libstdc++: Improve diagnostics for ill-formed std::_Destroy and std::_Destroy_n ...

By using std::is_trivially_destructible instead of the old
__has_trivial_destructor built-in we no longer need the static_assert to
deal with types with deleted destructors. All non-destructible types,
including those with deleted destructors, will now give user-friendly
diagnostics that clearly explain the problem.

Also combine the _Destroy_aux and _Destroy_n_aux class templates used
for C++98 into one, so that we perform fewer expensive class template
instantiations.

libstdc++-v3/ChangeLog:

	PR libstdc++/120390
	* include/bits/stl_construct.h (_Destroy_aux::__destroy_n): New
	static member function.
	(_Destroy_aux<true>::__destroy_n): Likewise.
	(_Destroy_n_aux): Remove.
	(_Destroy(ForwardIterator, ForwardIterator)): Remove
	static_assert. Use is_trivially_destructible instead of
	__has_trivial_destructor.
	(_Destroy_n): Likewise. Use _Destroy_aux::__destroy_n instead of
	_Destroy_n_aux::__destroy_n.
	* testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_neg.cc:
	Adjust dg-error strings. Move destroy_n tests to ...
	* testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_n_neg.cc:
	New test.
	* testsuite/23_containers/vector/cons/destructible_debug_neg.cc:
	Adjust dg-error strings.
	* testsuite/23_containers/vector/cons/destructible_neg.cc:
	Likewise.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

diff --git a/libstdc++-v3/include/bits/stl_construct.h b/libstdc++-v3/include/bits/stl_construct.h
index 23b8fb754710d80ee2d9070d12581a6fab6000ac..3ac75715e0e050ccbd94c4a0a9e5ac5f8f6051d7 100644 (file)
--- a/libstdc++-v3/include/bits/stl_construct.h
+++ b/libstdc++-v3/include/bits/stl_construct.h
@@ -181,6 +181,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
          for (; __first != __last; ++__first)
            std::_Destroy(std::__addressof(*__first));
        }
+
+      template<typename _ForwardIterator, typename _Size>
+       static _GLIBCXX20_CONSTEXPR _ForwardIterator
+       __destroy_n(_ForwardIterator __first, _Size __count)
+       {
+         for (; __count > 0; (void)++__first, --__count)
+           std::_Destroy(std::__addressof(*__first));
+         return __first;
+       }
     };
 
   template<>
@@ -189,6 +198,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _ForwardIterator>
         static void
         __destroy(_ForwardIterator, _ForwardIterator) { }
+
+      template<typename _ForwardIterator, typename _Size>
+       static _ForwardIterator
+       __destroy_n(_ForwardIterator __first, _Size __count)
+       {
+         std::advance(__first, __count);
+         return __first;
+       }
     };
 #endif
 
@@ -204,10 +221,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       typedef typename iterator_traits<_ForwardIterator>::value_type
                        _Value_type;
 #if __cplusplus >= 201103L
-      // A deleted destructor is trivial, this ensures we reject such types:
-      static_assert(is_destructible<_Value_type>::value,
-                   "value type is destructible");
-      if constexpr (!__has_trivial_destructor(_Value_type))
+      if constexpr (!is_trivially_destructible<_Value_type>::value)
        for (; __first != __last; ++__first)
          std::_Destroy(std::__addressof(*__first));
 #if __cpp_constexpr_dynamic_alloc // >= C++20
@@ -221,33 +235,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #endif
     }
 
-#if __cplusplus < 201103L
-  template<bool>
-    struct _Destroy_n_aux
-    {
-      template<typename _ForwardIterator, typename _Size>
-       static _GLIBCXX20_CONSTEXPR _ForwardIterator
-       __destroy_n(_ForwardIterator __first, _Size __count)
-       {
-         for (; __count > 0; (void)++__first, --__count)
-           std::_Destroy(std::__addressof(*__first));
-         return __first;
-       }
-    };
-
-  template<>
-    struct _Destroy_n_aux<true>
-    {
-      template<typename _ForwardIterator, typename _Size>
-        static _ForwardIterator
-        __destroy_n(_ForwardIterator __first, _Size __count)
-       {
-         std::advance(__first, __count);
-         return __first;
-       }
-    };
-#endif
-
   /**
    * Destroy a range of objects.  If the value_type of the object has
    * a trivial destructor, the compiler should optimize all of this
@@ -260,10 +247,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       typedef typename iterator_traits<_ForwardIterator>::value_type
                        _Value_type;
 #if __cplusplus >= 201103L
-      // A deleted destructor is trivial, this ensures we reject such types:
-      static_assert(is_destructible<_Value_type>::value,
-                   "value type is destructible");
-      if constexpr (!__has_trivial_destructor(_Value_type))
+      if constexpr (!is_trivially_destructible<_Value_type>::value)
        for (; __count > 0; (void)++__first, --__count)
          std::_Destroy(std::__addressof(*__first));
 #if __cpp_constexpr_dynamic_alloc // >= C++20
@@ -275,7 +259,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        std::advance(__first, __count);
       return __first;
 #else
-      return std::_Destroy_n_aux<__has_trivial_destructor(_Value_type)>::
+      return std::_Destroy_aux<__has_trivial_destructor(_Value_type)>::
        __destroy_n(__first, __count);
 #endif
     }

diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_n_neg.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_n_neg.cc
new file mode 100644 (file)
index 0000000..12c0dc5
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_n_neg.cc
@@ -0,0 +1,59 @@
+// Copyright (C) 2017-2025 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++17 } }
+
+#include <memory>
+
+// This has a trivial destructor, but should not be destructible!
+struct DeletedDtor {
+  ~DeletedDtor() = delete;
+};
+
+void
+test01()
+{
+  alignas(DeletedDtor) unsigned char buf[sizeof(DeletedDtor)];
+  auto p = ::new (buf) DeletedDtor();
+  std::destroy_n(p, 1);
+}
+
+class PrivateDtor {
+  ~PrivateDtor() { }
+};
+
+void
+test02()
+{
+  alignas(PrivateDtor) unsigned char buf[sizeof(PrivateDtor)];
+  auto p = ::new (buf) PrivateDtor();
+  std::destroy_n(p, 1);
+}
+
+#if __cpp_constexpr_dynamic_alloc // >= C++20
+consteval bool
+test03()
+{
+  DeletedDtor* p = nullptr;
+  std::destroy_n(p, 0);
+  return true;
+}
+static_assert(test03());
+#endif
+
+// { dg-error "deleted function .*DeletedDtor" "" { target *-*-* } 0 }
+// { dg-error "PrivateDtor.* is private" "" { target *-*-* } 0 }

diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_neg.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_neg.cc
index 5946a82de3bcb5d85e58267dd531a512b6b9a43e..096f218ee2be253c12ff7a278c65342828b12c52 100644 (file)
--- a/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/memory_management_tools/destroy_neg.cc
@@ -29,8 +29,7 @@ test01()
 {
   alignas(DeletedDtor) unsigned char buf[sizeof(DeletedDtor)];
   auto p = ::new (buf) DeletedDtor();
-  std::destroy(p, p + 1);      // { dg-error "here" }
-  std::destroy_n(p, 1);                // { dg-error "here" }
+  std::destroy(p, p + 1);
 }
 
 class PrivateDtor {
@@ -42,8 +41,19 @@ test02()
 {
   alignas(PrivateDtor) unsigned char buf[sizeof(PrivateDtor)];
   auto p = ::new (buf) PrivateDtor();
-  std::destroy(p, p + 1);      // { dg-error "here" }
-  std::destroy_n(p, 1);                // { dg-error "here" }
+  std::destroy(p, p + 1);
 }
 
-// { dg-error "value type is destructible" "" { target *-*-* } 0 }
+#if __cpp_constexpr_dynamic_alloc // >= C++20
+consteval bool
+test03()
+{
+  DeletedDtor* p = nullptr;
+  std::destroy(p, p);
+  return true;
+}
+static_assert(test03());
+#endif
+
+// { dg-error "deleted function .*DeletedDtor" "" { target *-*-* } 0 }
+// { dg-error "PrivateDtor.* is private" "" { target *-*-* } 0 }

diff --git a/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_debug_neg.cc b/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_debug_neg.cc
index 61b99d34a1caeacd524765f40fcb19609b0173ba..e6689f7ea265cc237be927ddd72c54f9982aa57d 100644 (file)
--- a/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_debug_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_debug_neg.cc
@@ -43,11 +43,8 @@ test02()
   std::vector<PrivateDtor> v;
 }
 
-// { dg-error "value type is destructible" "" { target *-*-* } 0 }
+// { dg-error "deleted function .*DeletedDtor" "" { target *-*-* } 0 }
+// { dg-error "PrivateDtor.* is private" "" { target *-*-* } 0 }
 
 // In Debug Mode the "required from here" errors come from <debug/vector>
 // { dg-error "required from here" "" { target *-*-* } 182 }
-
-// Needed because of PR c++/92193
-// { dg-prune-output "deleted function" }
-// { dg-prune-output "private within this context" }

diff --git a/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_neg.cc b/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_neg.cc
index 0807d158304cbd8fe557eddcde5e7a85df3d0d48..2bd15bc68eece72a117b37b55f9f89b74d25d178 100644 (file)
--- a/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/vector/cons/destructible_neg.cc
@@ -42,8 +42,5 @@ test02()
   std::vector<PrivateDtor> v; // { dg-error "here" }
 }
 
-// { dg-error "value type is destructible" "" { target *-*-* } 0 }
-
-// Needed because of PR c++/92193
-// { dg-prune-output "deleted function" }
-// { dg-prune-output "private within this context" }
+// { dg-error "deleted function .*DeletedDtor" "" { target *-*-* } 0 }
+// { dg-error "PrivateDtor.* is private" "" { target *-*-* } 0 }