# ============================================================================ # http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html # ============================================================================ # # SYNOPSIS # # AX_CXX_COMPILE_STDCXX_11([ext|noext],[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 (c) 2008 Benjamin Kosnik <bkoz@redhat.com> # Copyright (c) 2012 Zack Weinberg <zackw@panix.com> # Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu> # # 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 3 m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [ 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); auto d = a; ]) AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [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])])dnl 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 restore_it="$CXXFLAGS" 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="$CXXFLAGS" c11switch="$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="$CXXFLAGS" c11switch="$switch" ac_success=yes break fi done fi]) CXXFLAGS="$restore_it" AC_SUBST([CXX11_SWITCH], ["$c11switch"]) 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$ac_success = xno; then HAVE_CXX11=0 AC_MSG_NOTICE([No compiler with C++11 support was found]) else HAVE_CXX11=1 AC_DEFINE(HAVE_CXX11,1, [define if the compiler supports basic C++11 syntax]) fi AM_CONDITIONAL([HAVE_CXX11],[test "x$HAVE_CXX11" = "x1"]) AC_SUBST(HAVE_CXX11) fi ])