free causes exception

[Igor via Digitalmars-d-learn]

On Tuesday, 26 January 2016 at 20:17:20 UTC, Steven Schveighoffer 
wrote:
> On 1/26/16 9:20 AM, Igor wrote:
>> I have successfully malloc'ed an object but when I go to free 
>> it in the
>> destructor I get an exception. The destructor simply has
>>
>> ~this() // destructor for Foo
>> {
>>      core.stdc.stdlib.free(&this);
>> }
>>
>>
>> auto buffer = 
>> core.stdc.stdlib.malloc(__traits(classInstanceSize,
>> App))[0..__traits(classInstanceSize, App)];
>> auto app = cast(App)emplace!App(buffer[]);
>>
>> I tried to retain a ptr to buffer and free that but still no 
>> good. I
>> also get a depreciation warning that &this is not an lvalue. 
>> Hopefully I
>> don't have to keep a ptr around to this simply to free it and 
>> avoid
>> future issues?
>>
>> So how am I suppose to free an object?
>
> Don't do it in the destructor.
>
> I can only imagine that you are triggering the destructor with 
> destroy? In this case, destroy is calling the destructor, but 
> then tries to zero the memory (which has already been freed).
>
> There is a mechanism D supports (but I believe is deprecated) 
> by overriding new and delete. You may want to try that. It's 
> deprecated, but has been for years and years, and I doubt it's 
> going away any time soon.
>
> A class shouldn't care how it's allocated or destroyed. That is 
> for the memory manager to worry about.

um? Memory manager? I am doing it manually C++ style so I don't 
have to worry about the god forsaken memory manager. Why is it so 
difficult? I create the object and release it when I need to.

I can replace the destroy(f) with free(inline the code) but I 
don't see why that should matter. The whole point of destructors 
is to do this sort of stuff. That's why they were invented in the 
first place!?!