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[libc++] Implement bind_back (#81055)

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Implement `std::bind_back` function from P2387R3 "Pipe support for
user-defined range adaptors".
This commit is contained in:
Jakub Mazurkiewicz 2024-04-09 17:10:20 +02:00 committed by GitHub
parent 3bfd5c6424
commit c8917048e3
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GPG Key ID: B5690EEEBB952194
14 changed files with 582 additions and 64 deletions
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4
libcxx/docs/FeatureTestMacroTable.rst
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@ -308,7 +308,7 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_associative_heterogeneous_erasure`` *unimplemented*
---------------------------------------------------------- -----------------
``__cpp_lib_bind_back`` *unimplemented*
``__cpp_lib_bind_back`` ``202202L``
---------------------------------------------------------- -----------------
``__cpp_lib_byteswap`` ``202110L``
---------------------------------------------------------- -----------------
@ -398,8 +398,6 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_atomic_min_max`` *unimplemented*
---------------------------------------------------------- -----------------
``__cpp_lib_bind_back`` *unimplemented*
---------------------------------------------------------- -----------------
``__cpp_lib_bind_front`` ``202306L``
---------------------------------------------------------- -----------------
``__cpp_lib_bitset`` ``202306L``

1
libcxx/docs/Status/Cxx23.rst
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@ -43,6 +43,7 @@ Paper Status
.. [#note-P0533R9] P0533R9: ``isfinite``, ``isinf``, ``isnan`` and ``isnormal`` are implemented.
.. [#note-P1413R3] P1413R3: ``std::aligned_storage_t`` and ``std::aligned_union_t`` are marked deprecated, but
clang doesn't issue a diagnostic for deprecated using template declarations.
.. [#note-P2387R3] P2387R3: ``bind_back`` only
.. [#note-P2520R0] P2520R0: Libc++ implemented this paper as a DR in C++20 as well.
.. [#note-P2711R1] P2711R1: ``join_with_view`` hasn't been done yet since this type isn't implemented yet.
.. [#note-P2770R0] P2770R0: ``join_with_view`` hasn't been done yet since this type isn't implemented yet.

2
libcxx/docs/Status/Cxx23Papers.csv
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@ -45,7 +45,7 @@
"`P1413R3 <https://wg21.link/P1413R3>`__","LWG","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","February 2022","|Complete| [#note-P1413R3]_",""
"`P2255R2 <https://wg21.link/P2255R2>`__","LWG","A type trait to detect reference binding to temporary","February 2022","",""
"`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","|Complete|","16.0"
"`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","","","|ranges|"
"`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","|Partial| [#note-P2387R3]_","","|ranges|"
"`P2440R1 <https://wg21.link/P2440R1>`__","LWG","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","February 2022","","","|ranges|"
"`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_with``","February 2022","|In Progress|","","|ranges|"
"`P2442R1 <https://wg21.link/P2442R1>`__","LWG","Windowing range adaptors: ``views::chunk`` and ``views::slide``","February 2022","","","|ranges|"

Can't render this file because it has a wrong number of fields in line 2.

14
libcxx/include/__functional/bind_back.h
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@ -62,6 +62,20 @@ _LIBCPP_HIDE_FROM_ABI constexpr auto __bind_back(_Fn&& __f, _Args&&... __args) n
std::forward<_Fn>(__f), std::forward_as_tuple(std::forward<_Args>(__args)...));
}
# if _LIBCPP_STD_VER >= 23
template <class _Fn, class... _Args>
_LIBCPP_HIDE_FROM_ABI constexpr auto bind_back(_Fn&& __f, _Args&&... __args) {
static_assert(is_constructible_v<decay_t<_Fn>, _Fn>, "bind_back requires decay_t<F> to be constructible from F");
static_assert(is_move_constructible_v<decay_t<_Fn>>, "bind_back requires decay_t<F> to be move constructible");
static_assert((is_constructible_v<decay_t<_Args>, _Args> && ...),
"bind_back requires all decay_t<Args> to be constructible from respective Args");
static_assert((is_move_constructible_v<decay_t<_Args>> && ...),
"bind_back requires all decay_t<Args> to be move constructible");
return __bind_back_t<decay_t<_Fn>, tuple<decay_t<_Args>...>>(
std::forward<_Fn>(__f), std::forward_as_tuple(std::forward<_Args>(__args)...));
}
# endif // _LIBCPP_STD_VER >= 23
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD

