https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111421
--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- The definition of constexpr in C2x is intentionally minimal, with potential for future expansion in subsequent standard revisions. Allowing array element accesses would run into needing an appropriate definition of exactly what cases are allowed and don't count as accessing the value of an object (presumably including requiring the array element index itself to be an integer constant expression within range for the array in question).
