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binutils-gdb/gdb/ax_cxx_compile_stdcxx.m4
Andrew Burgess 1d506c26d9 Update copyright year range in header of all files managed by GDB 
This commit is the result of the following actions:

  - Running gdb/copyright.py to update all of the copyright headers to
    include 2024,

  - Manually updating a few files the copyright.py script told me to
    update, these files had copyright headers embedded within the
    file,

  - Regenerating gdbsupport/Makefile.in to refresh it's copyright
    date,

  - Using grep to find other files that still mentioned 2023.  If
    these files were updated last year from 2022 to 2023 then I've
    updated them this year to 2024.

I'm sure I've probably missed some dates.  Feel free to fix them up as
you spot them.
2024-01-12 15:49:57 +00:00

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# Copyright (c) 2016-2024 Free Software Foundation, Inc.
#
# Originally based on the AX_CXX_COMPILE_STDCXX macro found at the url
# below.
#
# Local GDB customizations:
#
# - AC_SUBST CXX_DIALECT instead of changing CXX/CXXCPP.
#
# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
#
# DESCRIPTION
#
# Check for baseline language coverage in the compiler for the specified
# version of the C++ standard. If necessary, add switches to CXX and
# CXXCPP to enable support. VERSION may be '11', '14', '17', or '20' for
# the respective C++ standard version.
#
# The second argument, if specified, indicates whether you insist on an
# extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
# -std=c++11). If neither is specified, you get whatever works, with
# preference for no added switch, and then for an extended mode.
#
# The third argument, if specified 'mandatory' or if left unspecified,
# indicates that baseline support for the specified C++ standard 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_CXX${VERSION} if and only if a
# supporting mode is found.
#
# LICENSE
#
# Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
# Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
# Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
# Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
# Copyright (c) 2015 Paul Norman <penorman@mac.com>
# Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
# Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
# Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
# Copyright (c) 2020 Jason Merrill <jason@redhat.com>
# Copyright (c) 2021 Jörn Heusipp <osmanx@problemloesungsmaschine.de>
#
# 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 18
dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
dnl (serial version number 13).
AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
[$1], [14], [ax_cxx_compile_alternatives="14 1y"],
[$1], [17], [ax_cxx_compile_alternatives="17 1z"],
[$1], [20], [ax_cxx_compile_alternatives="20"],
[m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
m4_if([$2], [], [],
[$2], [ext], [],
[$2], [noext], [],
[m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
[$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
[$3], [optional], [ax_cxx_compile_cxx$1_required=false],
[m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
AC_LANG_PUSH([C++])dnl
CXX_DIALECT=""
ac_success=no
m4_if([$2], [], [dnl
AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
ax_cv_cxx_compile_cxx$1,
[AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
[ax_cv_cxx_compile_cxx$1=yes],
[ax_cv_cxx_compile_cxx$1=no])])
if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
ac_success=yes
fi])
m4_if([$2], [noext], [], [dnl
if test x$ac_success = xno; then
for alternative in ${ax_cxx_compile_alternatives}; do
switch="-std=gnu++${alternative}"
cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
$cachevar,
[ac_save_CXX="$CXX"
CXX="$CXX $switch"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
[eval $cachevar=yes],
[eval $cachevar=no])
CXX="$ac_save_CXX"])
if eval test x\$$cachevar = xyes; then
CXX_DIALECT="$switch"
CXX="$CXX $switch"
if test -n "$CXXCPP" ; then
CXXCPP="$CXXCPP $switch"
fi
ac_success=yes
break
fi
done
fi])
m4_if([$2], [ext], [], [dnl
if test x$ac_success = xno; then
dnl HP's aCC needs +std=c++11 according to:
dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
dnl Cray's crayCC needs "-h std=c++11"
dnl MSVC needs -std:c++NN for C++17 and later (default is C++14)
for alternative in ${ax_cxx_compile_alternatives}; do
for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
if test x"$switch" = xMSVC; then
dnl AS_TR_SH maps both `:` and `=` to `_` so -std:c++17 would collide
dnl with -std=c++17. We suffix the cache variable name with _MSVC to
dnl avoid this.
