Re: [boost] [serialization] add_facet, VC7.1, and overloading operator new

From: Robert Ramey (ramey_at_[hidden])
Date: 2005-06-21 23:25:44

and what about all the new's in add_facet.hpp ?

Robert Ramey

Chris Byrne wrote:
> Hi,
>
>   I've been playing around with overloading global operator new and
> delete and came across a problem concerning facets with VC7.1 in debug
> mode. Internally facets are reference counted and destroyed in
> [locale0.cpp - locale::_Locimp::~_Locimp()] via a macro _DELETE_CRT
> [xdebug]. Now when _DEBUG is defined this macro will not call
> 'operator delete' directly. So any facets added to a locale using
> 'operator new'
> will not be freed with 'operator delete'.
>
> In my case this leads to an assertion in dbgheap.c. This is because
> the
> heap manager correctly recognizes that it was not responsible for the
> allocation.
>
> boost/archive/impl/basic_text_iprimitive.ipp:
>    add_facet(
>       std::locale::classic(),
>       new codecvt_null<BOOST_DEDUCED_TYPENAME IStream::char_type>
>    )
>
> Minimal example is appended to the bottom of this post. As for a
> possible work around (read hack) you can use _NEW_CRT instead of new
> directly. A some what nicer hack^H^H^H^Hsolution may be to get
> add_facet
> to perform the actual facet allocation itself using _NEW_CRT instead
> of
> the caller.
>
> Chris Byrne
>
>
////////////////////////////////////////////////////////////////////////////
> #include <boost/archive/add_facet.hpp>
> #include <boost/archive/codecvt_null.hpp>
> #include <boost/shared_ptr.hpp>
> #include <stdlib.h>
> #include <malloc.h>
>
> using namespace boost;
> using namespace boost::archive;
> using namespace std;
>
> void* operator new(size_t size) {
>     char* block = reinterpret_cast<char*>(malloc(size + 1));
>     return block + 1;
> }
>
> void operator delete(void* address) {
>     if (!address) return;
>     char* block = reinterpret_cast<char*>(address);
>     free(block - 1);
> }
>
> int main() {
>     shared_ptr<locale> p;
>     p.reset(
>        add_facet(locale::classic(), new codecvt_null<char>)
> //    add_facet(locale::classic(), _NEW_CRT codecvt_null<char>)
>     );
>     p.reset();
>     return 0;
> }
>
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