Expand (require A ...) into (begin (require A) ...)

- docs (including discussion of require scoping)
- tests

svn: r14232

collects/scheme/private/reqprov.ss

@@ -317,12 +317,12 @@
                                (syntax->list #'(elem ...))))]
                   [_ (transform-simple in 0 #| run phase |#)]))])
       (syntax-case stx ()
-        [(_ in ...)
-         (with-syntax ([(new-in ...)
-                        (apply append
-                               (map transform-one (syntax->list #'(in ...))))])
+        [(_ in)
+         (with-syntax ([(new-in ...) (transform-one #'in)])
            (syntax/loc stx
-             (#%require new-in ...)))])))
+             (#%require new-in ...)))]
+        [(_ in ...)
+         (syntax/loc stx (begin (require in) ...))])))
 
   ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;; require transformers

collects/scribblings/reference/syntax.scrbl

@@ -272,7 +272,8 @@ In a @tech{top-level context}, @scheme[require] instantiates modules
 (see @secref["module-eval-model"]). In a @tech{module context},
 @scheme[require] @tech{visits} modules (see @secref["mod-parse"]). In
 both contexts, @scheme[require] introduces bindings into a
-@tech{namespace} or a module (see @secref["intro-binding"]). A
+@tech{namespace} or a module (see @secref["intro-binding"]). 
+ A
 @scheme[require] form in a @tech{expression context} or
 @tech{internal-definition context} is a syntax error.
 
@@ -283,6 +284,12 @@ be different from the symbolic name of the originally exported
 identifier. Each identifier also binds at a particular @tech{phase
 level}.
 
+A @scheme[require] scopes over all subsequent forms in @tech{top-level
+contexts}, and all subsequent module top-level forms in a @tech{module
+context} as well as all expression forms in a module.  In both cases,
+each @scheme[require-spec] scopes over all subsequent
+@scheme[require-spec]s in them same @scheme[require] form.
+
 The syntax of @scheme[require-spec] can be extended via
 @scheme[define-require-syntax], but the
 pre-defined forms are as follows.

collects/tests/mzscheme/module.ss

@@ -236,6 +236,23 @@
 (require 'p3_cr)
 (test 18 values w_cr)
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Test `require' scoping
+
+
+(module fake-prefix-in scheme
+  (require scheme/require-syntax)
+  (define-require-syntax (pseudo-+ stx)
+    (syntax-case stx ()
+      [(_ id)
+       #'(only-in scheme [+ id])]))
+  (provide pseudo-+))
+
+(require 'fake-prefix-in
+         (pseudo-+ ++))
+(test 12 values (++ 7 5))
+
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Test proper bindings for `#%module-begin'