Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Implement LWG-4083 views::as_rvalue should reject non-input ranges #4786

Merged
merged 5 commits into from
Jul 11, 2024
Merged

Implement LWG-4083 views::as_rvalue should reject non-input ranges #4786

Show file tree
Hide file tree
Changes from 3 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
898428a
Implement LWG-4083
frederick-vs-ja Jul 4, 2024
e89a1ff
Workaround for DevCom-10698021
frederick-vs-ja Jul 6, 2024
7ce567e
Merge branch 'main' into lwg-4083
frederick-vs-ja Jul 6, 2024
5450af7
"perma-workaround" the direct-initialization
frederick-vs-ja Jul 7, 2024
7a66606
Code review feedback.
StephanTLavavej Jul 8, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 5 additions & 1 deletion stl/inc/ranges
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1524,15 +1524,19 @@ namespace ranges {

namespace views {
template <class _Rng>
#ifdef __EDG__ // TRANSITION, DevCom-10698021
concept _Can_as_rvalue = requires(_Rng&& __r) { as_rvalue_view(static_cast<_Rng&&>(__r)); };
#else // ^^^ workaround / no workaround vvv
StephanTLavavej marked this conversation as resolved.
Show resolved Hide resolved
concept _Can_as_rvalue = requires(_Rng&& __r) { as_rvalue_view{static_cast<_Rng&&>(__r)}; };
#endif // ^^^ no workaround ^^^

class _As_rvalue_fn : public _Pipe::_Base<_As_rvalue_fn> {
private:
enum class _St { _None, _All, _As_rvalue };

template <class _Rng>
_NODISCARD static consteval _Choice_t<_St> _Choose() noexcept {
if constexpr (same_as<range_rvalue_reference_t<_Rng>, range_reference_t<_Rng>>) {
if constexpr (input_range<_Rng> && same_as<range_rvalue_reference_t<_Rng>, range_reference_t<_Rng>>) {
return {_St::_All, noexcept(views::all(_STD declval<_Rng>()))};
} else if constexpr (_Can_as_rvalue<_Rng>) {
return {_St::_As_rvalue, noexcept(as_rvalue_view{_STD declval<_Rng>()})};
StephanTLavavej marked this conversation as resolved.
Show resolved Hide resolved
Expand Down
11 changes: 11 additions & 0 deletions tests/std/tests/P2446R2_views_as_rvalue/test.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -401,6 +401,17 @@ void test_example_from_p2446r2() {
assert(ranges::all_of(words, ranges::empty)); // all strings from words are empty (implementation assumption)
}

// LWG-4083 "views::as_rvalue should reject non-input ranges"
struct OutputRvalueIterator {
using difference_type = int;
int operator*() const;
OutputRvalueIterator& operator++();
void operator++(int);
};
using OutputRvalueRange = decltype(ranges::subrange{OutputRvalueIterator{}, unreachable_sentinel});

static_assert(!CanViewAsRvalue<OutputRvalueRange>);
frederick-vs-ja marked this conversation as resolved.
Show resolved Hide resolved

int main() {
{ // Validate views
// ... copyable
Expand Down