[libcxx-commits] [PATCH] D140568: [libc++] LWG3738 Validates a missing precondition.

[Mark de Wever via Phabricator via libcxx-commits]

Mordante created this revision.
Herald added a project: All.
Mordante requested review of this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.

No real changes were needed, but add an assert for the pre-condition.

This implements:

- 3738 Missing preconditions for take_view constructor


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140568

Files:
  libcxx/docs/Status/Cxx2bIssues.csv
  libcxx/include/__ranges/take_view.h


Index: libcxx/include/__ranges/take_view.h
===================================================================
--- libcxx/include/__ranges/take_view.h
+++ libcxx/include/__ranges/take_view.h
@@ -15,6 +15,7 @@
 #include <__concepts/constructible.h>
 #include <__concepts/convertible_to.h>
 #include <__config>
+#include <__debug>
 #include <__functional/bind_back.h>
 #include <__fwd/span.h>
 #include <__fwd/string_view.h>
@@ -63,9 +64,10 @@
   _LIBCPP_HIDE_FROM_ABI
   take_view() requires default_initializable<_View> = default;
 
-  _LIBCPP_HIDE_FROM_ABI
-  constexpr take_view(_View __base, range_difference_t<_View> __count)
-    : __base_(std::move(__base)), __count_(__count) {}
+  _LIBCPP_HIDE_FROM_ABI constexpr take_view(_View __base, range_difference_t<_View> __count)
+      : __base_(std::move(__base)), __count_(__count) {
+    _LIBCPP_ASSERT(__count >= 0, "precondition failure");
+  }
 
   _LIBCPP_HIDE_FROM_ABI
   constexpr _View base() const& requires copy_constructible<_View> { return __base_; }
Index: libcxx/docs/Status/Cxx2bIssues.csv
===================================================================
--- libcxx/docs/Status/Cxx2bIssues.csv
+++ libcxx/docs/Status/Cxx2bIssues.csv
@@ -203,7 +203,7 @@
 "`3732 <https://wg21.link/LWG3732>`__","``prepend_range`` and ``append_range`` can't be amortized constant time", "November 2022","|Nothing to do|","","|ranges|"
 "`3736 <https://wg21.link/LWG3736>`__","``move_iterator`` missing ``disable_sized_sentinel_for`` specialization", "November 2022","","","|ranges|"
 "`3737 <https://wg21.link/LWG3737>`__","``take_view::sentinel`` should provide ``operator-``", "November 2022","","","|ranges|"
-"`3738 <https://wg21.link/LWG3738>`__","Missing preconditions for ``take_view`` constructor", "November 2022","","","|ranges|"
+"`3738 <https://wg21.link/LWG3738>`__","Missing preconditions for ``take_view`` constructor", "November 2022","|Complete|","16.0","|ranges|"
 "`3743 <https://wg21.link/LWG3743>`__","``ranges::to``'s reserve may be ill-formed", "November 2022","","","|ranges|"
 "`3745 <https://wg21.link/LWG3745>`__","``std::atomic_wait`` and its friends lack ``noexcept``", "November 2022","","",""
 "`3746 <https://wg21.link/LWG3746>`__","``optional``'s spaceship with ``U`` with a type derived from optional causes infinite constraint meta-recursion", "November 2022","","","|spaceship|"


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