[libc++][spaceship] Implements X::iterator container requirements. #99343

mordante · 2024-07-17T15:46:25Z

This implements the requirements for the container iterator requirements for array, deque, vector, and vector<bool>.

Implements:

LWG3352 strong_equality isn't a thing

Implements parts of:

P1614R2 The Mothership has Landed

Fixes: #62486

llvmbot · 2024-07-17T15:46:58Z

@llvm/pr-subscribers-libcxx

Author: Mark de Wever (mordante)

Changes

This implements the requirements for the container iterator requirements for array, deque, vector, and vector<bool>.

Implements:

LWG3352 strong_equality isn't a thing

Implements parts of:

P1614R2 The Mothership has Landed

Fixes: #62486

Full diff: https://github.com/llvm/llvm-project/pull/99343.diff

9 Files Affected:

(modified) libcxx/docs/Status/Cxx20Issues.csv (+1-1)
(modified) libcxx/docs/Status/SpaceshipProjects.csv (+1-1)
(modified) libcxx/include/__bit_reference (+14)
(modified) libcxx/include/__iterator/wrap_iter.h (+19)
(modified) libcxx/include/deque (+12)
(modified) libcxx/test/std/containers/sequences/array/iterators.pass.cpp (+18)
(modified) libcxx/test/std/containers/sequences/deque/iterators.pass.cpp (+9)
(modified) libcxx/test/std/containers/sequences/vector.bool/iterators.pass.cpp (+9)
(modified) libcxx/test/std/containers/sequences/vector/iterators.pass.cpp (+9-1)

diff --git a/libcxx/docs/Status/Cxx20Issues.csv b/libcxx/docs/Status/Cxx20Issues.csv
index 1a40a4472a405..8a431c922a2d9 100644
--- a/libcxx/docs/Status/Cxx20Issues.csv
+++ b/libcxx/docs/Status/Cxx20Issues.csv
@@ -264,7 +264,7 @@
 "`3349 <https://wg21.link/LWG3349>`__","Missing ``__cpp_lib_constexpr_complex``\  for P0415R1","Prague","|Complete|","16.0"
 "`3350 <https://wg21.link/LWG3350>`__","Simplify return type of ``lexicographical_compare_three_way``\ ","Prague","|Complete|","17.0","|spaceship|"
 "`3351 <https://wg21.link/LWG3351>`__","``ranges::enable_safe_range``\  should not be constrained","Prague","|Complete|","15.0","|ranges|"
-"`3352 <https://wg21.link/LWG3352>`__","``strong_equality``\  isn't a thing","Prague","|Nothing To Do|","","|spaceship|"
+"`3352 <https://wg21.link/LWG3352>`__","``strong_equality``\  isn't a thing","Prague","|Complete|","19.0","|spaceship|"
 "`3354 <https://wg21.link/LWG3354>`__","``has_strong_structural_equality``\  has a meaningless definition","Prague","|Nothing To Do|","","|spaceship|"
 "`3355 <https://wg21.link/LWG3355>`__","The memory algorithms should support move-only input iterators introduced by P1207","Prague","|Complete|","15.0","|ranges|"
 "`3356 <https://wg21.link/LWG3356>`__","``__cpp_lib_nothrow_convertible``\  should be ``__cpp_lib_is_nothrow_convertible``\ ","Prague","|Complete|","12.0"
diff --git a/libcxx/docs/Status/SpaceshipProjects.csv b/libcxx/docs/Status/SpaceshipProjects.csv
index e1cf2044cfd78..4dc43cdbbd08f 100644
--- a/libcxx/docs/Status/SpaceshipProjects.csv
+++ b/libcxx/docs/Status/SpaceshipProjects.csv
@@ -83,7 +83,7 @@ Section,Description,Dependencies,Assignee,Complete
 "| `[string.view.synop] <https://wg21.link/string.view.synop>`_
 | `[string.view.comparison] <https://wg21.link/string.view.comparison>`_",| `basic_string_view <https://reviews.llvm.org/D130295>`_,None,Mark de Wever,|Complete|
 - `5.7 Clause 22: Containers library <https://wg21.link/p1614r2#clause-22-containers-library>`_,,,,
-| `[container.requirements.general] <https://wg21.link/container.requirements.general>`_,|,None,Unassigned,|Not Started|
+| `[container.requirements.general] <https://wg21.link/container.requirements.general>`_,|,None,Mark de Wever,|Complete|
 | `[array.syn] <https://wg21.link/array.syn>`_ (`general <https://wg21.link/container.opt.reqmts>`_),| `array <https://reviews.llvm.org/D132265>`_,[expos.only.func],"| Adrian Vogelsgesang
 | Hristo Hristov",|Complete|
 | `[deque.syn] <https://wg21.link/deque.syn>`_ (`general <https://wg21.link/container.opt.reqmts>`_),| `deque <https://reviews.llvm.org/D144821>`_,[expos.only.func],Hristo Hristov,|Complete|
diff --git a/libcxx/include/__bit_reference b/libcxx/include/__bit_reference
index 606069d98be72..ba56ac412a100 100644
--- a/libcxx/include/__bit_reference
+++ b/libcxx/include/__bit_reference
@@ -16,6 +16,7 @@
 #include <__bit/countr.h>
 #include <__bit/invert_if.h>
 #include <__bit/popcount.h>
+#include <__compare/strong_order.h>
 #include <__config>
 #include <__fwd/bit_reference.h>
 #include <__iterator/iterator_traits.h>
@@ -913,6 +914,7 @@ public:
     return __x.__seg_ == __y.__seg_ && __x.__ctz_ == __y.__ctz_;
   }
 
