blob: af37acdb5ca2c9f76bffdc1a12edfb862282af56 [file] [log] [blame]
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
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 -std=gnu++0x; 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 -std=c++0x; 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])