https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88664
Bug ID: 88664
Summary: False positive -Waddress-of-packed-member
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nathan at gcc dot gnu.org
Target Milestone: ---
Created attachment 45316
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45316&action=edit
extracted from code using epoll_event structure
nathans@devvm2452:29>./cc1plus -Waddress-of-packed-member ../../../packed.cc
-quiet
../../../packed.cc: In function 'void foo(epoll_event*)':
../../../packed.cc:10:49: warning: taking address of packed member of
'epoll_event' may result in an unaligned pointer value
[-Waddress-of-packed-member]
10 | int *actionable = static_cast <int *> (event->ptr);
| ~~~~~~~^~~
But we're not taking the address of the packed field, we're converting the
value the field holds to a different pointer.
epoll_event is packed, and I imagine more code than mine squirrels away data
pointers in its data field. I suppose the FE could internally be taking a
reference to preserve lvalueness ...