+#if _LIBCPP_STD_VER <= 17
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 friend bool
   operator!=(const __bit_iterator& __x, const __bit_iterator& __y) {
     return !(__x == __y);
@@ -937,6 +939,18 @@ public:
   operator>=(const __bit_iterator& __x, const __bit_iterator& __y) {
     return !(__x < __y);
   }
+#else  // _LIBCPP_STD_VER <= 17
+  _LIBCPP_HIDE_FROM_ABI constexpr friend strong_ordering
+  operator<=>(const __bit_iterator& __x, const __bit_iterator& __y) {
+    if (__x.__seg_ < __y.__seg_)
+      return strong_ordering::less;
+
+    if (__x.__seg_ == __y.__seg_)
+      return __x.__ctz_ <=> __y.__ctz_;
+
+    return strong_ordering::greater;
+  }
+#endif // _LIBCPP_STD_VER <= 17
 
 private:
   _LIBCPP_HIDE_FROM_ABI
diff --git a/libcxx/include/__iterator/wrap_iter.h b/libcxx/include/__iterator/wrap_iter.h
index 252d13b26c9e2..a955d3be918b9 100644
--- a/libcxx/include/__iterator/wrap_iter.h
+++ b/libcxx/include/__iterator/wrap_iter.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___ITERATOR_WRAP_ITER_H
 #define _LIBCPP___ITERATOR_WRAP_ITER_H
 
+#include <__compare/strong_order.h>
 #include <__config>
 #include <__iterator/iterator_traits.h>
 #include <__memory/addressof.h>
@@ -119,6 +120,8 @@ operator==(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEX
   return __x.base() == __y.base();
 }
 
+#if _LIBCPP_STD_VER <= 17
+
 template <class _Iter1>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
 operator<(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT {
@@ -179,6 +182,22 @@ operator<=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEX
   return !(__y < __x);
 }
 
+#else // _LIBCPP_STD_VER <= 17
+
+template <class _Iter1>
+_LIBCPP_HIDE_FROM_ABI constexpr strong_ordering
+operator<=>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) noexcept {
+  return __x.base() <=> __y.base();
+}
+
+template <class _Iter1, class _Iter2>
+_LIBCPP_HIDE_FROM_ABI constexpr strong_ordering
+operator<=>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) noexcept {
+  return __x.base() <=> __y.base();
+}
+
+#endif // _LIBCPP_STD_VER <= 17
+
 template <class _Iter1, class _Iter2>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
 #ifndef _LIBCPP_CXX03_LANG
diff --git a/libcxx/include/deque b/libcxx/include/deque
index 4fc994a6e229b..1073187a99909 100644
--- a/libcxx/include/deque
+++ b/libcxx/include/deque
@@ -376,6 +376,7 @@ public:
     return __x.__ptr_ == __y.__ptr_;
   }
 
+#if _LIBCPP_STD_VER <= 17
   _LIBCPP_HIDE_FROM_ABI friend bool operator!=(const __deque_iterator& __x, const __deque_iterator& __y) {
     return !(__x == __y);
   }
@@ -395,6 +396,17 @@ public:
   _LIBCPP_HIDE_FROM_ABI friend bool operator>=(const __deque_iterator& __x, const __deque_iterator& __y) {
     return !(__x < __y);
   }
+#else // _LIBCPP_STD_VER <= 17
+  _LIBCPP_HIDE_FROM_ABI friend strong_ordering operator<=>(const __deque_iterator& __x, const __deque_iterator& __y) {
+    if (__x.__m_iter_ < __y.__m_iter_)
+      return strong_ordering::less;
+
+    if (__x.__m_iter_ == __y.__m_iter_)
+      return __x.__ptr_ <=> __y.__ptr_;
+
+    return strong_ordering::greater;
+  }
+#endif // _LIBCPP_STD_VER <= 17
 