6
libcxx/include/functional
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@ -207,6 +207,12 @@ binary_negate<Predicate> not2(const Predicate& pred);
template <class F>
constexpr unspecified not_fn(F&& f); // C++17, constexpr in C++20
// [func.bind.partial], function templates bind_front and bind_back
template<class F, class... Args>
constexpr unspecified bind_front(F&&, Args&&...); // C++20
template<class F, class... Args>
constexpr unspecified bind_back(F&&, Args&&...); // C++23
template<class T> struct is_bind_expression;
template<class T> struct is_placeholder;

7
libcxx/include/version
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@ -41,8 +41,7 @@ __cpp_lib_atomic_shared_ptr 201711L <atomic>
__cpp_lib_atomic_value_initialization 201911L <atomic> <memory>
__cpp_lib_atomic_wait 201907L <atomic>
__cpp_lib_barrier 201907L <barrier>
__cpp_lib_bind_back 202306L <functional>
202202L // C++23
__cpp_lib_bind_back 202202L <functional>
__cpp_lib_bind_front 202306L <functional>
201907L // C++20
__cpp_lib_bit_cast 201806L <bit>
@ -449,7 +448,7 @@ __cpp_lib_within_lifetime 202306L <type_traits>
# define __cpp_lib_adaptor_iterator_pair_constructor 202106L
# define __cpp_lib_allocate_at_least 202302L
// # define __cpp_lib_associative_heterogeneous_erasure 202110L
// # define __cpp_lib_bind_back 202202L
# define __cpp_lib_bind_back 202202L
# define __cpp_lib_byteswap 202110L
# define __cpp_lib_constexpr_bitset 202207L
# define __cpp_lib_constexpr_charconv 202207L
@ -498,8 +497,6 @@ __cpp_lib_within_lifetime 202306L <type_traits>
#if _LIBCPP_STD_VER >= 26
// # define __cpp_lib_associative_heterogeneous_insertion 202306L
// # define __cpp_lib_atomic_min_max 202403L
# undef __cpp_lib_bind_back
// # define __cpp_lib_bind_back 202306L
# undef __cpp_lib_bind_front
# define __cpp_lib_bind_front 202306L
# define __cpp_lib_bitset 202306L

4
libcxx/modules/std/functional.inc
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@ -56,8 +56,10 @@ export namespace std {
using std::not_fn;
// [func.bind.partial], function templates bind_front and bind_back
// using std::bind_back;
using std::bind_front;
#if _LIBCPP_STD_VER >= 23
using std::bind_back;
#endif
// [func.bind], bind
using std::is_bind_expression;

33
libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp
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@ -17,7 +17,6 @@
/* Constant Value
__cpp_lib_bind_back 202202L [C++23]
202306L [C++26]
__cpp_lib_bind_front 201907L [C++20]
202306L [C++26]
__cpp_lib_boyer_moore_searcher 201603L [C++17]
@ -337,17 +336,11 @@
#elif TEST_STD_VER == 23
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++23"
# endif
# if __cpp_lib_bind_back != 202202L
# error "__cpp_lib_bind_back should have the value 202202L in c++23"
# endif
# else // _LIBCPP_VERSION
# ifdef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should not be defined because it is unimplemented in libc++!"
# endif
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++23"
# endif
# if __cpp_lib_bind_back != 202202L
# error "__cpp_lib_bind_back should have the value 202202L in c++23"
# endif
# ifndef __cpp_lib_bind_front
@ -447,17 +440,11 @@
#elif TEST_STD_VER > 23
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++26"
# endif
# if __cpp_lib_bind_back != 202306L
# error "__cpp_lib_bind_back should have the value 202306L in c++26"
# endif
# else // _LIBCPP_VERSION
# ifdef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should not be defined because it is unimplemented in libc++!"
# endif
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++26"
# endif
# if __cpp_lib_bind_back != 202202L
# error "__cpp_lib_bind_back should have the value 202202L in c++26"
# endif
# ifndef __cpp_lib_bind_front

