'optional', then configuration proceeds regardless, after defining
Chris@526: #   HAVE_CXX11 if and only if a supporting mode is found.
Chris@526: #
Chris@526: # LICENSE
Chris@526: #
Chris@526: #   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
Chris@526: #   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
Chris@526: #   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
Chris@526: #   Copyright (c) 2014 Alexey Sokolov <sokolov@google.com>
Chris@526: #
Chris@526: #   Copying and distribution of this file, with or without modification, are
Chris@526: #   permitted in any medium without royalty provided the copyright notice
Chris@526: #   and this notice are preserved. This file is offered as-is, without any
Chris@526: #   warranty.
Chris@526: 
Chris@526: m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
Chris@526:   template <typename T>
Chris@526:     struct check
Chris@526:     {
Chris@526:       static_assert(sizeof(int) <= sizeof(T), "not big enough");
Chris@526:     };
Chris@526: 
Chris@526:     struct Base {
Chris@526:     virtual void f() {}
Chris@526:     };
Chris@526:     struct Child : public Base {
Chris@526:     virtual void f() override {}
Chris@526:     };
Chris@526: 
Chris@526:     typedef check<check<bool>> right_angle_brackets;
Chris@526: 
Chris@526:     int a;
Chris@526:     decltype(a) b;
Chris@526: 
Chris@526:     typedef check<int> check_type;
Chris@526:     check_type c;
Chris@526:     check_type&& cr = static_cast<check_type&&>(c);
Chris@526: 
Chris@526:     auto d = a;
Chris@526:     auto l = [](){};
Chris@526: ]])
Chris@526: 
Chris@526: AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
Chris@526:   m4_if([$1], [], [],
Chris@526:         [$1], [ext], [],
Chris@526:         [$1], [noext], [],
Chris@526:         [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl
Chris@526:   m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
Chris@526:         [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
Chris@526:         [$2], [optional], [ax_cxx_compile_cxx11_required=false],
Chris@526:         [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])
Chris@526:   AC_LANG_PUSH([C++])dnl
Chris@526:   ac_success=no
Chris@526:   AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
Chris@526:   ax_cv_cxx_compile_cxx11,
Chris@526:   [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
Chris@526:     [ax_cv_cxx_compile_cxx11=yes],
Chris@526:     [ax_cv_cxx_compile_cxx11=no])])
Chris@526:   if test x$ax_cv_cxx_compile_cxx11 = xyes; then
Chris@526:     ac_success=yes
Chris@526:   fi
Chris@526: 
Chris@526:   m4_if([$1], [noext], [], [dnl
Chris@526:   if test x$ac_success = xno; then
Chris@526:     for switch in -std=gnu++11 -std=gnu++0x; do
Chris@526:       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
Chris@526:       AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
Chris@526:                      $cachevar,
Chris@526:         [ac_save_CXXFLAGS="$CXXFLAGS"
Chris@526:          CXXFLAGS="$CXXFLAGS $switch"
Chris@526:          AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
Chris@526:           [eval $cachevar=yes],
Chris@526:           [eval $cachevar=no])
Chris@526:          CXXFLAGS="$ac_save_CXXFLAGS"])
Chris@526:       if eval test x\$$cachevar = xyes; then
Chris@526:         CXXFLAGS="$CXXFLAGS $switch"
Chris@526:         ac_success=yes
Chris@526:         break
Chris@526:       fi
Chris@526:     done
Chris@526:   fi])
Chris@526: 
Chris@526:   m4_if([$1], [ext], [], [dnl
Chris@526:   if test x$ac_success = xno; then
Chris@526:     for switch in -std=c++11 -std=c++0x; do
Chris@526:       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
Chris@526:       AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
Chris@526:                      $cachevar,
Chris@526:         [ac_save_CXXFLAGS="$CXXFLAGS"
Chris@526:          CXXFLAGS="$CXXFLAGS $switch"
Chris@526:          AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
Chris@526:           [eval $cachevar=yes],
Chris@526:           [eval $cachevar=no])
Chris@526:          CXXFLAGS="$ac_save_CXXFLAGS"])
Chris@526:       if eval test x\$$cachevar = xyes; then
Chris@526:         CXXFLAGS="$CXXFLAGS $switch"
Chris@526:         ac_success=yes
Chris@526:         break
Chris@526:       fi
Chris@526:     done
Chris@526:   fi])
Chris@526:   AC_LANG_POP([C++])
Chris@526:   if test x$ax_cxx_compile_cxx11_required = xtrue; then
Chris@526:     if test x$ac_success = xno; then
Chris@526:       AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
Chris@526:     fi
Chris@526:   else
Chris@526:     if test x$ac_success = xno; then
Chris@526:       HAVE_CXX11=0
Chris@526:       AC_MSG_NOTICE([No compiler with C++11 support was found])
Chris@526:     else
Chris@526:       HAVE_CXX11=1
Chris@526:       AC_DEFINE(HAVE_CXX11,1,
Chris@526:                 [define if the compiler supports basic C++11 syntax])
Chris@526:     fi
Chris@526: 
Chris@526:     AC_SUBST(HAVE_CXX11)
Chris@526:   fi
Chris@526: ])