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# bison-cxx-std.m4 serial 1
# Copyright (C) 2018-2022 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.
m4_define([_BISON_CXXSTD_98_snippet],
[[]])
m4_define([_BISON_CXXSTD_03_snippet],
[[]])
m4_define([_BISON_CXXSTD_11_snippet],
[[ // C++11
#include <algorithm>
#include <cassert>
#include <memory>
#include <set>
#include <sstream>
#include <string>
#include <utility> // std::swap
#include <vector>
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), "not big enough");
};
using right_angle_brackets = check<check<bool>>;
auto f = std::make_shared<std::string>("shared_ptr");
int a;
decltype(a) b;
typedef check<int> check_type;
check_type c;
check_type&& cr = static_cast<check_type&&>(c);
auto d = a;
// Some versions of libstdc++ do not support std::set::emplace.
void foo()
{
std::set<int> is;
is.emplace(42);
}
// Clang++ 3.5, for a while, was unable to process properly
// the for-loop because its variable, r, is a typedef...
// It failed as follows:
//
// error: unexpected ':' in nested name specifier; did you mean '::'?
// for (auto r: std::set<int>{1, 2})
// ^
// ::
using r = std::set<int>;
void bar()
{
for (int r: std::set<int>{1, 2})
continue;
}
// GCC 4.8.2 on Solaris 11.3 does not support to_string.
auto e = std::to_string(42);
// Needed by glr2.cc.
void cxx11_vector_data ()
{
std::vector<int> ints;
ints.emplace_back (42);
assert (ints.data () == &ints[0]);
}
// Needed by glr2.cc.
void cxx11_array_swap ()
{
int i0[4] = { 1, 2, 3, 4 };
int i1[4] = { 5, 6, 7, 8 };
std::swap (i0, i1);
}
]])
m4_define([_BISON_CXXSTD_14_snippet],
[[ // C++14
void mismatch()
{
using ints = std::vector<int>;
auto v1 = ints{1, 2, 3};
auto v2 = ints{1, 2};
std::mismatch(std::begin(v1), std::end(v1),
std::begin(v2), std::end(v2));
}
]])
m4_define([_BISON_CXXSTD_17_snippet],
[[ // C++17
namespace ns1::ns2::ns3 {}
#include <optional>
auto opt_string = std::optional<std::string>{};
auto out = std::ostringstream{};
]])
m4_define([_BISON_CXXSTD_20_snippet],
[[ // C++20
]])
m4_define([_BISON_CXXSTD_2B_snippet],
[[ // C++2B
]])
m4_define([_BISON_CXXSTD_testbody(98)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
])])
m4_define([_BISON_CXXSTD_testbody(03)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
_BISON_CXXSTD_03_snippet
])])
m4_define([_BISON_CXXSTD_testbody(11)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
_BISON_CXXSTD_03_snippet
_BISON_CXXSTD_11_snippet
])])
m4_define([_BISON_CXXSTD_testbody(14)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
_BISON_CXXSTD_03_snippet
_BISON_CXXSTD_11_snippet
_BISON_CXXSTD_14_snippet
])])
m4_define([_BISON_CXXSTD_testbody(17)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
_BISON_CXXSTD_03_snippet
_BISON_CXXSTD_11_snippet
_BISON_CXXSTD_14_snippet
_BISON_CXXSTD_17_snippet
])])
m4_define([_BISON_CXXSTD_testbody(20)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
_BISON_CXXSTD_03_snippet
_BISON_CXXSTD_11_snippet
_BISON_CXXSTD_14_snippet
_BISON_CXXSTD_17_snippet
_BISON_CXXSTD_20_snippet
])])
m4_define([_BISON_CXXSTD_testbody(2b)],
[AC_LANG_PROGRAM([
_BISON_CXXSTD_98_snippet
_BISON_CXXSTD_03_snippet
_BISON_CXXSTD_11_snippet
_BISON_CXXSTD_14_snippet
_BISON_CXXSTD_17_snippet
_BISON_CXXSTD_20_snippet
_BISON_CXXSTD_2B_snippet
])])
m4_define([_BISON_CXXSTD_testbody],
[m4_ifdef([$0($1)],
[m4_indir([$0($1)], m4_shift2($@))],
[m4_fatal([$0: unknown C++ standard: $1])])])
# BISON_CXXSTD(STD)
# -----------------
# Check whether the C++ compiler supports STD (11, 98, 2b, etc.).
# If it does, AC_SUBST 'CXX<STD>_CXXFLAGS' to the corresponding flags.
AC_DEFUN([BISON_CXXSTD],
[AC_REQUIRE([AC_PROG_CXX])
AC_LANG_PUSH([C++])
for f in '-std=c++$1' '-std=c++$1 -stdlib=libc++'
do
BISON_CHECK_COMPILER_FLAG([$f],
[AC_SUBST(m4_toupper([CXX$1_CXXFLAGS]), [$f]) break],
[], [],
[_BISON_CXXSTD_testbody($1)])
done
AC_LANG_POP([C++])
])
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