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, 35 insertions, 9 deletions

diff --git a/ractor.c b/ractor.c
index 272a4bc3b7..a89da04b33 100644
--- a/ractor.c
+++ b/ractor.c
@@ -21,6 +21,12 @@ static VALUE rb_eRactorMovedError;
 static VALUE rb_eRactorClosedError;
 static VALUE rb_cRactorMovedObject;
 
+VALUE
+rb_ractor_error_class(void)
+{
+    return rb_eRactorError;
+}
+
 RUBY_SYMBOL_EXPORT_BEGIN
 // to share with MJIT
 bool ruby_multi_ractor;
@@ -2069,28 +2075,44 @@ rb_obj_traverse(VALUE obj,
 }
 
 static int
-frozen_shareable_p(VALUE obj)
+frozen_shareable_p(VALUE obj, bool *made_shareable)
 {
-    if (!RB_TYPE_P(obj, T_DATA) ||
-        (RTYPEDDATA_P(obj) &&
-         RTYPEDDATA_TYPE(obj)->flags & RUBY_TYPED_FROZEN_SHAREABLE)) {
+    if (!RB_TYPE_P(obj, T_DATA)) {
         return true;
     }
-    else {
-        return false;
+    else if (RTYPEDDATA_P(obj)) {
+        const rb_data_type_t *type = RTYPEDDATA_TYPE(obj);
+        if (type->flags & RUBY_TYPED_FROZEN_SHAREABLE) {
+            return true;
+        }
+        else if (made_shareable && rb_obj_is_proc(obj)) {
+            // special path to make shareable Proc.
+            rb_proc_ractor_make_shareable(obj);
+            *made_shareable = true;
+            VM_ASSERT(RB_OBJ_SHAREABLE_P(obj));
+            return false;
+        }
     }
+
+    return false;
 }
 
 static enum obj_traverse_iterator_result
 make_shareable_check_shareable(VALUE obj)
 {
     VM_ASSERT(!SPECIAL_CONST_P(obj));
+    bool made_shareable = false;
 
     if (RB_OBJ_SHAREABLE_P(obj)) {
         return traverse_skip;
     }
-    else if (!frozen_shareable_p(obj)) {
-        rb_raise(rb_eRactorError, "can not make shareable object for %"PRIsVALUE, obj);
+    else if (!frozen_shareable_p(obj, &made_shareable)) {
+        if (made_shareable) {
+            return traverse_skip;
+        }
+        else {
+            rb_raise(rb_eRactorError, "can not make shareable object for %"PRIsVALUE, obj);
+        }
     }
 
     if (!RB_OBJ_FROZEN_RAW(obj)) {
@@ -2099,6 +2121,10 @@ make_shareable_check_shareable(VALUE obj)
         if (UNLIKELY(!RB_OBJ_FROZEN_RAW(obj))) {
             rb_raise(rb_eRactorError, "#freeze does not freeze object correctly");
         }
+
+        if (RB_OBJ_SHAREABLE_P(obj)) {
+            return traverse_skip;
+        }
     }
 
     return traverse_cont;
@@ -2134,7 +2160,7 @@ shareable_p_enter(VALUE obj)
         return traverse_skip;
     }
     else if (RB_OBJ_FROZEN_RAW(obj) &&
-             frozen_shareable_p(obj)) {
+             frozen_shareable_p(obj, NULL)) {
         return traverse_cont;
     }