proc_macro: stop using a remote object handle for Group

This greatly reduces round-trips to fetch relevant extra information about the
token in proc macro code, and avoids RPC messages to create Group tokens.

compiler/rustc_expand/src/proc_macro_server.rs

@@ -2,7 +2,7 @@ use crate::base::ExtCtxt;
 
 use rustc_ast as ast;
 use rustc_ast::token;
-use rustc_ast::tokenstream::{self, DelimSpan, Spacing::*, TokenStream, TreeAndSpacing};
+use rustc_ast::tokenstream::{self, Spacing::*, TokenStream};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
@@ -14,7 +14,7 @@ use rustc_span::def_id::CrateNum;
 use rustc_span::symbol::{self, kw, sym, Symbol};
 use rustc_span::{BytePos, FileName, Pos, SourceFile, Span};
 
-use pm::bridge::{server, ExpnGlobals, Punct, TokenTree};
+use pm::bridge::{server, DelimSpan, ExpnGlobals, Group, Punct, TokenTree};
 use pm::{Delimiter, Level, LineColumn};
 use std::ops::Bound;
 use std::{ascii, panic};
@@ -49,46 +49,57 @@ impl ToInternal<token::Delimiter> for Delimiter {
     }
 }
 
-impl FromInternal<(TreeAndSpacing, &'_ mut Vec<Self>, &mut Rustc<'_, '_>)>
+impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)>
-    for TokenTree<Span, Group, Ident, Literal>
+    for Vec<TokenTree<TokenStream, Span, Ident, Literal>>
 {
-    fn from_internal(
+    fn from_internal((stream, rustc): (TokenStream, &mut Rustc<'_, '_>)) -> Self {
-        ((tree, spacing), stack, rustc): (TreeAndSpacing, &mut Vec<Self>, &mut Rustc<'_, '_>),
-    ) -> Self {
         use rustc_ast::token::*;
 
+        let mut cursor = stream.into_trees();
+        let mut trees = Vec::new();
+
+        while let Some((tree, spacing)) = cursor.next_with_spacing() {
             let joint = spacing == Joint;
             let Token { kind, span } = match tree {
                 tokenstream::TokenTree::Delimited(span, delim, tts) => {
                     let delimiter = pm::Delimiter::from_internal(delim);
-                return TokenTree::Group(Group { delimiter, stream: tts, span, flatten: false });
+                    trees.push(TokenTree::Group(Group {
+                        delimiter,
+                        stream: Some(tts),
+                        span: DelimSpan {
+                            open: span.open,
+                            close: span.close,
+                            entire: span.entire(),
+                        },
+                    }));
+                    continue;
                 }
                 tokenstream::TokenTree::Token(token) => token,
             };
 
             macro_rules! tt {
                 ($ty:ident { $($field:ident $(: $value:expr)*),+ $(,)? }) => (
-                TokenTree::$ty(self::$ty {
+                    trees.push(TokenTree::$ty(self::$ty {
                         $($field $(: $value)*,)+
                         span,
-                })
+                    }))
                 );
                 ($ty:ident::$method:ident($($value:expr),*)) => (
-                TokenTree::$ty(self::$ty::$method($($value,)* span))
+                    trees.push(TokenTree::$ty(self::$ty::$method($($value,)* span)))
                 );
             }
             macro_rules! op {
-            ($a:expr) => {
+                ($a:expr) => {{
-                tt!(Punct { ch: $a, joint })
+                    tt!(Punct { ch: $a, joint });
-            };
+                }};
                 ($a:expr, $b:expr) => {{
-                stack.push(tt!(Punct { ch: $b, joint }));
+                    tt!(Punct { ch: $a, joint: true });
-                tt!(Punct { ch: $a, joint: true })
+                    tt!(Punct { ch: $b, joint });
                 }};
                 ($a:expr, $b:expr, $c:expr) => {{
-                stack.push(tt!(Punct { ch: $c, joint }));
+                    tt!(Punct { ch: $a, joint: true });
-                stack.push(tt!(Punct { ch: $b, joint: true }));
+                    tt!(Punct { ch: $b, joint: true });
-                tt!(Punct { ch: $a, joint: true })
+                    tt!(Punct { ch: $c, joint });
                 }};
             }
 
