linux-kernel - Re: [PATCH] Documentation: coding-style: ask function-like macros to evaluate parameters

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Message-ID: <CAGsJ_4zpXwVEhsdffoZVBVWiwT4Lw2qEMrW-X92ib=kv=9Yx9g@mail.gmail.com>
Date: Wed, 20 Mar 2024 16:24:30 +1300
From: Barry Song <21cnbao@...il.com>
To: Stephen Rothwell <sfr@...b.auug.org.au>
Cc: corbet@....net, workflows@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Barry Song <v-songbaohua@...o.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Chris Zankel <chris@...kel.net>, 
	Huacai Chen <chenhuacai@...ngson.cn>, Herbert Xu <herbert@...dor.apana.org.au>, 
	Guenter Roeck <linux@...ck-us.net>, Max Filippov <jcmvbkbc@...il.com>
Subject: Re: [PATCH] Documentation: coding-style: ask function-like macros to
 evaluate parameters

Hi Stephen,
Thanks for reviewing.

On Wed, Mar 20, 2024 at 2:42 PM Stephen Rothwell <sfr@...b.auug.orgau> wrote:
>
> Hi Barry,
>
> On Wed, 20 Mar 2024 13:16:56 +1300 Barry Song <21cnbao@...il.com> wrote:
> >
> > diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
> > index 9c7cf7347394..8065747fddff 100644
> > --- a/Documentation/process/coding-style.rst
> > +++ b/Documentation/process/coding-style.rst
> > @@ -827,6 +827,13 @@ Macros with multiple statements should be enclosed in a do - while block:
> >                               do_this(b, c);          \
> >               } while (0)
> >
> > +Function-like macros should evaluate their parameters, for unused parameters,
> > +cast them to void:
> > +
> > +.. code-block:: c
> > +
> > +     #define macrofun(a) do { (void) (a); } while (0)
> > +
>
> Maybe add some comment about using a static inline function for these
> simple versions instead, if at all possible, (it is suggested just
> above this section) since that will still type check arguments.

right, what about adding the below section together with the above (void) cast?

+Another approach could involve utilizing a static inline function to replace
+the macro.:
+
+.. code-block:: c
+
+       static inline void fun(struct foo *foo)
+       {
+       }
+

>
> --
> Cheers,
> Stephen Rothwell

Thanks
Barry