CHICKEN Scheme

Summary

reexport with renaming fails when import libraries are used

Metadata

Id: 1894d733cd096ab7e35b64d430da3d55eb1f1308
Trac id: 219
Type: defect
Reporter: felix
Owner: sjamaan
Cc:
Status: closed
Component: expander
Estimated difficulty:
Resolution: fixed
Priority: major
Milestone: 4.9.0
Version:
Changetime: 2014-03-12 19:23:03 UTC
Created: 2010-04-28 08:40:28 UTC
Keywords: syntax

Attachments

1894d733cd096ab7e35b64d430da3d55eb1f1308/attachments/0001-Attempt-to-fix-219-where-renamed-reexports-are-not-c.patch

Description

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)

Changes and comments

[2012-05-18 12:51:16 UTC] felix set milestone to 4.9.0

[2012-09-30 00:07:33 UTC] sjamaan wrote:

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 It's been replaced by the foreach loops.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?

[2012-09-30 00:08:00 UTC] sjamaan wrote:

Damn you, Trac syntax

[2014-02-22 15:00:03 UTC] felix changed status from new to assigned

[2014-02-22 15:00:03 UTC] felix set owner to sjamaan

[2014-02-22 15:00:03 UTC] felix wrote:

I think you are on the right track, sjamaan. I have modified `##sys#register-compiled-module` to merge the new SE with the existing SE for each import, instead of blindly overwriting it. I'm not completely sure whether this is necessary for all imports, but so far it seems to work.

I have added a test-case and all other tests seem to run ok. I have not attempted a full bootstrap, but since chicken itself doesn't use such deep module magic, this shouldn't be a problem.

A patch is attached.