Fix location of invocable check for unique_ptr deleter

The deleter only needs to be invocable when the unique_ptr destructor
and reset member function are instantiated. In other contexts it might
not be possible to pass unique_ptr<T, D>::pointer to the deleter, if
that requires a derived-to-base conversion from T* and T is incomplete.

	* include/bits/unique_ptr.h (__uniq_ptr_impl): Remove static assertion
	checking invocable condition.
	(unique_ptr::~unique_ptr, unique_ptr::reset): Restore static assertion
	here, where types must be complete. Pass pointer to deleter as an
	rvalue.
	* testsuite/20_util/unique_ptr/requirements/incomplete.cc: New test.

From-SVN: r264399

libstdc++-v3/ChangeLog

+2018-09-18  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/bits/unique_ptr.h (__uniq_ptr_impl): Remove static assertion
+	checking invocable condition.
+	(unique_ptr::~unique_ptr, unique_ptr::reset): Restore static assertion
+	here, where types must be complete. Pass pointer to deleter as an
+	rvalue.
+	* testsuite/20_util/unique_ptr/requirements/incomplete.cc: New test.
+
 2018-09-13  Jonathan Wakely  <jwakely@redhat.com>
 
 	* include/std/variant (variant) [__clang__]: Limit workaround to

libstdc++-v3/include/bits/unique_ptr.h

@@ -142,8 +142,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static_assert( !is_rvalue_reference<_Dp>::value,
 		     "unique_ptr's deleter type must be a function object type"
 		     " or an lvalue reference type" );
-      static_assert( __is_invocable<_Dp&, pointer&>::value,
-	             "unique_ptr's deleter must be invocable with a pointer" );
 
       __uniq_ptr_impl() = default;
       __uniq_ptr_impl(pointer __p) : _M_t() { _M_ptr() = __p; }
@@ -282,9 +280,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       /// Destructor, invokes the deleter if the stored pointer is not null.
       ~unique_ptr() noexcept
       {
+	static_assert(__is_invocable<deleter_type&, pointer>::value,
+		      "unique_ptr's deleter must be invocable with a pointer");
 	auto& __ptr = _M_t._M_ptr();
 	if (__ptr != nullptr)
-	  get_deleter()(__ptr);
+	  get_deleter()(std::move(__ptr));
 	__ptr = pointer();
       }
 
@@ -389,10 +389,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       void
       reset(pointer __p = pointer()) noexcept
       {
+	static_assert(__is_invocable<deleter_type&, pointer>::value,
+		      "unique_ptr's deleter must be invocable with a pointer");
 	using std::swap;
 	swap(_M_t._M_ptr(), __p);
 	if (__p != pointer())
-	  get_deleter()(__p);
+	  get_deleter()(std::move(__p));
       }
 
       /// Exchange the pointer and deleter with another object.

libstdc++-v3/testsuite/20_util/unique_ptr/requirements/incomplete.cc

+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do compile { target c++11 } }
+
+#include <memory>
+
+struct Base; // incomplete
+
+struct BaseDeleter {
+  void operator()(Base*) const;
+};
+
+struct Derived; // incomplete
+
+struct X {
+  std::unique_ptr<Derived, BaseDeleter> p;
+  ~X(); // defined elsewhere, where Derived is complete
+};