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Implement LWG-3715: view_interface::empty is overconstrained #2946

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Merged
merged 20 commits into from
Jul 28, 2022
Merged

Implement LWG-3715: view_interface::empty is overconstrained #2946

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b51548c
Test non-forward sizeable views (LWG-3715)
frederick-vs-ja Jul 26, 2022
32fc1f2
Implement LWG-3715
frederick-vs-ja Jul 26, 2022
d69afd5
Oops, I forgot operator bool
frederick-vs-ja Jul 26, 2022
dc0b7b3
Update test for take_view according to LWG-3715
frederick-vs-ja Jul 26, 2022
04bbc5a
Update test for drop_view according to LWG-3715
frederick-vs-ja Jul 26, 2022
b7a0d11
Update test for elements_view according to LWG-3715
frederick-vs-ja Jul 26, 2022
f2a8029
Update test for chunk_view according to LWG-3715
frederick-vs-ja Jul 26, 2022
13da3f6
Oops...
frederick-vs-ja Jul 26, 2022
34c7252
Parentheses
frederick-vs-ja Jul 26, 2022
25db483
Parentheses
frederick-vs-ja Jul 26, 2022
92bcbc2
Parentheses
frederick-vs-ja Jul 26, 2022
58c6426
Update test for transform_view according to LWG-3715
frederick-vs-ja Jul 26, 2022
fa18c19
using ranges::sized_range
frederick-vs-ja Jul 26, 2022
8737f43
Clang-format
frederick-vs-ja Jul 26, 2022
88f5bdc
Clang-format
frederick-vs-ja Jul 26, 2022
d12dd1b
Revert the wrong change
frederick-vs-ja Jul 26, 2022
791336f
using ranges::sized_range
frederick-vs-ja Jul 26, 2022
2529c1a
Fix for misread conditions
frederick-vs-ja Jul 26, 2022
5f3026d
Try a strange fix
frederick-vs-ja Jul 26, 2022
8f39864
Style: Binary operator at beginning of line.
StephanTLavavej Jul 27, 2022
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20 changes: 14 additions & 6 deletions stl/inc/xutility
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Original file line number Diff line number Diff line change
Expand Up @@ -2722,24 +2722,32 @@ namespace ranges {
public:
#ifdef __clang__ // TRANSITION, LLVM-44833
template <class _Dx = _Derived>
_NODISCARD constexpr bool empty() requires forward_range<_Dx>
_NODISCARD constexpr bool empty() requires sized_range<_Dx> || forward_range<_Dx>
#else // ^^^ workaround / no workaround vvv
_NODISCARD constexpr bool empty() requires forward_range<_Derived>
_NODISCARD constexpr bool empty() requires sized_range<_Derived> || forward_range<_Derived>
#endif // TRANSITION, LLVM-44833
{
auto& _Self = _Cast();
return _RANGES begin(_Self) == _RANGES end(_Self);
if constexpr (sized_range<_Derived>) {
return _RANGES size(_Self) == 0;
} else {
return _RANGES begin(_Self) == _RANGES end(_Self);
}
}

#ifdef __clang__ // TRANSITION, LLVM-44833
template <class _Dx = _Derived>
_NODISCARD constexpr bool empty() const requires forward_range<const _Dx>
_NODISCARD constexpr bool empty() const requires sized_range<const _Dx> || forward_range<const _Dx>
#else // ^^^ workaround / no workaround vvv
_NODISCARD constexpr bool empty() const requires forward_range<const _Derived>
_NODISCARD constexpr bool empty() const requires sized_range<const _Derived> || forward_range<const _Derived>
#endif // TRANSITION, LLVM-44833
{
auto& _Self = _Cast();
return _RANGES begin(_Self) == _RANGES end(_Self);
if constexpr (sized_range<const _Derived>) {
return _RANGES size(_Self) == 0;
} else {
return _RANGES begin(_Self) == _RANGES end(_Self);
}
}

#ifdef __clang__ // TRANSITION, LLVM-44833
Expand Down
40 changes: 22 additions & 18 deletions tests/std/tests/P0896R4_ranges_subrange/test.compile.pass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,10 @@ namespace test_view_interface {

S end();
S end() const requires (to_bool(HasConstRange));

unsigned int size() requires (to_bool(Diff) && !std::derived_from<Cat, forward_iterator_tag>);
unsigned int size() const requires (to_bool(HasConstRange) && to_bool(Diff)
&& !std::derived_from<Cat, forward_iterator_tag>);
};
// clang-format on

