fix r6rs let[rec]-syntax for expression positions

svn: r8982

collects/rnrs/base-6.ss

@@ -478,6 +478,14 @@
 (define-for-syntax (do-let-syntax stx rec?)
   (syntax-case stx ()
     [(_ ([id expr] ...) body ...)
+     (if (eq? 'expression (syntax-local-context))
+         (with-syntax ([let-stx (if rec?
+                                    #'letrec-syntax
+                                    #'let-syntax)])
+           (syntax/loc stx
+             (let-stx ([id (wrap-as-needed expr)] ...)
+               (#%expression body)
+               ...)))
          (let ([sli (if (list? (syntax-local-context))
                         syntax-local-introduce
                         values)])
@@ -505,7 +513,7 @@
                  #'(begin
                      (define-syntax id (wrap-as-needed expr))
                      ...
-                 body ...)))))]))
+                     body ...))))))]))
 
 (define-syntax (r6rs:let-syntax stx)
   (do-let-syntax stx #f))

collects/tests/r6rs/syntax-case.ss

@@ -88,6 +88,17 @@
             (dolet a)) 
           7)
 
+    ;; check that it's ok as an expression:
+    (test 6
+          (let-syntax ([foo
+                        (syntax-rules ()
+                          [(_)
+                           (let-syntax ([bar
+                                         (syntax-rules ()
+                                           [(_) 5])])
+                             (bar))])])
+            (+ 1 (foo))))
+
     #;
     (test/exn (let ([else #f])
                 (case 0 [else (write "oops")]))