Re: debugging tool?

[tmoran@acm.org]

> > Is there a tool around that would scan a large program to check for
> > instances of an object being accessed *after* it's been Finalized?
>
> Remember that Ada permits itself to finalize an object more than once.
  I don't mean multiple Finalize calls - that's easy.  I mean accessing an
object *after* it's been finalized.  For instance:
  Main_Object : Main_Object_Type;      -- Controlled type
  Helper_Object : Helper_Object_Type;  -- also Controlled
  procedure Finalize(X : in out Helper_Object_Type) is ...
  procedure Finalize(X : in out Main_Object_Type) is
  begin
    do something that accesses Helper_Object
    other stuff
  end Finalize;
At program termination things are Finalized in the reverse order of their
creation.  So Helper_Object gets Finalized.  Then Main_Object is Finalized
- but that process includes accessing Helper_Object, which has already
been finalized.  Perhaps it contained pointers that were deallocated so
the attempt to use it *after finalization* crashes.  If Helper_Object is
declared *before* Main_Object, all is well.  I recently ran into something
like this where Helper involved a protected object and an attempt to call
the protected object after it had been finalized was not good.  It seems
to me a fairly easy mistake to declare the helper after the main object,
and it seems like a fairly simple minded source code analysis tool could
detect the problem.