33
libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
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@ -39,7 +39,6 @@
__cpp_lib_atomic_wait 201907L [C++20]
__cpp_lib_barrier 201907L [C++20]
__cpp_lib_bind_back 202202L [C++23]
202306L [C++26]
__cpp_lib_bind_front 201907L [C++20]
202306L [C++26]
__cpp_lib_bit_cast 201806L [C++20]
@ -4605,17 +4604,11 @@
# endif
# endif
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++23"
# endif
# if __cpp_lib_bind_back != 202202L
# error "__cpp_lib_bind_back should have the value 202202L in c++23"
# endif
# else // _LIBCPP_VERSION
# ifdef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should not be defined because it is unimplemented in libc++!"
# endif
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++23"
# endif
# if __cpp_lib_bind_back != 202202L
# error "__cpp_lib_bind_back should have the value 202202L in c++23"
# endif
# ifndef __cpp_lib_bind_front
@ -6240,17 +6233,11 @@
# endif
# endif
# if !defined(_LIBCPP_VERSION)
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++26"
# endif
# if __cpp_lib_bind_back != 202306L
# error "__cpp_lib_bind_back should have the value 202306L in c++26"
# endif
# else // _LIBCPP_VERSION
# ifdef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should not be defined because it is unimplemented in libc++!"
# endif
# ifndef __cpp_lib_bind_back
# error "__cpp_lib_bind_back should be defined in c++26"
# endif
# if __cpp_lib_bind_back != 202202L
# error "__cpp_lib_bind_back should have the value 202202L in c++26"
# endif
# ifndef __cpp_lib_bind_front

