obscurity

br-parser-tools/br-parser-tools-lib/br-parser-tools/cfg-parser.rkt

@@ -489,6 +489,12 @@
                                                 (fail-k max-depth tasks))))])
                  (k end max-depth tasks new-got-k new-fail-k)))])))))
 
+;; These temp identifiers can't be `gensym` or `generate-temporary`
+;; because they have to be consistent between module loads
+;; (IIUC, the parser is multi-threaded, and this approach is not thread-safe)
+;; so I see no alternative to the old standby of making them ludicrously unlikely
+(define-for-syntax start-id-temp 'start_jihqolbbafscgxvsufnepvmxqipnxgmlpxukmdoqxqzmzgaogaftbkbyqjttwwfimifowdxfyekjiixdmtprfkcvfciraehoeuaz)
+(define-for-syntax atok-id-temp 'atok_wrutdjgecmybyfipiwsgjlvsveryodlgassuzcargiuznzgdghrykfqfbwcjgzdhdoeqxcucmtjkuyucskzethozhqkasphdwbht)
 (define-syntax (cfg-parser stx)
   (syntax-case stx ()
     [(_ clause ...)
@@ -652,8 +658,6 @@
                                                 pats (caddr old-list))))
                                    nt-ids patss)
                                   ;; Build a definition for each non-term:
-                                  (let ([start-id-temp (gensym)]
-                                        [atok-id-temp (gensym)])
                                   (loop (cdr clauses)
                                         cfg-start
                                         (map (lambda (nt pats handles $ctxs)
@@ -717,7 +721,7 @@
                                                       (%atok [(tok) (make-tok 'tok-id 'tok $e pos ...)] ...)))
                                          (with-syntax ([%start start-id-temp])
                                            #`(start %start))
-                                           parser-clauses))))]
+                                         parser-clauses)))]
                                [(grammar . _)
                                 (raise-syntax-error
                                  #f