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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 13 Oct 2023 12:22:02 -0700
Message-ID: <CAHk-=wiiBpw-0MKBbPkvo54=Cvyi0b3_1bDtqbgiD4ixd+OPow@mail.gmail.com>
Subject: Re: [PATCH v10 25/27] x86: enable initial Rust support
To:     "H. Peter Anvin" <hpa@zytor.com>
Cc:     Ramon de C Valle <rcvalle@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Kees Cook <keescook@chromium.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, patches@lists.linux.dev,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@google.com>,
        David Gow <davidgow@google.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        linux-doc@vger.kernel.org
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On Fri, 13 Oct 2023 at 12:01, H. Peter Anvin <hpa@zytor.com> wrote:
>
> Transparent unions have been standard C since C99.

Ahh, I didn't realize they made it into the standard.

In gcc, they've been usable for a lot longer (ie --std=gnu89 certainly
is happy with them), but the kernel never really picked up on them.

I think they've mainly been used by glibc for a couple of functions
that can take a couple of different types without complaining.

           Linus