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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sun, 15 Jan 2023 11:48:15 +0900
Message-ID: <CAK7LNASawny3wSTvjB8-CZJ2Mw8UnB0C4k5-X8yC8TyrmsM8RQ@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 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.


> Cheers,
> Miguel


-- 
Best Regards
Masahiro Yamada