[gcc r11-4275] libstdc++: Ensure std::forward_as_tuple is defined

[Jonathan Wakely]

https://gcc.gnu.org/g:ca021ac617277ba73cb694f8d26ec0f5e1293451

commit r11-4275-gca021ac617277ba73cb694f8d26ec0f5e1293451
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Oct 23 00:58:35 2020 +0100

    libstdc++: Ensure std::forward_as_tuple is defined
    
    The recent changes to reduce includes in <memory_resource> went a bit
    too far, and it's possible for std::forward_as_tuple to not be defined
    when used.
    
    While doing this, I noticed the problematic calls to forward_as_tuple
    were not qualified, so performed unwanted ADL.
    
    libstdc++-v3/ChangeLog:
    
            * include/experimental/memory_resource: Include <tuple>.
            (polymorphic_allocator::construct): Qualify forward_as_tuple.
            * include/std/memory_resource: Likewise.

Diff:
---
 libstdc++-v3/include/experimental/memory_resource | 13 +++++++------
 libstdc++-v3/include/std/memory_resource          | 13 +++++++------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/libstdc++-v3/include/experimental/memory_resource b/libstdc++-v3/include/experimental/memory_resource
index 1c4de70c533..ca1bad9ecd0 100644
--- a/libstdc++-v3/include/experimental/memory_resource
+++ b/libstdc++-v3/include/experimental/memory_resource
@@ -36,6 +36,7 @@
 
 #include <memory>			// align, uses_allocator, __uses_alloc
 #include <experimental/utility>		// pair, experimental::erased_type
+#include <tuple>			// tuple, forward_as_tuple
 #include <atomic>			// atomic
 #include <new>				// placement new
 #include <cstddef>			// max_align_t
@@ -196,8 +197,8 @@ namespace pmr {
 	construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
 	{
 	  this->construct(__p, piecewise_construct,
-			  forward_as_tuple(std::forward<_Up>(__x)),
-			  forward_as_tuple(std::forward<_Vp>(__y)));
+	      std::forward_as_tuple(std::forward<_Up>(__x)),
+	      std::forward_as_tuple(std::forward<_Vp>(__y)));
 	}
 
       template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
@@ -205,8 +206,8 @@ namespace pmr {
 	construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
 	{
 	  this->construct(__p, piecewise_construct,
-			  forward_as_tuple(__pr.first),
-			  forward_as_tuple(__pr.second));
+	      std::forward_as_tuple(__pr.first),
+	      std::forward_as_tuple(__pr.second));
 	}
 
       template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
@@ -214,8 +215,8 @@ namespace pmr {
 	construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
 	{
 	  this->construct(__p, piecewise_construct,
-			  forward_as_tuple(std::forward<_Up>(__pr.first)),
-			  forward_as_tuple(std::forward<_Vp>(__pr.second)));
+	      std::forward_as_tuple(std::forward<_Up>(__pr.first)),
+	      std::forward_as_tuple(std::forward<_Vp>(__pr.second)));
 	}
 
       template <typename _Up>
diff --git a/libstdc++-v3/include/std/memory_resource b/libstdc++-v3/include/std/memory_resource
index 350799ee382..40e23a2f9ce 100644
--- a/libstdc++-v3/include/std/memory_resource
+++ b/libstdc++-v3/include/std/memory_resource
@@ -45,6 +45,7 @@
 
 #if ! __cpp_lib_make_obj_using_allocator
 # include <utility>			// pair, index_sequence
+# include <tuple>			// tuple, forward_as_tuple
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
@@ -286,8 +287,8 @@ namespace pmr
 	construct(pair<_Tp1, _Tp2>* __p, _Up&& __x, _Vp&& __y)
 	{
 	  this->construct(__p, piecewise_construct,
-			  forward_as_tuple(std::forward<_Up>(__x)),
-			  forward_as_tuple(std::forward<_Vp>(__y)));
+	      std::forward_as_tuple(std::forward<_Up>(__x)),
+	      std::forward_as_tuple(std::forward<_Vp>(__y)));
 	}
 
       template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
@@ -296,8 +297,8 @@ namespace pmr
 	construct(pair<_Tp1, _Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
 	{
 	  this->construct(__p, piecewise_construct,
-			  forward_as_tuple(__pr.first),
-			  forward_as_tuple(__pr.second));
+	      std::forward_as_tuple(__pr.first),
+	      std::forward_as_tuple(__pr.second));
 	}
 
       template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
@@ -306,8 +307,8 @@ namespace pmr
 	construct(pair<_Tp1, _Tp2>* __p, pair<_Up, _Vp>&& __pr)
 	{
 	  this->construct(__p, piecewise_construct,
-			  forward_as_tuple(std::forward<_Up>(__pr.first)),
-			  forward_as_tuple(std::forward<_Vp>(__pr.second)));
+	      std::forward_as_tuple(std::forward<_Up>(__pr.first)),
+	      std::forward_as_tuple(std::forward<_Vp>(__pr.second)));
 	}
 #else // make_obj_using_allocator
       template<typename _Tp1, typename... _Args>