Delete operators with additional allocator reference/pointer parameters
are needed if the constructor of an 'new(allocator)' allocated object
throws an exception. Also, destroy now uses the operator to free memory
and provides variants with allocator reference and pointer.
The commit includes a simple test scripts 'run/new_delete', which
exercises the several 'delete' cases.
Related to #1030.
Splitting the new Genode::Deallocator interface from the former
Genode::Allocator interface enables us to restrict the accessible
operations for code that is only supposed to release memory, but not
perform any allocations.
Additionally, this patch introduces variants of the 'new' operator
that takes a reference (as opposed to a pointer) to a Genode::Allocator
as argument.
The 'delete (void *)' operator gets referenced by compiler generated code,
so it must be publicly defined in the 'cxx' library. These compiler
generated calls seem to get executed only subsequently to explicit
'delete (void *)' calls in application code, which are not supported by
the 'cxx' library, so the 'delete (void *)' implementation in the 'cxx'
library does not have to do anything. Applications should use the
'delete (void *)' implementation of the 'stdcxx' library instead. To make
this possible, the 'delete (void *)' implementation in the 'cxx' library
must be 'weak'.
Fixes#419.
This patch implements the support needed to handle exceptions that occur
during the construction of objects dynamically allocated via the
'Allocator' interface. In this case, the compiler automatically invokes
a special delete operator that takes the allocator type (as supplied to
'new') as second argument. The implementation of this delete operator
has been added to the 'cxx' library. Because the operator delete is
called without the size of the object, we can use only those allocators
that ignore the size argument of the free function and print a warning
otherwise. The added 'Allocator::need_size_for_free()' function is used
to distinguish safe and unsafe allocators.
