For a reflection value `r` that represents a variable, `std::meta::alignment_of(r)` is specified to return the alignment requirement of the variable. If the variable's definition has an `alignas` specifier, its non-defining declaration does not (as permitted by [dcl.align] p6), and only the latter is reachable in the evaluation context, is the `std::meta::alignment_of` call valid? If yes, what should it return?

Example:

#include <meta>

extern char ch;
constexpr auto x = std::meta::alignment_of(^^ch);

alignas(64) char ch;
constexpr auto x2 = x; // x2 is 1 or 64?