[PATCH v3 02/12] rust: macros: use `quote!` from vendored crate

[Gary Guo <gary@kernel.org>]

From: Gary Guo <gary@garyguo.net>

With `quote` crate now vendored in the kernel, we can remove our custom
`quote!` macro implementation and just rely on that crate instead.

The `quote` crate uses types from the `proc-macro2` library so we also
update to use that, and perform conversion in the top-level lib.rs.

Clippy complains about unnecessary `.to_string()` as `proc-macro2`
provides additional `PartialEq` impl, so they are removed.

Reviewed-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/macros/concat_idents.rs |   2 +-
 rust/macros/export.rs        |   4 +-
 rust/macros/fmt.rs           |   4 +-
 rust/macros/helpers.rs       |   4 +-
 rust/macros/kunit.rs         |   5 +-
 rust/macros/lib.rs           |  21 ++--
 rust/macros/module.rs        |   6 +-
 rust/macros/paste.rs         |   2 +-
 rust/macros/quote.rs         | 182 -----------------------------------
 rust/macros/vtable.rs        |   7 +-
 10 files changed, 32 insertions(+), 205 deletions(-)
 delete mode 100644 rust/macros/quote.rs

diff --git a/rust/macros/concat_idents.rs b/rust/macros/concat_idents.rs
index 7e4b450f3a507..12cb231c3d715 100644
--- a/rust/macros/concat_idents.rs
+++ b/rust/macros/concat_idents.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{token_stream, Ident, TokenStream, TokenTree};
+use proc_macro2::{token_stream, Ident, TokenStream, TokenTree};
 
 use crate::helpers::expect_punct;
 
diff --git a/rust/macros/export.rs b/rust/macros/export.rs
index a08f6337d5c8d..92d9b30971929 100644
--- a/rust/macros/export.rs
+++ b/rust/macros/export.rs
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 
+use proc_macro2::TokenStream;
+use quote::quote;
+
 use crate::helpers::function_name;
-use proc_macro::TokenStream;
 
 /// Please see [`crate::export`] for documentation.
 pub(crate) fn export(_attr: TokenStream, ts: TokenStream) -> TokenStream {
diff --git a/rust/macros/fmt.rs b/rust/macros/fmt.rs
index 2f4b9f6e22110..19f709262552b 100644
--- a/rust/macros/fmt.rs
+++ b/rust/macros/fmt.rs
@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{Ident, TokenStream, TokenTree};
 use std::collections::BTreeSet;
 
+use proc_macro2::{Ident, TokenStream, TokenTree};
+use quote::quote_spanned;
+
 /// Please see [`crate::fmt`] for documentation.
 pub(crate) fn fmt(input: TokenStream) -> TokenStream {
     let mut input = input.into_iter();
diff --git a/rust/macros/helpers.rs b/rust/macros/helpers.rs
index 365d7eb499c08..13fafaba12261 100644
--- a/rust/macros/helpers.rs
+++ b/rust/macros/helpers.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{token_stream, Group, Ident, TokenStream, TokenTree};
+use proc_macro2::{token_stream, Group, Ident, TokenStream, TokenTree};
 
 pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
     if let Some(TokenTree::Ident(ident)) = it.next() {
@@ -86,7 +86,7 @@ pub(crate) fn function_name(input: TokenStream) -> Option<Ident> {
     let mut input = input.into_iter();
     while let Some(token) = input.next() {
         match token {
-            TokenTree::Ident(i) if i.to_string() == "fn" => {
+            TokenTree::Ident(i) if i == "fn" => {
                 if let Some(TokenTree::Ident(i)) = input.next() {
                     return Some(i);
                 }
diff --git a/rust/macros/kunit.rs b/rust/macros/kunit.rs
index b395bb0536959..5cd6aa5eef07d 100644
--- a/rust/macros/kunit.rs
+++ b/rust/macros/kunit.rs
@@ -4,10 +4,11 @@
 //!
 //! Copyright (c) 2023 José Expósito <jose.exposito89@gmail.com>
 
-use proc_macro::{Delimiter, Group, TokenStream, TokenTree};
 use std::collections::HashMap;
 use std::fmt::Write;
 
+use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
+
 pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {
     let attr = attr.to_string();
 
@@ -59,7 +60,7 @@ pub(crate) fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {
                 }
                 _ => (),
             },
-            TokenTree::Ident(i) if i.to_string() == "fn" && attributes.contains_key("test") => {
+            TokenTree::Ident(i) if i == "fn" && attributes.contains_key("test") => {
                 if let Some(TokenTree::Ident(test_name)) = body_it.next() {
                     tests.push((test_name, attributes.remove("cfg").unwrap_or_default()))
                 }
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index b38002151871a..945982c21f703 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -11,8 +11,6 @@
 // to avoid depending on the full `proc_macro_span` on Rust >= 1.88.0.
 #![cfg_attr(not(CONFIG_RUSTC_HAS_SPAN_FILE), feature(proc_macro_span))]
 
