linux-kernel - Re: [PATCH v2 2/5] rust: macros: support additional tokens in quote!

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJ-ks9nn1_gAqz9f3H9O47QA7dwk5MaT5YK3NQtZtUJHyNXbVg@mail.gmail.com>
Date: Fri, 28 Feb 2025 10:25:40 -0500
From: Tamir Duberstein <tamird@...il.com>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Miguel Ojeda <ojeda@...nel.org>, 
	Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Rasmus Villemoes <linux@...musvillemoes.dk>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Boqun Feng <boqun.feng@...il.com>, 
	Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <benno.lossin@...ton.me>, Andreas Hindborg <a.hindborg@...nel.org>, 
	Trevor Gross <tmgross@...ch.edu>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, linux-kernel@...r.kernel.org, 
	rust-for-linux@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 2/5] rust: macros: support additional tokens in quote!

On Fri, Feb 28, 2025 at 7:42 AM Alice Ryhl <aliceryhl@...gle.com> wrote:
>
> This gives the quote! macro support for the following additional tokens:
>
> * The = token.
> * The _ token.
> * Using #my_var with variables of type Ident.
>
> Additionally, some type annotations are added to allow cases where
> groups are empty. For example, quote! does support () in the input, but
> only when it is *not* empty. When it is empty, the compiler cannot infer
> the item type of `tokens`.
>
> These additional quote! features are used by a new proc macro that
> generates code looking like this:
>
>         const _: () = {
>             if true {
>                 ::kernel::bindings::#name
>             } else {
>                 #name
>             };
>         };
>
> where #name has type Ident.
>
> Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
> ---
>  rust/macros/quote.rs | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs
> index 33a199e4f176..c18960a91082 100644
> --- a/rust/macros/quote.rs
> +++ b/rust/macros/quote.rs
> @@ -20,6 +20,12 @@ fn to_tokens(&self, tokens: &mut TokenStream) {
>      }
>  }
>
> +impl ToTokens for proc_macro::Ident {
> +    fn to_tokens(&self, tokens: &mut TokenStream) {
> +        tokens.extend([TokenTree::from(self.clone())]);
> +    }
> +}
> +
>  impl ToTokens for TokenTree {
>      fn to_tokens(&self, tokens: &mut TokenStream) {
>          tokens.extend([self.clone()]);
> @@ -40,7 +46,7 @@ fn to_tokens(&self, tokens: &mut TokenStream) {
>  /// `quote` crate but provides only just enough functionality needed by the current `macros` crate.
>  macro_rules! quote_spanned {
>      ($span:expr => $($tt:tt)*) => {{
> -        let mut tokens;
> +        let mut tokens: ::std::vec::Vec<::proc_macro::TokenTree>;
>          #[allow(clippy::vec_init_then_push)]
>          {
>              tokens = ::std::vec::Vec::new();
> @@ -65,7 +71,8 @@ macro_rules! quote_spanned {
>          quote_spanned!(@proc $v $span $($tt)*);
>      };
>      (@proc $v:ident $span:ident ( $($inner:tt)* ) $($tt:tt)*) => {
> -        let mut tokens = ::std::vec::Vec::new();
> +        #[allow(unused_mut)]

It'd be nice to mention the need for this attribute in the commit
message along with the added type annotations.

> +        let mut tokens = ::std::vec::Vec::<::proc_macro::TokenTree>::new();
>          quote_spanned!(@proc tokens $span $($inner)*);
>          $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new(
>              ::proc_macro::Delimiter::Parenthesis,
> @@ -136,6 +143,16 @@ macro_rules! quote_spanned {
>          ));
>          quote_spanned!(@proc $v $span $($tt)*);
>      };
> +    (@proc $v:ident $span:ident = $($tt:tt)*) => {
> +        $v.push(::proc_macro::TokenTree::Punct(
> +                ::proc_macro::Punct::new('=', ::proc_macro::Spacing::Alone)
> +        ));
> +        quote_spanned!(@proc $v $span $($tt)*);
> +    };
> +    (@proc $v:ident $span:ident _ $($tt:tt)*) => {
> +        $v.push(::proc_macro::TokenTree::Ident(::proc_macro::Ident::new("_", $span)));
> +        quote_spanned!(@proc $v $span $($tt)*);
> +    };
>      (@proc $v:ident $span:ident $id:ident $($tt:tt)*) => {
>          $v.push(::proc_macro::TokenTree::Ident(::proc_macro::Ident::new(stringify!($id), $span)));
>          quote_spanned!(@proc $v $span $($tt)*);
>
> --
> 2.48.1.711.g2feabab25a-goog

Reviewed-by: Tamir Duberstein <tamird@...il.com>