[PATCH] libstdc++/ranges: Use C++23 deducing this for _Pipe and _Partial
Patrick Palka
ppalka@redhat.com
Thu Jan 11 00:26:23 GMT 2024
Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
-- >8 --
This simplifies the operator() of the _Pipe and _Partial range adaptor
closure objects using C++23 deducing this, allowing us to condense
multiple operator() overloads into one.
The new __like_t alias template is similar to the expositional one from
P0847R6, except it's implemented in terms of forward_like instead of vice
versa, and thus ours always yields a reference, so e.g. __like_t<A, char>
is char&&. This shouldn't make a difference in practice, I think..
libstdc++-v3/ChangeLog:
* include/bits/move.h (__like_t): Define.
* include/std/ranges (views::__adaptor::Partial::operator()):
Implement using C++23 deducing this when available.
(views::__adaptor::_Pipe::operator()): Likewise.
* testsuite/std/ranges/adaptors/100577.cc: Adjust testcase to
accept "no match for call" errors issued in C++23 mode instead
of "use of deleted function".
* testsuite/std/ranges/adaptors/lazy_split_neg.cc: Likewise.
---
libstdc++-v3/include/bits/move.h | 3 ++
libstdc++-v3/include/std/ranges | 37 ++++++++++++++++++-
.../testsuite/std/ranges/adaptors/100577.cc | 18 ++++-----
.../std/ranges/adaptors/lazy_split_neg.cc | 2 +-
4 files changed, 48 insertions(+), 12 deletions(-)
diff --git a/libstdc++-v3/include/bits/move.h b/libstdc++-v3/include/bits/move.h
index 4e741bcdeb0..bb200c95964 100644
--- a/libstdc++-v3/include/bits/move.h
+++ b/libstdc++-v3/include/bits/move.h
@@ -110,6 +110,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return static_cast<_Up&>(__x);
}
}
+
+ template<typename _Tp, typename _Up>
+ using __like_t = decltype(std::forward_like<_Tp>(std::declval<_Up>()));
#endif
/**
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 0734daa42bf..8d2649cf5b9 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -1016,7 +1016,19 @@ namespace views::__adaptor
// Invoke _Adaptor with arguments __r, _M_args... according to the
// value category of this _Partial object.
- // TODO: use explicit object functions ("deducing this").
+#if __cpp_explicit_this_parameter
+ template<typename _Self, typename _Range>
+ requires __adaptor_invocable<_Adaptor, _Range, __like_t<_Self, _Args>...>
+ constexpr auto
+ operator()(this _Self&& __self, _Range&& __r)
+ {
+ auto __forwarder = [&__r] (auto&&... __args) {
+ return _Adaptor{}(std::forward<_Range>(__r),
+ std::forward<decltype(__args)>(__args)...);
+ };
+ return std::apply(__forwarder, std::forward<_Self>(__self)._M_args);
+ }
+#else
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
constexpr auto
@@ -1042,6 +1054,7 @@ namespace views::__adaptor
template<typename _Range>
constexpr auto
operator()(_Range&& __r) const && = delete;
+#endif
};
// A lightweight specialization of the above primary template for
@@ -1058,6 +1071,14 @@ namespace views::__adaptor
: _M_arg(std::forward<_Tp>(__arg))
{ }
+#if __cpp_explicit_this_parameter
+ template<typename _Self, typename _Range>
+ requires __adaptor_invocable<_Adaptor, _Range, __like_t<_Self, _Arg>>
+ constexpr auto
+ operator()(this _Self&& __self, _Range&& __r)
+ { return _Adaptor{}(std::forward<_Range>(__r),
+ std::forward<_Self>(__self)._M_arg); }
+#else
template<typename _Range>
requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
constexpr auto
@@ -1073,6 +1094,7 @@ namespace views::__adaptor
template<typename _Range>
constexpr auto
operator()(_Range&& __r) const && = delete;
+#endif
};
// Partial specialization of the primary template for the case where the extra
@@ -1154,7 +1176,17 @@ namespace views::__adaptor
// Invoke _M_rhs(_M_lhs(__r)) according to the value category of this
// range adaptor closure object.
