[committed] libstdc++: Fix last std::tuple constructor missing 'constexpr' [PR102270]

[Jonathan Wakely via Gcc-patches]

Also rename the test so it actually runs.

Signed-off-by: Jonathan Wakely <jwak...@redhat.com>

libstdc++-v3/ChangeLog:

        PR libstdc++/102270
        * include/std/tuple (_Tuple_impl): Add constexpr to constructor
        missed in previous patch.
        * testsuite/20_util/tuple/cons/102270.C: Moved to...
        * testsuite/20_util/tuple/cons/102270.cc: ...here.
        * testsuite/util/testsuite_allocator.h (SimpleAllocator): Add
        constexpr to constructor so it can be used for C++20 tests.

Tested powerpc64le-linux. Committed to trunk.

git mailpatch 42eff613d0c10f88dc7a44b14981876401a09981

commit 1fa2c5a695bb962ffcf8abed49f69cdcc59d0e61
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Fri Sep 17 12:27:02 2021

    libstdc++: Fix last std::tuple constructor missing 'constexpr' [PR102270]
    
    Also rename the test so it actually runs.
    
    Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/102270
            * include/std/tuple (_Tuple_impl): Add constexpr to constructor
            missed in previous patch.
            * testsuite/20_util/tuple/cons/102270.C: Moved to...
            * testsuite/20_util/tuple/cons/102270.cc: ...here.
            * testsuite/util/testsuite_allocator.h (SimpleAllocator): Add
            constexpr to constructor so it can be used for C++20 tests.

diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index 6f0dc6346e1..120c80a2b78 100644
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -330,6 +330,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        { }
 
       template<typename _Alloc>
+       _GLIBCXX20_CONSTEXPR
        _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
                    const _Head& __head, const _Tail&... __tail)
        : _Inherited(__tag, __a, __tail...),
diff --git a/libstdc++-v3/testsuite/20_util/tuple/cons/102270.C 
b/libstdc++-v3/testsuite/20_util/tuple/cons/102270.cc
similarity index 95%
rename from libstdc++-v3/testsuite/20_util/tuple/cons/102270.C
rename to libstdc++-v3/testsuite/20_util/tuple/cons/102270.cc
index 998329817c7..5500cacab6d 100644
--- a/libstdc++-v3/testsuite/20_util/tuple/cons/102270.C
+++ b/libstdc++-v3/testsuite/20_util/tuple/cons/102270.cc
@@ -56,6 +56,9 @@ constexpr bool construct_using_allocator()
 
   std::tuple<X1a, X1a, X1b, X1b> t1a1b(std::allocator_arg, a, 1, i, 1, i);
 
+  const int c = 0;
+  std::tuple<int, int> tii(std::allocator_arg, a, c, c);
+
   return true;
 }
 static_assert( construct_using_allocator() );
diff --git a/libstdc++-v3/testsuite/util/testsuite_allocator.h 
b/libstdc++-v3/testsuite/util/testsuite_allocator.h
index 1f7912ea6eb..b5b402858a6 100644
--- a/libstdc++-v3/testsuite/util/testsuite_allocator.h
+++ b/libstdc++-v3/testsuite/util/testsuite_allocator.h
@@ -514,7 +514,7 @@ namespace __gnu_test
     {
       typedef Tp value_type;
 
-      SimpleAllocator() noexcept { }
+      constexpr SimpleAllocator() noexcept { }
 
       template <class T>
         SimpleAllocator(const SimpleAllocator<T>&) { }