[libc++] P2602R2 Poison Pills are Too Toxic

libcxx/docs/FeatureTestMacroTable.rst

@@ -266,7 +266,7 @@ Status
     --------------------------------------------------- -----------------
     ``__cpp_lib_polymorphic_allocator``                 ``201902L``
     --------------------------------------------------- -----------------
-    ``__cpp_lib_ranges``                                ``202207L``
+    ``__cpp_lib_ranges``                                ``202110L``
     --------------------------------------------------- -----------------
     ``__cpp_lib_remove_cvref``                          ``201711L``
     --------------------------------------------------- -----------------

libcxx/docs/Status/Cxx23Papers.csv

@@ -100,7 +100,7 @@
 "`P2396R1 <https://wg21.link/P2396R1>`__","LWG", "Concurrency TS 2 fixes ", "November 2022","","","|concurrency TS|"
 "`P2505R5 <https://wg21.link/P2505R5>`__","LWG", "Monadic Functions for ``std::expected``", "November 2022","|Complete|","17.0",""
 "`P2539R4 <https://wg21.link/P2539R4>`__","LWG", "Should the output of ``std::print`` to a terminal be synchronized with the underlying stream?", "November 2022","|Complete|","18.0","|format|"
-"`P2602R2 <https://wg21.link/P2602R2>`__","LWG", "Poison Pills are Too Toxic", "November 2022","","","|ranges|"
+"`P2602R2 <https://wg21.link/P2602R2>`__","LWG", "Poison Pills are Too Toxic", "November 2022","|Complete|","19.0","|ranges|"
 "`P2708R1 <https://wg21.link/P2708R1>`__","LWG", "No Further Fundamentals TSes", "November 2022","|Nothing to do|","",""
 "","","","","","",""
 "`P0290R4 <https://wg21.link/P0290R4>`__","LWG", "``apply()`` for ``synchronized_value<T>``","February 2023","","","|concurrency TS|"

libcxx/include/__compare/partial_order.h

@@ -28,6 +28,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 // [cmp.alg]
 namespace __partial_order {
+void partial_order() = delete;
+
 struct __fn {
   // NOLINTBEGIN(libcpp-robust-against-adl) partial_order should use ADL, but only here
   template <class _Tp, class _Up>

libcxx/include/__compare/strong_order.h

@@ -37,6 +37,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 // [cmp.alg]
 namespace __strong_order {
+void strong_order() = delete;
+
 struct __fn {
   // NOLINTBEGIN(libcpp-robust-against-adl) strong_order should use ADL, but only here
   template <class _Tp, class _Up>

libcxx/include/__compare/weak_order.h

@@ -30,6 +30,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 // [cmp.alg]
 namespace __weak_order {
+void weak_order() = delete;
+
 struct __fn {
   // NOLINTBEGIN(libcpp-robust-against-adl) weak_order should use ADL, but only here
   template <class _Tp, class _Up>

libcxx/include/__iterator/iter_move.h

@@ -35,7 +35,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 namespace ranges {
 namespace __iter_move {
 
-void iter_move();
+void iter_move() = delete;
 
 template <class _Tp>
 concept __unqualified_iter_move = __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {

libcxx/include/__ranges/access.h

@@ -45,8 +45,7 @@ concept __member_begin = __can_borrow<_Tp> && __workaround_52970<_Tp> && require
   { _LIBCPP_AUTO_CAST(__t.begin()) } -> input_or_output_iterator;
 };
 
-void begin(auto&)       = delete;
-void begin(const auto&) = delete;
+void begin() = delete;
 
 template <class _Tp>
 concept __unqualified_begin =
@@ -109,8 +108,7 @@ concept __member_end = __can_borrow<_Tp> && __workaround_52970<_Tp> && requires(
   { _LIBCPP_AUTO_CAST(__t.end()) } -> sentinel_for<iterator_t<_Tp>>;
 };
 
-void end(auto&)       = delete;
-void end(const auto&) = delete;
+void end() = delete;
 
 template <class _Tp>
 concept __unqualified_end =

libcxx/include/__ranges/rbegin.h

@@ -40,8 +40,7 @@ concept __member_rbegin = __can_borrow<_Tp> && __workaround_52970<_Tp> && requir
   { _LIBCPP_AUTO_CAST(__t.rbegin()) } -> input_or_output_iterator;
 };
 
-void rbegin(auto&)       = delete;
-void rbegin(const auto&) = delete;
+void rbegin() = delete;
 
 template <class _Tp>
 concept __unqualified_rbegin =

libcxx/include/__ranges/rend.h

@@ -42,8 +42,7 @@ concept __member_rend = __can_borrow<_Tp> && __workaround_52970<_Tp> && requires
   { _LIBCPP_AUTO_CAST(__t.rend()) } -> sentinel_for<decltype(ranges::rbegin(__t))>;
 };
 
