@@ -73,6 +73,58 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bool = __empty_not_final<_Head>::value>
struct _Head_base;
+#if __has_cpp_attribute(no_unique_address)
+ template<size_t _Idx, typename _Head>
+ struct _Head_base<_Idx, _Head, true>
+ {
+ constexpr _Head_base()
+ : _M_head_impl() { }
+
+ constexpr _Head_base(const _Head& __h)
+ : _M_head_impl(__h) { }
+
+ constexpr _Head_base(const _Head_base&) = default;
+ constexpr _Head_base(_Head_base&&) = default;
+
+ template<typename _UHead>
+ constexpr _Head_base(_UHead&& __h)
+ : _M_head_impl(std::forward<_UHead>(__h)) { }
+
+ _GLIBCXX20_CONSTEXPR
+ _Head_base(allocator_arg_t, __uses_alloc0)
+ : _M_head_impl() { }
+
+ template<typename _Alloc>
+ _Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
+ : _M_head_impl(allocator_arg, *__a._M_a) { }
+
+ template<typename _Alloc>
+ _Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
+ : _M_head_impl(*__a._M_a) { }
+
+ template<typename _UHead>
+ _GLIBCXX20_CONSTEXPR
+ _Head_base(__uses_alloc0, _UHead&& __uhead)
+ : _M_head_impl(std::forward<_UHead>(__uhead)) { }
+
+ template<typename _Alloc, typename _UHead>
+ _Head_base(__uses_alloc1<_Alloc> __a, _UHead&& __uhead)
+ : _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
+ { }
+
+ template<typename _Alloc, typename _UHead>
+ _Head_base(__uses_alloc2<_Alloc> __a, _UHead&& __uhead)
+ : _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) { }
+
+ static constexpr _Head&
+ _M_head(_Head_base& __b) noexcept { return __b._M_head_impl; }
+
+ static constexpr const _Head&
+ _M_head(const _Head_base& __b) noexcept { return __b._M_head_impl; }
+
+ [[no_unique_address]] _Head _M_head_impl;
+ };
+#else
template<size_t _Idx, typename _Head>
struct _Head_base<_Idx, _Head, true>
: public _Head
@@ -119,6 +171,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static constexpr const _Head&
_M_head(const _Head_base& __b) noexcept { return __b; }
};
+#endif
template<size_t _Idx, typename _Head>
struct _Head_base<_Idx, _Head, false>
new file mode 100644
@@ -0,0 +1,36 @@
+// Copyright (C) 2020 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 <tuple>
+
+struct A {
+ bool operator == (A) const { return true; }
+};
+
+struct B {
+ bool operator == (B) const { return true; }
+};
+
+using Tuple = std::tuple<A, B>;
+
+bool example(Tuple a, Tuple b)
+{
+ return a == b; // PR libstdc++/93147
+}
new file mode 100644
@@ -0,0 +1,33 @@
+// Copyright (C) 2020 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 <tuple>
+
+struct A { };
+
+void f(A);
+
+struct B { B(std::tuple<A>); };
+
+void f(B);
+
+void test01()
+{
+ f(std::make_tuple(A())); // PR libstdc++/55713
+}
new file mode 100644
@@ -0,0 +1,30 @@
+// Copyright (C) 2020 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 <tuple>
+
+struct A {};
+struct B : std::tuple<A> {};
+
+void
+test01()
+{
+ std::tuple<B> t;
+ std::get<0>(t); // PR libstdc++/71096
+}
@@ -29,7 +29,7 @@ main()
// { dg-final { note-test t1 {empty std::tuple} } }
std::tuple<std::string, int, std::tuple<>> t2{ "Johnny", 5, {} };
-// { dg-final { regexp-test t2 {std::tuple containing = {\[1\] = "Johnny", \[2\] = 5, \[3\] = {<std::(__8::)?tuple<>> = empty std::tuple, <No data fields>}}} } }
+// { dg-final { regexp-test t2 {std::tuple containing = {\[1\] = "Johnny", \[2\] = 5, \[3\] = empty std::tuple}} } }
std::cout << "\n";
return 0; // Mark SPOT
This fixes a number of std::tuple bugs by no longer making use of the empty base-class optimization. By using the C++20 [[no_unique_address]] attribute we can always store the element as a data member, while still compressing the layout of tuples containing empty types. Since we no longer use inheritance we could also apply the compression optimization for final types and for tuples of tuples, but doing so would be an ABI break. Using [[no_unique_address]] more liberally for the unstable std::__8 configuration is left for a later date. There may be reasons not to apply the attribute unconditionally, e.g. see the discussion about guaranteed elision in PR 94062. libstdc++-v3/ChangeLog: PR libstdc++/55713 PR libstdc++/71096 PR libstdc++/93147 * include/std/tuple [__has_cpp_attribute(no_unique_address)] (_Head_base<Idx, Head, true>): New definition of the partial specialization, using [[no_unique_address]] instead of inheritance. * testsuite/libstdc++-prettyprinters/48362.cc: Adjust expected output. * testsuite/20_util/tuple/comparison_operators/93147.cc: New test. * testsuite/20_util/tuple/creation_functions/55713.cc: New test. * testsuite/20_util/tuple/element_access/71096.cc: New test. Tested powerpc64le-linux. Committed to trunk. commit 91e6226f880b048275a7ceedef716e159c7cefd9 Author: Jonathan Wakely <jwakely@redhat.com> Date: Fri Aug 7 17:13:56 2020 libstdc++: Remove inheritance from elements in std::tuple This fixes a number of std::tuple bugs by no longer making use of the empty base-class optimization. By using the C++20 [[no_unique_address]] attribute we can always store the element as a data member, while still compressing the layout of tuples containing empty types. Since we no longer use inheritance we could also apply the compression optimization for final types and for tuples of tuples, but doing so would be an ABI break. Using [[no_unique_address]] more liberally for the unstable std::__8 configuration is left for a later date. There may be reasons not to apply the attribute unconditionally, e.g. see the discussion about guaranteed elision in PR 94062. libstdc++-v3/ChangeLog: PR libstdc++/55713 PR libstdc++/71096 PR libstdc++/93147 * include/std/tuple [__has_cpp_attribute(no_unique_address)] (_Head_base<Idx, Head, true>): New definition of the partial specialization, using [[no_unique_address]] instead of inheritance. * testsuite/libstdc++-prettyprinters/48362.cc: Adjust expected output. * testsuite/20_util/tuple/comparison_operators/93147.cc: New test. * testsuite/20_util/tuple/creation_functions/55713.cc: New test. * testsuite/20_util/tuple/element_access/71096.cc: New test.