From: Eric Wong <normalperson@...>
Date: 2013-10-09T02:25:47+00:00
Subject: [ruby-core:57757] Re: [ruby-trunk - Feature #8992] Use String#freeze and compiler tricks to replace "str"f suffix

"headius (Charles Nutter)" <headius@headius.com> wrote:
> So here's the same question I asked in the #frozen feature: why can't
> #freeze just use the fstring table?

That would be an interesting experiment.  After all, it is #freeze and
not #freeze!, so maybe we have some leverage there.

> * fstrings will GC and clear themselves from that table

I think this needs some work for the non-parser case, there seems to
be a bad interaction with lazy sweep.  My analysis of my failed
patch for Feature #8998:
  http://mid.gmane.org/20131009021547.GA1839@dcvr.yhbt.net

I also get (identical?) segfaults with the following:

diff --git a/object.c b/object.c
--- a/object.c
+++ b/object.c
@@ -1029,6 +1029,8 @@ VALUE
 rb_obj_freeze(VALUE obj)
 {
     if (!OBJ_FROZEN(obj)) {
+	if (TYPE(obj) == T_STRING)
+	    return rb_fstring(obj);
 	OBJ_FREEZE(obj);
 	if (SPECIAL_CONST_P(obj)) {
 	    if (!immediate_frozen_tbl) {