switch=-std:c++${alternative}
cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_${switch}_MSVC])
else
cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
fi
AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
$cachevar,
[ac_save_CXX="$CXX"
CXX="$CXX $switch"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
[eval $cachevar=yes],
[eval $cachevar=no])
CXX="$ac_save_CXX"])
if eval test x\$$cachevar = xyes; then
CXX_DIALECT="$switch"
CXX="$CXX $switch"
if test -n "$CXXCPP" ; then
CXXCPP="$CXXCPP $switch"
fi
ac_success=yes
break
fi
done
if test x$ac_success = xyes; then
break
fi
done
fi])
AC_LANG_POP([C++])
if test x$ax_cxx_compile_cxx$1_required = xtrue; then
if test x$ac_success = xno; then
AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
fi
fi
if test x$ac_success = xno; then
HAVE_CXX$1=0
AC_MSG_NOTICE([No compiler with C++$1 support was found])
else
HAVE_CXX$1=1
AC_DEFINE(HAVE_CXX$1,1,
[define if the compiler supports basic C++$1 syntax])
fi
AC_SUBST(HAVE_CXX$1)
AC_SUBST(CXX_DIALECT)
])
dnl Test body for checking C++11 support
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
)
dnl Test body for checking C++14 support
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
)
dnl Test body for checking C++17 support
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
_AX_CXX_COMPILE_STDCXX_testbody_new_in_17
)
dnl Test body for checking C++20 support
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20],
_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
_AX_CXX_COMPILE_STDCXX_testbody_new_in_17
_AX_CXX_COMPILE_STDCXX_testbody_new_in_20
)
dnl Tests for new features in C++11
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
// If the compiler admits that it is not ready for C++11, why torture it?
// Hopefully, this will speed up the test.
#ifndef __cplusplus
#error "This is not a C++ compiler"
// MSVC always sets __cplusplus to 199711L in older versions; newer versions
// only set it correctly if /Zc:__cplusplus is specified as well as a
// /std:c++NN switch:
// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
#elif __cplusplus < 201103L && !defined _MSC_VER
#error "This is not a C++11 compiler"
#else
namespace cxx11
{
namespace test_static_assert
{
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), "not big enough");
};
}
namespace test_final_override
{
struct Base
{
virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
virtual ~Derived() override {}
virtual void f() override {}
};
}
namespace test_double_right_angle_brackets
{
template < typename T >
struct check {};
typedef check<void> single_type;
typedef check<check<void>> double_type;
typedef check<check<check<void>>> triple_type;
typedef check<check<check<check<void>>>> quadruple_type;
}
namespace test_decltype
{
int
f()
{
int a = 1;
decltype(a) b = 2;
return a + b;
}
}
namespace test_type_deduction
{
template < typename T1, typename T2 >
struct is_same
{
static const bool value = false;
};
template < typename T >
struct is_same<T, T>
{
static const bool value = true;
};
template < typename T1, typename T2 >
auto
add(T1 a1, T2 a2) -> decltype(a1 + a2)
{
return a1 + a2;
}
int
test(const int c, volatile int v)
{
static_assert(is_same<int, decltype(0)>::value == true, "");
static_assert(is_same<int, decltype(c)>::value == false, "");
static_assert(is_same<int, decltype(v)>::value == false, "");
auto ac = c;
auto av = v;
auto sumi = ac + av + 'x';
auto sumf = ac + av + 1.0;
static_assert(is_same<int, decltype(ac)>::value == true, "");
static_assert(is_same<int, decltype(av)>::value == true, "");
static_assert(is_same<int, decltype(sumi)>::value == true, "");
static_assert(is_same<int, decltype(sumf)>::value == false, "");
static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
return (sumf > 0.0) ? sumi : add(c, v);
}
}
namespace test_noexcept
{
int f() { return 0; }
int g() noexcept { return 0; }
static_assert(noexcept(f()) == false, "");
static_assert(noexcept(g()) == true, "");
}
namespace test_constexpr
{
template < typename CharT >
unsigned long constexpr
strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
{
return *s ? strlen_c_r(s + 1, acc + 1) : acc;
}
template < typename CharT >
unsigned long constexpr
strlen_c(const CharT *const s) noexcept
{
return strlen_c_r(s, 0UL);
}
static_assert(strlen_c("") == 0UL, "");
static_assert(strlen_c("1") == 1UL, "");
