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From: Arvydas Silanskas <nma.arvydas.silanskas@gmail.com>
Date: Wed, 21 Sep 2022 00:41:33 +0300
Message-ID: <CAPh7weBX4WF4L8x_EB5ntEpn20WcoPCsKY8aBU0UQq5gcBTKYw@mail.gmail.com>
Subject: Re: "void-valued expression where value is needed"
To: Panicz Maciej Godek <godek.maciek@gmail.com>
Cc: kawa mailing list <kawa@sourceware.org>
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I think this is a sensible warning. If I see #!void ending up somewhere
inside a value object like a list (`result` in your snippet), that
immediately alarms me that something is wrong. An empty `values` call is a
defined case, it would simply yield an empty `result` list.

2022-09-21, tr, 00:02 Panicz Maciej Godek via Kawa <kawa@sourceware.org>
ra=C5=A1=C4=97:

> Suppose that I have some code like
>
> (define (f)::void
>   (call-with-values
>       (=CE=BB () #!void)
>     (=CE=BB result
>       (apply values result))))
>
> When I compile it, Kawa issues the warning:
>
> void-valued expression where value is needed
>
> I wonder whether this warning is desired in such circumstances?
>
> (It surely makes it difficult to write values-agnostic macros)
>
> What is interesting is that the warning disappears if I replace #!void wi=
th
> (values) [unless I declare the function's return type as ::void].
>

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