core: start macro tier — move comment/if-not to the Clojure overlay (jolt-1j0 phase 3)

New 30-macros tier (registered after 20-coll) for user-facing macros expressed as
defmacro + syntax-quote instead of hand-built Janet form-transformers. Validated
end to end: overlay-defined macros expand in interpret, compile AND self-host
modes (conformance 228/228 x3).

Moved comment and if-not; removed their Janet core-X fns + core-macro-names
entries. Note: Jolt defmacro is single-arity, so multi-arglist macros become one
arglist with & rest / destructuring (if-not uses [test then & [else]]). Macros
used by the compiler or earlier tiers (and/or/when/cond/case/cond->/->/declare/
doseq/when-let) stay in Janet until a load-order story exists for them.

full suite green, clojure-test-suite 3930.

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

@@ -0,0 +1,18 @@
+;; clojure.core — macro tier. Macros expressed in Clojure (defmacro + syntax-quote)
+;; rather than as hand-built Janet form-transformers. Loaded after the fn tiers,
+;; so a macro here may use any already-frozen core fn/macro.
+;;
+;; IMPORTANT — only macros NOT used by the self-hosted compiler (jolt-core/jolt/*)
+;; or by the earlier overlay tiers belong here; those (and/or/when/when-not/
+;; when-let/cond/case/doseq/declare/cond->/->) must stay available before this
+;; tier loads, so they remain in Janet for now. Everything here is user-facing.
+;;
+;; Migration: remove the Janet core-X macro fn AND its core-macro-names entry when
+;; moving a macro here (defmacro installs the :macro flag itself).
+
+(defmacro comment [& body] nil)
+
+;; Single arglist (Jolt defmacro is single-arity); the optional else defaults nil
+;; via rest-destructuring.
+(defmacro if-not [test then & [else]]
+  `(if (not ~test) ~then ~else))

src/jolt/api.janet

@@ -39,7 +39,8 @@
 (def- core-tiers
   [{:ns "clojure.core.00-kernel" :kernel true}
    {:ns "clojure.core.10-seq"    :kernel false}
-   {:ns "clojure.core.20-coll"   :kernel false}])
+   {:ns "clojure.core.20-coll"   :kernel false}
+   {:ns "clojure.core.30-macros" :kernel false}])
 
 (defn- eval-overlay-source [ctx src]
   (var s src)

src/jolt/core.janet

@@ -2200,13 +2200,6 @@
   (array/push result sym)
   result)
 
-(defn core-if-not
-  "Macro: (if-not test then else?) -> (if (not test) then else?)"
-  [test then-form & else-forms]
-  @[{:jolt/type :symbol :ns nil :name "if"}
-    @[{:jolt/type :symbol :ns nil :name "not"} test]
-    then-form
-    ;else-forms])
 
 (defn core-when-first
   "Macro: (when-first [sym coll] & body) -> (when-let [sym (first coll)] body...)"
@@ -2626,9 +2619,6 @@
     name-sym
     @{}])
 
-# comment macro — ignores body, returns nil
-(defn core-comment [& body]
-  nil)
 
 # defrecord — creates a proper type via deftype + factory functions
 (defn core-defrecord [name-sym fields-vec & body]
@@ -3845,7 +3835,6 @@
     "for" core-for
     "when" core-when
     "when-not" core-when-not
-    "if-not" core-if-not
     "when-first" core-when-first
     "if-let" core-if-let
     "when-let" core-when-let
@@ -3899,7 +3888,6 @@
     "IllegalStateException" core-IllegalStateException
     "definterface" core-definterface
     "defrecord" core-defrecord
-    "comment" core-comment
     "resolve" core-resolve
     "ns-name" core-ns-name
     "update-in" core-update-in
@@ -3944,7 +3932,7 @@
 (defn core-macro-names
   "Set of core binding names that are macros."
   []
-  @{"and" true "or" true "cond" true "case" true "for" true "when" true "when-not" true "if-let" true "when-let" true "if-some" true "when-some" true "doto" true "defn" true "defn-" true "declare" true "fn" true "let" true "loop" true "defrecord" true "defprotocol" true "extend-type" true "extend-protocol" true "extend" true "reify" true "proxy" true "definterface" true "comment" true "binding" true "lazy-seq" true "lazy-cat" true "if-not" true "when-first" true "condp" true "dotimes" true "while" true "some->" true "some->>" true "cond->" true "cond->>" true "as->" true "->" true "->>" true "letfn" true "doseq" true "delay" true "assert" true "future" true})
+  @{"and" true "or" true "cond" true "case" true "for" true "when" true "when-not" true "if-let" true "when-let" true "if-some" true "when-some" true "doto" true "defn" true "defn-" true "declare" true "fn" true "let" true "loop" true "defrecord" true "defprotocol" true "extend-type" true "extend-protocol" true "extend" true "reify" true "proxy" true "definterface" true "binding" true "lazy-seq" true "lazy-cat" true "when-first" true "condp" true "dotimes" true "while" true "some->" true "some->>" true "cond->" true "cond->>" true "as->" true "->" true "->>" true "letfn" true "doseq" true "delay" true "assert" true "future" true})
 
 (def init-core!
   (fn [& args]

test/spec/macros-spec.janet

@@ -25,3 +25,13 @@
    "(= (gensym) (gensym))"]
   ["gensym# in template" "true"
    "(do (defmacro m [] `(let [x# 1] x#)) (= 1 (m)))"])
+
+# Core macros ported from Janet to the Clojure overlay (jolt-1j0 phase 3,
+# jolt-core/clojure/core/30-macros.clj).
+(defspec "macros / core-overlay"
+  ["if-not true branch"  ":then"  "(if-not false :then :else)"]
+  ["if-not else branch"  ":else"  "(if-not true :then :else)"]
+  ["if-not no else"      "nil"    "(if-not true :then)"]
+  ["if-not no else hit"  ":then"  "(if-not false :then)"]
+  ["comment -> nil"      "nil"    "(comment a b c)"]
+  ["comment in do"       "42"     "(do (comment ignored) 42)"])