fix some "phaseless" module holes

collects/scribblings/reference/eval-model.scrbl

@@ -629,7 +629,7 @@ is specified as @tech{phaseless} (such as
 @racketmodname[racket/kernel]).
 
 @;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-@subsection[#:tag "module-redeclare"]{Module Re-declarations}
+@subsection[#:tag "module-redeclare"]{Module Redeclarations}
 
 @section-index["modules" "re-define"]
 
@@ -642,9 +642,17 @@ module body. If a new variable definition has a counterpart in the old
 declaration, it effectively assigns to the old variable.
 
 If a module is @tech{instantiate}d in any @tech{phase}s before it is
-re-declared, each re-declaration of the module is immediately
+redeclared, each redeclaration of the module is immediately
 @tech{instantiate}d in the same @tech{phase}s.
 
+If the current @tech{inspector} does not manage a module's declaration
+inspector (see @secref["modprotect"]), then the module cannot be
+redeclared. Similarly, a @tech{phaseless} module cannot be redeclared.
+Even if redeclrection succeeds, instantiation of a module that is
+previously instantiated may fail if instantiation for the
+redeclaration attempts to modify variables that are constant (see
+@racket[compile-enforce-module-constants]).
+
 @;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 @subsection[#:tag "submodules"]{Submodules}
 

collects/scribblings/reference/syntax-model.scrbl

@@ -992,8 +992,9 @@ to syntax transformers, via @racket[syntax-local-name].
 @section[#:tag "phaseless-grammar"]{Phaseless Module Declarations}
 
 A module is @tech{phaseless} only if it fits the following grammar,
-which uses non-terminals from @secref["fully-expanded"], and only if
+which uses non-terminals from @secref["fully-expanded"], only if
-it includes no uses of @racket[quote-syntax] or @racket[#%variable-reference]:
+it includes no uses of @racket[quote-syntax] or @racket[#%variable-reference], 
+and only if no module-level binding is @racket[set!]ed.
 
 @racketgrammar*[
 #:literals (module module* #%plain-module-begin begin #%provide

collects/tests/racket/phaseless.rkt

@@ -9,7 +9,7 @@
     (define i (open-input-bytes (get-output-bytes o)))
     (define e (zo-parse i))
     (unless (equal? is? (and (memq 'phaseless (mod-flags (compilation-top-code e))) #t))
-      (error 'phaseless "failed: ~s ~s\n" is? form))))
+      (error 'phaseless "failed: ~s ~s" is? form))))
 
 (check-phaseless #t '(define-values (x) 5))
 (check-phaseless #t '(define-values (x) '5))
@@ -35,6 +35,7 @@
 
 (check-phaseless #f '(define-values (x) #(x)))
 (check-phaseless #f '(define-values (x) '(x)))
+(check-phaseless #f '(define-values (x) (lambda () (set! x 8))))
 (check-phaseless #f '(define-values (x) (quote-syntax x)))
 (check-phaseless #f '(define-values (x) (lambda () (quote-syntax x))))
 (check-phaseless #f '(define-values (x) (#%variable-reference)))
@@ -74,5 +75,22 @@
   (check-attach namespace-attach-module)
   (check-attach namespace-attach-module-declaration))
 
+;; Check disallowing redeclaration:
+(parameterize ([current-namespace (make-base-namespace)])
+  (parameterize ([compile-enforce-module-constants #f])
+    (eval `(module m racket/kernel
+             (#%provide x)
+             (define-values (x) 5)))
+    (compile `(module m racket/kernel
+                (#%provide x)
+                (define-values (x) 6)))
+    (unless (void?
+             (with-handlers ([exn:fail? void])
+               (eval `(module m racket/kernel
+                        (#%provide x)
+                        (define-values (x) 6)))
+               'ok))
+      (error 'phaseless "redeclaration should have been disallowed"))))
+
 (displayln "All tests passed.")
 

src/racket/src/compile.c

@@ -1203,6 +1203,7 @@ set_syntax (Scheme_Object *form, Scheme_Comp_Env *env, Scheme_Compile_Info *rec,
     var = scheme_register_toplevel_in_prefix(var, env, rec, drec, 0, NULL);
     if (env->genv->module)
       SCHEME_TOPLEVEL_FLAGS(var) |= SCHEME_TOPLEVEL_MUTATED;
+    env->prefix->non_phaseless = 1;
   }
 
   scheme_compile_rec_done_local(rec, drec);

src/racket/src/module.c

@@ -6272,7 +6272,7 @@ static Scheme_Object *do_module_execute(Scheme_Object *data, Scheme_Env *genv,
                                         Scheme_Object *prefix,
                                         Scheme_Object *supermodule)
 {
-  Scheme_Module *m;
+  Scheme_Module *m, *old_m;
   Scheme_Env *env;
   Scheme_Env *old_menv;
   Scheme_Config *config;
@@ -6366,13 +6366,26 @@ static Scheme_Object *do_module_execute(Scheme_Object *data, Scheme_Env *genv,
   if (old_menv) {
     if (scheme_module_protected_wrt(old_menv->guard_insp, insp) || old_menv->attached) {
       scheme_contract_error("module->namespace",
-                            "current code inspector cannot re-declare module",
+                            "current code inspector cannot redeclare module",
                             "module name", 1, m->modname,
                             NULL);
       return NULL;
     }
   }
 
+  if (old_menv)
+    old_m = old_menv->module;
+  else
+    old_m = (Scheme_Module *)scheme_hash_get(env->module_registry->loaded, m->modname);
+  
+  if (old_m && old_m->phaseless) {
+    scheme_contract_error("module->namespace",
+                          "cannot redeclare phaseless module",
+                          "module name", 1, m->modname,
+                          NULL);
+    return NULL;
+  }
+
   if (!set_in_pre) {
     /* execute pre-submodules: */
     execute_submodules(m, 1, genv, set_cache, set_in_pre, prefix);
@@ -7117,7 +7130,7 @@ static Scheme_Object *do_module(Scheme_Object *form, Scheme_Comp_Env *env,
   m->tt_requires = scheme_null;
   m->dt_requires = scheme_null;
 
-  if (iim && iim->phaseless)
+  if (iim && iim->phaseless && rec[drec].comp)
     m->phaseless = scheme_true;
 
   if (iidx) {