[Bug c/82599] Assignments from statically initialized flexible arrays copy too much

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82599

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid, wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-10-18
            Version|5.4.0                       |7.2.1
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  I think the issue is that we make the new type created by
constructing the object compatible (or the same) as the second.  Then we get to
invalid GIMPLE
being simply

  second = first;

which ends up using expr_size from the source.  Iff the C FE wants to support
this kind of assignments (not sure if it really should!) then it needs to
tack appropriate WITH_SIZE_EXPRs on the decls.