ceph/src/jaegertracing/thrift/contrib/fb303/aclocal/ax_cxx_compile_stdcxx_11.m4

   1 # ============================================================================
   2 #  http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
   3 # ============================================================================
   4 #
   5 # SYNOPSIS
   6 #
   7 #   AX_CXX_COMPILE_STDCXX_11([ext|noext],[mandatory|optional])
   8 #
   9 # DESCRIPTION
  10 #
  11 #   Check for baseline language coverage in the compiler for the C++11
  12 #   standard; if necessary, add switches to CXXFLAGS to enable support.
  13 #
  14 #   The first argument, if specified, indicates whether you insist on an
  15 #   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
  16 #   -std=c++11).  If neither is specified, you get whatever works, with
  17 #   preference for an extended mode.
  18 #
  19 #   The second argument, if specified 'mandatory' or if left unspecified,
  20 #   indicates that baseline C++11 support is required and that the macro
  21 #   should error out if no mode with that support is found.  If specified
  22 #   'optional', then configuration proceeds regardless, after defining
  23 #   HAVE_CXX11 if and only if a supporting mode is found.
  24 #
  25 # LICENSE
  26 #
  27 #   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
  28 #   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
  29 #   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
  30 #
  31 #   Copying and distribution of this file, with or without modification, are
  32 #   permitted in any medium without royalty provided the copyright notice
  33 #   and this notice are preserved. This file is offered as-is, without any
  34 #   warranty.
  35
  36 #serial 3
  37
  38 m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [
  39   template <typename T>
  40     struct check
  41     {
  42       static_assert(sizeof(int) <= sizeof(T), "not big enough");
  43     };
  44
  45     typedef check<check<bool>> right_angle_brackets;
  46
  47     int a;
  48     decltype(a) b;
  49
  50     typedef check<int> check_type;
  51     check_type c;
  52     check_type&& cr = static_cast<check_type&&>(c);
  53
  54     auto d = a;
  55 ])
  56
  57 AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
  58   m4_if([$1], [], [],
  59         [$1], [ext], [],
  60         [$1], [noext], [],
  61         [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl
  62   m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
  63         [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
  64         [$2], [optional], [ax_cxx_compile_cxx11_required=false],
  65         [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])dnl
  66   AC_LANG_PUSH([C++])dnl
  67   ac_success=no
  68   AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
  69   ax_cv_cxx_compile_cxx11,
  70   [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
  71     [ax_cv_cxx_compile_cxx11=yes],
  72     [ax_cv_cxx_compile_cxx11=no])])
  73   if test x$ax_cv_cxx_compile_cxx11 = xyes; then
  74     ac_success=yes
  75   fi
  76
  77   m4_if([$1], [noext], [], [dnl
  78   if test x$ac_success = xno; then
  79     for switch in -std=gnu++11; do
  80       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
  81       AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
  82                      $cachevar,
  83         [ac_save_CXXFLAGS="$CXXFLAGS"
  84          CXXFLAGS="$CXXFLAGS $switch"
  85          AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
  86           [eval $cachevar=yes],
  87           [eval $cachevar=no])
  88          CXXFLAGS="$ac_save_CXXFLAGS"])
  89       if eval test x\$$cachevar = xyes; then
  90         CXXFLAGS="$CXXFLAGS $switch"
  91         ac_success=yes
  92         break
  93       fi
  94     done
  95   fi])
  96
  97   m4_if([$1], [ext], [], [dnl
  98   if test x$ac_success = xno; then
  99     for switch in -std=c++11; do
 100       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
 101       AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
 102                      $cachevar,
 103         [ac_save_CXXFLAGS="$CXXFLAGS"
 104          CXXFLAGS="$CXXFLAGS $switch"
 105          AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
 106           [eval $cachevar=yes],
 107           [eval $cachevar=no])
 108          CXXFLAGS="$ac_save_CXXFLAGS"])
 109       if eval test x\$$cachevar = xyes; then
 110         CXXFLAGS="$CXXFLAGS $switch"
 111         ac_success=yes
 112         break
 113       fi
 114     done
 115   fi])
 116   AC_LANG_POP([C++])
 117   if test x$ax_cxx_compile_cxx11_required = xtrue; then
 118     if test x$ac_success = xno; then
 119       AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
 120     fi
 121   else
 122     if test x$ac_success = xno; then
 123       HAVE_CXX11=0
 124       AC_MSG_NOTICE([No compiler with C++11 support was found])
 125     else
 126       HAVE_CXX11=1
 127       AC_DEFINE(HAVE_CXX11,1,
 128                 [define if the compiler supports basic C++11 syntax])
 129     fi
 130
 131     AC_SUBST(HAVE_CXX11)
 132   fi
 133 ])
 134