Implement LWG 2905 changes to constrain unique_ptr constructors

Message ID 20180911105542.GA9412@redhat.com
State New
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  • Implement LWG 2905 changes to constrain unique_ptr constructors
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Commit Message

Jonathan Wakely Sept. 11, 2018, 10:56 a.m.
LWG DR 2905 says that is_constructible_v<unique_ptr<P, D>, P, D const &>
should be false when D is not copy constructible. This commit implements
the changes from the DR and simplifies the signatures as per
https://github.com/cplusplus/draft/issues/1530

	* include/bits/unique_ptr.h (__uniq_ptr_impl): Add assertions to
	check deleter type.
	(unique_ptr::unique_ptr(pointer, const deleter_type&)): Add copy
	constructible constraint.
	(unique_ptr::unique_ptr(pointer, deleter_type&&)): Disable for
	deleters of reference type and add move constructible constraint.
	(unique_ptr::unique_ptr(pointer, remove_reference_t<deleter_type>&&)):
	Disable for deleters of non-reference type. Define as deleted.
	(unique_ptr<T[], D>): Likewise.
	* testsuite/20_util/unique_ptr/assign/48635_neg.cc: Replace dg-error
	directives with unstable line numbers with dg-prune-output.
	* testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc: Likewise.
	* testsuite/20_util/unique_ptr/cons/lwg2905.cc: New test.
	* testsuite/20_util/unique_ptr/specialized_algorithms/swap_cxx17.cc:
	Make deleter types invocable.

Tested x86_64-linux, committed to trunk.
commit a5a9ca63acf949d4dddec9822019505344347459
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Sep 11 10:14:24 2018 +0100

    Implement LWG 2905 changes to constrain unique_ptr constructors
    
    LWG DR 2905 says that is_constructible_v<unique_ptr<P, D>, P, D const &>
    should be false when D is not copy constructible. This commit implements
    the changes from the DR and simplifies the signatures as per
    https://github.com/cplusplus/draft/issues/1530
    
            * include/bits/unique_ptr.h (__uniq_ptr_impl): Add assertions to
            check deleter type.
            (unique_ptr::unique_ptr(pointer, const deleter_type&)): Add copy
            constructible constraint.
            (unique_ptr::unique_ptr(pointer, deleter_type&&)): Disable for
            deleters of reference type and add move constructible constraint.
            (unique_ptr::unique_ptr(pointer, remove_reference_t<deleter_type>&&)):
            Disable for deleters of non-reference type. Define as deleted.
            (unique_ptr<T[], D>): Likewise.
            * testsuite/20_util/unique_ptr/assign/48635_neg.cc: Replace dg-error
            directives with unstable line numbers with dg-prune-output.
            * testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc: Likewise.
            * testsuite/20_util/unique_ptr/cons/lwg2905.cc: New test.
            * testsuite/20_util/unique_ptr/specialized_algorithms/swap_cxx17.cc:
            Make deleter types invocable.

Patch

diff --git a/libstdc++-v3/include/bits/unique_ptr.h b/libstdc++-v3/include/bits/unique_ptr.h
index 4c99a9c0d9b..ddc6ae0e233 100644
--- a/libstdc++-v3/include/bits/unique_ptr.h
+++ b/libstdc++-v3/include/bits/unique_ptr.h
@@ -139,6 +139,12 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       using pointer = typename _Ptr<_Tp, _Dp>::type;
 
+      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; }
 
@@ -159,9 +165,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template <typename _Tp, typename _Dp = default_delete<_Tp>>
     class unique_ptr
     {
-      template <class _Up>
-      using _DeleterConstraint =
-	typename __uniq_ptr_impl<_Tp, _Up>::_DeleterConstraint::type;
+      template <typename _Up>
+	using _DeleterConstraint =
+	  typename __uniq_ptr_impl<_Tp, _Up>::_DeleterConstraint::type;
 
       __uniq_ptr_impl<_Tp, _Dp> _M_t;
 
@@ -170,6 +176,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using element_type  = _Tp;
       using deleter_type  = _Dp;
 
+    private:
       // helper template for detecting a safe conversion from another
       // unique_ptr
       template<typename _Up, typename _Ep>
@@ -183,11 +190,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
                 >
               >;
 
+    public:
       // Constructors.
 
