[Bug-kawa] [bug #17986] syntax bindings in letrec-syntax may mask literal identifiers inside

[Chris Wegrzyn]

URL:
  <http://savannah.gnu.org/bugs/?17986>

                 Summary: syntax bindings in letrec-syntax may mask literal
identifiers inside
                 Project: Kawa
            Submitted by: cwegrzyn
            Submitted on: Thursday 10/12/2006 at 20:27
                Category: Scheme language
                Severity: 3 - Normal
              Item Group: Unexpected result
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open

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Details:

When keywords bound to syntax in letrec-syntax are also used in the literal
identifiers list of one of the contained bindings, the literal identifier may
be treated as a variable, rather than a literal.

The attached testcase should more clearly illustrate this. From my reading of
r5rs, the output of the cases with and without the "masker" should be
equivalent. I have also confirmed this behavior with MIT Scheme 7.7.1.

I am honestly not sure if this is in fact a bug or just a misunderstanding on
my part of r5rs. I have tracked the issue to the call to literalIdentifierEq
in SyntaxPattern.translate. If this is indeed a bug, I think the solution may
be to have the literal identifiers considered as sharing the scope of the
scope outside the pattern scope. I have included a patch that does this.





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File Attachments:


-------------------------------------------------------
Date: Thursday 10/12/2006 at 20:27  Name: syntax-masking.scm  Size: 1kB   By:
cwegrzyn
test case
<http://savannah.gnu.org/bugs/download.php?file_id=10956>

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