make-struct-type: fix far-fetched gc/stability issue.

* struct.c (make_struct_type): The length and plus operations
can cons if the number of static slots doesn't fit into a
fixnum. Let's move that operation out of the sensitive object
construction region.

1 files changed, 2 insertions, 2 deletions

diff --git a/struct.c b/struct.c
index 2374a612..604ba041 100644
--- a/struct.c
+++ b/struct.c
@@ -309,11 +309,11 @@ val make_struct_type(val name, val super,
     val id = num_fast(coerce(ucnum, st) / (uptopow2(sizeof *st) / 2));
     val super_slots = if2(su, su->slots);
     val all_slots = uniq(append2(super_slots, append2(static_slots, slots)));
+    cnum stsl_upb = c_num(plus(length(static_slots),
+                               num(if3(su, su->nstslots, 0))));
     val stype = cobj(coerce(mem_t *, st), struct_type_s, &struct_type_ops);
     val iter;
     cnum sl, stsl;
-    cnum stsl_upb = c_num(plus(length(static_slots),
-                               num(if3(su, su->nstslots, 0))));
     struct stslot null_ptr = { nil, 0, 0, nil };
 
     st->self = stype;