fix a problem with `syntax-local-lift-require' at top level

The problem was exposed by improved error checking
in the expander to detect references to exports of a module that
is not yet visited, and as triggered by the documentation for
`2htdp/planetcute'.

collects/tests/racket/module.rktl

@@ -965,6 +965,19 @@
              (lambda (exn) (and (exn? exn)
                                 (regexp-match? #rx"module that is not available"
                                                (exn-message exn)))))
+
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Check that a `syntax-local-ift-require' into a top-level context
+;; appropriately forces a visit of compile-time code:
+
+(parameterize ([current-namespace (make-base-namespace)])
+  (eval '(module m racket/base
+           (provide x)
+           (define-syntax-rule (x) 5)))
+  (eval '(require (for-syntax racket/base)))
+  (eval '(define-syntax (m stx)
+           (syntax-local-lift-require ''m (datum->syntax stx '(x)))))
+  (eval '(m)))
   
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 

src/racket/src/compenv.c

@@ -2367,6 +2367,10 @@ Scheme_Object *scheme_local_lift_require(Scheme_Object *form, Scheme_Object *ori
 
   SCHEME_EXPAND_OBSERVE_LIFT_REQUIRE(scheme_get_expand_observe(), req_form, orig_form, form);
 
+  /* In a top-level context, may need to force compile-time evaluation: */
+  if (!env->genv->module)
+    scheme_prepare_compile_env(env->genv);
+
   return form;
 }