[Bug c++/68727] [5/6/7 regression] invalid offsetof expressions accepted

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68727

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 40572
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40572&action=edit
gcc7-pr68727.patch

Untested patch that implements the extra finish_offsetof argument.