Correction to COBJ initialization pattern.

In fact, the previosuly documented process is not correct and still
leaves a corruption problem under generational GC (which has been the
default for some time).

* HACKING: Document flaw in the initialization pattern previously
thought to be correct, and show fix.

* hash.c (copy_hash): Fix instance of incorrect pattern.

* regex.c (regex_compile): Likewise.

1 files changed, 3 insertions, 2 deletions

diff --git a/hash.c b/hash.c
index 4ece8a54..543c2d62 100644
--- a/hash.c
+++ b/hash.c
@@ -523,13 +523,14 @@ val copy_hash(val existing)
 {
   struct hash *ex = coerce(struct hash *, cobj_handle(existing, hash_s));
   struct hash *h = coerce(struct hash *, chk_malloc(sizeof *h));
-  val hash = cobj(coerce(mem_t *, h), hash_s, &hash_ops);
   val mod = num_fast(ex->modulus);
+  val table = vector(mod, nil);
+  val hash = cobj(coerce(mem_t *, h), hash_s, &hash_ops);
   val iter;
 
   h->modulus = ex->modulus;
   h->count = ex->count;
-  h->table = vector(mod, nil);
+  h->table = table;
   h->userdata = ex->userdata;
 
   h->flags = ex->flags;