how to debug memory errors

[bachmeier via Digitalmars-d-learn]

On Monday, 7 November 2016 at 02:22:35 UTC, Steven Schveighoffer 
wrote:
> Imagine a resource wrapper like so:
>
> class Foo
> {
>    int *mem;
>    this() { mem = cast(int *)malloc(int.sizeof); }
>    ~this() { .free(mem); }
> }
>
> Now, you have a problem if you do something like this:
>
> class Bar
> {
>    Foo foo;
>    ~this() { delete foo; }
> }
>

Is there a valid use case for something like this? Why would you 
want to do anything inside ~this with GC memory?