Fix [_ _] inline method field binding + Var protocol dispatch

Two gaps reitit-core surfaced (now 322/0/1 -> 327/0/0):

- A deftype/defrecord inline method with two _ params, (m [_ _] field), read
  the field as nil: mk-clause bound fields off (get _ :field) where _ was the
  first param, but the second _ shadowed it. Each _ param is now renamed to a
  fresh symbol so the instance is unambiguous.

- A var did not dispatch to a protocol's clojure.lang.Var extension (reitit
  extends Expand to Var for a #'handler route): value-host-tags gained a var arm
  (Var/clojure.lang.Var/IDeref/IFn) and host-type-set gained Var/IDeref so the
  extension keys under Var.

deftype/defrecord is a seed source, re-minted.

host/chez/records.ss

@@ -450,6 +450,9 @@
                        "Map" "java.util.Map" "Iterable" "java.lang.Iterable" "Object"))
         ((pset? obj) '("PersistentHashSet" "APersistentSet" "IPersistentSet" "Set" "java.util.Set" "Collection" "Iterable" "java.lang.Iterable" "Object"))
         ((or (cseq? obj) (empty-list-t? obj)) '("ASeq" "ISeq" "IPersistentCollection" "Sequential" "Collection" "Iterable" "java.lang.Iterable" "Object"))
+        ;; a var is clojure.lang.Var (also IDeref / IFn) — reitit's Expand protocol
+        ;; extends to Var so a #'handler route dispatches.
+        ((var-cell? obj) '("Var" "clojure.lang.Var" "IDeref" "IFn" "Object"))
         ;; java.net.URI jhost — extend-protocol java.net.URI (hiccup ToURI/ToStr).
         ((and (jhost? obj) (string=? (jhost-tag obj) "uri")) '("URI" "java.net.URI" "Object"))
         ;; a ByteBuffer — extend-protocol java.nio.ByteBuffer (aws-api util).
@@ -560,7 +563,7 @@
               '("Long" "Integer" "Number" "Double" "Ratio" "BigInt" "BigInteger"
                 "String" "CharSequence" "Boolean" "Character"
                 "Keyword" "Symbol" "Named" "Object" "nil"
-                "Fn" "IFn" "AFn" "URI"
+                "Fn" "IFn" "AFn" "URI" "Var" "IDeref"
                 "PersistentVector" "APersistentVector" "IPersistentVector"
                 "PersistentArrayMap" "APersistentMap" "IPersistentMap"
                 "PersistentHashSet" "APersistentSet" "IPersistentSet"

jolt-core/clojure/core/30-macros.clj

@@ -377,7 +377,9 @@
         ;; The clause is DATA, not a syntax-quote: a body that is itself a syntax-
         ;; quote would have its ~unquotes consumed a level early if re-spliced.
         mk-clause (fn [spec]
-                    (let [argv (nth spec 1)
+                    ;; fresh-name each _ param so two _ params don't collide on the
+                    ;; field binds / live-read instance (see defrecord's mk-clause).
+                    (let [argv (mapv (fn [p] (if (= p (quote _)) (gensym "_p") p)) (nth spec 1))
                           inst (first argv)
                           ;; let-bind only immutable fields; mutable ones are read live
                           ;; via rewrite-body so a set! within the method is observed.
@@ -597,7 +599,11 @@
         ;; one clause from a spec; `this` is hinted with the record type so the
         ;; inference reads its fields bare-index. Clause as DATA (see deftype).
         mk-clause (fn [spec]
-                    (let [argv (nth spec 1)
+                    ;; rename each _ parameter to a fresh symbol so two _ params
+                    ;; (the common (m [_ _] …) on a 1-arg protocol method) don't
+                    ;; collide — the field binds read (get this :field) off the
+                    ;; FIRST param, which an ignored second _ would otherwise shadow.
+                    (let [argv (mapv (fn [p] (if (= p (quote _)) (gensym "_p") p)) (nth spec 1))
                           inst (first argv)
                           hinted (assoc argv 0 (vary-meta inst assoc :tag (name name-sym)))
                           binds (vec (mapcat (fn [f] [f `(get ~inst ~(keyword (name f)))]) fields))]

test/chez/unit.edn

@@ -570,4 +570,7 @@
   {:suite "macro-args" :expr "(do (defmacro sm [x] [(set? x) (map? x)]) (sm #{1 2}))" :expected "[true false]"}
   {:suite "macro-args" :expr "(do (defmacro ws [x] (conj x :z)) (= #{1 :z} (ws #{1})))" :expected "true"}
   {:suite "macro-args" :expr "(do (defmacro vm [x] (vector? x)) (vm [1 2]))" :expected "true"}
+  {:suite "deftype-method" :expr "(do (defprotocol P (m [_ o])) (defrecord R [n] P (m [_ _] n)) (m (->R 5) :x))" :expected "5"}
+  {:suite "deftype-method" :expr "(do (defprotocol P2 (m2 [_ o])) (deftype T [n] P2 (m2 [_ _] n)) (m2 (->T 7) :x))" :expected "7"}
+  {:suite "protocol-host" :expr "(do (defprotocol Q (e [_])) (extend-protocol Q clojure.lang.Var (e [_] :var)) [(satisfies? Q (var map)) (e (var map))])" :expected "[true :var]"}
 ]