From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 12 Oct 2021 14:09:50 +0000 (+0100)
Subject: libstdc++: Fix move construction of std::tuple with array elements [PR101960]
X-Git-Tag: releases/gcc-11.3.0~772
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e748216c237cff2915390e9653de2db63b2161ac;p=thirdparty%2Fgcc.git

libstdc++: Fix move construction of std::tuple with array elements [PR101960]

The r12-3022 commit only fixed the case where an array is the last
element of the tuple. This fixes the other cases too. We can just define
the move constructor as defaulted, which does the right thing. Changing
the move constructor to be trivial would be an ABI break, but since the
last base class still has a non-trivial move constructor, defining the
derived ones as defaulted doesn't change anything.

libstdc++-v3/ChangeLog:

	PR libstdc++/101960
	* include/std/tuple (_Tuple_impl(_Tuple_impl&&)): Define as
	defauled.
	* testsuite/20_util/tuple/cons/101960.cc: Check tuples with
	array elements before the last element.

(cherry picked from commit 7481021364e75ba583972e15ed421a53988368ea)
---

diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index 23fad918c573..dcf30bd9a8d5 100644
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -298,13 +298,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // 2729. Missing SFINAE on std::pair::operator=
       _Tuple_impl& operator=(const _Tuple_impl&) = delete;
 
-      constexpr
-      _Tuple_impl(_Tuple_impl&& __in)
-      noexcept(__and_<is_nothrow_move_constructible<_Head>,
-		      is_nothrow_move_constructible<_Inherited>>::value)
-      : _Inherited(std::move(_M_tail(__in))),
-	_Base(std::forward<_Head>(_M_head(__in)))
-      { }
+      _Tuple_impl(_Tuple_impl&&) = default;
 
       template<typename... _UElements>
 	constexpr
diff --git a/libstdc++-v3/testsuite/20_util/tuple/cons/101960.cc b/libstdc++-v3/testsuite/20_util/tuple/cons/101960.cc
index f14604cdc697..42d17b182ed5 100644
--- a/libstdc++-v3/testsuite/20_util/tuple/cons/101960.cc
+++ b/libstdc++-v3/testsuite/20_util/tuple/cons/101960.cc
@@ -1,4 +1,13 @@
 // { dg-do compile { target c++11 } }
 #include <tuple>
+
+// PR libstdc++/101960
+
 std::tuple<int[1]> t;
-auto tt = std::move(t); // PR libstdc++/101960
+auto tt = std::move(t);
+
+std::tuple<int[1], int> t2;
+auto tt2 = std::move(t2);
+
+std::tuple<int[1], int[2], int[3]> t3;
+auto tt3 = std::move(t3);