static_assert(strlen_c("example") == 7UL, "");
static_assert(strlen_c("another\0example") == 7UL, "");
}
namespace test_rvalue_references
{
template < int N >
struct answer
{
static constexpr int value = N;
};
answer<1> f(int&) { return answer<1>(); }
answer<2> f(const int&) { return answer<2>(); }
answer<3> f(int&&) { return answer<3>(); }
void
test()
{
int i = 0;
const int c = 0;
static_assert(decltype(f(i))::value == 1, "");
static_assert(decltype(f(c))::value == 2, "");
static_assert(decltype(f(0))::value == 3, "");
}
}
namespace test_uniform_initialization
{
struct test
{
static const int zero {};
static const int one {1};
};
static_assert(test::zero == 0, "");
static_assert(test::one == 1, "");
}
namespace test_lambdas
{
void
test1()
{
auto lambda1 = [](){};
auto lambda2 = lambda1;
lambda1();
lambda2();
}
int
test2()
{
auto a = [](int i, int j){ return i + j; }(1, 2);
auto b = []() -> int { return '0'; }();
auto c = [=](){ return a + b; }();
auto d = [&](){ return c; }();
auto e = [a, &b](int x) mutable {
const auto identity = [](int y){ return y; };
for (auto i = 0; i < a; ++i)
a += b--;
return x + identity(a + b);
}(0);
return a + b + c + d + e;
}
int
test3()
{
const auto nullary = [](){ return 0; };
const auto unary = [](int x){ return x; };
using nullary_t = decltype(nullary);
using unary_t = decltype(unary);
const auto higher1st = [](nullary_t f){ return f(); };
const auto higher2nd = [unary](nullary_t f1){
return [unary, f1](unary_t f2){ return f2(unary(f1())); };
};
return higher1st(nullary) + higher2nd(nullary)(unary);
}
}
namespace test_variadic_templates
{
template <int...>
struct sum;
template <int N0, int... N1toN>
struct sum<N0, N1toN...>
{
static constexpr auto value = N0 + sum<N1toN...>::value;
};
template <>
struct sum<>
{
static constexpr auto value = 0;
};
static_assert(sum<>::value == 0, "");
static_assert(sum<1>::value == 1, "");
static_assert(sum<23>::value == 23, "");
static_assert(sum<1, 2>::value == 3, "");
static_assert(sum<5, 5, 11>::value == 21, "");
static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
}
// 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();
void test() { func<foo>(0); }
}
} // namespace cxx11
#endif // __cplusplus >= 201103L
]])
dnl Tests for new features in C++14
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
// If the compiler admits that it is not ready for C++14, why torture it?
// Hopefully, this will speed up the test.
#ifndef __cplusplus
#error "This is not a C++ compiler"
#elif __cplusplus < 201402L && !defined _MSC_VER
#error "This is not a C++14 compiler"
#else
namespace cxx14
{
namespace test_polymorphic_lambdas
{
int
test()
{
const auto lambda = [](auto&&... args){
const auto istiny = [](auto x){
return (sizeof(x) == 1UL) ? 1 : 0;
};
const int aretiny[] = { istiny(args)... };
return aretiny[0];
};
return lambda(1, 1L, 1.0f, '1');
}
}
namespace test_binary_literals
{
constexpr auto ivii = 0b0000000000101010;
static_assert(ivii == 42, "wrong value");
}
namespace test_generalized_constexpr
{
template < typename CharT >
constexpr unsigned long
strlen_c(const CharT *const s) noexcept
{
auto length = 0UL;
for (auto p = s; *p; ++p)
++length;
return length;
}
static_assert(strlen_c("") == 0UL, "");
static_assert(strlen_c("x") == 1UL, "");
static_assert(strlen_c("test") == 4UL, "");
static_assert(strlen_c("another\0test") == 7UL, "");
}
namespace test_lambda_init_capture
{
int
test()
{
auto x = 0;
const auto lambda1 = [a = x](int b){ return a + b; };
const auto lambda2 = [a = lambda1(x)](){ return a; };
return lambda2();
}
}
namespace test_digit_separators
{
constexpr auto ten_million = 100'000'000;
static_assert(ten_million == 100000000, "");
}
namespace test_return_type_deduction
{
auto f(int& x) { return x; }
decltype(auto) g(int& x) { return x; }
template < typename T1, typename T2 >
struct is_same
{
static constexpr auto value = false;
};
template < typename T >
struct is_same<T, T>
{
static constexpr auto value = true;
};
int
test()
{
auto x = 0;
static_assert(is_same<int, decltype(f(x))>::value, "");
static_assert(is_same<int&, decltype(g(x))>::value, "");
return x;
}
}
} // namespace cxx14
#endif // __cplusplus >= 201402L
]])
dnl Tests for new features in C++17
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
// If the compiler admits that it is not ready for C++17, why torture it?
// Hopefully, this will speed up the test.
