Represent hash table weakness as an enum internally

This takes less space (saves an entire word) and is more type-safe.
No change in behaviour.

* src/lisp.h (hash_table_weakness_t): New.
(struct Lisp_Hash_Table): Replace Lisp object `weak` with enum
`weakness`.
* src/fns.c
(keep_entry_p, hash_table_weakness_symbol): New.
(make_hash_table): Retype argument.  All callers updated.
(sweep_weak_table, Fmake_hash_table, Fhash_table_weakness):
* src/alloc.c (purecopy_hash_table, purecopy, process_mark_stack):
* src/pdumper.c (dump_hash_table):
* src/print.c (print_object): Use retyped field.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/alloc.c b/src/alloc.c
index af9c169a3a0..17ed711a318 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -5887,7 +5887,7 @@ make_pure_vector (ptrdiff_t len)
 static struct Lisp_Hash_Table *
 purecopy_hash_table (struct Lisp_Hash_Table *table)
 {
-  eassert (NILP (table->weak));
+  eassert (table->weakness == Weak_None);
   eassert (table->purecopy);
 
   struct Lisp_Hash_Table *pure = pure_alloc (sizeof *pure, Lisp_Vectorlike);
@@ -5960,7 +5960,7 @@ purecopy (Lisp_Object obj)
       /* Do not purify hash tables which haven't been defined with
          :purecopy as non-nil or are weak - they aren't guaranteed to
          not change.  */
-      if (!NILP (table->weak) || !table->purecopy)
+      if (table->weakness != Weak_None || !table->purecopy)
         {
           /* Instead, add the hash table to the list of pinned objects,
              so that it will be marked during GC.  */
@@ -7233,7 +7233,7 @@ process_mark_stack (ptrdiff_t base_sp)
                   mark_stack_push_value (h->test.name);
                   mark_stack_push_value (h->test.user_hash_function);
                   mark_stack_push_value (h->test.user_cmp_function);
-                  if (NILP (h->weak))
+                  if (h->weakness == Weak_None)
                     mark_stack_push_value (h->key_and_value);
                   else
                     {