Ractor.make_shareable(a_proc)

Ractor.make_shareable() supports Proc object if
(1) a Proc only read outer local variables (no assignments)
(2) read outer local variables are shareable.

Read local variables are stored in a snapshot, so after making
shareable Proc, any assignments are not affeect like that:

```ruby
a = 1
pr = Ractor.make_shareable(Proc.new{p a})
pr.call #=> 1
a = 2
pr.call #=> 1 # `a = 2` doesn't affect
```

[Feature #17284]

1 files changed, 1 insertions, 0 deletions

diff --git a/vm_core.h b/vm_core.h
index c4341b474c..9ef3af515c 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -1065,6 +1065,7 @@ typedef struct {
 
 VALUE rb_proc_isolate(VALUE self);
 VALUE rb_proc_isolate_bang(VALUE self);
+VALUE rb_proc_ractor_make_shareable(VALUE self);
 
 typedef struct {
     VALUE flags; /* imemo header */