381
libcxx/test/std/utilities/function.objects/func.bind.partial/bind_back.pass.cpp Normal file
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@ -0,0 +1,381 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
// <functional>
// template<class F, class... Args>
// constexpr unspecified bind_back(F&& f, Args&&... args);
#include <functional>
#include <cassert>
#include <concepts>
#include <tuple>
#include <utility>
#include "callable_types.h"
#include "types.h"
constexpr void test_basic_bindings() {
{ // Bind arguments, call without arguments
{
auto f = std::bind_back(MakeTuple{});
assert(f() == std::make_tuple());
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{});
assert(f() == std::make_tuple(Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
assert(f() == std::make_tuple(Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f() == std::make_tuple(Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
}
{ // Bind no arguments, call with arguments
{
auto f = std::bind_back(MakeTuple{});
assert(f(Elem<1>{}) == std::make_tuple(Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{});
assert(f(Elem<1>{}, Elem<2>{}) == std::make_tuple(Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{});
assert(f(Elem<1>{}, Elem<2>{}, Elem<3>{}) == std::make_tuple(Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
}
{ // Bind arguments, call with arguments
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{});
assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{});
assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f(Elem<10>{}, Elem<11>{}, Elem<12>{}) ==
std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<12>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
}
{ // Basic tests with fundamental types
int n = 2;
int m = 1;
int sum = 0;
auto add = [](int x, int y) { return x + y; };
auto add_n = [](int a, int b, int c, int d, int e, int f) { return a + b + c + d + e + f; };
auto add_ref = [&](int x, int y) -> int& { return sum = x + y; };
auto add_rref = [&](int x, int y) -> int&& { return std::move(sum = x + y); };
auto a = std::bind_back(add, m, n);
assert(a() == 3);
auto b = std::bind_back(add_n, m, n, m, m, m, m);
assert(b() == 7);
auto c = std::bind_back(add_n, n, m);
assert(c(1, 1, 1, 1) == 7);
auto d = std::bind_back(add_ref, n, m);
std::same_as<int&> decltype(auto) dresult(d());
assert(dresult == 3);
auto e = std::bind_back(add_rref, n, m);
std::same_as<int&&> decltype(auto) eresult(e());
assert(eresult == 3);
auto f = std::bind_back(add, n);
assert(f(3) == 5);
auto g = std::bind_back(add, n, 1);
assert(g() == 3);
auto h = std::bind_back(add_n, 1, 1, 1);
assert(h(2, 2, 2) == 9);
auto i = std::bind_back(add_ref, n);
std::same_as<int&> decltype(auto) iresult(i(5));
assert(iresult == 7);
auto j = std::bind_back(add_rref, m);
std::same_as<int&&> decltype(auto) jresult(j(4));
assert(jresult == 5);
}
}
constexpr void test_edge_cases() {
{ // Make sure we don't treat std::reference_wrapper specially.
auto sub = [](std::reference_wrapper<int> a, std::reference_wrapper<int> b) { return a.get() - b.get(); };
int i = 1;
int j = 2;
auto f = std::bind_back(sub, std::ref(i));
assert(f(std::ref(j)) == 1);
}
{ // Make sure we can call a function that's a pointer to a member function.
struct MemberFunction {
constexpr int foo(int x, int y) { return x * y; }
};
MemberFunction value;
auto fn = std::bind_back(&MemberFunction::foo, 2, 3);
assert(fn(value) == 6);
}
{ // Make sure we can call a function that's a pointer to a member object.
struct MemberObject {
int obj;
};
MemberObject value{.obj = 3};
auto fn = std::bind_back(&MemberObject::obj);
assert(fn(value) == 3);
}
}
constexpr void test_passing_arguments() {
{ // Make sure that we copy the bound arguments into the unspecified-type.
auto add = [](int x, int y) { return x + y; };
int n = 2;
auto f = std::bind_back(add, n, 1);
n = 100;
assert(f() == 3);
}
{ // Make sure we pass the bound arguments to the function object
// with the right value category.
{
auto was_copied = [](CopyMoveInfo info) { return info.copy_kind == CopyMoveInfo::copy; };
CopyMoveInfo info;
auto f = std::bind_back(was_copied, info);
assert(f());
}
{
auto was_moved = [](CopyMoveInfo info) { return info.copy_kind == CopyMoveInfo::move; };
CopyMoveInfo info;
auto f = std::bind_back(was_moved, info);
assert(std::move(f)());
}
}
}
constexpr void test_function_objects() {
{ // Make sure we call the correctly cv-ref qualified operator()
// based on the value category of the bind_back unspecified-type.
struct X {
constexpr int operator()() & { return 1; }
constexpr int operator()() const& { return 2; }
constexpr int operator()() && { return 3; }
constexpr int operator()() const&& { return 4; }
};
auto f = std::bind_back(X{});
using F = decltype(f);
assert(static_cast<F&>(f)() == 1);
assert(static_cast<const F&>(f)() == 2);
assert(static_cast<F&&>(f)() == 3);
assert(static_cast<const F&&>(f)() == 4);
}
// Make sure the `bind_back` unspecified-type does not model invocable
// when the call would select a differently-qualified operator().
//
// For example, if the call to `operator()() &` is ill-formed, the call to the unspecified-type
// should be ill-formed and not fall back to the `operator()() const&` overload.
{ // Make sure we delete the & overload when the underlying call isn't valid.
{
struct X {
void operator()() & = delete;
void operator()() const&;
void operator()() &&;
void operator()() const&&;
};
using F = decltype(std::bind_back(X{}));
static_assert(!std::invocable<F&>);
static_assert(std::invocable<const F&>);
static_assert(std::invocable<F>);
static_assert(std::invocable<const F>);
}
// There's no way to make sure we delete the const& overload when the underlying call isn't valid,
// so we can't check this one.
{ // Make sure we delete the && overload when the underlying call isn't valid.
struct X {
void operator()() &;
void operator()() const&;
void operator()() && = delete;
void operator()() const&&;
};
using F = decltype(std::bind_back(X{}));
static_assert(std::invocable<F&>);
static_assert(std::invocable<const F&>);
static_assert(!std::invocable<F>);
static_assert(std::invocable<const F>);
}
{ // Make sure we delete the const&& overload when the underlying call isn't valid.
struct X {
void operator()() &;
void operator()() const&;
void operator()() &&;
void operator()() const&& = delete;
};
using F = decltype(std::bind_back(X{}));
static_assert(std::invocable<F&>);
static_assert(std::invocable<const F&>);
static_assert(std::invocable<F>);
static_assert(!std::invocable<const F>);
}
}
{ // Extra value category tests
struct X {};
{
struct Y {
void operator()(X&&) const&;
void operator()(X&&) && = delete;
};
using F = decltype(std::bind_back(Y{}));
static_assert(std::invocable<F&, X>);
static_assert(!std::invocable<F, X>);
}
{
struct Y {
void operator()(const X&) const;
void operator()(X&&) const = delete;
};
using F = decltype(std::bind_back(Y{}, X{}));
static_assert(std::invocable<F&>);
static_assert(!std::invocable<F>);
}
}
}
constexpr void test_return_type() {
{ // Test properties of the constructor of the unspecified-type returned by bind_back.
{ // Test move constructor when function is move only.
MoveOnlyCallable<bool> value(true);
auto f = std::bind_back(std::move(value), 1);
assert(f());
assert(f(1, 2, 3));
auto f1 = std::move(f);
assert(!f());
assert(f1());
assert(f1(1, 2, 3));
using F = decltype(f);
static_assert(std::is_move_constructible<F>::value);
static_assert(!std::is_copy_constructible<F>::value);
static_assert(!std::is_move_assignable<F>::value);
static_assert(!std::is_copy_assignable<F>::value);
}
{ // Test move constructor when function is copyable but not assignable.
CopyCallable<bool> value(true);
auto f = std::bind_back(value, 1);
assert(f());
assert(f(1, 2, 3));
auto f1 = std::move(f);
assert(!f());
assert(f1());
assert(f1(1, 2, 3));
auto f2 = std::bind_back(std::move(value), 1);
assert(f1());
assert(f2());
assert(f2(1, 2, 3));
using F = decltype(f);
static_assert(std::is_move_constructible<F>::value);
static_assert(std::is_copy_constructible<F>::value);
static_assert(!std::is_move_assignable<F>::value);
static_assert(!std::is_copy_assignable<F>::value);
}
{ // Test constructors when function is copy assignable.
using F = decltype(std::bind_back(std::declval<CopyAssignableWrapper&>(), 1));
static_assert(std::is_move_constructible<F>::value);
static_assert(std::is_copy_constructible<F>::value);
static_assert(std::is_move_assignable<F>::value);
static_assert(std::is_copy_assignable<F>::value);
}
{ // Test constructors when function is move assignable only.
using F = decltype(std::bind_back(std::declval<MoveAssignableWrapper>(), 1));
static_assert(std::is_move_constructible<F>::value);
static_assert(!std::is_copy_constructible<F>::value);
static_assert(std::is_move_assignable<F>::value);
static_assert(!std::is_copy_assignable<F>::value);
}
}
{ // Make sure bind_back's unspecified type's operator() is SFINAE-friendly.
using F = decltype(std::bind_back(std::declval<int (*)(int, int)>(), 1));
static_assert(!std::is_invocable<F>::value);
static_assert(std::is_invocable<F, int>::value);
static_assert(!std::is_invocable<F, void*>::value);
static_assert(!std::is_invocable<F, int, int>::value);
}
}
constexpr bool test() {
test_basic_bindings();
test_edge_cases();
test_passing_arguments();
test_function_objects();
test_return_type();
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}

