[Bug debug/68904] DWARF for class ios_base says it's a declaration

[chihin.ko at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68904

--- Comment #2 from chihin ko <chihin.ko at oracle dot com> ---
Created attachment 37032
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37032&action=edit
test case