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Date:   Tue, 9 Oct 2018 18:54:42 +0200 (CEST)
From:   Jan Engelhardt <jengelh@inai.de>
To:     David Howells <dhowells@redhat.com>
cc:     linux-api@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Coly Li <colyli@suse.de>,
        Kent Overstreet <kent.overstreet@gmail.com>,
        linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/11] UAPI: bcache: Fix use of embedded flexible array
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On Tuesday 2018-10-09 17:41, David Howells wrote:

>Jan Engelhardt <jengelh@inai.de> wrote:
>
>> """it [the array size expression] shall be a converted constant expression of
>> type std::size_t and its value shall be greater than zero."""
>> —http://eel.is/c++draft/dcl.array
>
>Interesting.  You're not actually quoting the full sentence:
>
>	If the constant-expression is present, it shall be a converted
>	constant expression of type std​::​size_­t and its value shall be
>	greater than zero.
>
>This suggests that:
>
>	__u64 ptr[]
>
>is actually valid

I think that kind of validity only goes for this kind of standalone 
decl:

	extern int myints[];

but not for []-inside-struct.