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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sat, 14 Jan 2023 21:33:46 +0900
Message-ID: <CAK7LNARnNEJVuBKaFnE2TL60ku_6F03C749BVjzr8E6-khPTJg@mail.gmail.com>
Subject: Re: [PATCH 4/6] kbuild: rust_is_available: check if the script was
 invoked from Kbuild
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 8:12 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Thu, Jan 12, 2023 at 6:29 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > I do not like this.
> > We do not need to cater to every oddity.
> >
> > Checking MAKEFLAGS is too much.
>
> I agree we should not attempt to catch every possible mistake in the
> script, but there have been several people hitting precisely this case
> (the latest is in the linked thread in the commit message), i.e. some
> people read the `Makefile` and notice the script invocation, and go
> execute it, but they are unlikely to be aware of the target in that
> case.
>
> > You can check RUSTC/BINDGEN/CC if you persist in this.
>
> This is fine, and actually we should do it regardless of `MAKEFLAGS`.
> I can add it to v2.
>
> However, that does not cover the same thing as `MAKEFLAGS` is trying
> to here. The reason is that even if they see e.g. "RUSTC is not set",
> they will not know about how to call the script properly, i.e. through
> the `Makefile` target.
>
> For `RUSTC` and `BINDGEN`, it does not really matter (and we could
> give a default to the variable, since the name rarely would be
> different). However, for `CC`, the logic that Kbuild uses is more
> complex, so it seems best to me to let Kbuild tell us what the actual
> compiler is.
>
> Cheers,
> Miguel


OK, you maintain this script, so it is up to you.


-- 
Best Regards
Masahiro Yamada