* src/alloc.c: Keep track of symbols referenced from pure space (bug#17168).

(symbol_block_pinned): New var.
(Fmake_symbol): Initialize `pinned'.
(purecopy): New function, extracted from Fpurecopy.  Mark symbols as
pinned and signal an error for un-purifiable objects.
(pure_cons): Use it.
(Fpurecopy): Use it, except for objects that can't be purified.
(mark_pinned_symbols): New function.
(Fgarbage_collect): Use it.
(gc_sweep): Remove hack made unnecessary.
* src/lisp.h (struct Lisp_Symbol): New bitfield `pinned'.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 30f52b9070c..ea294f8d1da 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1568,6 +1568,9 @@ struct Lisp_Symbol
      special (with `defvar' etc), and shouldn't be lexically bound.  */
   bool_bf declared_special : 1;
 
+  /* True if pointed to from purespace and hence can't be GC'd.  */
+  bool_bf pinned : 1;
+
   /* The symbol's name, as a Lisp string.  */
   Lisp_Object name;