[libcxx-commits] [libcxx] [libc++] Remove _IsThisTuple (PR #213909)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 updated https://github.com/llvm/llvm-project/pull/213909

>From 6f740eed92f394f3159b47e8da7ed2a36531d183 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Tue, 4 Aug 2026 13:22:08 +0200
Subject: [PATCH] [libc++] Remove _IsThisTuple

---
 libcxx/include/__configuration/namespace.h | 4 +++-
 libcxx/include/tuple                       | 8 ++------
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/libcxx/include/__configuration/namespace.h b/libcxx/include/__configuration/namespace.h
index 1f4b8ce247b13..3142c4132189d 100644
--- a/libcxx/include/__configuration/namespace.h
+++ b/libcxx/include/__configuration/namespace.h
@@ -30,10 +30,12 @@
     _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wc++17-extensions")                                                             \
     _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wc++20-extensions")                                                             \
     _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wc++23-extensions")                                                             \
+    _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wc++26-extensions")                                                             \
     _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++14-extensions")                                                               \
     _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++17-extensions")                                                               \
     _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++20-extensions")                                                               \
-    _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++23-extensions")
+    _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++23-extensions")                                                               \
+    _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++26-extensions")
 #  define _LIBCPP_POP_EXTENSION_DIAGNOSTICS _LIBCPP_DIAGNOSTIC_POP
 #  define _LIBCPP_PUSH_ABI_PRAGMA_DIAGNOSTICS                                                                          \
     _LIBCPP_DIAGNOSTIC_PUSH _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wpragma-clang-attribute")                               \
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
index 2f0127bc7388d..b3f4ac92ccd4a 100644
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -604,14 +604,10 @@ public:
       : __base_(allocator_arg_t(), __a, __forward_args{}, __t...) {}
 
   // tuple(U&& ...) constructors (including allocator_arg_t variants)
-  template <class... _Up>
-  struct _IsThisTuple : false_type {};
-  template <class _Up>
-  struct _IsThisTuple<_Up> : is_same<__remove_cvref_t<_Up>, tuple> {};
-
   template <class... _Up>
   struct _EnableUTypesCtor
-      : _And<_Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors
+      : _And<_Or<integral_constant<bool, sizeof...(_Up) != 1>,
+                 _IsNotSame<__remove_cvref_t<_Up...[0]>, tuple>>, // extension to allow mis-behaved user constructors
              is_constructible<_Tp, _Up>... > {};
 
   template <class... _Up,