       /// Default constructor, creates a unique_ptr that owns nothing.
-      template <typename _Up = _Dp,
-		typename = _DeleterConstraint<_Up>>
+      template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 	constexpr unique_ptr() noexcept
 	: _M_t()
         { }
@@ -198,8 +205,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *
        * The deleter will be value-initialized.
        */
-      template <typename _Up = _Dp,
-		typename = _DeleterConstraint<_Up>>
+      template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 	explicit
 	unique_ptr(pointer __p) noexcept
 	: _M_t(__p)
@@ -212,27 +218,34 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *
        * The deleter will be initialized with @p __d
        */
-      unique_ptr(pointer __p,
-	  typename conditional<is_reference<deleter_type>::value,
-	    deleter_type, const deleter_type&>::type __d) noexcept
-      : _M_t(__p, __d) { }
+      template<typename _Del = deleter_type,
+	       typename = _Require<is_copy_constructible<_Del>>>
+	unique_ptr(pointer __p, const deleter_type& __d) noexcept
+	: _M_t(__p, __d) { }
 
       /** Takes ownership of a pointer.
        *
        * @param __p  A pointer to an object of @c element_type
-       * @param __d  An rvalue reference to a deleter.
+       * @param __d  An rvalue reference to a (non-reference) deleter.
        *
        * The deleter will be initialized with @p std::move(__d)
        */
-      unique_ptr(pointer __p,
-	  typename remove_reference<deleter_type>::type&& __d) noexcept
-      : _M_t(std::move(__p), std::move(__d))
-      { static_assert(!std::is_reference<deleter_type>::value,
-		      "rvalue deleter bound to reference"); }
+      template<typename _Del = deleter_type,
+	       typename = _Require<is_move_constructible<_Del>>>
+	unique_ptr(pointer __p,
+		   __enable_if_t<!is_lvalue_reference<_Del>::value,
+				 _Del&&> __d) noexcept
+	: _M_t(__p, std::move(__d))
+	{ }
+
+      template<typename _Del = deleter_type,
+	       typename _DelUnref = typename remove_reference<_Del>::type>
+	unique_ptr(pointer,
+		   __enable_if_t<is_lvalue_reference<_Del>::value,
+				 _DelUnref&&>) = delete;
 
       /// Creates a unique_ptr that owns nothing.
-      template <typename _Up = _Dp,
-		typename = _DeleterConstraint<_Up>>
+      template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 	constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
 
       // Move constructors.
@@ -454,8 +467,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // Constructors.
 
       /// Default constructor, creates a unique_ptr that owns nothing.
-      template <typename _Up = _Dp,
-		typename = _DeleterConstraint<_Up>>
+      template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 	constexpr unique_ptr() noexcept
 	: _M_t()
         { }
@@ -485,12 +497,10 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *
        * The deleter will be initialized with @p __d
        */
-      template<typename _Up,
-               typename = typename enable_if<
-                 __safe_conversion_raw<_Up>::value, bool>::type>
-      unique_ptr(_Up __p,
-                 typename conditional<is_reference<deleter_type>::value,
-                 deleter_type, const deleter_type&>::type __d) noexcept
+      template<typename _Up, typename _Del = deleter_type,
+	       typename = _Require<__safe_conversion_raw<_Up>,
+				   is_copy_constructible<_Del>>>
+      unique_ptr(_Up __p, const deleter_type& __d) noexcept
       : _M_t(__p, __d) { }
 
