Annex F (informative) Core undefined behavior [ub]

F.3 [expr]: Expressions [ub.expr]

F.3.23[ub:expr.delete.array.mismatch]
Specified in: [expr.delete]

Using single object delete on the result of an array new expression has undefined behavior.
[Example 1: int* x = new int[10]; delete x; // undefined behavior, allocated using array new expression — end example]