[libcxx-commits] [libcxx] [libc++] Simplify the implementation of ranges::iter_move a bit (PR #198081)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/198081

None

>From 517cb8f1ce9a8c07adbea056c555179c7a4f5b29 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Sat, 16 May 2026 12:19:54 +0200
Subject: [PATCH] [libc++] Simplify the implementation of ranges::iter_move a
 bit

---
 libcxx/include/__iterator/iter_move.h | 31 +++++++--------------------
 1 file changed, 8 insertions(+), 23 deletions(-)

diff --git a/libcxx/include/__iterator/iter_move.h b/libcxx/include/__iterator/iter_move.h
index a726b6e329e90..528ed600ce8cd 100644
--- a/libcxx/include/__iterator/iter_move.h
+++ b/libcxx/include/__iterator/iter_move.h
@@ -44,18 +44,6 @@ concept __unqualified_iter_move = __class_or_enum<remove_cvref_t<_Tp>> && requir
   iter_move(std::forward<_Tp>(__t));
 };
 
-template <class _Tp>
-concept __move_deref = !__unqualified_iter_move<_Tp> && requires(_Tp&& __t) {
-  *__t;
-  requires is_lvalue_reference_v<decltype(*__t)>;
-};
-
-template <class _Tp>
-concept __just_deref = !__unqualified_iter_move<_Tp> && !__move_deref<_Tp> && requires(_Tp&& __t) {
-  *__t;
-  requires(!is_lvalue_reference_v<decltype(*__t)>);
-};
-
 // [iterator.cust.move]
 
 struct __fn {
@@ -69,17 +57,14 @@ struct __fn {
   // NOLINTEND(libcpp-robust-against-adl)
 
   template <class _Ip>
-    requires __move_deref<_Ip>
-  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
-      noexcept(noexcept(std::move(*std::forward<_Ip>(__i)))) -> decltype(std::move(*std::forward<_Ip>(__i))) {
-    return std::move(*std::forward<_Ip>(__i));
-  }
-
-  template <class _Ip>
-    requires __just_deref<_Ip>
-  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
-      noexcept(noexcept(*std::forward<_Ip>(__i))) -> decltype(*std::forward<_Ip>(__i)) {
-    return *std::forward<_Ip>(__i);
+    requires (!__unqualified_iter_move<_Ip> && requires(_Ip&& __t) { *__t; })
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const
+      noexcept(noexcept(*std::forward<_Ip>(__i))) {
+    if constexpr (is_lvalue_reference_v<decltype(*__i)>) {
+      return std::move(*std::forward<_Ip>(__i));
+    } else {
+      return *std::forward<_Ip>(__i);
+    }
   }
 };
 } // namespace __iter_move