https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85009
--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- It's not obvious that this is a bug, in that _Atomic is syntactically a qualifier, but excluded semantically for most purposes. In particular, that conversion is permitted by ISO C, so the _Atomic case must *not* be a pedwarn, even if it receives a -Wdiscarded-qualifiers warning.
