Re: Free called instead of delete

From:

=?Utf-8?B?Qm9IdWFuZw==?= <BoHuang@discussions.microsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 19 Aug 2009 09:15:01 -0700

Message-ID:

<E5CACC75-BD77-4FDA-BB28-2236E37732FC@microsoft.com>

My base class A news and correspondingly deletes a list of objects in its
cstor and dstor, respectively. I found that if I create class B : public A in
a different file, and new the objects in B's cstor instead of A's cstor, the
destors of those objects are actually called, though cannot step into any
operator delete() function.

If this is due to operator overloading, it would be nice to know which.

As for the mem leak, if you look at the cstor of std::map, within it
eventually an Allocate() is called which calls new to create a default value
type object to populate the map, perhaps similar in mechanic to 'new int[0]'.

Though I do not manually insert into myStdMap, I would assume std::map's
dstor would destroy the hidden default value type object. But MFC traces a
dozen leaks corresponding to a dozen std::maps (empty or not) to the above
scenario.

Well, I would need to resolve the dstor problem before trying to manually
call myStdMap.clear() in dstors as a potential solution.

"Joseph M. Newcomer" wrote:

But then you have to look at all the definitions of std::map.

When a std::map is cleared, destructors are called for the elements of the map. If these
elements are of CMyClass (not CMyClass *), then your CMyClass::~CMyClass destructor will
be called for every one of the elements deleted, before the destructor for your derived
std::map is called. So you are probably correct here; by setting the breakpoint, you are
seeing the destructors of the components of the map being called.

I rarely use the browser capabilities; since the editor sucks, once I've found something,
I certainly don't want to be editing it in the VS editor, so it's usually easier to use my
own editor to do the search. So I can't answer the question.
joe

On Wed, 19 Aug 2009 06:14:09 -0700, BoHuang <BoHuang@discussions.microsoft.com> wrote:

In any case, my class' destructor is not called. It contains a
myStdMap.clear() call.

I am doing this because my class' myStdMap member calls Allocate() to new a
default element in the std::map constructor, which MFC eventually reports as
memory leak. This happens even if no element was added to myStdMap.

I was recommended to manually call myStdMap.clear() in my class' destructor.
But perhaps because ATL::CCRTAllocator::Free() was called, my break point in
the class' virtual destructor is never reached. (My class doesn't inherit
others. The break point in constructor is reached however)

Is there a way to perform 'go to definition' when mousing over delete to
know its exact definition?

Thanks

"Joseph M. Newcomer" wrote:

Note that for many classes,

void operator delete(void *p) { free(p); }

is the definition; the automatic inlining of code will therefore ignore the levels of
indirection and simply call 'free' directly.

Note, however, that you have confused a class method Free (note that it is in a DLL, and
it is ATL::CCRTAllocator::Free, not raw 'free'). So you are still some levels from the
raw free function of the C runtime.
joe

On Tue, 18 Aug 2009 15:16:01 -0700, BoHuang <BoHuang@discussions.microsoft.com> wrote:

I created an object in with new and

mfc90d.dll!operator new(unsigned int nSize=72, const char * lpszFileName=0x007f64e8, int nLine=183) Line 60 C++

myDLL.dll!Test::RTRT::RTRT() Line 183 + 0x11 bytes C++

And cleaned it up with delete. But instead of delete, Free is called:

    mfc90d.dll!ATL::CCRTAllocator::Free(void * p=0x023e8d78) Line 247 C++
    myDLL.dll!myRTRT::~myRTRT() Line 335 + 0x15 bytes C++

Is this due to delete being overloaded somewhere?

Thanks

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm