[ruby-core:37646] Module#mix documentation request and possible bug report

Hello, I discovered Module#mix while chasing down segfaults at exit with
timer thread [ruby-core:37642].

Can we have more documentation for Module#mix, please?

I'm not entirely certain what it does, but I found some possible bug
which I will highlight with diff+comments:

--- a/class.c
+++ b/class.c
@@ -736,6 +736,11 @@ do_mix_const_i(st_data_t key, st_data_t value, st_data_t arg)
 	argp->id = id;
 	return ST_STOP;
     }
+
+    /*
+     * value is rb_const_entry_t here, does it need be ALLOC()-ed and
+     * copied to avoid double-free later?
+     */
     st_insert(argp->mtbl, id, value);
     return ST_CONTINUE;
 }
@@ -801,6 +806,8 @@ rb_mix_module(VALUE klass, VALUE module, st_table *constants, st_table *methods)
     methodarg.id = 0;
     methodarg.aliasing = methods;
     methodarg.klass = klass;
+
+    /* Shouldn't the following be RMODULE_CONST_TBL(klass)? */
     constarg.mtbl = RMODULE_IV_TBL(klass);
     constarg.id = 0;
     constarg.aliasing = constants;
@@ -809,6 +816,9 @@ rb_mix_module(VALUE klass, VALUE module, st_table *constants, st_table *methods)
     if (methodarg.id) {
 	rb_raise(rb_eArgError, "method would conflict - %s", rb_id2name(methodarg.id));
     }
+
+    /* mtbl_from is still RMODULE_M_TBL(module) here, should it be
+     * mtbl_from = RMODULE_CONST_TBL(module)  instead? */
     st_foreach(mtbl_from, check_mix_const_i, (st_data_t)&constarg);
     if (constarg.id) {
 	rb_raise(rb_eArgError, "constant would conflict - %s", rb_id2name(constarg.id));
---
Thanks for reading!
-- 
Eric Wong