[Bug c++/72753] sole flexible array member in a typedef rejected

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72753

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Same problem with an unnamed struct defined via an alias-declaration:

  using S = struct { int a[]; };