 private:
   _LIBCPP_HIDE_FROM_ABI explicit __deque_iterator(__map_iterator __m, pointer __p) _NOEXCEPT
diff --git a/libcxx/test/std/containers/sequences/array/iterators.pass.cpp b/libcxx/test/std/containers/sequences/array/iterators.pass.cpp
index 106bc45c70998..9cbe3cb396c9a 100644
--- a/libcxx/test/std/containers/sequences/array/iterators.pass.cpp
+++ b/libcxx/test/std/containers/sequences/array/iterators.pass.cpp
@@ -148,6 +148,15 @@ TEST_CONSTEXPR_CXX17 bool tests()
             assert(std::rbegin(c)  != std::rend(c));
             assert(std::cbegin(c)  != std::cend(c));
             assert(std::crbegin(c) != std::crend(c));
+
+#  if TEST_STD_VER >= 20
+            // P1614 + LWG3352
+            std::same_as<std::strong_ordering> decltype(auto) r1 = ii1 <=> ii2;
+            assert(r1 == std::strong_ordering::equal);
+
+            std::same_as<std::strong_ordering> decltype(auto) r2 = ii1 <=> ii2;
+            assert(r2 == std::strong_ordering::equal);
+#  endif
         }
         {
             typedef std::array<int, 0> C;
@@ -189,6 +198,15 @@ TEST_CONSTEXPR_CXX17 bool tests()
             assert(std::rbegin(c)  == std::rend(c));
             assert(std::cbegin(c)  == std::cend(c));
             assert(std::crbegin(c) == std::crend(c));
+
+#  if TEST_STD_VER >= 20
+            // P1614 + LWG3352
+            std::same_as<std::strong_ordering> decltype(auto) r1 = ii1 <=> ii2;
+            assert(r1 == std::strong_ordering::equal);
+
+            std::same_as<std::strong_ordering> decltype(auto) r2 = ii1 <=> ii2;
+            assert(r2 == std::strong_ordering::equal);
+#  endif
         }
     }
 #endif
diff --git a/libcxx/test/std/containers/sequences/deque/iterators.pass.cpp b/libcxx/test/std/containers/sequences/deque/iterators.pass.cpp
index 1f06ffde41ac2..a8b5db656b205 100644
--- a/libcxx/test/std/containers/sequences/deque/iterators.pass.cpp
+++ b/libcxx/test/std/containers/sequences/deque/iterators.pass.cpp
@@ -74,6 +74,15 @@ int main(int, char**)
 //         assert ( cii != c.begin());
 //         assert ( cii != c.cend());
 //         assert ( ii1 != c.end());
+
+#  if TEST_STD_VER >= 20
+        // P1614 + LWG3352
+        std::same_as<std::strong_ordering> decltype(auto) r1 = ii1 <=> ii2;
+        assert(r1 == std::strong_ordering::equal);
+
+        std::same_as<std::strong_ordering> decltype(auto) r2 = ii1 <=> ii2;
+        assert(r2 == std::strong_ordering::equal);
+#  endif // TEST_STD_VER > 20
     }
 #endif
 
diff --git a/libcxx/test/std/containers/sequences/vector.bool/iterators.pass.cpp b/libcxx/test/std/containers/sequences/vector.bool/iterators.pass.cpp
index 9aaaac7a5557f..2a701cc4ad19f 100644
--- a/libcxx/test/std/containers/sequences/vector.bool/iterators.pass.cpp
+++ b/libcxx/test/std/containers/sequences/vector.bool/iterators.pass.cpp
@@ -131,6 +131,15 @@ TEST_CONSTEXPR_CXX20 bool tests()
         assert ( (cii >= ii1 ));
         assert (cii - ii1 == 0);
         assert (ii1 - cii == 0);
+
+#  if TEST_STD_VER >= 20
+        // P1614 + LWG3352
+        std::same_as<std::strong_ordering> decltype(auto) r1 = ii1 <=> ii2;
+        assert(r1 == std::strong_ordering::equal);
+
+        std::same_as<std::strong_ordering> decltype(auto) r2 = ii1 <=> ii2;
+        assert(r2 == std::strong_ordering::equal);
+#  endif // TEST_STD_VER > 20
     }
 #endif
 
