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<ranges>: Fix the return types and overload resolution of range adaptor closure objects #4211

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Merged
Stephan T. Lavavej (StephanTLavavej) merged 1 commit into from
Nov 29, 2023
Merged

<ranges>: Fix the return types and overload resolution of range adaptor closure objects #4211

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25 changes: 16 additions & 9 deletions stl/inc/ranges
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Original file line number Diff line number Diff line change
Expand Up @@ -133,34 +133,41 @@ namespace ranges {
is_nothrow_constructible_v<_Ty1, _ClosureLeft>&& is_nothrow_constructible_v<_Ty2, _ClosureRight>)
: _Left(_STD forward<_Ty1>(_Val1)), _Right(_STD forward<_Ty2>(_Val2)) {}

void operator()(auto&&) & = delete;
void operator()(auto&&) const& = delete;
void operator()(auto&&) && = delete;
void operator()(auto&&) const&& = delete;

// TRANSITION, DevCom-10519736, explicit `this->` shouldn't be needed.

template <class _Ty>
_NODISCARD constexpr auto operator()(_Ty&& _Val) & noexcept(
_NODISCARD constexpr decltype(auto) operator()(_Ty&& _Val) & noexcept(
noexcept(_Right(_Left(_STD forward<_Ty>(_Val)))))
requires requires { _Right(_Left(_STD forward<_Ty>(_Val))); }
requires requires { this->_Right(this->_Left(_STD forward<_Ty>(_Val))); }
{
return _Right(_Left(_STD forward<_Ty>(_Val)));
}

template <class _Ty>
_NODISCARD constexpr auto operator()(_Ty&& _Val) const& noexcept(
_NODISCARD constexpr decltype(auto) operator()(_Ty&& _Val) const& noexcept(
noexcept(_Right(_Left(_STD forward<_Ty>(_Val)))))
requires requires { _Right(_Left(_STD forward<_Ty>(_Val))); }
requires requires { this->_Right(this->_Left(_STD forward<_Ty>(_Val))); }
{
return _Right(_Left(_STD forward<_Ty>(_Val)));
}

template <class _Ty>
_NODISCARD constexpr auto operator()(_Ty&& _Val) && noexcept(
_NODISCARD constexpr decltype(auto) operator()(_Ty&& _Val) && noexcept(
noexcept(_STD move(_Right)(_STD move(_Left)(_STD forward<_Ty>(_Val)))))
requires requires { _STD move(_Right)(_STD move(_Left)(_STD forward<_Ty>(_Val))); }
requires requires { _STD move(this->_Right)(_STD move(this->_Left)(_STD forward<_Ty>(_Val))); }
{
return _STD move(_Right)(_STD move(_Left)(_STD forward<_Ty>(_Val)));
}

template <class _Ty>
_NODISCARD constexpr auto operator()(_Ty&& _Val) const&& noexcept(
_NODISCARD constexpr decltype(auto) operator()(_Ty&& _Val) const&& noexcept(
noexcept(_STD move(_Right)(_STD move(_Left)(_STD forward<_Ty>(_Val)))))
requires requires { _STD move(_Right)(_STD move(_Left)(_STD forward<_Ty>(_Val))); }
requires requires { _STD move(this->_Right)(_STD move(this->_Left)(_STD forward<_Ty>(_Val))); }
{
return _STD move(_Right)(_STD move(_Left)(_STD forward<_Ty>(_Val)));
}
Expand All @@ -180,7 +187,7 @@ namespace ranges {

_EXPORT_STD template <class _Left, class _Right>
requires (_Range_adaptor_closure_object<_Right> && range<_Left>)
_NODISCARD constexpr auto operator|(_Left&& __l, _Right&& __r) noexcept(
_NODISCARD constexpr decltype(auto) operator|(_Left&& __l, _Right&& __r) noexcept(
noexcept(_STD forward<_Right>(__r)(_STD forward<_Left>(__l))))
requires requires { static_cast<_Right&&>(__r)(static_cast<_Left&&>(__l)); }
{
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75 changes: 75 additions & 0 deletions tests/std/tests/P2387R3_pipe_support_for_user_defined_range_adaptors/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -223,6 +223,81 @@ constexpr bool test_mixing_of_range_adaptors() {
return true;
}

struct Pinned {
Pinned() = default;
Pinned(const Pinned&) = delete;
Pinned& operator=(const Pinned&) = delete;
};

constexpr Pinned pinned_object{};

struct PinnedReturningRaco : ranges::range_adaptor_closure<PinnedReturningRaco> {
constexpr const Pinned& operator()(ranges::range auto&&) const noexcept {
return pinned_object;
}
};

struct RangeIdentity : ranges::range_adaptor_closure<RangeIdentity> {
constexpr auto&& operator()(ranges::range auto&& t) const noexcept {
return forward<decltype(t)>(t);
}
};

struct ConstOnlyRangeIdentity : ranges::range_adaptor_closure<ConstOnlyRangeIdentity> {
constexpr auto&& operator()(ranges::range auto&& t) const noexcept {
return forward<decltype(t)>(t);
}
void operator()(ranges::range auto&&) = delete;
};

void test_perfect_forwarding_properties() { // COMPILE-ONLY
// GH-4153: <ranges>: operator|(_Left&& __l, _Right&& __r) should return decltype(auto)
// Intentionally avoid using some traits/concepts to test correctness in non-immediate contexts.
{
PinnedReturningRaco raco{};

static_assert(same_as<decltype(TestRange{} | raco), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | as_const(raco)), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | move(raco)), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | move(as_const(raco))), const Pinned&>);

static_assert(same_as<decltype(raco(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(as_const(raco)(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(move(raco)(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(move(as_const(raco))(TestRange{})), const Pinned&>);
}
{

auto combined_pipeline = RangeIdentity{} | PinnedReturningRaco{};

static_assert(same_as<decltype(TestRange{} | combined_pipeline), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | as_const(combined_pipeline)), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | move(combined_pipeline)), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | move(as_const(combined_pipeline))), const Pinned&>);

static_assert(same_as<decltype(combined_pipeline(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(as_const(combined_pipeline)(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(move(combined_pipeline)(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(move(as_const(combined_pipeline))(TestRange{})), const Pinned&>);
}
{
auto weird_pipeline = ConstOnlyRangeIdentity{} | PinnedReturningRaco{};
using WeirdPipelineType = decltype(weird_pipeline);

static_assert(same_as<decltype(TestRange{} | as_const(weird_pipeline)), const Pinned&>);
static_assert(same_as<decltype(TestRange{} | move(as_const(weird_pipeline))), const Pinned&>);

static_assert(!CanPipe<WeirdPipelineType, TestRange>);
static_assert(!CanPipe<WeirdPipelineType&, TestRange>);

static_assert(same_as<decltype(as_const(weird_pipeline)(TestRange{})), const Pinned&>);
static_assert(same_as<decltype(move(as_const(weird_pipeline))(TestRange{})), const Pinned&>);

static_assert(!invocable<WeirdPipelineType, TestRange>);
static_assert(!invocable<WeirdPipelineType&, TestRange>);
}
}

int main() {
assert(test_user_defined_adaptors());
static_assert(test_user_defined_adaptors());
Expand Down