85
libcxx/test/std/utilities/function.objects/func.bind.partial/bind_back.verify.cpp Normal file
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@ -0,0 +1,85 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
// <functional>
// template<class F, class... Args>
// constexpr unspecified bind_back(F&& f, Args&&... args);
#include <functional>
#include "types.h"
constexpr int pass(int n) { return n; }
void test() {
{ // Test calling constexpr function from non-constexpr `bind_back` result
auto f1 = std::bind_back(pass, 1);
static_assert(f1() == 1); // expected-error {{static assertion expression is not an integral constant expression}}
}
{ // Test calling `bind_back` with template function
auto f1 = std::bind_back(do_nothing, 2);
// expected-error@-1 {{no matching function for call to 'bind_back'}}
}
{ // Mandates: is_constructible_v<decay_t<F>, F>
struct F {
F() = default;
F(const F&) = default;
F(F&) = delete;
void operator()() {}
};
F f;
auto f1 = std::bind_back(f);
// expected-error-re@*:* {{static assertion failed{{.*}}bind_back requires decay_t<F> to be constructible from F}}
}
{ // Mandates: is_move_constructible_v<decay_t<F>>
struct F {
F() = default;
F(const F&) = default;
F(F&&) = delete;
void operator()() {}
};
F f;
auto f1 = std::bind_back(f);
// expected-error-re@*:* {{static assertion failed{{.*}}bind_back requires decay_t<F> to be move constructible}}
}
{ // Mandates: (is_constructible_v<decay_t<Args>, Args> && ...)
struct Arg {
Arg() = default;
Arg(const Arg&) = default;
Arg(Arg&) = delete;
};
Arg x;
auto f = std::bind_back([](const Arg&) {}, x);
// expected-error-re@*:* {{static assertion failed{{.*}}bind_back requires all decay_t<Args> to be constructible from respective Args}}
// expected-error@*:* {{no matching constructor for initialization}}
}
{ // Mandates: (is_move_constructible_v<decay_t<Args>> && ...)
struct Arg {
Arg() = default;
Arg(const Arg&) = default;
Arg(Arg&&) = delete;
};
Arg x;
auto f = std::bind_back([](Arg&) {}, x);
// expected-error-re@*:* {{static assertion failed{{.*}}bind_back requires all decay_t<Args> to be move constructible}}
}
}

