On 07/03/25 17:44 +0100, Tomasz Kamiński wrote:
Add missing move_constructible && regular_invocable constrains on functor type,
and is_object on functor result type for invocations of views::zip_transform
without range arguments.
PR libstdc++/111138
libstdc++-v3/ChangeLog:
* include/std/ranges (_ZipTransform::operator()):
Create separate overload for calls with empty range pack,
and add move_constructible, regular_invocable and
is_object_v<invoke_result_t<...>>> constraints.
* testsuite/std/ranges/zip_transform/1.cc: New tests
---
Move the empty-ranges case into separate `operator()`.
Add missing `is_object<invoke_result_t<....>>`.
Tested on x86_64-linux. OK for trunk?
libstdc++-v3/include/std/ranges | 16 +++++++++-----
.../testsuite/std/ranges/zip_transform/1.cc | 21 +++++++++++++++++++
2 files changed, 32 insertions(+), 5 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index e21f5284b46..97d22a12dc6 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -5331,15 +5331,21 @@ namespace views::__adaptor
struct _ZipTransform
{
+ template<typename _Fp>
I'd have been tempted to write this:
template<typename _Fp, typename _Fd = decay_t<_Fp>>
and then use _Fd in the constraints and the body, but this way is fine
(and the downside of adding _Fd is that it would allow sociopaths to
call zip_transform.operator()<Foo&, Foo&>(foo) which would be even
worse than allowing zip_transform.operator()<Foo&>(foo) today!)
OK for trunk, without the change above. Thanks.
+ requires move_constructible<decay_t<_Fp>> &&
regular_invocable<decay_t<_Fp>&>
+ && is_object_v<decay_t<invoke_result_t<decay_t<_Fp>&>>>
+ constexpr auto
+ operator() [[nodiscard]] (_Fp&& __f) const
+ {
+ return views::empty<decay_t<invoke_result_t<decay_t<_Fp>&>>>;
+ }
+
template<typename _Fp, typename... _Ts>
- requires (sizeof...(_Ts) == 0) || __detail::__can_zip_transform_view<_Fp,
_Ts...>
+ requires (sizeof...(_Ts) != 0) && __detail::__can_zip_transform_view<_Fp,
_Ts...>
constexpr auto
operator() [[nodiscard]] (_Fp&& __f, _Ts&&... __ts) const
{
- if constexpr (sizeof...(_Ts) == 0)
- return views::empty<decay_t<invoke_result_t<decay_t<_Fp>&>>>;
- else
- return zip_transform_view(std::forward<_Fp>(__f),
std::forward<_Ts>(__ts)...);
+ return zip_transform_view(std::forward<_Fp>(__f),
std::forward<_Ts>(__ts)...);
}
};
diff --git a/libstdc++-v3/testsuite/std/ranges/zip_transform/1.cc
b/libstdc++-v3/testsuite/std/ranges/zip_transform/1.cc
index 20abdcba0f8..9a0ad3814e6 100644
--- a/libstdc++-v3/testsuite/std/ranges/zip_transform/1.cc
+++ b/libstdc++-v3/testsuite/std/ranges/zip_transform/1.cc
@@ -9,6 +9,23 @@
namespace ranges = std::ranges;
namespace views = std::views;
+template<typename T>
+concept can_zip_transform = requires (T t) {
+ views::zip_transform(std::forward<T>(t));
+};
+
+static_assert(!can_zip_transform<int>);
+
+struct NonMovable {
+ NonMovable(NonMovable&&) = delete;
+};
+
+static_assert(!can_zip_transform<NonMovable>);
+static_assert(!can_zip_transform<NonMovable&>);
+
+static_assert(!can_zip_transform<void(*)()>);
+static_assert(can_zip_transform<int(&(*)())[3]>);
+
constexpr bool
test01()
{
@@ -46,6 +63,10 @@ test01()
VERIFY( ranges::size(z3) == 3 );
VERIFY( ranges::equal(z3, (int[]){3, 6, 9}) );
+ auto z4 = views::zip_transform([] () { return 1; });
+ VERIFY( ranges::size(z4) == 0 );
+ static_assert( std::same_as<ranges::range_value_t<decltype(z4)>, int> );
+
return true;
}
--
2.48.1
