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stdcxx_14.m4
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stdcxx_14.m4
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# ============================================================================
# Based on http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
# ============================================================================
#
# SYNOPSIS
#
# AX_CXX_COMPILE_STDCXX_14([ext|noext],[mandatory|optional])
#
# DESCRIPTION
#
# Check for baseline language coverage in the compiler for the C++14
# 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++14) or a strict conformance mode (e.g.
# -std=c++14). 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++14 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_CXX14 if and only if a supporting mode is found.
#
# LICENSE
#
# Copyright (c) 2008 Benjamin Kosnik <[email protected]>
# Copyright (c) 2012 Zack Weinberg <[email protected]>
# Copyright (c) 2013 Roy Stogner <[email protected]>
# Copyright (c) 2014 Alexey Sokolov <[email protected]>
# Copyright (c) 2014, 2015 Google Inc.
# Copyright (c) 2015, 2019 VLC authors and VideoLAN
#
# 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 7
m4_define([_AX_CXX_COMPILE_STDCXX_14_testbody], [[
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), "not big enough");
};
struct Base {
virtual void f() {}
};
struct Child : public Base {
virtual void f() override {}
};
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;
auto l = [](){};
// http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
// Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function because of this
namespace test_template_alias_sfinae {
struct foo {};
template<typename T>
using member = typename T::member_type;
template<typename T>
void func(...) {}
template<typename T>
void func(member<T>*) {}
void test() {
func<foo>(0);
}
}
#include <cinttypes>
#include <climits>
#include <cstddef>
constexpr uint64_t constant_u64 = UINT64_C(0x100000000);
constexpr unsigned constant_lim = UINT_MAX;
const char *constant_fmt = "%" PRIu64, *constant_scn = "%" SCNu64;
constexpr size_t constant_align = alignof (std::max_align_t);
#include <memory>
namespace lambda_init_capture
{
void foo()
{
std::unique_ptr<int> ptr(new int);
auto lambda = [p = std::move(ptr)](){};
lambda();
}
}
#include <type_traits>
namespace traits_helper_types
{
static_assert( std::is_same<char, std::remove_pointer_t<char*>>::value, "plonk" );
}
]])
AC_DEFUN([AX_CXX_COMPILE_STDCXX_14], [dnl
m4_if([$1], [], [],
[$1], [ext], [],
[$1], [noext], [],
[m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_14])])dnl
m4_if([$2], [], [ax_cxx_compile_cxx14_required=true],
[$2], [mandatory], [ax_cxx_compile_cxx14_required=true],
[$2], [optional], [ax_cxx_compile_cxx14_required=false],
[m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_14])])
AC_LANG_PUSH([C++])dnl
ac_success=no
AC_CACHE_CHECK(whether $CXX supports C++14 features by default,
ax_cv_cxx_compile_cxx14,
[AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_14_testbody])],
[ax_cv_cxx_compile_cxx14=yes],
[ax_cv_cxx_compile_cxx14=no])])
if test x$ax_cv_cxx_compile_cxx14 = xyes; then
ac_success=yes
fi
m4_if([$1], [noext], [], [dnl
if test x$ac_success = xno; then
for switch in -std=gnu++14 -std=gnu++1y; do
cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx14_$switch])
AC_CACHE_CHECK(whether $CXX supports C++14 features with $switch,
$cachevar,
[ac_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS $switch"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_14_testbody])],
[eval $cachevar=yes],
[eval $cachevar=no])
CXXFLAGS="$ac_save_CXXFLAGS"])
if eval test x\$$cachevar = xyes; then
CXXFLAGS="$CXXFLAGS $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++14 -std=c++1y; do
cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx14_$switch])
AC_CACHE_CHECK(whether $CXX supports C++14 features with $switch,
$cachevar,
[ac_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS $switch"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_14_testbody])],
[eval $cachevar=yes],
[eval $cachevar=no])
CXXFLAGS="$ac_save_CXXFLAGS"])
if eval test x\$$cachevar = xyes; then
CXXFLAGS="$CXXFLAGS $switch"
ac_success=yes
break
fi
done
fi])
AC_LANG_POP([C++])
if test x$ax_cxx_compile_cxx14_required = xtrue; then
if test x$ac_success = xno; then
AC_MSG_ERROR([*** A compiler with support for C++14 language features is required.])
fi
else
if test x$ac_success = xno; then
HAVE_CXX14=0
AC_MSG_NOTICE([No compiler with C++14 support was found])
else
HAVE_CXX14=1
AC_DEFINE(HAVE_CXX14,1,
[define if the compiler supports basic C++14 syntax])
fi
AC_SUBST(HAVE_CXX14)
fi
])