-void rend(auto&)       = delete;
-void rend(const auto&) = delete;
+void rend() = delete;
 
 template <class _Tp>
 concept __unqualified_rend =

libcxx/include/__ranges/size.h

@@ -41,8 +41,7 @@ inline constexpr bool disable_sized_range = false;
 
 namespace ranges {
 namespace __size {
-void size(auto&)       = delete;
-void size(const auto&) = delete;
+void size() = delete;
 
 template <class _Tp>
 concept __size_enabled = !disable_sized_range<remove_cvref_t<_Tp>>;

libcxx/include/version

@@ -164,7 +164,7 @@ __cpp_lib_parallel_algorithm                            201603L <algorithm> <num
 __cpp_lib_polymorphic_allocator                         201902L <memory_resource>
 __cpp_lib_print                                         202207L <ostream> <print>
 __cpp_lib_quoted_string_io                              201304L <iomanip>
-__cpp_lib_ranges                                        202207L <algorithm> <functional> <iterator>
+__cpp_lib_ranges                                        202110L <algorithm> <functional> <iterator>
                                                                 <memory> <ranges>
 __cpp_lib_ranges_as_const                               202207L <ranges>
 __cpp_lib_ranges_as_rvalue                              202207L <ranges>
@@ -410,7 +410,7 @@ __cpp_lib_within_lifetime                               202306L <type_traits>
 # if _LIBCPP_AVAILABILITY_HAS_PMR
 #   define __cpp_lib_polymorphic_allocator              201902L
 # endif
-# define __cpp_lib_ranges                               202207L
+# define __cpp_lib_ranges                               202110L
 # define __cpp_lib_remove_cvref                         201711L
 # if !defined(_LIBCPP_HAS_NO_THREADS) && _LIBCPP_AVAILABILITY_HAS_SYNC
 #   define __cpp_lib_semaphore                          201907L

libcxx/test/std/iterators/iterator.requirements/iterator.cust/iterator.cust.move/iter_move.pass.cpp

@@ -11,6 +11,13 @@
 // template<class I>
 // unspecified iter_move;
 
+// Intentionally defined before including headers.
+namespace ordinary_unqualified_lookup_helpers {
+struct StructWithGlobalIterMove {};
+} // namespace ordinary_unqualified_lookup_helpers
+
+int&& iter_move(ordinary_unqualified_lookup_helpers::StructWithGlobalIterMove);
+
 #include <algorithm>
 #include <array>
 #include <cassert>
@@ -186,6 +193,9 @@ template<class T> struct Holder { T t; };
 static_assert(std::is_invocable_v<IterMoveT, Holder<Incomplete>**>);
 static_assert(std::is_invocable_v<IterMoveT, Holder<Incomplete>**&>);
 
+// Ordinary unqualified lookup should not be performed.
+static_assert(!std::is_invocable_v<IterMoveT, ordinary_unqualified_lookup_helpers::StructWithGlobalIterMove&>);
+
 int main(int, char**)
 {
   test();

libcxx/test/std/iterators/iterator.requirements/iterator.cust/iterator.cust.swap/iter_swap.pass.cpp

@@ -47,6 +47,13 @@ static_assert( std::is_invocable_v<IterSwapT&&, HasIterSwap&, HasIterSwap&>);
 static_assert( std::is_invocable_v<IterSwapT&&, HasIterSwap&, int&>);
 static_assert(!std::is_invocable_v<IterSwapT&&, int&, HasIterSwap&>);
 
+struct StructWithNotMoreSpecializedIterSwap {
+  friend void iter_swap(auto&, auto&);
+};
+
+static_assert(
+    !std::is_invocable_v<IterSwapT, StructWithNotMoreSpecializedIterSwap&, StructWithNotMoreSpecializedIterSwap&>);
+
 struct NodiscardIterSwap {
   [[nodiscard]] friend int iter_swap(NodiscardIterSwap&, NodiscardIterSwap&) { return 0; }
 };

libcxx/test/std/language.support/cmp/cmp.alg/ordinary_unqualified_lookup_helpers.h

@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_STD_LANGUAGE_SUPPORT_CMP_CMP_ALG_ORDINARY_UNQUALIFIED_LOOKUP_HELPERS_H
+#define TEST_STD_LANGUAGE_SUPPORT_CMP_CMP_ALG_ORDINARY_UNQUALIFIED_LOOKUP_HELPERS_H
+
+namespace ordinary_unqualified_lookup_helpers {
+struct StructWithGlobalCmpFunctions {};
+} // namespace ordinary_unqualified_lookup_helpers
+
+struct ConvertibleToCmpType;
+
+ConvertibleToCmpType strong_order(ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions,
+                                  ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions);
+ConvertibleToCmpType weak_order(ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions,
+                                ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions);
+ConvertibleToCmpType partial_order(ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions,
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions);
+
+#include <compare> // Intentionally included here, so we can define `ConvertibleToCmpType` later.
+
+struct ConvertibleToCmpType {
+  operator std::strong_ordering() const;
+  operator std::weak_ordering() const;
+  operator std::partial_ordering() const;
+};
+
+#endif // TEST_STD_LANGUAGE_SUPPORT_CMP_CMP_ALG_ORDINARY_UNQUALIFIED_LOOKUP_HELPERS_H

libcxx/test/std/language.support/cmp/cmp.alg/partial_order.pass.cpp

@@ -12,6 +12,8 @@
 
 // template<class T> constexpr partial_ordering partial_order(const T& a, const T& b);
 
