reexport with renaming fails when import libraries are used

[felix]

In the following code s2 in the expansion of s1 will not be found when foo1 is used via an import library:

(module foo *
(import scheme)
(define-syntax s1 
  (syntax-rules () ((_) (s2))))
(define-syntax s2 
  (syntax-rules () ((_) (display 1)))))

(module foo1 ()
(reexport (prefix foo f:)))

(import foo1)
(f:s1)

[sjamaan]

After some investigation, it became clear that the set-car! calls in the foreaches of {{##sys#register-compiled-module}} are clobbering the carefully saved syntax environments of each macro.

In the example, when {{foo1}} is imported and the {{find-reexport}} helper procedure in {{##sys#register-compiled-module}} finds the matching original binding ({{s1}} for {{f1:s1}}) that's being re-exported, it has a syntax environment containing both {{s1}} and {{s2}}.
You can see this in action if you apply this debugging patch:

diff --git a/modules.scm b/modules.scm
index b1571c2..4c78320 100644
--- a/modules.scm
+++ b/modules.scm
@@ -33,7 +33,7 @@
 
 (include "common-declarations.scm")
 
-(define-syntax d (syntax-rules () ((_ . _) (void))))
+#;(define-syntax d (syntax-rules () ((_ . _) (void))))
 
 (define-alias dd d)
 (define-alias dm d)
@@ -347,7 +347,7 @@
   (define (find-reexport name)
     (let ((a (assq name (##sys#macro-environment))))
       (if (and a (pair? (cdr a)))
-	  a
+	  (begin (dm `(FOUND-REEXP: ,(car a) ---> ,(map-se (cadr a)))) a)
 	  (##sys#error
 	   'import "cannot find implementation of re-exported syntax"
 	   name))))

However, after the module is register, if you inspect {{##sys#module-environment}}, the syntax environment attached to {{f1:s1}} contains {{f1:s1}} and {{f1:s2}}. It's been replaced by the foreach loops.

I'm unsure how to fix this. What's the reason these environments are reset the way they are?

[sjamaan]

Damn you, Trac syntax