Date: Tue, 26 Sep 2017 00:55:11 -0400 From: George Mitchell <george+freebsd@m5p.com> To: freebsd-arm@freebsd.org Subject: Re: Why does this compile? Message-ID: <2b4d4179-9bda-c4ab-95af-5200463600cb@m5p.com> In-Reply-To: <CABx9NuSzSzK87WF07S0B2aZpddKxYJf69kR2gWqBmHxaEQO6JA@mail.gmail.com> References: <CABx9NuSzSzK87WF07S0B2aZpddKxYJf69kR2gWqBmHxaEQO6JA@mail.gmail.com>
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From: George Mitchell <george+freebsd@m5p.com>
To: freebsd-arm@freebsd.org
Message-ID: <2b4d4179-9bda-c4ab-95af-5200463600cb@m5p.com>
Subject: Re: Why does this compile?
References: <CABx9NuSzSzK87WF07S0B2aZpddKxYJf69kR2gWqBmHxaEQO6JA@mail.gmail.com>
In-Reply-To: <CABx9NuSzSzK87WF07S0B2aZpddKxYJf69kR2gWqBmHxaEQO6JA@mail.gmail.com>
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On 09/26/17 00:38, Russell Haley wrote:
> [...]
> #include <netinet/in.h>
>=20
> int main()
> {
> struct in_pktinfo;
> return 0;
> }
> [...]
This is a perfectly valid forward declaration of a struct type. In
most normal cases, you would follow this up with something that contains
a pointer to a thing of that type, and later a full declaration of the
type. As it stands, though, it's simply a statement to the compiler
that you are possibly using (and fully declaring) the structure type
later on in your program. -- George
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