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From: Mike Frysinger via Gdb-patches <gdb-patches@sourceware.org>
To: John Baldwin <jhb@FreeBSD.org>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH] sim/d10v: Use offsetof in a static assertion about structure layout.
Date: Wed, 19 May 2021 19:35:20 -0400	[thread overview]
Message-ID: <YKWguEtbEFKMxxVs@vapier> (raw)
In-Reply-To: <20210519174537.17278-1-jhb@FreeBSD.org>

On 19 May 2021 10:45, John Baldwin wrote:
> clang 11 fails to compile the static assertion as it cannot compute
> the pointer value at a compile time:
> 
> gdb/sim/d10v/interp.c:1149:37: error: static_assert expression is not an integral constant expression
>   static_assert ((uintptr_t) &State == (uintptr_t) &State.regs,
>                  ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
> 1 error generated.
> 
> Instead, assert that the offset of State.regs is 0.

idea is good ...

> --- a/sim/d10v/interp.c
> +++ b/sim/d10v/interp.c
>
> -  static_assert ((uintptr_t) &State == (uintptr_t) &State.regs,
> -		 "&State != &State.regs");
> +  static_assert (offsetof(typeof(State), regs) == 0,

stylewise:
* need space before the (
* i think we want __typeof since it's not in C11 afaik
-mike

  reply	other threads:[~2021-05-19 23:35 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 17:45 John Baldwin
2021-05-19 23:35 ` Mike Frysinger via Gdb-patches [this message]
2021-05-21 17:46   ` John Baldwin
2021-05-21 22:39     ` Mike Frysinger via Gdb-patches

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