       /** Takes ownership of a pointer.
@@ -501,22 +511,28 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *
        * The deleter will be initialized with @p std::move(__d)
        */
-      template<typename _Up,
-               typename = typename enable_if<
-                 __safe_conversion_raw<_Up>::value, bool>::type>
-      unique_ptr(_Up __p, typename
-		 remove_reference<deleter_type>::type&& __d) noexcept
-      : _M_t(std::move(__p), std::move(__d))
-      { static_assert(!is_reference<deleter_type>::value,
-		      "rvalue deleter bound to reference"); }
+      template<typename _Up, typename _Del = deleter_type,
+	       typename = _Require<__safe_conversion_raw<_Up>,
+				   is_move_constructible<_Del>>>
+	unique_ptr(_Up __p,
+		   __enable_if_t<!is_lvalue_reference<_Del>::value,
+				 _Del&&> __d) noexcept
+	: _M_t(std::move(__p), std::move(__d))
+	{ }
+
+      template<typename _Up, typename _Del = deleter_type,
+	       typename _DelUnref = typename remove_reference<_Del>::type,
+	       typename = _Require<__safe_conversion_raw<_Up>>>
+	unique_ptr(_Up,
+		   __enable_if_t<is_lvalue_reference<_Del>::value,
+				 _DelUnref&&>) = delete;
 
       /// Move constructor.
       unique_ptr(unique_ptr&& __u) noexcept
       : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter())) { }
 
       /// Creates a unique_ptr that owns nothing.
-      template <typename _Up = _Dp,
-		typename = _DeleterConstraint<_Up>>
+      template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 	constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
 
       template<typename _Up, typename _Ep,
diff --git a/libstdc++-v3/testsuite/20_util/unique_ptr/assign/48635_neg.cc b/libstdc++-v3/testsuite/20_util/unique_ptr/assign/48635_neg.cc
index b22d0e123b4..0c8f8b357bb 100644
--- a/libstdc++-v3/testsuite/20_util/unique_ptr/assign/48635_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/unique_ptr/assign/48635_neg.cc
@@ -42,10 +42,10 @@  void f()
   std::unique_ptr<int, D&> ud(nullptr, d);
   ub = std::move(ud); // { dg-error "no match" }
   ub2 = ud; // { dg-error "no match" }
-// { dg-error "no type" "" { target *-*-* } 307 }
 
   std::unique_ptr<int[], B&> uba(nullptr, b);
   std::unique_ptr<int[], D&> uda(nullptr, d);
   uba = std::move(uda); // { dg-error "no match" }
-// { dg-error "no type" "" { target *-*-* } 566 }
 }
+
+// { dg-prune-output "no type" }
diff --git a/libstdc++-v3/testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc b/libstdc++-v3/testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc
index c1b1c9efc64..7e820ba129a 100644
--- a/libstdc++-v3/testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/unique_ptr/cons/cv_qual_neg.cc
@@ -39,7 +39,7 @@  test07()
   std::unique_ptr<const A[]> cA3(p); // { dg-error "no matching function" }
   std::unique_ptr<volatile A[]> vA3(p); // { dg-error "no matching function" }
   std::unique_ptr<const volatile A[]> cvA3(p); // { dg-error "no matching function" }
-  // { dg-error "no type" "" { target *-*-* } 473 }
+  // { dg-prune-output "no type" }
 }
 