-#[macro_use]
-mod quote;
 mod concat_idents;
 mod export;
 mod fmt;
@@ -132,7 +130,7 @@
 ///     the kernel module.
 #[proc_macro]
 pub fn module(ts: TokenStream) -> TokenStream {
-    module::module(ts)
+    module::module(ts.into()).into()
 }
 
 /// Declares or implements a vtable trait.
@@ -207,7 +205,7 @@ pub fn module(ts: TokenStream) -> TokenStream {
 /// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
 #[proc_macro_attribute]
 pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
-    vtable::vtable(attr, ts)
+    vtable::vtable(attr.into(), ts.into()).into()
 }
 
 /// Export a function so that C code can call it via a header file.
@@ -230,7 +228,7 @@ pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
 /// automatically exported with `EXPORT_SYMBOL_GPL`.
 #[proc_macro_attribute]
 pub fn export(attr: TokenStream, ts: TokenStream) -> TokenStream {
-    export::export(attr, ts)
+    export::export(attr.into(), ts.into()).into()
 }
 
 /// Like [`core::format_args!`], but automatically wraps arguments in [`kernel::fmt::Adapter`].
@@ -248,7 +246,7 @@ pub fn export(attr: TokenStream, ts: TokenStream) -> TokenStream {
 /// [`pr_info!`]: ../kernel/macro.pr_info.html
 #[proc_macro]
 pub fn fmt(input: TokenStream) -> TokenStream {
-    fmt::fmt(input)
+    fmt::fmt(input.into()).into()
 }
 
 /// Concatenate two identifiers.
@@ -306,7 +304,7 @@ pub fn fmt(input: TokenStream) -> TokenStream {
 /// ```
 #[proc_macro]
 pub fn concat_idents(ts: TokenStream) -> TokenStream {
-    concat_idents::concat_idents(ts)
+    concat_idents::concat_idents(ts.into()).into()
 }
 
 /// Paste identifiers together.
@@ -444,9 +442,12 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream {
 /// [`paste`]: https://docs.rs/paste/
 #[proc_macro]
 pub fn paste(input: TokenStream) -> TokenStream {
-    let mut tokens = input.into_iter().collect();
+    let mut tokens = proc_macro2::TokenStream::from(input).into_iter().collect();
     paste::expand(&mut tokens);
-    tokens.into_iter().collect()
+    tokens
+        .into_iter()
+        .collect::<proc_macro2::TokenStream>()
+        .into()
 }
 
 /// Registers a KUnit test suite and its test cases using a user-space like syntax.
@@ -473,5 +474,5 @@ pub fn paste(input: TokenStream) -> TokenStream {
 /// ```
 #[proc_macro_attribute]
 pub fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {
-    kunit::kunit_tests(attr, ts)
+    kunit::kunit_tests(attr.into(), ts.into()).into()
 }
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 80cb9b16f5aaf..b855a2b586e18 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -1,9 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use crate::helpers::*;
-use proc_macro::{token_stream, Delimiter, Literal, TokenStream, TokenTree};
 use std::fmt::Write;
 
+use proc_macro2::{token_stream, Delimiter, Literal, TokenStream, TokenTree};
+
+use crate::helpers::*;
+
 fn expect_string_array(it: &mut token_stream::IntoIter) -> Vec<String> {
     let group = expect_group(it);
     assert_eq!(group.delimiter(), Delimiter::Bracket);
diff --git a/rust/macros/paste.rs b/rust/macros/paste.rs
index cce712d19855b..2181e312a7d32 100644
--- a/rust/macros/paste.rs
+++ b/rust/macros/paste.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{Delimiter, Group, Ident, Spacing, Span, TokenTree};
+use proc_macro2::{Delimiter, Group, Ident, Spacing, Span, TokenTree};
 
