Received-SPF: pass (google.com: domain of linux-kernel+bounces-213970-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Date: Thu, 13 Jun 2024 16:10:12 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>, linux-kernel@vger.kernel.org,
 linux-mm@kvack.org, linux-security-module@vger.kernel.org,
 linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH] linux++: delete some forward declarations
Message-ID: <20240613161012.1dd2ff60@rorschach.local.home>
In-Reply-To: <20240613130420.a62ed8965a73b0f8d35890d4@linux-foundation.org>
References: <5ad5556c-7c32-45b7-89cf-f723c9d7332b@p183>
	<20240613153402.3b067d4b@rorschach.local.home>
	<20240613130420.a62ed8965a73b0f8d35890d4@linux-foundation.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

On Thu, 13 Jun 2024 13:04:20 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Thu, 13 Jun 2024 15:34:02 -0400 Steven Rostedt <rostedt@goodmis.org> w=
rote:
>=20
> > On Thu, 13 Jun 2024 22:22:18 +0300
> > Alexey Dobriyan <adobriyan@gmail.com> wrote:
> >  =20
> > > g++ doesn't like forward enum declarations:
> > >=20
> > > 	error: use of enum =E2=80=98E=E2=80=99 without previous declaration
> > > 	   64 | enum E; =20
> >=20
> > But we don't care about g++. Do we? =20
>=20
> It appears that g++ is a useful enum declaration detector.
>=20
> I'm curious to know how even the above warning was generated.  Does g++
> work at all on Linux?
>=20
> > I would make that a separate patch. =20
>=20
> What are you referring to here?

The enum change should be separate from the struct changes.

>=20
> > >=20
> > > Delete those which aren't used.
> > >=20
> > > Delete some unused/unnecessary forward struct declarations for a chan=
ge. =20
> >=20
> > This is a clean up, but should have a better change log. Just something
> > simple like:
> >=20
> >   Delete unnecessary forward struct declarations. =20
>=20
> Alexey specializes in cute changelogs.

eh

>=20
> I do have a concern about the patch: has it been tested with all
> possible Kconfigs?  No.  There may be some configs in which the forward
> declaration is required.
>=20
> And...  I'm a bit surprised that forward declarations are allowed in C.
> A billion years ago I used a C compiler which would use 16 bits for
> an enum if the enumted values would fit in 16 bits.  And it would use 32
> bits otherwise.  So the enumerated values were *required* for the
> compiler to be able to figure out the sizeof.  But it was a billion
> years ago.

Well, I only looked at the one change in ftrace.h which has a
"struct seq_file;" that is not used anywhere else in the file, so that
one definitely can go.

-- Steve