 template<typename T>
diff --git a/libstdc++-v3/testsuite/20_util/unique_ptr/cons/lwg2905.cc b/libstdc++-v3/testsuite/20_util/unique_ptr/cons/lwg2905.cc
new file mode 100644
index 00000000000..8700630d1b3
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/unique_ptr/cons/lwg2905.cc
@@ -0,0 +1,78 @@ 
+// Copyright (C) 2017 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>
+
+template<typename T, typename D, typename P, typename E>
+constexpr bool check()
+{ return std::is_constructible<std::unique_ptr<T, D>, P, E>::value; }
+
+struct Del { void operator()(void*) const { } };
+
+static_assert( ! check<int, Del&, int*, Del>(), "" );
+static_assert( check<int, Del&, int*, Del&>(), "" );
+static_assert( check<int, const Del&, int*, Del&>(), "" );
+static_assert( ! check<int, Del&, int*, const Del&>(), "" );
+static_assert( check<int, Del, int*, const Del&>(), "" );
+static_assert( check<int, Del, int*, Del>(), "" );
+
+static_assert( ! check<int[], Del&, int*, Del>(), "" );
+static_assert( check<int[], Del&, int*, Del&>(), "" );
+static_assert( check<int[], const Del&, int*, Del&>(), "" );
+static_assert( ! check<int[], Del&, int*, const Del&>(), "" );
+static_assert( check<int[], Del, int*, const Del&>(), "" );
+static_assert( check<int[], Del, int*, Del>(), "" );
+
+struct DelNoCopy {
+  DelNoCopy() = default;
+  DelNoCopy(const DelNoCopy&) = delete;
+  DelNoCopy(DelNoCopy&&) = default;
+  void operator()(void*) const { }
+};
+
+static_assert( ! check<int, DelNoCopy&, int*, DelNoCopy>(), "" );
+static_assert( check<int, DelNoCopy&, int*, DelNoCopy&>(), "" );
+static_assert( check<int, const DelNoCopy&, int*, DelNoCopy&>(), "" );
+static_assert( ! check<int, DelNoCopy&, int*, const DelNoCopy&>(), "" );
+static_assert( ! check<int, DelNoCopy, int*, const DelNoCopy&>(), "" );
+static_assert( check<int, DelNoCopy, int*, DelNoCopy>(), "" );
+
+static_assert( ! check<int[], DelNoCopy&, int*, DelNoCopy>(), "" );
+static_assert( check<int[], DelNoCopy&, int*, DelNoCopy&>(), "" );
+static_assert( check<int[], const DelNoCopy&, int*, DelNoCopy&>(), "" );
+static_assert( ! check<int[], DelNoCopy&, int*, const DelNoCopy&>(), "" );
+static_assert( ! check<int[], DelNoCopy, int*, const DelNoCopy&>(), "" );
+static_assert( check<int[], DelNoCopy, int*, DelNoCopy>(), "" );
+
+struct Base { virtual ~Base() { } };
+struct Derived : Base { };
+
+static_assert( ! check<Base[], Del&, Base*, Del>(), "" );
+static_assert( check<Base[], Del&, Base*, Del&>(), "" );
+static_assert( check<Base[], const Del&, Base*, Del&>(), "" );
+static_assert( ! check<Base[], Del&, Base*, const Del&>(), "" );
+static_assert( check<Base[], Del, Base*, const Del&>(), "" );
+static_assert( check<Base[], Del, Base*, Del>(), "" );
+
+static_assert( ! check<Base[], Del&, Derived*, Del>(), "" );
+static_assert( ! check<Base[], Del&, Derived*, Del&>(), "" );
+static_assert( ! check<Base[], const Del&, Derived*, Del&>(), "" );
+static_assert( ! check<Base[], Del&, Derived*, const Del&>(), "" );
+static_assert( ! check<Base[], Del, Derived*, const Del&>(), "" );
+static_assert( ! check<Base[], Del, Derived*, Del>(), "" );
diff --git a/libstdc++-v3/testsuite/20_util/unique_ptr/specialized_algorithms/swap_cxx17.cc b/libstdc++-v3/testsuite/20_util/unique_ptr/specialized_algorithms/swap_cxx17.cc
index 298d951d319..604685c1ab1 100644
--- a/libstdc++-v3/testsuite/20_util/unique_ptr/specialized_algorithms/swap_cxx17.cc
+++ b/libstdc++-v3/testsuite/20_util/unique_ptr/specialized_algorithms/swap_cxx17.cc
@@ -21,13 +21,18 @@ 
 #include <memory>
 
 // Not swappable, and unique_ptr not swappable via the generic std::swap.
-struct C { };
+struct C {
+  void operator()(void*) const { }
+};
 void swap(C&, C&) = delete;
 
 static_assert( !std::is_swappable_v<std::unique_ptr<int, C>> );
 
 // Not swappable, and unique_ptr not swappable via the generic std::swap.
-struct D { D(D&&) = delete; };
+struct D {
+  D(D&&) = delete;
+  void operator()(void*) const { }
+};
 
 static_assert( !std::is_swappable_v<std::unique_ptr<int, D>> );