@@ -145,8 +156,8 @@ impl FromInternal<(TreeAndSpacing, &'_ mut Vec<Self>, &mut Rustc<'_, '_>)>
                 Ident(name, is_raw) => tt!(Ident::new(rustc.sess(), name, is_raw)),
                 Lifetime(name) => {
                     let ident = symbol::Ident::new(name, span).without_first_quote();
-                stack.push(tt!(Ident::new(rustc.sess(), ident.name, false)));
+                    tt!(Punct { ch: '\'', joint: true });
-                tt!(Punct { ch: '\'', joint: true })
+                    tt!(Ident::new(rustc.sess(), ident.name, false));
                 }
                 Literal(lit) => tt!(Literal { lit }),
                 DocComment(_, attr_style, data) => {
@@ -154,7 +165,7 @@ impl FromInternal<(TreeAndSpacing, &'_ mut Vec<Self>, &mut Rustc<'_, '_>)>
                     for ch in data.as_str().chars() {
                         escaped.extend(ch.escape_debug());
                     }
-                let stream = [
+                    let stream = vec![
                         Ident(sym::doc, false),
                         Eq,
                         TokenKind::lit(token::Str, Symbol::intern(&escaped), None),
@@ -162,44 +173,54 @@ impl FromInternal<(TreeAndSpacing, &'_ mut Vec<Self>, &mut Rustc<'_, '_>)>
                     .into_iter()
                     .map(|kind| tokenstream::TokenTree::token(kind, span))
                     .collect();
-                stack.push(TokenTree::Group(Group {
+                    tt!(Punct { ch: '#', joint: false });
-                    delimiter: pm::Delimiter::Bracket,
-                    stream,
-                    span: DelimSpan::from_single(span),
-                    flatten: false,
-                }));
                     if attr_style == ast::AttrStyle::Inner {
-                    stack.push(tt!(Punct { ch: '!', joint: false }));
+                        tt!(Punct { ch: '!', joint: false });
                     }
-                tt!(Punct { ch: '#', joint: false })
+                    trees.push(TokenTree::Group(Group {
+                        delimiter: pm::Delimiter::Bracket,
+                        stream: Some(stream),
+                        span: DelimSpan::from_single(span),
+                    }));
                 }
 
                 Interpolated(nt) if let NtIdent(ident, is_raw) = *nt => {
-                TokenTree::Ident(Ident::new(rustc.sess(), ident.name, is_raw, ident.span))
+                    trees.push(TokenTree::Ident(Ident::new(rustc.sess(), ident.name, is_raw, ident.span)))
                 }
+
                 Interpolated(nt) => {
-                TokenTree::Group(Group {
+                    let stream = TokenStream::from_nonterminal_ast(&nt);
+                    if crate::base::nt_pretty_printing_compatibility_hack(&nt, rustc.sess()) {
+                        trees.extend(Self::from_internal((stream, rustc)));
+                    } else {
+                        trees.push(TokenTree::Group(Group {
                             delimiter: pm::Delimiter::None,
-                    stream: TokenStream::from_nonterminal_ast(&nt),
+                            stream: Some(stream),
                             span: DelimSpan::from_single(span),
-                    flatten: crate::base::nt_pretty_printing_compatibility_hack(&nt, rustc.sess()),
+                        }))
-                })
+                    }
                 }
 
                 OpenDelim(..) | CloseDelim(..) => unreachable!(),
                 Eof => unreachable!(),
             }
         }
+        trees
+    }
 }
 
-impl ToInternal<TokenStream> for TokenTree<Span, Group, Ident, Literal> {
+impl ToInternal<TokenStream> for TokenTree<TokenStream, Span, Ident, Literal> {
     fn to_internal(self) -> TokenStream {
         use rustc_ast::token::*;
 
         let (ch, joint, span) = match self {
             TokenTree::Punct(Punct { ch, joint, span }) => (ch, joint, span),
-            TokenTree::Group(Group { delimiter, stream, span, .. }) => {
+            TokenTree::Group(Group { delimiter, stream, span: DelimSpan { open, close, .. } }) => {
-                return tokenstream::TokenTree::Delimited(span, delimiter.to_internal(), stream)
+                return tokenstream::TokenTree::Delimited(
+                    tokenstream::DelimSpan { open, close },
+                    delimiter.to_internal(),
+                    stream.unwrap_or_default(),
+                )
                 .into();
             }
             TokenTree::Ident(self::Ident { sym, is_raw, span }) => {
@@ -277,17 +298,6 @@ impl ToInternal<rustc_errors::Level> for Level {
 
 pub struct FreeFunctions;
 