+#include "ordinary_unqualified_lookup_helpers.h" // Intentionally included before other headers.
+
 #include <compare>
 
 #include <cassert>
@@ -240,6 +242,11 @@ constexpr bool test_1_4()
     return true;
 }
 
+// Ordinary unqualified lookup should not be performed.
+static_assert(!std::is_invocable_v<decltype(std::partial_order),
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions,
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions>);
+
 int main(int, char**)
 {
     test_1_1();

libcxx/test/std/language.support/cmp/cmp.alg/strong_order.pass.cpp

@@ -12,6 +12,8 @@
 
 // template<class T> constexpr strong_ordering strong_order(const T& a, const T& b);
 
+#include "ordinary_unqualified_lookup_helpers.h" // Intentionally included before other headers.
+
 #include <compare>
 
 #include <cassert>
@@ -448,6 +450,11 @@ constexpr bool test_1_4()
     return true;
 }
 
+// Ordinary unqualified lookup should not be performed.
+static_assert(!std::is_invocable_v<decltype(std::strong_order),
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions,
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions>);
+
 int main(int, char**)
 {
     test_1_1();

libcxx/test/std/language.support/cmp/cmp.alg/weak_order.pass.cpp

@@ -12,6 +12,8 @@
 
 // template<class T> constexpr weak_ordering weak_order(const T& a, const T& b);
 
+#include "ordinary_unqualified_lookup_helpers.h" // Intentionally included before other headers.
+
 #include <compare>
 
 #include <cassert>
@@ -493,6 +495,11 @@ constexpr bool test_1_5()
     return true;
 }
 
+// Ordinary unqualified lookup should not be performed.
+static_assert(!std::is_invocable_v<decltype(std::weak_order),
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions,
+                                   ordinary_unqualified_lookup_helpers::StructWithGlobalCmpFunctions>);
+
 int main(int, char**)
 {
     test_1_1();

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

@@ -20,7 +20,7 @@
     __cpp_lib_constexpr_algorithms           201806L [C++20]
     __cpp_lib_freestanding_algorithm         202311L [C++26]
     __cpp_lib_parallel_algorithm             201603L [C++17]
-    __cpp_lib_ranges                         202207L [C++20]
+    __cpp_lib_ranges                         202110L [C++20]
     __cpp_lib_ranges_starts_ends_with        202106L [C++23]
     __cpp_lib_robust_nonmodifying_seq_ops    201304L [C++14]
     __cpp_lib_sample                         201603L [C++17]
@@ -201,8 +201,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++20"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++20"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++20"
 # endif
 
 # ifdef __cpp_lib_ranges_starts_ends_with
@@ -266,8 +266,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++23"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++23"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++23"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
@@ -349,8 +349,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++26"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++26"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++26"
 # endif
 
 # if !defined(_LIBCPP_VERSION)

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

@@ -28,7 +28,7 @@
     __cpp_lib_invoke_r                 202106L [C++23]
     __cpp_lib_move_only_function       202110L [C++23]
     __cpp_lib_not_fn                   201603L [C++17]
-    __cpp_lib_ranges                   202207L [C++20]
+    __cpp_lib_ranges                   202110L [C++20]
     __cpp_lib_result_of_sfinae         201210L [C++14]
     __cpp_lib_transparent_operators    201210L [C++14]
                                        201510L [C++17]
@@ -293,8 +293,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++20"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++20"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++20"
 # endif
 
 # ifndef __cpp_lib_result_of_sfinae
@@ -399,8 +399,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++23"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++23"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++23"
 # endif
 
 # ifndef __cpp_lib_result_of_sfinae
@@ -523,8 +523,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++26"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++26"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++26"
 # endif
 
 # ifndef __cpp_lib_result_of_sfinae

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

@@ -23,7 +23,7 @@
     __cpp_lib_move_iterator_concept         202207L [C++20]
     __cpp_lib_nonmember_container_access    201411L [C++17]
     __cpp_lib_null_iterators                201304L [C++14]
-    __cpp_lib_ranges                        202207L [C++20]
+    __cpp_lib_ranges                        202110L [C++20]
     __cpp_lib_ssize                         201902L [C++20]
 */
 
@@ -197,8 +197,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++20"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++20"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++20"
 # endif
 
 # ifndef __cpp_lib_ssize
@@ -255,8 +255,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++23"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++23"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++23"
 # endif
 
 # ifndef __cpp_lib_ssize
@@ -313,8 +313,8 @@
 # ifndef __cpp_lib_ranges
 #   error "__cpp_lib_ranges should be defined in c++26"
 # endif
-# if __cpp_lib_ranges != 202207L
-#   error "__cpp_lib_ranges should have the value 202207L in c++26"
+# if __cpp_lib_ranges != 202110L
+#   error "__cpp_lib_ranges should have the value 202110L in c++26"
 # endif
 
 # ifndef __cpp_lib_ssize