From: Eric Wong <normalperson@...>
Date: 2013-10-09T02:15:47+00:00
Subject: [ruby-core:57756] Re: [ruby-trunk - Feature #8998] string keys for hash literals should use fstrings

I think my failed patch exposes a bug with lazy sweep + rb_fstring.
Lazy sweep GC means the element remains in the frozen_string hash,

	fstr1 = rb_fstring(str)
	fstr1 goes out of scope
	GC mark runs ...
	fstr1 is eligible for lazy sweep
	fstr2 = rb_fstring(str)
	fstr2 is identical to fstr1
	fstr1 is swept
	fstr2 use attempted -> crash