Expand Down Expand Up @@ -133,13 +137,13 @@ namespace test_view_interface {
STATIC_ASSERT(ranges::range<V>);
STATIC_ASSERT(!ranges::range<V const>);
STATIC_ASSERT(ranges::view<V>);
STATIC_ASSERT(!CanEmpty<V&>);
STATIC_ASSERT(CanEmpty<V&>);
STATIC_ASSERT(!CanEmpty<V const&>);
STATIC_ASSERT(!CanBool<V&>);
STATIC_ASSERT(CanBool<V&>);
STATIC_ASSERT(!CanBool<V const&>);
STATIC_ASSERT(!CanData<V&>);
STATIC_ASSERT(!CanData<V const&>);
STATIC_ASSERT(!CanSize<V&>);
STATIC_ASSERT(CanSize<V&>);
STATIC_ASSERT(!CanSize<V const&>);
STATIC_ASSERT(!CanMemberFront<V&>);
STATIC_ASSERT(!CanMemberFront<V const&>);
Expand All @@ -154,14 +158,14 @@ namespace test_view_interface {
STATIC_ASSERT(ranges::range<V>);
STATIC_ASSERT(ranges::range<V const>);
STATIC_ASSERT(ranges::view<V>);
STATIC_ASSERT(!CanEmpty<V&>);
STATIC_ASSERT(!CanEmpty<V const&>);
STATIC_ASSERT(!CanBool<V&>);
STATIC_ASSERT(!CanBool<V const&>);
STATIC_ASSERT(CanEmpty<V&>);
STATIC_ASSERT(CanEmpty<V const&>);
STATIC_ASSERT(CanBool<V&>);
STATIC_ASSERT(CanBool<V const&>);
STATIC_ASSERT(!CanData<V&>);
STATIC_ASSERT(!CanData<V const&>);
STATIC_ASSERT(!CanSize<V&>);
STATIC_ASSERT(!CanSize<V const&>);
STATIC_ASSERT(CanSize<V&>);
STATIC_ASSERT(CanSize<V const&>);
STATIC_ASSERT(!CanMemberFront<V&>);
STATIC_ASSERT(!CanMemberFront<V const&>);
STATIC_ASSERT(!CanMemberBack<V&>);
Expand Down Expand Up @@ -217,13 +221,13 @@ namespace test_view_interface {
STATIC_ASSERT(ranges::range<V>);
STATIC_ASSERT(!ranges::range<V const>);
STATIC_ASSERT(ranges::view<V>);
STATIC_ASSERT(!CanEmpty<V&>);
STATIC_ASSERT(CanEmpty<V&>);
STATIC_ASSERT(!CanEmpty<V const&>);
STATIC_ASSERT(!CanBool<V&>);
STATIC_ASSERT(CanBool<V&>);
STATIC_ASSERT(!CanBool<V const&>);
STATIC_ASSERT(!CanData<V&>);
STATIC_ASSERT(!CanData<V const&>);
STATIC_ASSERT(!CanSize<V&>);
STATIC_ASSERT(CanSize<V&>);
STATIC_ASSERT(!CanSize<V const&>);
STATIC_ASSERT(!CanMemberFront<V&>);
STATIC_ASSERT(!CanMemberFront<V const&>);
Expand All @@ -238,14 +242,14 @@ namespace test_view_interface {
STATIC_ASSERT(ranges::range<V>);
STATIC_ASSERT(ranges::range<V const>);
STATIC_ASSERT(ranges::view<V>);
STATIC_ASSERT(!CanEmpty<V&>);
STATIC_ASSERT(!CanEmpty<V const&>);
STATIC_ASSERT(!CanBool<V&>);
STATIC_ASSERT(!CanBool<V const&>);
STATIC_ASSERT(CanEmpty<V&>);
STATIC_ASSERT(CanEmpty<V const&>);
STATIC_ASSERT(CanBool<V&>);
STATIC_ASSERT(CanBool<V const&>);
STATIC_ASSERT(!CanData<V&>);
STATIC_ASSERT(!CanData<V const&>);
STATIC_ASSERT(!CanSize<V&>);
STATIC_ASSERT(!CanSize<V const&>);
STATIC_ASSERT(CanSize<V&>);
STATIC_ASSERT(CanSize<V const&>);
STATIC_ASSERT(!CanMemberFront<V&>);
STATIC_ASSERT(!CanMemberFront<V const&>);
STATIC_ASSERT(!CanMemberBack<V&>);
Expand Down
2 changes: 1 addition & 1 deletion tests/std/tests/P0896R4_views_drop/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -219,7 +219,7 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}

// Validate view_interface::empty and operator bool
STATIC_ASSERT(CanMemberEmpty<R> == forward_range<Rng>);
STATIC_ASSERT(CanMemberEmpty<R> == (sized_range<Rng> || forward_range<Rng>) );
STATIC_ASSERT(CanBool<R> == CanEmpty<R>);
if constexpr (CanMemberEmpty<R>) {
assert(r.empty() == is_empty);
Expand Down
6 changes: 3 additions & 3 deletions tests/std/tests/P0896R4_views_elements/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ template <ranges::input_range Rng>
constexpr bool test_one(Rng&& rng) {
using ranges::elements_view, ranges::bidirectional_range, ranges::common_range, ranges::contiguous_range,
ranges::enable_borrowed_range, ranges::forward_range, ranges::input_range, ranges::iterator_t, ranges::prev,
ranges::random_access_range, ranges::range, ranges::range_reference_t, ranges::sentinel_t,
ranges::random_access_range, ranges::range, ranges::range_reference_t, ranges::sentinel_t, ranges::sized_range,
ranges::borrowed_range;

using V = views::all_t<Rng>;
Expand Down Expand Up @@ -157,7 +157,7 @@ constexpr bool test_one(Rng&& rng) {
const bool is_empty = ranges::empty(expected_keys);

