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From: Alexander Korotkov <aekorotkov@gmail.com>
Date: Tue, 9 Feb 2021 03:35:01 +0300
Message-ID: 
 <CAPpHfdvmNwqEZajGsERi6y2Q7DRN892dPDt+WPTZqqsWDTFTZw@mail.gmail.com>
Subject: Re: Detecting pointer misalignment (was Re: pgsql: Implementation of
 subscripting for jsonb)
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>,
 Alexander Korotkov <akorotkov@postgresql.org>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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On Mon, Feb 8, 2021 at 7:49 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I wrote:
> > After digging in gcc's release history, it seems they invented
> > "-fsanitize=alignment" in GCC 5, so we can make this work for gcc
> > by writing
> > #if __GNUC__ >= 5
> > (the likely() macro already uses a similar approach).  Can't say
> > if that's close enough for clang too.
>
> Ugh, no it isn't: even pretty recent clang releases only define
> __GNUC__ as 4.  It looks like we need a separate test on clang's
> version.  I looked at their version history and sanitizers seem
> to have come in around clang 7, so I propose the attached (where
> I worked a bit harder on the comment, too).

Looks good to me.  Thank you for revising!

------
Regards,
Alexander Korotkov