reader: fix "original?" property on #lang-derived module name

pkgs/racket-test-core/tests/racket/stx.rktl

@@ -400,6 +400,14 @@
         (syntax-case stx ()
           [(_ () (_ () e)) (car (syntax-property #'e 'origin))])))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Make sure a language name via `#lang` is original
+
+(parameterize ([read-accept-reader #t])
+  (syntax-case (read-syntax 'hi (open-input-string "#lang racket/base 10")) ()
+    [(_ _ lang . _)
+     (test #t syntax-original? #'lang)]))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; #%app, etc.
 

racket/src/expander/read/extension.rkt

@@ -121,7 +121,7 @@
   
   (define submod-path `(submod ,(string->symbol lang-str) reader))
   (define reader-path (string->symbol (string-append lang-str "/lang/reader")))
-  
+
   (read-extension #:try-first-mod-path submod-path
                   reader-path read-recur in (reading-at config line col pos)
                   #:get-info? get-info?

racket/src/expander/syntax/read-syntax.rkt

@@ -117,8 +117,14 @@
     (cond
      [(syntax? v) (syntax->datum v)]
      [else v])]
+   [(syntax? v) v]
+   [(pair? v)
+    (read-to-syntax (cons (read-coerce #t (car v) srcloc)
+                          (read-coerce #t (cdr v) srcloc))
+                    srcloc
+                    #f)]
    [else
-    (datum->syntax #f v (and srcloc (to-srcloc-stx srcloc)))]))
+    (read-to-syntax v srcloc #f)]))
 
 (define (read-coerce-key for-syntax? k)
   (cond

racket/src/racket/src/startup.inc

@@ -56648,7 +56648,15 @@ static const char *startup_source =
 "(begin"
 "(if(not for-syntax?_12)"
 "(let-values()(if(syntax?$1 v_246)(let-values()(syntax->datum$1 v_246))(let-values() v_246)))"
-"(let-values()(datum->syntax$1 #f v_246(if srcloc_12(to-srcloc-stx srcloc_12) #f)))))))"
+"(if(syntax?$1 v_246)"
+"(let-values() v_246)"
+"(if(pair? v_246)"
+"(let-values()"
+"(read-to-syntax"
+"(cons(read-coerce #t(car v_246) srcloc_12)(read-coerce #t(cdr v_246) srcloc_12))"
+" srcloc_12"
+" #f))"
+"(let-values()(read-to-syntax v_246 srcloc_12 #f))))))))"
 "(define-values"
 "(read-coerce-key)"
 "(lambda(for-syntax?_13 k_42)"