K-ballo created this revision.
Implement LWG2993, `reference_wrapper<T>` conversion from `T&&`.
The conversion fail test currently fails to fail (passes), due to
https://bugs.llvm.org/show_bug.cgi?id=35332. Flagging it `XFAIL` does not seem
to have any effect.
https://reviews.llvm.org/D40259
Files:
include/__functional_base
test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.fail.cpp
test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp
Index: test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp
===================================================================
--- /dev/null
+++ test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp
@@ -0,0 +1,58 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <functional>
+
+// reference_wrapper
+
+// template <typename U> reference_wrapper(U&&);
+
+// XFAIL: c++98, c++03, c++11, c++14, c++17
+
+#include <functional>
+#include <cassert>
+
+struct convertible_to_int_ref {
+ int val = 0;
+ operator int&() { return val; }
+ operator int const&() const { return val; }
+};
+
+struct convertible_from_int {
+ convertible_from_int(int) {}
+};
+
+void meow(std::reference_wrapper<int>) {}
+void meow(convertible_from_int) {}
+
+int gi;
+std::reference_wrapper<int> purr() { return gi; };
+
+template <class T>
+void
+test(T& t)
+{
+ std::reference_wrapper<T> r(t);
+ assert(&r.get() == &t);
+}
+
+void f() {}
+
+int main()
+{
+ convertible_to_int_ref convi;
+ test(convi);
+ convertible_to_int_ref const convic;
+ test(convic);
+
+ {
+ meow(0);
+ (true) ? purr() : 0;
+ }
+}
Index: test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.fail.cpp
===================================================================
--- /dev/null
+++ test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.fail.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <functional>
+
+// reference_wrapper
+
+// template <typename U> reference_wrapper(U&&);
+
+// XFAIL: c++98, c++03, c++11, c++14, c++17
+
+#include <functional>
+#include <cassert>
+
+struct convertible_to_float_ref {
+ float val = 0;
+ operator float const&() const { return val; }
+};
+
+int main()
+{
+ convertible_to_float_ref convf;
+ std::reference_wrapper<const int> r(convf);
+}
Index: test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
===================================================================
--- test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
+++ test/std/utilities/function.objects/refwrap/refwrap.assign/copy_assign.pass.cpp
@@ -20,6 +20,12 @@
{
};
+struct convertible_to_int_ref {
+ int val = 0;
+ operator int&() { return val; }
+ operator int const&() const { return val; }
+};
+
template <class T>
void
test(T& t)
@@ -54,4 +60,11 @@
test(i);
const int j = 0;
test(j);
+
+#if TEST_STD_VER > 17
+ convertible_to_int_ref convi;
+ test(convi);
+ convertible_to_int_ref const convic;
+ test(convic);
+#endif
}
Index: include/__functional_base
===================================================================
--- include/__functional_base
+++ include/__functional_base
@@ -371,6 +371,15 @@
#endif
};
+#if _LIBCPP_STD_VER > 17
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_Tp& __lvref_bind(_Tp& r) _NOEXCEPT { return r; }
+
+template <class _Tp>
+_Tp& __lvref_bind(_Tp&& r) = delete;
+#endif
+
template <class _Tp>
class _LIBCPP_TEMPLATE_VIS reference_wrapper
: public __weak_result_type<_Tp>
@@ -383,11 +392,22 @@
public:
// construct/copy/destroy
+#if _LIBCPP_STD_VER > 17
+ template <class _Up, class = enable_if_t<
+ !is_same<__uncvref_t<_Up>, reference_wrapper>::value
+ >, class = typename __void_t<
+ decltype(_VSTD::__lvref_bind<_Tp>(_VSTD::declval<_Up>()))
+ >::type>
+ _LIBCPP_INLINE_VISIBILITY reference_wrapper(_Up&& __u)
+ _NOEXCEPT_(noexcept(_VSTD::__lvref_bind<_Tp>(_VSTD::forward<_Up>(__u))))
+ : __f_(_VSTD::addressof(_VSTD::__lvref_bind<_Tp>(_VSTD::forward<_Up>(__u)))) {}
+#else
_LIBCPP_INLINE_VISIBILITY reference_wrapper(type& __f) _NOEXCEPT
: __f_(_VSTD::addressof(__f)) {}
#ifndef _LIBCPP_CXX03_LANG
private: reference_wrapper(type&&); public: // = delete; // do not bind to temps
#endif
+#endif
// access
_LIBCPP_INLINE_VISIBILITY operator type& () const _NOEXCEPT {return *__f_;}
@@ -509,6 +529,10 @@
#endif // _LIBCPP_CXX03_LANG
};
+#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
+template <class _Tp>
+reference_wrapper(_Tp&) -> reference_wrapper<_Tp>;
+#endif
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
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