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Date:   Tue, 24 Oct 2023 13:54:52 +0100
From:   Gary Guo <gary@garyguo.net>
To:     Trevor Gross <tmgross@umich.edu>
Cc:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        =?UTF-8?B?QmrDtnJu?= Roy Baron <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Andreas Hindborg <a.hindborg@samsung.com>,
        Alice Ryhl <aliceryhl@google.com>,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        FUJITA Tomonori <fujita.tomonori@gmail.com>
Subject: Re: [PATCH] rust: macros: update 'paste!' macro to accept string
 literals
Message-ID: <20231024135452.223d8d85@eugeo>
In-Reply-To: <20231008094816.320424-1-tmgross@umich.edu>
References: <20231008094816.320424-1-tmgross@umich.edu>
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On Sun,  8 Oct 2023 05:48:18 -0400
Trevor Gross <tmgross@umich.edu> wrote:

> Enable combining identifiers with string literals in the 'paste!' macro.
> This allows combining user-specified strings with affixes to create
> namespaced identifiers.
> 
> This sample code:
> 
>     macro_rules! m {
>         ($name:lit) => {
>             paste!(struct [<_some_ $name _struct_>];)
>         }
>     }
> 
>     m!("foo_bar");
> 
> Would previously cause a compilation error. It will now generate:
> 
>     struct _some_foo_bar_struct_;
> 
> Reported-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
> Signed-off-by: Trevor Gross <tmgross@umich.edu>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
> 
> Original mention of this problem in [1]
> 
> [1]: https://lore.kernel.org/rust-for-linux/20231008.164906.1151622782836568538.fujita.tomonori@gmail.com/
> 
>  rust/macros/paste.rs | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/rust/macros/paste.rs b/rust/macros/paste.rs
> index 385a78434224..f40d42b35b58 100644
> --- a/rust/macros/paste.rs
> +++ b/rust/macros/paste.rs
> @@ -9,7 +9,15 @@ fn concat(tokens: &[TokenTree], group_span: Span) -> TokenTree {
>      loop {
>          match tokens.next() {
>              None => break,
> -            Some(TokenTree::Literal(lit)) => segments.push((lit.to_string(), lit.span())),
> +            Some(TokenTree::Literal(lit)) => {
> +                // Allow us to concat string literals by stripping quotes
> +                let mut value = lit.to_string();
> +                if value.starts_with('"') && value.ends_with('"') {
> +                    value.remove(0);
> +                    value.pop();
> +                }
> +                segments.push((value, lit.span()));
> +            }
>              Some(TokenTree::Ident(ident)) => {
>                  let mut value = ident.to_string();
>                  if value.starts_with("r#") {