- // TODO: use explicit object functions ("deducing this").
+#if __cpp_explicit_this_parameter
+ template<typename _Self, typename _Range>
+ requires __pipe_invocable<__like_t<_Self, _Lhs>, __like_t<_Self, _Rhs>, _Range>
+ constexpr auto
+ operator()(this _Self&& __self, _Range&& __r)
+ {
+ return (std::forward<_Self>(__self)._M_rhs
+ (std::forward<_Self>(__self)._M_lhs
+ (std::forward<_Range>(__r))));
+ }
+#else
template<typename _Range>
requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
constexpr auto
@@ -1170,6 +1202,7 @@ namespace views::__adaptor
template<typename _Range>
constexpr auto
operator()(_Range&& __r) const && = delete;
+#endif
};
// A partial specialization of the above primary template for the case where
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
index 69072d69fec..3a52f5b4ce0 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
@@ -98,28 +98,28 @@ test02()
(views::take_while(badarg) | views::all)(x); // { dg-error "no match" }
(views::drop_while(badarg) | views::all)(x); // { dg-error "no match" }
- // In practice, range adaptor closures with non-simple operator() are
+ // In C++20 mode, range adaptor closures with non-simple operator() are
// implemented using a fallback deleted overload, so when a call is
// ill-formed overload resolution succeeds but selects the deleted overload
// (but only when the closure is invoked as an rvalue).
- views::lazy_split(badarg)(x); // { dg-error "deleted function" }
- (views::lazy_split(badarg) | views::all)(x); // { dg-error "deleted function" }
+ views::lazy_split(badarg)(x); // { dg-error "deleted function|no match" }
+ (views::lazy_split(badarg) | views::all)(x); // { dg-error "deleted function|no match" }
auto a0 = views::lazy_split(badarg);
a0(x); // { dg-error "no match" };
auto a1 = a0 | views::all;
a1(x); // { dg-error "no match" }
- views::split(badarg)(x); // { dg-error "deleted function" }
- (views::split(badarg) | views::all)(x); // { dg-error "deleted function" }
+ views::split(badarg)(x); // { dg-error "deleted function|no match" }
+ (views::split(badarg) | views::all)(x); // { dg-error "deleted function|no match" }
auto a0a = views::split(badarg);
a0a(x); // { dg-error "no match" };
auto a1a = a0a | views::all;
a1a(x); // { dg-error "no match" }
- views::take(badarg)(x); // { dg-error "deleted" }
- views::drop(badarg)(x); // { dg-error "deleted" }
- (views::take(badarg) | views::all)(x); // { dg-error "deleted" }
- (views::drop(badarg) | views::all)(x); // { dg-error "deleted" }
+ views::take(badarg)(x); // { dg-error "deleted|no match" }
+ views::drop(badarg)(x); // { dg-error "deleted|no match" }
+ (views::take(badarg) | views::all)(x); // { dg-error "deleted|no match" }
+ (views::drop(badarg) | views::all)(x); // { dg-error "deleted|no match" }
}
void
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split_neg.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split_neg.cc
index 683ea76da07..85632759fcc 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split_neg.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split_neg.cc
@@ -38,7 +38,7 @@ test02()
{
using namespace std::literals;
auto x = "the quick brown fox"sv;
- auto v1 = views::lazy_split(std::initializer_list<char>{' ', ' '})(x); // { dg-error "deleted" }
+ auto v1 = views::lazy_split(std::initializer_list<char>{' ', ' '})(x); // { dg-error "deleted|no match" }
auto v2 = x | views::lazy_split(std::initializer_list<char>{' ', ' '}); // { dg-error "no match" }
}
--
2.43.0.283.ga54a84b333
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