[Voted into the WP at the February, 2012 meeting; moved to DR at the October, 2012 meeting.]

Proposed resolution (August, 2011):

Change 7.7 [expr.const] paragraph 2 as follows:

• ...

• a result that is not mathematically defined or not in the range of representable values for its type;

• an operation that would have undefined behavior [Note: including, for example, signed integer overflow ( Clause 7 [expr]), certain pointer arithmetic (7.6.6 [expr.add]), division by zero (7.6.5 [expr.mul]), or certain shift operations (7.6.7 [expr.shift]) —end note];

• ...

• a subtraction (7.6.6 [expr.add]) where both operands are pointers;

• ...

The requirements for constant expressions do not currently, but should, exclude expressions that have undefined behavior, such as pointer arithmetic when the pointers do not point to elements of the same array.