Proposed resolution (February, 2017):

Change 7.6.2.8 [expr.new] paragraph 27 as follows:

A declaration of a placement deallocation function matches the declaration of a placement allocation function if it has the same number of parameters and, after parameter transformations (9.3.4.6 [dcl.fct]), all parameter types except the first are identical. If the lookup finds a single matching deallocation function, that function will be called; otherwise, no deallocation function will be called. If the lookup finds a usual deallocation function with a parameter of type std::size_t (6.7.6.5.3 [basic.stc.dynamic.deallocation]) and that function, considered as a placement deallocation function, would have been selected as a match for the allocation function, the program is ill-formed. For a non-placement allocation function, the normal deallocation function lookup is used to find the matching deallocation function (7.6.2.9 [expr.delete]). [Example:...

[Accepted as a DR at the November, 2019 meeting.]

The restrictions in 7.6.2.8 [expr.new] against a placement deallocation function signature matching a usual deallocation function signature consider only std::size_t parameters, omitting std::align_val_t parameters.