Chez inc7: namespace :as aliases on the Chez-hosted analyzer

(require '[clojure.string :as s]) then s/foo crashed "Unknown class s": the
Chez analyzer resolved a qualified symbol's ns literally, and there was no
alias table (ns.ss jolt-ns-aliases was a stub, require a no-op). Add an alias
table + chez-register-spec! (parses [ns :as a]) in ns.ss; hc-resolve-cell now
resolves a qualified ns through it; compile-eval pre-registers a form's
require/use :as aliases before analysis (analysis precedes the runtime require,
so the runtime require staying a no-op is fine). The batched gate runner clears
the alias table between cases.

Zero-Janet corpus parity 2159 -> 2240, 0 divergences. spine-test 35/35.

host/chez/compile-eval.ss

@@ -20,13 +20,36 @@
 ;; once, here, so every analyze->emit on this spine sees the full core (jolt-qjr0).
 ((var-deref "jolt.backend-scheme" "set-prelude-mode!") #t)
 
+;; (quote X) -> X, else x — unwraps a quoted require spec.
+(define (ce-unquote x)
+  (if (and (cseq? x) (cseq-list? x))
+      (let ((items (seq->list x)))
+        (if (and (pair? items) (symbol-t? (car items))
+                 (string=? (symbol-t-name (car items)) "quote") (pair? (cdr items)))
+            (cadr items) x))
+      x))
+
+;; Pre-register any (require ...)/(use ...) :as aliases under `ns` BEFORE analysis,
+;; so a qualified s/foo resolves while compiling (analysis precedes the runtime
+;; require). Walks the whole form (a require may be nested in a do/let). jolt-qjr0.
+(define (ce-scan-requires! form ns)
+  (when (and (cseq? form) (cseq-list? form))
+    (let ((items (seq->list form)))
+      (when (pair? items)
+        (let ((h (car items)))
+          (if (and (symbol-t? h)
+                   (let ((n (symbol-t-name h))) (or (string=? n "require") (string=? n "use"))))
+              (for-each (lambda (a) (chez-register-spec! ns (ce-unquote a))) (cdr items))
+              (for-each (lambda (x) (ce-scan-requires! x ns)) items)))))))
+
 ;; Source string -> Scheme source string (read -> analyze -> emit, all on Chez).
 ;; `ns` is the compile namespace unqualified symbols resolve against.
 (define (jolt-analyze-emit src ns)
-  (let* ((form (jolt-ce-read src))
-         (ctx (make-analyze-ctx ns))
-         (ir (jolt-ce-analyze ctx form)))
-    (jolt-ce-emit ir)))
+  (let* ((form (jolt-ce-read src)))
+    (ce-scan-requires! form ns)
+    (let* ((ctx (make-analyze-ctx ns))
+           (ir (jolt-ce-analyze ctx form)))
+      (jolt-ce-emit ir))))
 
 ;; Source string -> value (compile on Chez, then eval the emitted Scheme in the
 ;; top-level environment where rt.ss's runtime procedures live).

host/chez/driver.janet

@@ -416,6 +416,7 @@
     "                           (var-cell-root-set! (car cr) (cdr cr)))) zj-roots)\n"
     "  (zj-prune! ns-registry zj-ns-base)\n"
     "  (zj-prune! type-registry zj-type-base)\n"
+    "  (hashtable-clear! ns-alias-table)\n"
     "  (when zj-ghier (jolt-invoke (var-deref \"clojure.core\" \"reset!\")\n"
     "                   (var-cell-root zj-ghier) (jolt-invoke (var-deref \"clojure.core\" \"make-hierarchy\"))))\n"
     "  (set-chez-ns! \"user\"))\n"

host/chez/host-contract.ss

@@ -130,7 +130,9 @@
          (sns (symbol-t-ns sym))
          (qualified (and sns (not (jolt-nil? sns)) (not (null? sns)) sns)))
     (if qualified
-        (var-cell-lookup qualified nm)
+        ;; a qualified ns may be a require :as alias (s/split -> clojure.string/split)
+        (let ((target (or (chez-resolve-alias (chez-actx-cns ctx) qualified) qualified)))
+          (var-cell-lookup target nm))
         (or (var-cell-lookup (chez-actx-cns ctx) nm)
             (var-cell-lookup "clojure.core" nm)))))
 

host/chez/ns.ss

@@ -24,6 +24,31 @@
 (intern-ns! "user")
 (intern-ns! "clojure.core")
 
+;; --- namespace aliases (jolt-qjr0) -----------------------------------------
+;; (require '[ns :as a]) registers a -> ns so the analyzer can resolve a/foo to
+;; ns/foo. Keyed by (compile-ns . alias). On the zero-Janet spine the requires are
+;; pre-registered at analyze time (compile-eval.ss) — analysis precedes eval, so a
+;; runtime require no-op is fine. Also drives jolt-ns-aliases below.
+(define ns-alias-table (make-hashtable equal-hash equal?))
+(define (chez-register-alias! cns alias target)
+  (hashtable-set! ns-alias-table (cons cns alias) target))
+(define (chez-resolve-alias cns alias)
+  (hashtable-ref ns-alias-table (cons cns alias) #f))
+;; parse a require/use spec FORM and register its :as alias under `cns`.
+;; spec: [ns :as a ...] / (ns :as a ...) / bare ns (no alias).
+(define (chez-register-spec! cns spec)
+  (let ((items (cond ((pvec? spec) (seq->list spec))
+                     ((or (cseq? spec) (empty-list-t? spec)) (seq->list spec))
+                     (else '()))))
+    (when (and (pair? items) (symbol-t? (car items)))
+      (let ((target (symbol-t-name (car items))))
+        (let loop ((xs (cdr items)))
+          (cond ((or (null? xs) (null? (cdr xs))) #f)
+                ((and (keyword? (car xs)) (string=? (keyword-t-name (car xs)) "as")
+                      (symbol-t? (cadr xs)))
+                 (chez-register-alias! cns (symbol-t-name (cadr xs)) target))
+                (else (loop (cdr xs)))))))))
+
 ;; a namespace designator -> its name string (a jns or a symbol; the corpus never
 ;; passes a bare string).
 (define (ns-desig->name d)