From: David Kastrup <dak@gnu.org>
Date: Mon, 05 May 2014 05:19:35 GMT
Subject: Re: [PATCH 1/9] Define a structure for object IDs.
Message-ID: <87lhugu7iw.fsf@fencepost.gnu.org>
In-Reply-To: <87ppjt6xjv.fsf@igel.home>

Andreas Schwab <schwab@linux-m68k.org> writes:

> Johannes Sixt <j6t@kdbg.org> writes:
>
>> Isn't internal padding only allowed between members to achieve correct
>> alignment of later members, and at the end only sufficient padding so
>> that members are aligned correctly when the struct is part of an array?
>
> The standard allows arbitrary internal padding, it doesn't have to be
> minimal.

What the standard does guarantee is that a pointer to a struct can be
cast to a pointer to its first member and vice versa.  It does not as
far as I can see guarantee that a pointer to something of the same type
of its first member can be converted to a pointer to a struct even if
the struct only contains a member of such type.

-- 
David Kastrup