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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sun, 15 Jan 2023 19:48:58 +0900
Message-ID: <CAK7LNAT0p0N=DtNpUsCuw=rhLNRY5VeozYr-XL4WxJ+0bfszyg@mail.gmail.com>
Subject: Re: [PATCH 6/6] kbuild: rust_is_available: normalize version matching
To:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     Miguel Ojeda <ojeda@kernel.org>, linux-kbuild@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        patches@lists.linux.dev, Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>
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On Sun, Jan 15, 2023 at 11:48 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Sat, Jan 14, 2023 at 8:15 AM Miguel Ojeda
> <miguel.ojeda.sandonis@gmail.com> wrote:
> >
> > On Thu, Jan 12, 2023 at 7:23 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > Maybe, your purpose is to use sed consistently, but
> > > perhaps you can avoid forking sed if you know the
> > > format of the first line.
> >
> > The most unknown format would be the one of the libclang check, where
> > there may be other lines before the one we are interested in. However,
> > the pattern expansion would still match newlines, right?
> >
> > > BTW, what is missing here is, you do not check if
> > > ${RUSTC} is really rustc.
> > >
> > > I can fool this script to print
> > > "arithmetic expression: expecting primary: "100000 *  + 100 *  + "
> >
> > We can test if nothing was printed by `sed` for that (or do it with
> > shell builtins).
> >
> > Having said that, I would say fooling the script on purpose is an more
> > of an oddity compared to the case `MAKEFLAGS` attempts to cover
> > (please see my reply on the other patch). So if we cover this, then I
> > would say we should really cover the other one.
>
>
>
> get_canonical_version() in scripts/as-version.sh has
> a little more trick to avoid
> "arithmetic expression: expecting primary: "100000 *  + 100 *  + "
> but it is up to you.


My code accepts anything that is separated by dots
(and non-numerical strings are silently turned into zero).

Your code takes exactly the "([0-9]+\.[0-9]+\.[0-9]+)" pattern,
so it works very safely.

I think using sed is fine.


-- 
Best Regards
Masahiro Yamada