43
libcxx/test/std/utilities/function.objects/func.bind.partial/types.h Normal file
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@ -0,0 +1,43 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef TEST_STD_UTILITIES_FUNCTION_OBJECTS_FUNC_BIND_PARTIAL_TYPES_H
#define TEST_STD_UTILITIES_FUNCTION_OBJECTS_FUNC_BIND_PARTIAL_TYPES_H
#include <tuple>
#include <utility>
struct MakeTuple {
template <class... Args>
constexpr auto operator()(Args&&... args) const {
return std::make_tuple(std::forward<Args>(args)...);
}
};
template <int X>
struct Elem {
template <int Y>
constexpr bool operator==(const Elem<Y>&) const {
return X == Y;
}
};
struct CopyMoveInfo {
enum { none, copy, move } copy_kind;
constexpr CopyMoveInfo() : copy_kind(none) {}
constexpr CopyMoveInfo(const CopyMoveInfo&) : copy_kind(copy) {}
constexpr CopyMoveInfo(CopyMoveInfo&&) : copy_kind(move) {}
};
template <class T>
T do_nothing(T t) {
return t;
}
#endif // TEST_STD_UTILITIES_FUNCTION_OBJECTS_FUNC_BIND_PARTIAL_TYPES_H

30
libcxx/test/std/utilities/function.objects/func.bind_front/bind_front.pass.cpp
View File

@ -15,6 +15,7 @@
#include <functional>
#include <cassert>
#include <concepts>
#include <tuple>
#include <type_traits>
#include <utility>
@ -142,12 +143,13 @@ constexpr bool test() {
// Basic tests with fundamental types
{
int n = 2;
int m = 1;
auto add = [](int x, int y) { return x + y; };
auto addN = [](int a, int b, int c, int d, int e, int f) {
return a + b + c + d + e + f;
};
int n = 2;
int m = 1;
int sum = 0;
auto add = [](int x, int y) { return x + y; };
auto addN = [](int a, int b, int c, int d, int e, int f) { return a + b + c + d + e + f; };
auto add_ref = [&](int x, int y) -> int& { return sum = x + y; };
auto add_rref = [&](int x, int y) -> int&& { return std::move(sum = x + y); };
auto a = std::bind_front(add, m, n);
assert(a() == 3);
@ -158,6 +160,14 @@ constexpr bool test() {
auto c = std::bind_front(addN, n, m);
assert(c(1, 1, 1, 1) == 7);
auto d = std::bind_front(add_ref, n, m);
std::same_as<int&> decltype(auto) dresult(d());
assert(dresult == 3);
auto e = std::bind_front(add_rref, n, m);
std::same_as<int&&> decltype(auto) eresult(e());
assert(eresult == 3);
auto f = std::bind_front(add, n);
assert(f(3) == 5);
@ -166,6 +176,14 @@ constexpr bool test() {
auto h = std::bind_front(addN, 1, 1, 1);
assert(h(2, 2, 2) == 9);
auto i = std::bind_front(add_ref, n);
std::same_as<int&> decltype(auto) iresult(i(5));
assert(iresult == 7);
auto j = std::bind_front(add_rref, m);
std::same_as<int&&> decltype(auto) jresult(j(4));
assert(jresult == 5);
}
// Make sure we don't treat std::reference_wrapper specially.

3
libcxx/utils/generate_feature_test_macro_components.py
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@ -211,10 +211,9 @@ feature_test_macros = [
"name": "__cpp_lib_bind_back",
"values": {
"c++23": 202202,
"c++26": 202306, # P2714R1 Bind front and back to NTTP callables
# "c++26": 202306, # P2714R1 Bind front and back to NTTP callables
},
"headers": ["functional"],
"unimplemented": True,
},
{
"name": "__cpp_lib_bind_front",