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2 # From autoconf archive:
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3
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4 # ============================================================================
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5 # http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
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6 # ============================================================================
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7 #
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8 # SYNOPSIS
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9 #
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10 # AX_CXX_COMPILE_STDCXX_11([ext|noext],[mandatory|optional])
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11 #
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12 # DESCRIPTION
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13 #
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14 # Check for baseline language coverage in the compiler for the C++11
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15 # standard; if necessary, add switches to CXXFLAGS to enable support.
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16 #
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17 # The first argument, if specified, indicates whether you insist on an
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18 # extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
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19 # -std=c++11). If neither is specified, you get whatever works, with
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20 # preference for an extended mode.
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21 #
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22 # The second argument, if specified 'mandatory' or if left unspecified,
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23 # indicates that baseline C++11 support is required and that the macro
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24 # should error out if no mode with that support is found. If specified
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25 # 'optional', then configuration proceeds regardless, after defining
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26 # HAVE_CXX11 if and only if a supporting mode is found.
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27 #
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28 # LICENSE
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29 #
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30 # Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
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31 # Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
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32 # Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
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33 # Copyright (c) 2014 Alexey Sokolov <sokolov@google.com>
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34 #
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35 # Copying and distribution of this file, with or without modification, are
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36 # permitted in any medium without royalty provided the copyright notice
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37 # and this notice are preserved. This file is offered as-is, without any
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38 # warranty.
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39
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40 m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
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41 template <typename T>
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42 struct check
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43 {
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44 static_assert(sizeof(int) <= sizeof(T), "not big enough");
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45 };
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46
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47 struct Base {
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48 virtual void f() {}
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49 };
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50 struct Child : public Base {
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51 virtual void f() override {}
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52 };
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53
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54 typedef check<check<bool>> right_angle_brackets;
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55
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56 int a;
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57 decltype(a) b;
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58
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59 typedef check<int> check_type;
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60 check_type c;
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61 check_type&& cr = static_cast<check_type&&>(c);
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62
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63 auto d = a;
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64 auto l = [](){};
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65 ]])
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66
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67 AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
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68 m4_if([$1], [], [],
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69 [$1], [ext], [],
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70 [$1], [noext], [],
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71 [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl
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72 m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
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73 [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
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74 [$2], [optional], [ax_cxx_compile_cxx11_required=false],
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75 [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])
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76 AC_LANG_PUSH([C++])dnl
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77 ac_success=no
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78 AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
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79 ax_cv_cxx_compile_cxx11,
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80 [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
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81 [ax_cv_cxx_compile_cxx11=yes],
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82 [ax_cv_cxx_compile_cxx11=no])])
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83 if test x$ax_cv_cxx_compile_cxx11 = xyes; then
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84 ac_success=yes
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85 fi
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86
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87 m4_if([$1], [noext], [], [dnl
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88 if test x$ac_success = xno; then
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89 for switch in -std=gnu++11 -std=gnu++0x; do
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90 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
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91 AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
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92 $cachevar,
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93 [ac_save_CXXFLAGS="$CXXFLAGS"
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94 CXXFLAGS="$CXXFLAGS $switch"
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95 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
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96 [eval $cachevar=yes],
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97 [eval $cachevar=no])
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98 CXXFLAGS="$ac_save_CXXFLAGS"])
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99 if eval test x\$$cachevar = xyes; then
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100 CXXFLAGS="$CXXFLAGS $switch"
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101 ac_success=yes
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102 break
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103 fi
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104 done
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105 fi])
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106
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107 m4_if([$1], [ext], [], [dnl
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108 if test x$ac_success = xno; then
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109 for switch in -std=c++11 -std=c++0x; do
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110 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
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111 AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
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112 $cachevar,
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113 [ac_save_CXXFLAGS="$CXXFLAGS"
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114 CXXFLAGS="$CXXFLAGS $switch"
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115 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
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116 [eval $cachevar=yes],
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117 [eval $cachevar=no])
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118 CXXFLAGS="$ac_save_CXXFLAGS"])
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119 if eval test x\$$cachevar = xyes; then
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120 CXXFLAGS="$CXXFLAGS $switch"
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121 ac_success=yes
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122 break
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123 fi
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124 done
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125 fi])
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126 AC_LANG_POP([C++])
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127 if test x$ax_cxx_compile_cxx11_required = xtrue; then
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128 if test x$ac_success = xno; then
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129 AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
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130 fi
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131 else
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132 if test x$ac_success = xno; then
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133 HAVE_CXX11=0
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134 AC_MSG_NOTICE([No compiler with C++11 support was found])
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135 else
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136 HAVE_CXX11=1
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137 AC_DEFINE(HAVE_CXX11,1,
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138 [define if the compiler supports basic C++11 syntax])
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139 fi
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140
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141 AC_SUBST(HAVE_CXX11)
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142 fi
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143 ])
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