 fn concat_helper(tokens: &[TokenTree]) -> Vec<(String, Span)> {
     let mut tokens = tokens.iter();
diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs
deleted file mode 100644
index ddfc21577539c..0000000000000
--- a/rust/macros/quote.rs
+++ /dev/null
@@ -1,182 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use proc_macro::{TokenStream, TokenTree};
-
-pub(crate) trait ToTokens {
-    fn to_tokens(&self, tokens: &mut TokenStream);
-}
-
-impl<T: ToTokens> ToTokens for Option<T> {
-    fn to_tokens(&self, tokens: &mut TokenStream) {
-        if let Some(v) = self {
-            v.to_tokens(tokens);
-        }
-    }
-}
-
-impl ToTokens for proc_macro::Group {
-    fn to_tokens(&self, tokens: &mut TokenStream) {
-        tokens.extend([TokenTree::from(self.clone())]);
-    }
-}
-
-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()]);
-    }
-}
-
-impl ToTokens for TokenStream {
-    fn to_tokens(&self, tokens: &mut TokenStream) {
-        tokens.extend(self.clone());
-    }
-}
-
-/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with
-/// the given span.
-///
-/// This is a similar to the
-/// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_spanned.html) macro from the
-/// `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 = ::proc_macro::TokenStream::new();
-        {
-            #[allow(unused_variables)]
-            let span = $span;
-            quote_spanned!(@proc tokens span $($tt)*);
-        }
-        tokens
-    }};
-    (@proc $v:ident $span:ident) => {};
-    (@proc $v:ident $span:ident #$id:ident $($tt:tt)*) => {
-        $crate::quote::ToTokens::to_tokens(&$id, &mut $v);
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident #(#$id:ident)* $($tt:tt)*) => {
-        for token in $id {
-            $crate::quote::ToTokens::to_tokens(&token, &mut $v);
-        }
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident ( $($inner:tt)* ) $($tt:tt)*) => {
-        #[allow(unused_mut)]
-        let mut tokens = ::proc_macro::TokenStream::new();
-        quote_spanned!(@proc tokens $span $($inner)*);
-        $v.extend([::proc_macro::TokenTree::Group(::proc_macro::Group::new(
-            ::proc_macro::Delimiter::Parenthesis,
-            tokens,
-        ))]);
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident [ $($inner:tt)* ] $($tt:tt)*) => {
-        let mut tokens = ::proc_macro::TokenStream::new();
-        quote_spanned!(@proc tokens $span $($inner)*);
-        $v.extend([::proc_macro::TokenTree::Group(::proc_macro::Group::new(
-            ::proc_macro::Delimiter::Bracket,
-            tokens,
-        ))]);
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident { $($inner:tt)* } $($tt:tt)*) => {
-        let mut tokens = ::proc_macro::TokenStream::new();
-        quote_spanned!(@proc tokens $span $($inner)*);
-        $v.extend([::proc_macro::TokenTree::Group(::proc_macro::Group::new(
-            ::proc_macro::Delimiter::Brace,
-            tokens,
-        ))]);
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident :: $($tt:tt)*) => {
-        $v.extend([::proc_macro::Spacing::Joint, ::proc_macro::Spacing::Alone].map(|spacing| {
-            ::proc_macro::TokenTree::Punct(::proc_macro::Punct::new(':', spacing))
-        }));
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident : $($tt:tt)*) => {
-        $v.extend([::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.extend([::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.extend([::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.extend([::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.extend([::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.extend([::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.extend([::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.extend([::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.extend([::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.extend([::proc_macro::TokenTree::Ident(
-            ::proc_macro::Ident::new("_", $span),
-        )]);
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-    (@proc $v:ident $span:ident $id:ident $($tt:tt)*) => {
-        $v.extend([::proc_macro::TokenTree::Ident(
-            ::proc_macro::Ident::new(stringify!($id), $span),
-        )]);
-        quote_spanned!(@proc $v $span $($tt)*);
-    };
-}
-
-/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with
-/// mixed site span ([`Span::mixed_site()`]).
-///
-/// This is a similar to the [`quote!`](https://docs.rs/quote/latest/quote/macro.quote.html) macro
-/// from the `quote` crate but provides only just enough functionality needed by the current
-/// `macros` crate.
-///
-/// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.mixed_site
-macro_rules! quote {
-    ($($tt:tt)*) => {
-        quote_spanned!(::proc_macro::Span::mixed_site() => $($tt)*)
-    }
-}
diff --git a/rust/macros/vtable.rs b/rust/macros/vtable.rs
index ee06044fcd4f3..a67d1cc81a2d3 100644
--- a/rust/macros/vtable.rs
+++ b/rust/macros/vtable.rs
@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{Delimiter, Group, TokenStream, TokenTree};
 use std::collections::HashSet;
 use std::fmt::Write;
 
+use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
+
 pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
     let mut tokens: Vec<_> = ts.into_iter().collect();
 
@@ -31,7 +32,7 @@ pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
     let mut consts = HashSet::new();
     while let Some(token) = body_it.next() {
         match token {
-            TokenTree::Ident(ident) if ident.to_string() == "fn" => {
+            TokenTree::Ident(ident) if ident == "fn" => {
                 let fn_name = match body_it.next() {
                     Some(TokenTree::Ident(ident)) => ident.to_string(),
                     // Possibly we've encountered a fn pointer type instead.
@@ -39,7 +40,7 @@ pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
                 };
                 functions.push(fn_name);
             }
-            TokenTree::Ident(ident) if ident.to_string() == "const" => {
+            TokenTree::Ident(ident) if ident == "const" => {
                 let const_name = match body_it.next() {
                     Some(TokenTree::Ident(ident)) => ident.to_string(),
                     // Possibly we've encountered an inline const block instead.
-- 
2.51.2