// Validate view_interface::empty and operator bool
STATIC_ASSERT(CanMemberEmpty<R> == forward_range<Rng>);
STATIC_ASSERT(CanMemberEmpty<R> == (sized_range<Rng> || forward_range<Rng>) );
STATIC_ASSERT(CanBool<R> == CanEmpty<R>);
if constexpr (CanMemberEmpty<R>) {
assert(r.empty() == is_empty);
Expand All @@ -170,7 +170,7 @@ constexpr bool test_one(Rng&& rng) {
}
}

STATIC_ASSERT(CanMemberEmpty<const R> == forward_range<const Rng>);
STATIC_ASSERT(CanMemberEmpty<const R> == (sized_range<const Rng> || forward_range<const Rng>) );
STATIC_ASSERT(CanBool<const R> == CanEmpty<const R>);
if constexpr (CanMemberEmpty<const R>) {
assert(as_const(r).empty() == is_empty);
Expand Down
4 changes: 2 additions & 2 deletions tests/std/tests/P0896R4_views_take/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -219,7 +219,7 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}

// Validate view_interface::empty and operator bool
STATIC_ASSERT(CanMemberEmpty<R> == forward_range<Rng>);
STATIC_ASSERT(CanMemberEmpty<R> == (sized_range<Rng> || forward_range<Rng>) );
STATIC_ASSERT(CanBool<R> == CanEmpty<R>);
if constexpr (CanMemberEmpty<R>) {
assert(r.empty() == is_empty);
Expand All @@ -232,7 +232,7 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}
}

STATIC_ASSERT(CanMemberEmpty<const R> == forward_range<const Rng>);
STATIC_ASSERT(CanMemberEmpty<const R> == (sized_range<const Rng> || forward_range<const Rng>) );
STATIC_ASSERT(CanBool<const R> == CanEmpty<const R>);
if constexpr (CanMemberEmpty<const R>) {
assert(as_const(r).empty() == is_empty);
Expand Down
6 changes: 3 additions & 3 deletions tests/std/tests/P0896R4_views_transform/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ template <ranges::input_range Rng, ranges::random_access_range Expected>
constexpr bool test_one(Rng&& rng, Expected&& expected) {
using ranges::transform_view, ranges::bidirectional_range, ranges::common_range, ranges::contiguous_range,
ranges::enable_borrowed_range, ranges::forward_range, ranges::input_range, ranges::iterator_t, ranges::prev,
ranges::random_access_range, ranges::range, ranges::range_reference_t, ranges::sentinel_t;
ranges::random_access_range, ranges::sized_range, ranges::range, ranges::range_reference_t, ranges::sentinel_t;

constexpr bool is_view = ranges::view<remove_cvref_t<Rng>>;

Expand Down Expand Up @@ -169,7 +169,7 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
constexpr bool const_invocable = regular_invocable<const Fun&, range_reference_t<const V>>;

// Validate view_interface::empty and operator bool
STATIC_ASSERT(CanMemberEmpty<R> == forward_range<Rng>);
STATIC_ASSERT(CanMemberEmpty<R> == (sized_range<Rng> || forward_range<Rng>) );
STATIC_ASSERT(CanBool<R> == CanEmpty<R>);
if constexpr (CanMemberEmpty<R>) {
assert(r.empty() == is_empty);
Expand All @@ -182,7 +182,7 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}
}

STATIC_ASSERT(CanMemberEmpty<const R> == (forward_range<const Rng> && const_invocable));
STATIC_ASSERT(CanMemberEmpty<const R> == ((sized_range<const Rng> || forward_range<const Rng>) &&const_invocable));
STATIC_ASSERT(CanBool<const R> == CanEmpty<const R>);
if constexpr (CanMemberEmpty<const R>) {
assert(as_const(r).empty() == is_empty);
Expand Down
5 changes: 3 additions & 2 deletions tests/std/tests/P2442R1_views_chunk/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,7 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}

// Validate view_interface::empty and operator bool
STATIC_ASSERT(CanMemberEmpty<R> == forward_range<V>);
STATIC_ASSERT(CanMemberEmpty<R> == (sized_range<V> || forward_range<V>) );
STATIC_ASSERT(CanBool<R> == CanEmpty<R>);
if constexpr (CanMemberEmpty<R>) {
assert(r.empty() == is_empty);
Expand All @@ -124,7 +124,8 @@ constexpr bool test_one(Rng&& rng, Expected&& expected) {
}
}

STATIC_ASSERT(CanMemberEmpty<const R> == forward_range<const Rng>);
STATIC_ASSERT(
CanMemberEmpty<const R> == ((forward_range<Rng> && sized_range<const V>) || forward_range<const Rng>) );
STATIC_ASSERT(CanBool<const R> == CanEmpty<const R>);
if constexpr (CanMemberEmpty<const R>) {
assert(as_const(r).empty() == is_empty);
Expand Down