[expr.delete] p7 The time of calling a deallocation function

If the value of the operand of the delete-expression is not a null pointer value, then:

• [...]
• Otherwise, if the allocation was extended or was provided by extending the allocation of another new-expression, and the delete-expression for every other pointer value produced by a new-expression that had storage provided by the extended new-expression has been evaluated, the delete-expression shall call a deallocation function. The value returned from the allocation call of the extended new-expression shall be passed as the first argument to the deallocation function.
• Otherwise, the delete-expression will not call a deallocation function.

Consider this example

struct Container{
   char memory[2];
};
auto ptr0 = new Container;  //#0
auto ptr1 = new char;  // #1
auto ptr2 = new char;  //#2
delete ptr1;  //#3
delete ptr2;  //#4
delete ptr0;  //#5

Assume the new-expression at #0 has been extended to provide the storage for #1 and #2. Note the emphasized wording in the second bullet, since there are only two new-expression that use the allocation provided by #0, hence at this point at #4, could we say the delete-expression for every other pointer value(...) has been evaluated? So, the deallocation function shall be called at #4? At the point of #5, the second bullet is also satisfied, hence it again call the deallocation function? Obviously, it does not make sense however it is what the second bullet saying.

I think the second bullet is intend to cover the following case

auto ptr0 = new Container;  //#0
auto ptr1 = new char;  // #1
auto ptr2 = new char;  //#2
delete ptr1;  //#3
delete ptr0;  //#5
delete ptr2;  //#4

This example is based on the first by adjusting the order of the delete-expression whose operand is produced by the extended allocation. The second bullet can work fine in this example, since #4 has not been evaluated, hence #5 cannot invoke the deallocation function, it's the responsibility of #4. However, as aforementioned, the second bullet seems not good at the first example.

Start with the quoted [expr.delete] wording and the two allocation/deallocation examples in issue #4850. Trace which delete-expressions satisfy the second bullet, then compare the intended sequencing with the current standard text; done means the ambiguity is resolved and the wording or interpretation is agreed upon.