[libcxx-commits] [libcxx] 0edc92e - [libc++] LWG3738 Validates a missing precondition.

[Mark de Wever via libcxx-commits]

Author: Mark de Wever
Date: 2022-12-23T17:20:57+01:00
New Revision: 0edc92e6e098e66e452a730f524b0905e2d4c78b

URL: https://github.com/llvm/llvm-project/commit/0edc92e6e098e66e452a730f524b0905e2d4c78b
DIFF: https://github.com/llvm/llvm-project/commit/0edc92e6e098e66e452a730f524b0905e2d4c78b.diff

LOG: [libc++] LWG3738 Validates a missing precondition.

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

This implements:
- 3738 Missing preconditions for take_view constructor

Reviewed By: #libc, philnik

Differential Revision: https://reviews.llvm.org/D140568

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/libcxx/docs/Status/Cxx2bIssues.csv b/libcxx/docs/Status/Cxx2bIssues.csv
index 3a6d2c8fff2a2..8171ce30c1c24 100644
--- a/libcxx/docs/Status/Cxx2bIssues.csv
+++ b/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","|Complete|","16.0",""
 "`3746 <https://wg21.link/LWG3746>`__","``optional``'s spaceship with ``U`` with a type derived from optional causes infinite constraint meta-recursion", "November 2022","","","|spaceship|"

diff  --git a/libcxx/include/__ranges/take_view.h b/libcxx/include/__ranges/take_view.h
index 546e898aec911..bea3862cd7c8c 100644
--- a/libcxx/include/__ranges/take_view.h
+++ b/libcxx/include/__ranges/take_view.h
@@ -12,6 +12,7 @@
 
 #include <__algorithm/min.h>
 #include <__algorithm/ranges_min.h>
+#include <__assert>
 #include <__concepts/constructible.h>
 #include <__concepts/convertible_to.h>
 #include <__config>
@@ -63,9 +64,10 @@ class take_view : public view_interface<take_view<_View>> {
   _LIBCPP_HIDE_FROM_ABI
   take_view() requires default_initializable<_View> = default;
 
-  _LIBCPP_HIDE_FROM_ABI
-  constexpr take_view(_View __base, range_
diff erence_t<_View> __count)
-    : __base_(std::move(__base)), __count_(__count) {}
+  _LIBCPP_HIDE_FROM_ABI constexpr take_view(_View __base, range_
diff erence_t<_View> __count)
+      : __base_(std::move(__base)), __count_(__count) {
+    _LIBCPP_ASSERT(__count >= 0, "count has to be greater than or equal to zero");
+  }
 
   _LIBCPP_HIDE_FROM_ABI
   constexpr _View base() const& requires copy_constructible<_View> { return __base_; }