Hi Ian,
Sorry for the late reply.
Ian Price <ianpric...@googlemail.com> skribis:
> l...@gnu.org (Ludovic Courtès) writes:
>
>> Hi Göran,
>>
>> Sorry for the delay.
>>
>> Göran Weinholt <go...@weinholt.se> skribis:
>>
>>> the case-lambda form is specified in r6rs-lib as accepting any number of
>>> clauses, including zero. So this should not give an error:
>>
>> My interpretation of the ‘case-lambda’ implementation on p. 15 of
>> r6rs-lib.pdf is that ‘case-lambda-help’ raises an assertion violation
>> when ‘case-lambda’ is called with zero clauses.
> The case-lambda-help macro is expanded from within
> (lambda args
> (let ((n (length args)))
> (case-lambda-help args n
> (fmls b1 b2 ...) ...)))
>
> So, the full expansion is
> (lambda args
> (let ((n (length args)))
> (assertion-violation #f "unexpected number of arguments")))
>
> and thus a procedure that always returns an assertion violation.
Indeed, thanks for the correction (I was thinking of
‘assertion-violation’ as a compile-time assertion.)
So, here’s a tentative patch for review:
Modified module/ice-9/psyntax.scm
diff --git a/module/ice-9/psyntax.scm b/module/ice-9/psyntax.scm
index 728ab12..c3aa6d8 100644
--- a/module/ice-9/psyntax.scm
+++ b/module/ice-9/psyntax.scm
@@ -1778,7 +1778,19 @@
r* w* mod)))))
(syntax-case clauses ()
- (() (values '() #f))
+ (() ; zero clauses
+ (values
+ '()
+ (build-lambda-case s '() '() 'rest #f '()
+ (list (build-lexical-var s 'rest))
+ (build-application s
+ (make-toplevel-ref s 'throw)
+ (list
+ (build-data
+ s 'wrong-number-of-args)
+ (build-data
+ s "Wrong number of arguments")))
+ #f)))
(((args e1 e2 ...) (args* e1* e2* ...) ...)
(call-with-values (lambda () (get-formals #'args))
(lambda (req opt rest kw)
@@ -2092,12 +2104,12 @@
(global-extend 'core 'case-lambda
(lambda (e r w s mod)
(syntax-case e ()
- ((_ (args e1 e2 ...) (args* e1* e2* ...) ...)
+ ((_ (args e1 e2 ...) ...)
(call-with-values
(lambda ()
(expand-lambda-case e r w s mod
lambda-formals
- #'((args e1 e2 ...) (args* e1* e2* ...) ...)))
+ #'((args e1 e2 ...) ...)))
(lambda (meta lcase)
(build-case-lambda s meta lcase))))
(_ (syntax-violation 'case-lambda "bad case-lambda" e)))))
@@ -2105,12 +2117,12 @@
(global-extend 'core 'case-lambda*
(lambda (e r w s mod)
(syntax-case e ()
- ((_ (args e1 e2 ...) (args* e1* e2* ...) ...)
+ ((_ (args e1 e2 ...) ...)
(call-with-values
(lambda ()
(expand-lambda-case e r w s mod
lambda*-formals
- #'((args e1 e2 ...) (args* e1* e2* ...) ...)))
+ #'((args e1 e2 ...) ...)))
(lambda (meta lcase)
(build-case-lambda s meta lcase))))
(_ (syntax-violation 'case-lambda "bad case-lambda*" e)))))
Modified test-suite/tests/compiler.test
diff --git a/test-suite/tests/compiler.test b/test-suite/tests/compiler.test
index ee688c0..bb2be06 100644
--- a/test-suite/tests/compiler.test
+++ b/test-suite/tests/compiler.test
@@ -1,5 +1,5 @@
;;;; compiler.test --- tests for the compiler -*- scheme -*-
-;;;; Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+;;;; Copyright (C) 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
@@ -163,4 +163,11 @@
(display (list x y))
(list x y))))
(display (t 'x)))))
- "(x y)(x y)")))
+ "(x y)(x y)"))
+
+ (pass-if-exception "zero clauses"
+ exception:wrong-num-args
+ ;; See <http://bugs.gnu.org/9776>.
+ (compile '(let ((p (case-lambda)))
+ (and (procedure? p) (p)))
+ #:to 'value)))
The problem is that the new test itself fails with:
ERROR: compiler.test: case-lambda: zero clauses - arguments:
((wrong-number-of-args "eval" "Wrong number of arguments" () #f))
and then a number of tests in tree-il.test fail because they were
assuming the previous behavior for zero-clause ‘case-lambda’.
In addition, this patch uses the Guilish ‘wrong-number-of-args’
exception, not the R6RS one. This is consistent, but it means that the
R6RS layer would have to convert exceptions again.
Thoughts?
Thanks,
Ludo’.
