[ooc-compiler] oo2c-2.0.18 released

[Michael v. A. <Mic...@de...>]

Almost all changes from 2.0.17 to .18 deal with the interaction
between the oo2c run-time system and the gc: atomic objects,
finalization, and weak references.  All of this was contributed by
Stewart Greenhill.


Changelog:

Heap objects of which the compiler knows that they do not contain any
pointers (or which are marked as NO_TRACED_POINTERS) are allocated
using GC_malloc_atomic().  Depending on the heap usage of a program,
this may reduce the chance that the GC classifies objects as live
because it considers non-pointer data as pointers, and may reduce the
cost of tracing live objects.

A finalization method can be specified for classes derived from
Object.Object (or RT0.Object), simply by redefining the Finalize()
method.  It is called by the run-time system before the object is
collected by the gc.

A new library module `WeakRef' implements weak pointers to objects;
that is, pointers that do not keep the referenced object live as far
as the gc is concerned.  If a WeakRef pointer refers to an object that
is reclaimed, then this pointer is automatically set to NIL.

Bug fixes for some scenarios involving parametric types (in
particular, parameter passing to procedure arguments of parametric
array types) are included as well.

-- mva