Rebase onto main to resolve conflicts

Author: winner245

libcxx/docs/FeatureTestMacroTable.rst

@@ -418,11 +418,9 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_bitset``                                       ``202306L``
     ---------------------------------------------------------- -----------------
-<<<<<<< HEAD
     ``__cpp_lib_constexpr_algorithms``                         ``202306L``
-=======
+    ---------------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_forward_list``                       ``202502L``
->>>>>>> 3e1b3b8f0316 (Make forward_list constexpr as part of P3372R3)
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_new``                                ``202406L``
     ---------------------------------------------------------- -----------------

libcxx/include/__memory/pointer_traits.h

@@ -302,6 +302,10 @@ concept __resettable_smart_pointer_with_args = requires(_Smart __s, _Pointer __p
 
 #endif
 
+// This function ensures safe conversions between fancy pointers at compile-time, where we avoid casts from/to
+// `__void_pointer` by obtaining the underlying raw pointer from the fancy pointer using `std::to_address`,
+// then dereferencing it to retrieve the pointed-to object, and finally constructing the target fancy pointer
+// to that object using the `std::pointer_traits<>::pinter_to` function.
 template <class _PtrTo, class _PtrFrom>
 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI _PtrTo __static_fancy_pointer_cast(const _PtrFrom& __p) {
   using __ptr_traits   = pointer_traits<_PtrTo>;

libcxx/include/forward_list

@@ -844,7 +844,8 @@ public:
   }
 #  endif // _LIBCPP_CXX03_LANG
   _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, const value_type& __v);
-  _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, size_type __n, const value_type& __v) {
+  _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator
+  insert_after(const_iterator __p, size_type __n, const value_type& __v) {
     return __insert_after(__p, __n, __v);
   }
   template <class _InputIterator, __enable_if_t<__has_input_iterator_category<_InputIterator>::value, int> = 0>

libcxx/test/std/language.support/support.limits/support.limits.general/forward_list.version.compile.pass.cpp

@@ -24,6 +24,10 @@
 #    error "__cpp_lib_allocator_traits_is_always_equal should not be defined before c++17"
 #  endif
 
+#  ifdef __cpp_lib_constexpr_forward_list
+#    error "__cpp_lib_constexpr_forward_list should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_containers_ranges
 #    error "__cpp_lib_containers_ranges should not be defined before c++23"
 #  endif
@@ -54,6 +58,10 @@
 #    error "__cpp_lib_allocator_traits_is_always_equal should not be defined before c++17"
 #  endif
 
+#  ifdef __cpp_lib_constexpr_forward_list
+#    error "__cpp_lib_constexpr_forward_list should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_containers_ranges
 #    error "__cpp_lib_containers_ranges should not be defined before c++23"
 #  endif
@@ -87,6 +95,10 @@
 #    error "__cpp_lib_allocator_traits_is_always_equal should have the value 201411L in c++17"
 #  endif
 
+#  ifdef __cpp_lib_constexpr_forward_list
+#    error "__cpp_lib_constexpr_forward_list should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_containers_ranges
 #    error "__cpp_lib_containers_ranges should not be defined before c++23"
 #  endif
@@ -126,6 +138,10 @@
 #    error "__cpp_lib_allocator_traits_is_always_equal should have the value 201411L in c++20"
 #  endif
 
+#  ifdef __cpp_lib_constexpr_forward_list
+#    error "__cpp_lib_constexpr_forward_list should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_containers_ranges
 #    error "__cpp_lib_containers_ranges should not be defined before c++23"
 #  endif
@@ -171,6 +187,10 @@
 #    error "__cpp_lib_allocator_traits_is_always_equal should have the value 201411L in c++23"
 #  endif
 
+#  ifdef __cpp_lib_constexpr_forward_list
+#    error "__cpp_lib_constexpr_forward_list should not be defined before c++26"
+#  endif
+
 #  ifndef __cpp_lib_containers_ranges
 #    error "__cpp_lib_containers_ranges should be defined in c++23"
 #  endif
@@ -219,6 +239,13 @@
 #    error "__cpp_lib_allocator_traits_is_always_equal should have the value 201411L in c++26"
 #  endif
 
+#  ifndef __cpp_lib_constexpr_forward_list
+#    error "__cpp_lib_constexpr_forward_list should be defined in c++26"
+#  endif
+#  if __cpp_lib_constexpr_forward_list != 202502L
+#    error "__cpp_lib_constexpr_forward_list should have the value 202502L in c++26"
+#  endif
+
 #  ifndef __cpp_lib_containers_ranges
 #    error "__cpp_lib_containers_ranges should be defined in c++26"
 #  endif