-#[derive(Clone)]
-pub struct Group {
-    delimiter: Delimiter,
-    stream: TokenStream,
-    span: DelimSpan,
-    /// A hack used to pass AST fragments to attribute and derive macros
-    /// as a single nonterminal token instead of a token stream.
-    /// FIXME: It needs to be removed, but there are some compatibility issues (see #73345).
-    flatten: bool,
-}
-
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Ident {
     sym: Symbol,
@@ -356,7 +366,6 @@ impl<'a, 'b> Rustc<'a, 'b> {
 impl server::Types for Rustc<'_, '_> {
     type FreeFunctions = FreeFunctions;
     type TokenStream = TokenStream;
-    type Group = Group;
     type Ident = Ident;
     type Literal = Literal;
     type SourceFile = Lrc<SourceFile>;
@@ -449,7 +458,7 @@ impl server::TokenStream for Rustc<'_, '_> {
 
     fn from_token_tree(
         &mut self,
-        tree: TokenTree<Self::Span, Self::Group, Self::Ident, Self::Literal>,
+        tree: TokenTree<Self::TokenStream, Self::Span, Self::Ident, Self::Literal>,
     ) -> Self::TokenStream {
         tree.to_internal()
     }
@@ -457,7 +466,7 @@ impl server::TokenStream for Rustc<'_, '_> {
     fn concat_trees(
         &mut self,
         base: Option<Self::TokenStream>,
-        trees: Vec<TokenTree<Self::Span, Self::Group, Self::Ident, Self::Literal>>,
+        trees: Vec<TokenTree<Self::TokenStream, Self::Span, Self::Ident, Self::Literal>>,
     ) -> Self::TokenStream {
         let mut builder = tokenstream::TokenStreamBuilder::new();
         if let Some(base) = base {
@@ -487,71 +496,8 @@ impl server::TokenStream for Rustc<'_, '_> {
     fn into_trees(
         &mut self,
         stream: Self::TokenStream,
-    ) -> Vec<TokenTree<Self::Span, Self::Group, Self::Ident, Self::Literal>> {
+    ) -> Vec<TokenTree<Self::TokenStream, Self::Span, Self::Ident, Self::Literal>> {
-        // FIXME: This is a raw port of the previous approach (which had a
+        FromInternal::from_internal((stream, self))
-        // `TokenStreamIter` server-side object with a single `next` method),
-        // and can probably be optimized (for bulk conversion).
-        let mut cursor = stream.into_trees();
-        let mut stack = Vec::new();
-        let mut tts = Vec::new();
-        loop {
-            let next = stack.pop().or_else(|| {
-                let next = cursor.next_with_spacing()?;
-                Some(TokenTree::from_internal((next, &mut stack, self)))
-            });
-            match next {
-                Some(TokenTree::Group(group)) => {
-                    // A hack used to pass AST fragments to attribute and derive
-                    // macros as a single nonterminal token instead of a token
-                    // stream.  Such token needs to be "unwrapped" and not
-                    // represented as a delimited group.
-                    // FIXME: It needs to be removed, but there are some
-                    // compatibility issues (see #73345).
-                    if group.flatten {
-                        tts.append(&mut self.into_trees(group.stream));
-                    } else {
-                        tts.push(TokenTree::Group(group));
-                    }
-                }
-                Some(tt) => tts.push(tt),
-                None => return tts,
-            }
-        }
-    }
-}
-
-impl server::Group for Rustc<'_, '_> {
-    fn new(&mut self, delimiter: Delimiter, stream: Option<Self::TokenStream>) -> Self::Group {
-        Group {
-            delimiter,
-            stream: stream.unwrap_or_default(),
-            span: DelimSpan::from_single(self.call_site),
-            flatten: false,
-        }
-    }
-
-    fn delimiter(&mut self, group: &Self::Group) -> Delimiter {
-        group.delimiter
-    }
-
-    fn stream(&mut self, group: &Self::Group) -> Self::TokenStream {
-        group.stream.clone()
-    }
-
-    fn span(&mut self, group: &Self::Group) -> Self::Span {
-        group.span.entire()
-    }
-
-    fn span_open(&mut self, group: &Self::Group) -> Self::Span {
-        group.span.open
-    }
-
-    fn span_close(&mut self, group: &Self::Group) -> Self::Span {
-        group.span.close
-    }
-
-    fn set_span(&mut self, group: &mut Self::Group, span: Self::Span) {
-        group.span = DelimSpan::from_single(span);
     }
 }
 

library/proc_macro/src/bridge/client.rs

@@ -175,7 +175,6 @@ define_handles! {
     'owned:
     FreeFunctions,
     TokenStream,
-    Group,
     Literal,
     SourceFile,
     MultiSpan,
@@ -198,12 +197,6 @@ impl Clone for TokenStream {
     }
 }
 
