[Bug sanitizer/67515] New: "invalid vptr" false positive or crash from ubsan for non-virtual call in initializer list

["rogero at howzatt dot demon.co.uk" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67515

            Bug ID: 67515
           Summary: "invalid vptr" false positive or crash from ubsan for
                    non-virtual call in initializer list
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rogero at howzatt dot demon.co.uk
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org
  Target Milestone: ---

Created attachment 36312
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36312&action=edit
Sample program showing the false positive and the seg fault

ubsan produces a warning at runtime from the attached code and then crashes.

The crash is provoked by performing a placement new with a pre-populated
buffer, but can occur 'in the wild' depending on what the memory contents are
at runtime.

Fails with trunk (as at 2015-09-08 using http://melpon.org/wandbox/) and gcc
5.2.0

(This may possibly be related to pr67258)