@@ -1,5 +1,5 @@
# ===========================================================================
-# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
# ===========================================================================
#
# SYNOPSIS
@@ -29,33 +29,12 @@
# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
#
-# This program is free software: you can redistribute it and/or modify it
-# under the terms of the GNU General Public License as published by the
-# Free Software Foundation, either version 3 of the License, or (at your
-# option) any later version.
-#
-# This program is distributed in the hope that it will be useful, but
-# WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-# Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program. If not, see <http://www.gnu.org/licenses/>.
-#
-# As a special exception, the respective Autoconf Macro's copyright owner
-# gives unlimited permission to copy, distribute and modify the configure
-# scripts that are the output of Autoconf when processing the Macro. You
-# need not follow the terms of the GNU General Public License when using
-# or distributing such scripts, even though portions of the text of the
-# Macro appear in them. The GNU General Public License (GPL) does govern
-# all other use of the material that constitutes the Autoconf Macro.
-#
-# This special exception to the GPL applies to versions of the Autoconf
-# Macro released by the Autoconf Archive. When you make and distribute a
-# modified version of the Autoconf Macro, you may extend this special
-# exception to the GPL to apply to your modified version as well.
+# 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 4
+#serial 6
AC_DEFUN([AX_CHECK_COMPILE_FLAG],
[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
@@ -1,5 +1,5 @@
# ===========================================================================
-# http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
+# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
# ===========================================================================
#
# SYNOPSIS
@@ -9,14 +9,14 @@
# DESCRIPTION
#
# Check for baseline language coverage in the compiler for the specified
-# version of the C++ standard. If necessary, add switches to CXX to
-# enable support. VERSION may be '11' (for the C++11 standard) or '14'
-# (for the C++14 standard).
+# 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 an extended mode.
+# 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
@@ -33,21 +33,26 @@
# 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 3
+#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], [],
- [$1], [14], [],
- [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])],
+ 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], [],
@@ -59,18 +64,21 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
[m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
AC_LANG_PUSH([C++])dnl
ac_success=no
- 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], [], [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 switch in -std=gnu++$1 -std=gnu++0x; do
+ 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,
$cachevar,
@@ -82,6 +90,9 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
CXX="$ac_save_CXX"])
if eval test x\$$cachevar = xyes; then
CXX="$CXX $switch"
+ if test -n "$CXXCPP" ; then
+ CXXCPP="$CXXCPP $switch"
+ fi
ac_success=yes
break
fi
@@ -93,19 +104,36 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
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"
- for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do
- 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="$CXX $switch"
- ac_success=yes
+ 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="$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
@@ -134,7 +162,6 @@ 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],
@@ -142,6 +169,23 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
_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
@@ -154,7 +198,11 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
#error "This is not a C++ compiler"
-#elif __cplusplus < 201103L
+// 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"
@@ -179,11 +227,13 @@ namespace cxx11
struct Base
{
+ virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
+ virtual ~Derived() override {}
virtual void f() override {}
};
@@ -443,7 +493,7 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
#error "This is not a C++ compiler"
-#elif __cplusplus < 201402L
+#elif __cplusplus < 201402L && !defined _MSC_VER
#error "This is not a C++14 compiler"
@@ -512,7 +562,7 @@ namespace cxx14
}
- namespace test_digit_seperators
+ namespace test_digit_separators
{
constexpr auto ten_million = 100'000'000;
@@ -554,3 +604,415 @@ 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
+
+]])