diff --git a/libcxx/test/std/containers/sequences/vector/iterators.pass.cpp b/libcxx/test/std/containers/sequences/vector/iterators.pass.cpp
index 70e0e35767e09..457791b8ee6af 100644
--- a/libcxx/test/std/containers/sequences/vector/iterators.pass.cpp
+++ b/libcxx/test/std/containers/sequences/vector/iterators.pass.cpp
@@ -164,8 +164,16 @@ TEST_CONSTEXPR_CXX20 bool tests()
         assert ( (cii >= ii1 ));
         assert (cii - ii1 == 0);
         assert (ii1 - cii == 0);
+#  if TEST_STD_VER >= 20
+        // P1614 + LWG3352
+        std::same_as<std::strong_ordering> decltype(auto) r1 = ii1 <=> ii2;
+        assert(r1 == std::strong_ordering::equal);
+
+        std::same_as<std::strong_ordering> decltype(auto) r2 = ii1 <=> ii2;
+        assert(r2 == std::strong_ordering::equal);
+#  endif // TEST_STD_VER > 20
     }
-#endif
+#endif // TEST_STD_VER > 11
 
     return true;
 }

github-actions · 2024-07-17T15:50:04Z

✅ With the latest revision this PR passed the C/C++ code formatter.

libcxx/docs/Status/SpaceshipProjects.csv

libcxx/include/__iterator/wrap_iter.h

ldionne

LGTM but we need to update __bounded_iter as mentioned by other reviewers. Thanks!

This implements the requirements for the container iterator requirements for array, deque, vector, and vector<bool>. Implements: - LWG3352 strong_equality isn't a thing Implements parts of: - P1614R2 The Mothership has Landed Fixes: #62486

Note the code is not yet conforming.

ldionne · 2024-07-23T15:46:52Z

libcxx/test/libcxx/iterators/bounded_iter/comparison.pass.cpp

+  tests<three_way_contiguous_iterator<int*>>();
+  static_assert(tests<three_way_contiguous_iterator<int*>>());


I would declare

template <class Iter, bool HasSpaceship = false> TEST_CONSTEXPR_CXX14 bool tests() { ... if constexpr (HasSpaceship) { ... } }

Then:

tests<three_way_contiguous_iterator<int*>, /* has spaceship */ true>(); static_assert(tests<three_way_contiguous_iterator<int*>, /* has spaceship */ true>());

Actually this is no longer needed. This was a left-over while reworking the patch. operator<=> always works on these iterators.

libcxx/test/std/containers/views/views.span/span.iterators/iterator.pass.cpp

ldionne · 2024-07-23T15:50:50Z

libcxx/test/std/containers/views/views.span/span.iterators/iterator.pass.cpp

+  // TODO Test against C++23 after implementing
+  // P2278R4 cbegin should always return a constant iterator


Suggested change

// TODO Test against C++23 after implementing

// P2278R4 cbegin should always return a constant iterator

// TODO Test against C++23 after implementing

// P2278R4 cbegin should always return a constant iterator

// and then remove the #ifdefs

The #ifdef should remain, but guard against C++23.

libcxx/test/std/containers/views/views.span/span.iterators/iterator.pass.cpp

libcxx/include/deque

ldionne · 2024-07-23T15:55:31Z

libcxx/include/__iterator/wrap_iter.h

+template <class _Iter1>
+_LIBCPP_HIDE_FROM_ABI constexpr strong_ordering
+operator<=>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) noexcept {
+  if constexpr (three_way_comparable<_Iter1, strong_ordering>) {
+    return __x.base() <=> __y.base();
+  } else {
+    if (__x.base() < __y.base())
+      return strong_ordering::less;
+
+    if (__x.base() == __y.base())
+      return strong_ordering::equal;
+
+    return strong_ordering::greater;
+  }
+}


Can't we simply get rid of this entirely? I think the reason we have those for operator< & friends was because we ran into some issue, but I am not certain that issue also exists for operator<=>. I would try removing it and see if that works.

libcxx/include/__iterator/bounded_iter.h

mordante · 2024-07-24T17:43:13Z

/cherry-pick 8d3252a

llvmbot · 2024-07-24T17:47:57Z

Failed to cherry-pick: 8d3252a

https://github.com/llvm/llvm-project/actions/runs/10081464221

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

…lvm#99343) This implements the requirements for the container iterator requirements for array, deque, vector, and `vector<bool>`. Implements: - LWG3352 strong_equality isn't a thing Implements parts of: - P1614R2 The Mothership has Landed Fixes: llvm#62486

This is a followup of llvm#99343. Since that patch was quite late in the LLVM-19 release cycle some of the unneeded relational operator were not removed in C++20. This removes them and gives the change a bit more "backing" time, just in case there are issues with this change in user code. This change should be an NFC.

