[gcc r14-2304] libstdc++: Add redundant 'typename' to std::projected

[Jonathan Wakely]

https://gcc.gnu.org/g:49f2b325ec7a49e41fc107239542eae0eb6d364e

commit r14-2304-g49f2b325ec7a49e41fc107239542eae0eb6d364e
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jul 4 15:29:35 2023 +0100

    libstdc++: Add redundant 'typename' to std::projected
    
    This is needed by Clang 15.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/iterator_concepts.h (projected): Add typename.

Diff:
---
 libstdc++-v3/include/bits/iterator_concepts.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/iterator_concepts.h b/libstdc++-v3/include/bits/iterator_concepts.h
index 6802582a459..e32e94dc9fc 100644
--- a/libstdc++-v3/include/bits/iterator_concepts.h
+++ b/libstdc++-v3/include/bits/iterator_concepts.h
@@ -798,7 +798,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// [projected], projected
   template<indirectly_readable _Iter,
 	   indirectly_regular_unary_invocable<_Iter> _Proj>
-    using projected = __detail::__projected<_Iter, _Proj>::__type;
+    using projected = typename __detail::__projected<_Iter, _Proj>::__type;
 
   // [alg.req], common algorithm requirements