[Bug libstdc++/29286] [4.0/4.1/4.2/4.3 Regression] placement new does not change the dynamic type as it should

["gdr at cs dot tamu dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #158 from gdr at cs dot tamu dot edu  2007-05-24 10:47 -------
Subject: Re:  [4.0/4.1/4.2/4.3 Regression] placement new does not change the
dynamic type as it should

"rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:

[...]

| > Now, if I understand your argument below correctly, you are saying
| > that even if we fixed the union rules for C++, we may still be facing
| > the same problem because assignment to POD objects does not just mean
| > that the object was there before, but that we are actually starting a
| > new one.  Do I understand your argument correctly?
| 
| Yes. 

Then, I'm not sure I agree with that.  I'll raise it as part of the
union problem.

| For non-PODs I'm not sure if it is allowed to start object
| lifetime via assignment rather than only by placement new.

Assignment for non-POD is equivalent to calling a member function for
an object, which means that the object already existed.  So, no you
cannot start lifetime for object of non-POD type by assignment.

-- Gaby


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29286