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

["mark at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #97 from mark at codesourcery dot com  2007-05-18 21:17 -------
Subject: Re:  [4.0/4.1/4.2/4.3 Regression] placement
 new does not change the dynamic type as it should

rguenth at gcc dot gnu dot org wrote:

> But construction/initialization of uninitalized memory in <memory> happens with
> placement new!  So we're back to square one.  What this PR initially was about
> is a fixed type memory allocator in C++ which needs to change memory from
> allocated type T to free-space-managing-structure S at deallocation time and
> the other way around at allocation time.  We absolutely _have_ to handle
> this case correct.  And we need to optimize the <memory> routines that use
> placement new, because they resemble patterns used in libraries like POOMA
> or Boost.

First and foremeost, we have to generate correct code.  If that means
the memory barrier solution, for now, then so be it.


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