#ifndef __cplusplus
#error "This is not a C++ compiler"
#elif __cplusplus < 201703L && !defined _MSC_VER
#error "This is not a C++17 compiler"
#else
#include <initializer_list>
#include <utility>
#include <type_traits>
namespace cxx17
{
namespace test_constexpr_lambdas
{
constexpr int foo = [](){return 42;}();
}
namespace test::nested_namespace::definitions
{
}
namespace test_fold_expression
{
template<typename... Args>
int multiply(Args... args)
{
return (args * ... * 1);
}
template<typename... Args>
bool all(Args... args)
{
return (args && ...);
}
}
namespace test_extended_static_assert
{
static_assert (true);
}
namespace test_auto_brace_init_list
{
auto foo = {5};
auto bar {5};
static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
static_assert(std::is_same<int, decltype(bar)>::value);
}
namespace test_typename_in_template_template_parameter
{
template<template<typename> typename X> struct D;
}
namespace test_fallthrough_nodiscard_maybe_unused_attributes
{
int f1()
{
return 42;
}
[[nodiscard]] int f2()
{
[[maybe_unused]] auto unused = f1();
switch (f1())
{
case 17:
f1();
[[fallthrough]];
case 42:
f1();
}
return f1();
}
}
namespace test_extended_aggregate_initialization
{
struct base1
{
int b1, b2 = 42;
};
struct base2
{
base2() {
b3 = 42;
}
int b3;
};
struct derived : base1, base2
{
int d;
};
derived d1 {{1, 2}, {}, 4}; // full initialization
derived d2 {{}, {}, 4}; // value-initialized bases
}
namespace test_general_range_based_for_loop
{
struct iter
{
int i;
int& operator* ()
{
return i;
}
const int& operator* () const
{
return i;
}
iter& operator++()
{
++i;
return *this;
}
};
struct sentinel
{
int i;
};
bool operator== (const iter& i, const sentinel& s)
{
return i.i == s.i;
}
bool operator!= (const iter& i, const sentinel& s)
{
return !(i == s);
}
struct range
{
iter begin() const
{
return {0};
}
sentinel end() const
{
return {5};
}
};
void f()
{
range r {};
for (auto i : r)
{
[[maybe_unused]] auto v = i;
}
}
}
namespace test_lambda_capture_asterisk_this_by_value
{
struct t
{
int i;
int foo()
{
return [*this]()
{
return i;
}();
}
};
}
namespace test_enum_class_construction
{
enum class byte : unsigned char
{};
byte foo {42};
}
namespace test_constexpr_if
{
template <bool cond>
int f ()
{
if constexpr(cond)
{
return 13;
}
else
{
return 42;
}
}
}
namespace test_selection_statement_with_initializer
{
int f()
{
return 13;
}
int f2()
{
if (auto i = f(); i > 0)
{
return 3;
}
switch (auto i = f(); i + 4)
{
case 17:
return 2;
default:
return 1;
}
}
}
namespace test_template_argument_deduction_for_class_templates
{
template <typename T1, typename T2>
struct pair
{
pair (T1 p1, T2 p2)
: m1 {p1},
m2 {p2}
{}
T1 m1;
T2 m2;
};
void f()
{
[[maybe_unused]] auto p = pair{13, 42u};
}
}
namespace test_non_type_auto_template_parameters
{
template <auto n>
struct B
{};
B<5> b1;
B<'a'> b2;
}
namespace test_structured_bindings
{
int arr[2] = { 1, 2 };
std::pair<int, int> pr = { 1, 2 };
auto f1() -> int(&)[2]
{
return arr;
}
auto f2() -> std::pair<int, int>&
{
return pr;
}
struct S
{
int x1 : 2;
volatile double y1;
};
S f3()
{
return {};
}
auto [ x1, y1 ] = f1();
auto& [ xr1, yr1 ] = f1();
auto [ x2, y2 ] = f2();
auto& [ xr2, yr2 ] = f2();
const auto [ x3, y3 ] = f3();
}
namespace test_exception_spec_type_system
{
struct Good {};
struct Bad {};
void g1() noexcept;
void g2();
template<typename T>
Bad
f(T*, T*);
template<typename T1, typename T2>
Good
f(T1*, T2*);
static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
}
namespace test_inline_variables
{
template<class T> void f(T)
{}
template<class T> inline T g(T)
{
return T{};
}
template<> inline void f<>(int)
{}
template<> int g<>(int)
{
return 5;
}
}
} // namespace cxx17
#endif // __cplusplus < 201703L && !defined _MSC_VER
]])
dnl Tests for new features in C++20
m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_20], [[
#ifndef __cplusplus
#error "This is not a C++ compiler"
#elif __cplusplus < 202002L && !defined _MSC_VER
#error "This is not a C++20 compiler"
#else
#include <version>
namespace cxx20
{
// As C++20 supports feature test macros in the standard, there is no
// immediate need to actually test for feature availability on the
// Autoconf side.
} // namespace cxx20
#endif // __cplusplus < 202002L && !defined _MSC_VER
]])
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