1 files changed, 42 insertions, 21 deletions
diff --git a/contrib/llvm-project/libcxx/include/__mdspan/extents.h b/contrib/llvm-project/libcxx/include/__mdspan/extents.h
index 42355678d60c..a510220d4096 100644
--- a/contrib/llvm-project/libcxx/include/__mdspan/extents.h
+++ b/contrib/llvm-project/libcxx/include/__mdspan/extents.h
@@ -171,11 +171,14 @@ public:
       _TStatic __static_val = _StaticValues::__get(__i);
       if (__static_val == _DynTag) {
         __dyn_vals_[_DynamicIdxMap::__get(__i)] = __values[__i];
-      }
-      // Precondition check
-      else
-        _LIBCPP_ASSERT_UNCATEGORIZED(__values[__i] == static_cast<_TDynamic>(__static_val),
-                                     "extents construction: mismatch of provided arguments with static extents.");
+      } else
+        // Not catching this could lead to out of bounds errors later
+        // e.g. using my_mdspan_t = mdspan<int, extents<int, 10>>; my_mdspan_t = m(new int[5], 5);
+        // Right-hand-side construction looks ok with allocation and size matching,
+        // but since (potentially elsewhere defined) my_mdspan_t has static size m now thinks its range is 10 not 5
+        _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
+            __values[__i] == static_cast<_TDynamic>(__static_val),
+            "extents construction: mismatch of provided arguments with static extents.");
     }
   }
 
@@ -187,11 +190,14 @@ public:
       _TStatic __static_val = _StaticValues::__get(__i);
       if (__static_val == _DynTag) {
         __dyn_vals_[_DynamicIdxMap::__get(__i)] = static_cast<_TDynamic>(__vals[__i]);
-      }
-      // Precondition check
-      else
-        _LIBCPP_ASSERT_UNCATEGORIZED(static_cast<_TDynamic>(__vals[__i]) == static_cast<_TDynamic>(__static_val),
-                                     "extents construction: mismatch of provided arguments with static extents.");
+      } else
+        // Not catching this could lead to out of bounds errors later
+        // e.g. using my_mdspan_t = mdspan<int, extents<int, 10>>; my_mdspan_t = m(new int[N], span<int,1>(&N));
+        // Right-hand-side construction looks ok with allocation and size matching,
+        // but since (potentially elsewhere defined) my_mdspan_t has static size m now thinks its range is 10 not N
+        _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
+            static_cast<_TDynamic>(__vals[__i]) == static_cast<_TDynamic>(__static_val),
+            "extents construction: mismatch of provided arguments with static extents.");
     }
   }
 
@@ -310,28 +316,37 @@ public:
              (sizeof...(_OtherIndexTypes) == __rank_ || sizeof...(_OtherIndexTypes) == __rank_dynamic_))
   _LIBCPP_HIDE_FROM_ABI constexpr explicit extents(_OtherIndexTypes... __dynvals) noexcept
       : __vals_(static_cast<index_type>(__dynvals)...) {
-    _LIBCPP_ASSERT_UNCATEGORIZED(__mdspan_detail::__are_representable_as<index_type>(__dynvals...),
-                                 "extents ctor: arguments must be representable as index_type and nonnegative");
+    // Not catching this could lead to out of bounds errors later
+    // e.g. mdspan m(ptr, dextents<char, 1>(200u)); leads to an extent of -56 on m
+    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__are_representable_as<index_type>(__dynvals...),
+                                        "extents ctor: arguments must be representable as index_type and nonnegative");
   }
 
   template <class _OtherIndexType, size_t _Size>
-    requires(is_convertible_v<_OtherIndexType, index_type> && is_nothrow_constructible_v<index_type, _OtherIndexType> &&
+    requires(is_convertible_v<const _OtherIndexType&, index_type> &&
+             is_nothrow_constructible_v<index_type, const _OtherIndexType&> &&
              (_Size == __rank_ || _Size == __rank_dynamic_))
   explicit(_Size != __rank_dynamic_)
       _LIBCPP_HIDE_FROM_ABI constexpr extents(const array<_OtherIndexType, _Size>& __exts) noexcept
       : __vals_(span(__exts)) {
-    _LIBCPP_ASSERT_UNCATEGORIZED(__mdspan_detail::__are_representable_as<index_type>(span(__exts)),
-                                 "extents ctor: arguments must be representable as index_type and nonnegative");
+    // Not catching this could lead to out of bounds errors later
+    // e.g. mdspan m(ptr, dextents<char, 1>(array<unsigned,1>(200))); leads to an extent of -56 on m
+    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__are_representable_as<index_type>(span(__exts)),
+                                        "extents ctor: arguments must be representable as index_type and nonnegative");
   }
 
   template <class _OtherIndexType, size_t _Size>
-    requires(is_convertible_v<_OtherIndexType, index_type> && is_nothrow_constructible_v<index_type, _OtherIndexType> &&
+    requires(is_convertible_v<const _OtherIndexType&, index_type> &&
+             is_nothrow_constructible_v<index_type, const _OtherIndexType&> &&
              (_Size == __rank_ || _Size == __rank_dynamic_))
   explicit(_Size != __rank_dynamic_)
       _LIBCPP_HIDE_FROM_ABI constexpr extents(const span<_OtherIndexType, _Size>& __exts) noexcept
       : __vals_(__exts) {
-    _LIBCPP_ASSERT_UNCATEGORIZED(__mdspan_detail::__are_representable_as<index_type>(__exts),
-                                 "extents ctor: arguments must be representable as index_type and nonnegative");
+    // Not catching this could lead to out of bounds errors later
+    // e.g. array a{200u}; mdspan<int, dextents<char,1>> m(ptr, extents(span<unsigned,1>(a))); leads to an extent of -56
+    // on m
+    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__are_representable_as<index_type>(__exts),
+                                        "extents ctor: arguments must be representable as index_type and nonnegative");
   }
 
 private:
@@ -380,10 +395,16 @@ public:
       for (size_t __r = 0; __r < rank(); __r++) {
         if constexpr (static_cast<make_unsigned_t<index_type>>(numeric_limits<index_type>::max()) <
                       static_cast<make_unsigned_t<_OtherIndexType>>(numeric_limits<_OtherIndexType>::max())) {
-          _LIBCPP_ASSERT_UNCATEGORIZED(__mdspan_detail::__is_representable_as<index_type>(__other.extent(__r)),
-                                       "extents ctor: arguments must be representable as index_type and nonnegative");
+          // Not catching this could lead to out of bounds errors later
+          // e.g. dextents<char,1>> e(dextents<unsigned,1>(200)) leads to an extent of -56 on e
+          _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
+              __mdspan_detail::__is_representable_as<index_type>(__other.extent(__r)),
+              "extents ctor: arguments must be representable as index_type and nonnegative");
         }
-        _LIBCPP_ASSERT_UNCATEGORIZED(
+        // Not catching this could lead to out of bounds errors later
+        // e.g. mdspan<int, extents<int, 10>> m = mdspan<int, dextents<int, 1>>(new int[5], 5);
+        // Right-hand-side construction was ok, but m now thinks its range is 10 not 5
+        _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
             (_Values::__static_value(__r) == dynamic_extent) ||
                 (static_cast<index_type>(__other.extent(__r)) == static_cast<index_type>(_Values::__static_value(__r))),
             "extents construction: mismatch of provided arguments with static extents.");