Profiling Garbage Collector

[Chad J]

As I contemplated the challenge of determining whether or not a library 
(not an entire program) causes heap activity and whether or not it 
leaves garbage for the gc, I decided that having a profiling garbage 
collector would be really useful for such tasks.

Such a profiling collector would have the following features:
- For each type in the program, it would track how many times each type 
is allocated, how many times each type is manually deleted, and how many 
times each type is collected by the garbage collector.
- It can return a string containing the above information.  Also, it'd 
be nice if the gc could summarize by saying which types were "leaked" 
most frequently.
- Ideally, it not only uses type information but also has some help from 
the compiler.  Thus it not only knows about types, but can keep track of 
every single allocation on a file by file, line by line, basis.  That 
way finding leaks would be as simple as reading "the allocation of Foo 
at line 42 in file bar.d was collected 1762 times".  This may require 
some extra origination information to be stored in each object/array/etc 
for programs undergoing GC profiling.

Well, other than spouting the idea and refusing to implement it, I am 
wondering - has anyone made this kind of thing yet?