Fix hash tables not being purified correctly.

* src/alloc.c
(purecopy_hash_table) New function, makes a copy of the given hash
table in pure storage.
Add new struct `pinned_object' and `pinned_objects' linked list for
pinning objects.
(Fpurecopy) Allow purifying hash tables
(purecopy) Pin hash tables that are either weak or not declared with
`:purecopy t`, use purecopy_hash_table otherwise.
(marked_pinned_objects) New function, marks all objects in pinned_objects.
(garbage_collect_1) Use it. Mark all pinned objects before sweeping.
* src/lisp.h Add new field `pure' to struct `Lisp_Hash_Table'.
* src/fns.c: Add `purecopy' parameter to hash tables.
(Fmake_hash_table): Check for a `:purecopy PURECOPY' argument, pass it
to make_hash_table.
(make_hash_table): Add `pure' parameter, set h->pure to it.
(Fclrhash, Fremhash, Fputhash): Enforce that the table is impure with
CHECK_IMPURE.
* src/lread.c: (read1) Parse for `purecopy' parameter while reading
  hash tables.
* src/print.c: (print_object) add the `purecopy' parameter while
  printing hash tables.
* src/category.c, src/emacs-module.c, src/image.c, src/profiler.c,
  src/xterm.c: Use new (make_hash_table).

1 files changed, 5 insertions, 1 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 84d53bb1eec..91c430fe98d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1995,6 +1995,10 @@ struct Lisp_Hash_Table
      hash table size to reduce collisions.  */
   Lisp_Object index;
 
+  /* Non-nil if the table can be purecopied. Any changes the table after
+     purecopy will result in an error.  */
+  Lisp_Object pure;
+
   /* Only the fields above are traced normally by the GC.  The ones below
      `count' are special and are either ignored by the GC or traced in
      a special way (e.g. because of weakness).  */
@@ -3364,7 +3368,7 @@ extern void sweep_weak_hash_tables (void);
 EMACS_UINT hash_string (char const *, ptrdiff_t);
 EMACS_UINT sxhash (Lisp_Object, int);
 Lisp_Object make_hash_table (struct hash_table_test, Lisp_Object, Lisp_Object,
-                             Lisp_Object, Lisp_Object);
+                             Lisp_Object, Lisp_Object, Lisp_Object);
 ptrdiff_t hash_lookup (struct Lisp_Hash_Table *, Lisp_Object, EMACS_UINT *);
 ptrdiff_t hash_put (struct Lisp_Hash_Table *, Lisp_Object, Lisp_Object,
 		    EMACS_UINT);