CPointer instances created via a native function call that takes a callback argument and has its result assigned to a scalar variable don't have DESTROY called

[p6rt]

Migrated from rt.perl.org#125738 (status was 'new')

Searchable as RT125738$

[p6rt]

From @hoelzro

See the attached file.

Let's say I have a native function that returns a pointer to a type and takes a callback​:

  my_struct *create_my_struct(size_t size, void (*error_callback)(error_t *error));

...and I call that function via NativeCall, and assign the result to a scalar variable​:

  class MyStruct is repr('CPointer') {
  my sub create_my_struct(int $size, &error-callback (Error)) returns MyStruct is native('mystructlib') { * }

  method new() {
  my $err;
  my $result = create_my_struct(8, -> Error $e { $err = $e.copy });
  $err.throw if $err;
  $result
  }
  }

In that case, the DESTROY finalizer on that pointer is never called. If I assign to a backslash variable​:

  my \result = create_my_struct(8, > Error $e { $err = $e.copy });

...DESTROY *is* called.

[p6rt]

From @hoelzro

pointy-pointer-mem-test.pl