Warn when a nonexistent slot is referenced.

Implementing warning for the situaton when the qref, uref, usl
and umeth macro operators are asked to refer to a slot that
doesn't exist in any struct type. This won't catch errors
referencing a slot on the wrong type, but it will catch slots
that are misspelled in such a way that the typo doesn't land
on any slot.

* share/txr/stdlib/struct.tl (defstruct): Register tenative
slot definitions for all slots to nuke warnings.
(sys:check-slot): New function.
(qref, usl, umeth): Check slots with sys:check-slot.
(uref): Drop :whole argument, which is unused.
(defmeth): Register tentative definition for slot.

* struct.c (slot_s, static_slot_s): New symbol variables.
(slot_type_hash, static_slot_type_hash): New hash tables,
associating symbols with lists of struct type names
in which they are defined.
(struct_init): Initialize and gc-protect hashes.
Initialize new symbols, interning in system package.
Register new intrinsic funtions sys:slot-types and
sys:static-slot-types.
(make_struct_type): Register slots in new hashes.
(static_slot_ens_rec): Register new slow in static
slot hash.
(slot_types, static_slot_types): New functions,
registered as intrinsics.
(slot_type_reg, static_slot_type_reg): New functions.

* struct.h (print_s): Declared.
(slot_s, static_slot_s): Declared.
(slot_types, static_slot_types, slot_type_reg,
static_slot_type_reg): Declared.

1 files changed, 6 insertions, 1 deletions

diff --git a/struct.h b/struct.h
index 10f87f72..e558745f 100644
--- a/struct.h
+++ b/struct.h
@@ -25,7 +25,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-extern val struct_type_s, meth_s, make_struct_lit_s;
+extern val struct_type_s, meth_s, print_s, make_struct_lit_s;
+extern val slot_s, static_slot_s;
 val make_struct_type(val name, val super,
                      val static_slots, val slots,
                      val static_initfun, val initfun, val boactor,
@@ -64,4 +65,8 @@ val uslot(val slot);
 val umethod(val slot, struct args *);
 val method_name(val fun);
 val get_slot_syms(val package, val is_current, val method_only);
+val slot_types(val slot);
+val static_slot_types(val slot);
+val slot_type_reg(val slot, val strct);
+val static_slot_type_reg(val slot, val strct);
 void struct_init(void);