This force-enables perfect forwarding call wrapper semantics whenever
the extra arguments of a partially applied range adaptor aren't all
trivially copyable, so as to avoid incurring unnecessary copies of
potentially expensive-to-copy objects (such as std::function objects)
when invoking the adaptor.
Tested on x86_64-pc-linux-gnu, does this look OK for trunk/11?
PR libstdc++/100940
libstdc++-v3/ChangeLog:
* include/std/ranges (__adaptor::__adaptor_has_simple_extra_args): Also
require that the extra arguments are trivially copyable.
* testsuite/std/ranges/adaptors/100577.cc (test04): New test.
---
libstdc++-v3/include/std/ranges | 6 ++++--
.../testsuite/std/ranges/adaptors/100577.cc | 19 +++++++++++++++++++
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 856975c6934..e858df88088 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -818,8 +818,10 @@ namespace views::__adaptor
// True if the behavior of the range adaptor non-closure _Adaptor is
// independent of the value category of its extra arguments _Args.
template<typename _Adaptor, typename... _Args>
- concept __adaptor_has_simple_extra_args =
_Adaptor::_S_has_simple_extra_args
- || _Adaptor::template _S_has_simple_extra_args<_Args...>;
+ concept __adaptor_has_simple_extra_args
+ = (_Adaptor::_S_has_simple_extra_args
+ || _Adaptor::template _S_has_simple_extra_args<_Args...>)
+ && (is_trivially_copyable_v<_Args> && ...);
// A range adaptor closure that represents partial application of
// the range adaptor _Adaptor with arguments _Args.
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
b/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
index 8ef084621f9..4040f474ad9 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/100577.cc
@@ -21,6 +21,7 @@
// PR libstdc++/100577
#include <ranges>
+#include <functional>
namespace ranges = std::ranges;
namespace views = std::ranges::views;
@@ -113,4 +114,22 @@ test03()
x | std::views::drop(S{});
}
+void
+test04()
+{
+ // Non-trivially-copyable extra arguments make a closure not simple.
+ using F = std::function<bool(bool)>;
+ static_assert(!std::is_trivially_copyable_v<F>);
+ using views::__adaptor::__adaptor_has_simple_extra_args;
+ using views::__adaptor::__closure_has_simple_call_op;
+ static_assert(!__adaptor_has_simple_extra_args<decltype(views::take_while),
F>);
+ static_assert(!__adaptor_has_simple_extra_args<decltype(views::drop_while),
F>);
+ static_assert(!__adaptor_has_simple_extra_args<decltype(views::filter), F>);
+ static_assert(!__adaptor_has_simple_extra_args<decltype(views::transform),
F>);
+
static_assert(!__closure_has_simple_call_op<decltype(views::take_while(std::declval<F>()))>);
+
static_assert(!__closure_has_simple_call_op<decltype(views::drop_while(std::declval<F>()))>);
+
static_assert(!__closure_has_simple_call_op<decltype(views::filter(std::declval<F>()))>);
+
static_assert(!__closure_has_simple_call_op<decltype(views::transform(std::declval<F>()))>);
+}
+
// { dg-prune-output "in requirements" }
--
2.32.0.93.g670b81a890
