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Jeff Thompsondc2c4302013-11-22 12:04:16 -08001# ============================================================================
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
38m4_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
57AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
Alexander Afanasyev0541cf42014-01-02 19:10:37 -080058 AC_ARG_WITH([c++11],
59 AS_HELP_STRING(
60 [--with-c++11=@<:@ARG@:>@],
Alexander Afanasyev9e92bfd2014-01-24 12:23:33 -080061 [use C++11 when available @<:@default=no@:>@]
Alexander Afanasyev0541cf42014-01-02 19:10:37 -080062 ),
63 [
Alexander Afanasyev9e92bfd2014-01-24 12:23:33 -080064 if test "$withval" = "yes"; then
65 WANT_CXX11="yes"
Jeff Thompsondc2c4302013-11-22 12:04:16 -080066 fi
Alexander Afanasyev0541cf42014-01-02 19:10:37 -080067 ],
Alexander Afanasyev9e92bfd2014-01-24 12:23:33 -080068 [WANT_CXX11="no"]
Alexander Afanasyev0541cf42014-01-02 19:10:37 -080069 )
70
71 if test "x$WANT_CXX11" = "xyes"; then
72 m4_if([$1], [], [],
73 [$1], [ext], [],
74 [$1], [noext], [],
75 [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl
76 m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
77 [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
78 [$2], [optional], [ax_cxx_compile_cxx11_required=false],
79 [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])dnl
80 AC_LANG_PUSH([C++])dnl
81 ac_success=no
82 AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
83 ax_cv_cxx_compile_cxx11,
84 [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
85 [ax_cv_cxx_compile_cxx11=yes],
86 [ax_cv_cxx_compile_cxx11=no])])
87 if test x$ax_cv_cxx_compile_cxx11 = xyes; then
88 ac_success=yes
89 fi
90
91 m4_if([$1], [noext], [], [dnl
Jeff Thompsondc2c4302013-11-22 12:04:16 -080092 if test x$ac_success = xno; then
Alexander Afanasyev0541cf42014-01-02 19:10:37 -080093 for switch in -std=gnu++11 -std=gnu++0x; do
94 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
95 AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
96 $cachevar,
97 [ac_save_CXXFLAGS="$CXXFLAGS"
98 CXXFLAGS="$CXXFLAGS $switch"
99 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
100 [eval $cachevar=yes],
101 [eval $cachevar=no])
102 CXXFLAGS="$ac_save_CXXFLAGS"])
103 if eval test x\$$cachevar = xyes; then
104 CXXFLAGS="$CXXFLAGS $switch"
105 ac_success=yes
106 break
107 fi
108 done
109 fi])
110
111 m4_if([$1], [ext], [], [dnl
112 if test x$ac_success = xno; then
113 for switch in -std=c++11 -std=c++0x; do
114 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
115 AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
116 $cachevar,
117 [ac_save_CXXFLAGS="$CXXFLAGS"
118 CXXFLAGS="$CXXFLAGS $switch"
119 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
120 [eval $cachevar=yes],
121 [eval $cachevar=no])
122 CXXFLAGS="$ac_save_CXXFLAGS"])
123 if eval test x\$$cachevar = xyes; then
124 CXXFLAGS="$CXXFLAGS $switch"
125 ac_success=yes
126 break
127 fi
128 done
129 fi])
130 AC_LANG_POP([C++])
131 if test x$ax_cxx_compile_cxx11_required = xtrue; then
132 if test x$ac_success = xno; then
133 AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
134 fi
Jeff Thompsondc2c4302013-11-22 12:04:16 -0800135 else
Alexander Afanasyev0541cf42014-01-02 19:10:37 -0800136 if test x$ac_success = xno; then
137 HAVE_CXX11=0
138 AC_MSG_NOTICE([No compiler with C++11 support was found])
139 else
140 HAVE_CXX11=1
141 AC_DEFINE(HAVE_CXX11,1,
142 [define if the compiler supports basic C++11 syntax])
143 fi
144
145 AC_SUBST(HAVE_CXX11)
Jeff Thompsondc2c4302013-11-22 12:04:16 -0800146 fi
Jeff Thompsondc2c4302013-11-22 12:04:16 -0800147 fi
148])