expander: fix shadowing require after shadowing define

Refines the repair in 11fd70c3dd to properly handle a `require` that
should be allowed to shadow the initial require.

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

@@ -712,6 +712,17 @@
 
 (test "last" dynamic-require ''definition-shadows-later-require/2 'result)
 
+(module definition-shadows-require-shadowing-initial-require racket/base
+  (provide result)
+  (define version 42)
+  (module M racket/base
+    (provide (all-defined-out))
+    (define version 42))
+  (require 'M)
+  (define result version))
+
+(test 42 dynamic-require ''definition-shadows-require-shadowing-initial-require 'result)
+
 (err/rt-test
  (eval
   '(module m racket/base

racket/src/expander/expand/require+provide.rkt

@@ -297,14 +297,6 @@
     (define defined? (and b (eq? (requires+provides-self r+p)
                                  (module-binding-module b))))
     (cond
-     [(and (not defined?) (not check-not-required?))
-      ;; Not defined, and we're shadowing all requires -- so, it's ok,
-      ;; but binding is non-simple
-      (set-requires+provides-all-bindings-simple?! r+p #f)
-      ;; Also, record the `require` binding, in case we see another
-      ;; `require` for the same identifier
-      (hash-set! (requires+provides-also-required r+p) (module-binding-sym b) b)
-      #f]
       [(and defined?
             ;; In case `#%module-begin` is expanded multiple times, check
             ;; that the definition has been seen this particular expansion
@@ -316,11 +308,13 @@
        ;; Doesn't count as previously defined
        #f]
       [else
+       (define define-shadowing-require? (and (not defined?) (not check-not-required?)))
        (define mpi (intern-mpi r+p (module-binding-nominal-module b)))
        (define at-mod (hash-ref (requires+provides-requires r+p) mpi #f))
-      (define ok-binding (if (procedure? ok-binding/delayed)
+       (define ok-binding (and (not define-shadowing-require?)
+                               (if (procedure? ok-binding/delayed)
                                    (ok-binding/delayed)
-                             ok-binding/delayed))
+                                   ok-binding/delayed)))
        (define (raise-already-bound defined?)
          (raise-syntax-error who
                              (string-append "identifier already "
@@ -333,7 +327,8 @@
                              orig-s
                              id))
        (cond
-       [(not at-mod)
+         [(and (not at-mod)
+               (not define-shadowing-require?))
           ;; Binding is from an enclosing context; if it's from an
           ;; enclosing module, then we've already marked bindings
           ;; a non-simple --- otherwise, we don't care
@@ -374,18 +369,31 @@
           (define nominal-phase (module-binding-nominal-require-phase b))
           (define sym-to-reqds (hash-ref at-mod nominal-phase #hasheq()))
           (define reqds (hash-ref sym-to-reqds (syntax-e id) null))
-        (for ([r (in-list-ish reqds)])
+          (define only-can-can-shadow-require?
+            (for/fold ([only-can-can-shadow-require? #t]) ([r (in-list-ish reqds)])
               (cond
                 [(if (bulk-required? r)
                      (bulk-required-can-be-shadowed? r)
                      (required-can-be-shadowed? r))
                  ;; Shadowing --- ok, but non-simple
-            (set-requires+provides-all-bindings-simple?! r+p #f)]
-           [else (raise-already-bound defined?)]))
+                 (set-requires+provides-all-bindings-simple?! r+p #f)
+                 only-can-can-shadow-require?]
+                [define-shadowing-require? #f]
+                [else (raise-already-bound defined?)])))
+          (cond
+            [define-shadowing-require?
+              ;; Not defined, but defining now (shadowing all requires);
+              ;; make sure we indicated that the binding is non-simple
+              (set-requires+provides-all-bindings-simple?! r+p #f)
+              (unless only-can-can-shadow-require?
+                ;; Record the `require` binding, if it's non-shadowable,
+                ;; in case we see another `require` for the same identifier
+                (hash-set! (requires+provides-also-required r+p) (module-binding-sym b) b))]
+            [else
              (when (and remove-shadowed!? (not (null? reqds)))
                ;; Same work as in `remove-required-id!`
                (hash-set! sym-to-reqds (syntax-e id)
-                     (remove-non-matching-requireds reqds id phase mpi nominal-phase (syntax-e id))))
+                          (remove-non-matching-requireds reqds id phase mpi nominal-phase (syntax-e id))))])
           #f])])]))
 
 (define (add-defined-syms! r+p syms phase)