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From: Joe Perches <joe@perches.com>
To: Masahiro Yamada <masahiroy@kernel.org>,
	David Laight <David.Laight@aculab.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>,
	Michal Marek <michal.lkml@markovi.net>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	stable <stable@vger.kernel.org>
Subject: Re: [PATCH] kbuild: Disable -Wpointer-to-enum-cast
Date: Tue, 10 Mar 2020 09:48:40 -0700	[thread overview]
Message-ID: <0fdd3a89033ce3d6e7ab6b12eddefc343ac43729.camel@perches.com> (raw)
In-Reply-To: <CAK7LNARMsO0AeO8-kH4czMuW0Y_=dN+ZhtXNdRE7CWGvU2PNvA@mail.gmail.com>

On Wed, 2020-03-11 at 00:30 +0900, Masahiro Yamada wrote:
> On Tue, Mar 10, 2020 at 8:31 PM David Laight <David.Laight@aculab.com> wrote:
> > From: Nathan Chancellor
> > > Sent: 10 March 2020 01:26
> > ...
> > > Sure, I can send v2 to do that but I think that sending 97 patches just
> > > casting the small values (usually less than twenty) to unsigned long
> > > then to the enum is rather frivolous. I audited at least ten to fifteen
> > > of these call sites when creating the clang patch and they are all
> > > basically false positives.
> > 
> > Such casts just make the code hard to read.
> > If misused casts can hide horrid bugs.
> > IMHO sprinkling the code with casts just to remove
> > compiler warnings will bite back one day.
> > 
> 
> I agree that too much casts make the code hard to read,
> but irrespective of this patch, there is no difference
> in the fact that we need a cast to convert
> (const void *) to a non-pointer value.
> 
> The difference is whether we use
> (uintptr_t) or (enum foo).

or hide it altogether in a macro like cast_to

#define cast_to(type, val)	\
	etc...

where cast_to could do the appropriate
intermediate cast if type is an enum
and sizeof(tupeof val) is larger than int



  parent reply	other threads:[~2020-03-10 16:50 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-08  7:34 Nathan Chancellor
2020-03-09  2:11 ` Masahiro Yamada
2020-03-10  1:25   ` Nathan Chancellor
2020-03-10 11:31     ` David Laight
2020-03-10 15:30       ` Masahiro Yamada
2020-03-10 16:16         ` Nick Desaulniers
2020-03-10 18:20           ` Saravana Kannan
2020-03-10 16:48         ` Joe Perches [this message]
2020-03-09 12:25 ` Sasha Levin
2020-03-10  1:14   ` Nathan Chancellor
2020-03-11 19:41 ` [PATCH v2] " Nathan Chancellor
2020-03-14  1:32   ` Masahiro Yamada

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