…99343) Summary: This implements the requirements for the container iterator requirements for array, deque, vector, and `vector<bool>`. Implements: - LWG3352 strong_equality isn't a thing Implements parts of: - P1614R2 The Mothership has Landed Fixes: #62486 Test Plan: Reviewers: Subscribers: Tasks: Tags: Differential Revision: https://phabricator.intern.facebook.com/D60250694

…lvm#99343) This implements the requirements for the container iterator requirements for array, deque, vector, and `vector<bool>`. Implements: - LWG3352 strong_equality isn't a thing Implements parts of: - P1614R2 The Mothership has Landed Fixes: llvm#62486

This is a followup of #99343. Since that patch was quite late in the LLVM-19 release cycle some of the unneeded relational operator were not removed in C++20. This removes them and gives the change a bit more "baking" time, just in case there are issues with this change in user code. This change is intended to be an NFC.

This is a followup of llvm/llvm-project#99343. Since that patch was quite late in the LLVM-19 release cycle some of the unneeded relational operator were not removed in C++20. This removes them and gives the change a bit more "baking" time, just in case there are issues with this change in user code. This change is intended to be an NFC. NOKEYCHECK=True GitOrigin-RevId: 39b6900852e7a1187bd742ba5c1387ca1be58e2c

mordante added this to the LLVM 19.X Release milestone Jul 17, 2024

mordante requested a review from a team as a code owner July 17, 2024 15:46

llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Jul 17, 2024

Zingam reviewed Jul 17, 2024

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libcxx/docs/Status/SpaceshipProjects.csv Show resolved Hide resolved

mordante force-pushed the users/mordante/spaceship_container_iterators branch 2 times, most recently from d0e8d06 to 00df20a Compare July 17, 2024 17:09

frederick-vs-ja reviewed Jul 18, 2024

View reviewed changes

libcxx/include/__iterator/wrap_iter.h Show resolved Hide resolved

ldionne approved these changes Jul 18, 2024

View reviewed changes

mordante added 2 commits July 20, 2024 14:02

bounded_iterator

2dc8392

mordante force-pushed the users/mordante/spaceship_container_iterators branch 2 times, most recently from 71a6a1b to 2115d64 Compare July 20, 2024 13:09

CI fixes.

cd9e497

mordante force-pushed the users/mordante/spaceship_container_iterators branch 3 times, most recently from c4db2df to b2216ca Compare July 21, 2024 11:02

mordante marked this pull request as draft July 21, 2024 11:03

CI fixes and improvements

0739782

Note the code is not yet conforming.

mordante force-pushed the users/mordante/spaceship_container_iterators branch from b2216ca to 0739782 Compare July 21, 2024 12:30

Polish the patch.

ecd6887

mordante marked this pull request as ready for review July 22, 2024 16:34

ldionne requested changes Jul 23, 2024

View reviewed changes

mordante marked this pull request as draft July 23, 2024 16:56

Addresses review comments.

e94dc78

mordante force-pushed the users/mordante/spaceship_container_iterators branch from 462924b to e94dc78 Compare July 24, 2024 15:43

mordante marked this pull request as ready for review July 24, 2024 15:43

ldionne approved these changes Jul 24, 2024

View reviewed changes

mordante merged commit 8d3252a into main Jul 24, 2024

mordante deleted the users/mordante/spaceship_container_iterators branch July 24, 2024 17:42

llvmbot added the release:cherry-pick-failed label Jul 24, 2024

mordante mentioned this pull request Jul 24, 2024

[libc++][spaceship] Implements X::iterator container requirements. (#99343) #100440

Merged

mordante mentioned this pull request Jul 24, 2024

[libc++][spaceship] Removes unneeded relational operators. #100441

Merged

philnik777 mentioned this pull request Aug 2, 2024

[Clang] Add a release note deprecating __is_nullptr #101638

Merged

mgabka mentioned this pull request Aug 22, 2024

Add release note about ABI mgabka/llvm-project#6

Open

thewtex mentioned this pull request Feb 10, 2025

llvmorg 19.1.5 libcxxabi pthread lib name #126605

Closed

		tests<three_way_contiguous_iterator<int*>>();
		static_assert(tests<three_way_contiguous_iterator<int*>>());

		// TODO Test against C++23 after implementing
		// P2278R4 cbegin should always return a constant iterator

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[libc++][spaceship] Implements X::iterator container requirements. #99343

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edited by ldionne

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