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

From: Chris Byrne (chris_at_[hidden])
Date: 2005-06-22 01:35:34

Robert Ramey wrote:
> and what about all the new's in add_facet.hpp ?

AFAICT only the facet allocation is causing a problem. 'new std::locale' 
is not affected as shared_ptr calls 'operator delete' correctly.

> 
> 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;
>>}
>>