-impl Clone for Group {
-    fn clone(&self) -> Self {
-        self.clone()
-    }
-}
-
 impl Clone for Literal {
     fn clone(&self) -> Self {
         self.clone()

library/proc_macro/src/bridge/mod.rs

@@ -65,11 +65,11 @@ macro_rules! with_api {
                 fn from_str(src: &str) -> $S::TokenStream;
                 fn to_string($self: &$S::TokenStream) -> String;
                 fn from_token_tree(
-                    tree: TokenTree<$S::Span, $S::Group, $S::Ident, $S::Literal>,
+                    tree: TokenTree<$S::TokenStream, $S::Span, $S::Ident, $S::Literal>,
                 ) -> $S::TokenStream;
                 fn concat_trees(
                     base: Option<$S::TokenStream>,
-                    trees: Vec<TokenTree<$S::Span, $S::Group, $S::Ident, $S::Literal>>,
+                    trees: Vec<TokenTree<$S::TokenStream, $S::Span, $S::Ident, $S::Literal>>,
                 ) -> $S::TokenStream;
                 fn concat_streams(
                     base: Option<$S::TokenStream>,
@@ -77,18 +77,7 @@ macro_rules! with_api {
                 ) -> $S::TokenStream;
                 fn into_trees(
                     $self: $S::TokenStream
-                ) -> Vec<TokenTree<$S::Span, $S::Group, $S::Ident, $S::Literal>>;
+                ) -> Vec<TokenTree<$S::TokenStream, $S::Span, $S::Ident, $S::Literal>>;
-            },
-            Group {
-                fn drop($self: $S::Group);
-                fn clone($self: &$S::Group) -> $S::Group;
-                fn new(delimiter: Delimiter, stream: Option<$S::TokenStream>) -> $S::Group;
-                fn delimiter($self: &$S::Group) -> Delimiter;
-                fn stream($self: &$S::Group) -> $S::TokenStream;
-                fn span($self: &$S::Group) -> $S::Span;
-                fn span_open($self: &$S::Group) -> $S::Span;
-                fn span_close($self: &$S::Group) -> $S::Span;
-                fn set_span($self: &mut $S::Group, span: $S::Span);
             },
             Ident {
                 fn new(string: &str, span: $S::Span, is_raw: bool) -> $S::Ident;
@@ -441,6 +430,30 @@ compound_traits!(
     }
 );
 
+#[derive(Copy, Clone)]
+pub struct DelimSpan<S> {
+    pub open: S,
+    pub close: S,
+    pub entire: S,
+}
+
+impl<S: Copy> DelimSpan<S> {
+    pub fn from_single(span: S) -> Self {
+        DelimSpan { open: span, close: span, entire: span }
+    }
+}
+
+compound_traits!(struct DelimSpan<Sp> { open, close, entire });
+
+#[derive(Clone)]
+pub struct Group<T, S> {
+    pub delimiter: Delimiter,
+    pub stream: Option<T>,
+    pub span: DelimSpan<S>,
+}
+
+compound_traits!(struct Group<T, Sp> { delimiter, stream, span });
+
 #[derive(Clone)]
 pub struct Punct<S> {
     pub ch: char,
@@ -451,15 +464,15 @@ pub struct Punct<S> {
 compound_traits!(struct Punct<Sp> { ch, joint, span });
 
 #[derive(Clone)]
-pub enum TokenTree<S, G, I, L> {
+pub enum TokenTree<T, S, I, L> {
-    Group(G),
+    Group(Group<T, S>),
     Punct(Punct<S>),
     Ident(I),
     Literal(L),
 }
 
 compound_traits!(
-    enum TokenTree<Sp, G, I, L> {
+    enum TokenTree<T, Sp, I, L> {
         Group(tt),
         Punct(tt),
         Ident(tt),

library/proc_macro/src/bridge/server.rs

@@ -8,7 +8,6 @@ use super::client::HandleStore;
 pub trait Types {
     type FreeFunctions: 'static;
     type TokenStream: 'static + Clone;
-    type Group: 'static + Clone;
     type Ident: 'static + Copy + Eq + Hash;
     type Literal: 'static + Clone;
     type SourceFile: 'static + Clone;

library/proc_macro/src/lib.rs

@@ -212,8 +212,8 @@ pub use quote::{quote, quote_span};
 fn tree_to_bridge_tree(
     tree: TokenTree,
 ) -> bridge::TokenTree<
+    bridge::client::TokenStream,
     bridge::client::Span,
-    bridge::client::Group,
     bridge::client::Ident,
     bridge::client::Literal,
 > {
@@ -238,8 +238,8 @@ impl From<TokenTree> for TokenStream {
 struct ConcatTreesHelper {
     trees: Vec<
         bridge::TokenTree<
+            bridge::client::TokenStream,
             bridge::client::Span,
-            bridge::client::Group,
             bridge::client::Ident,
             bridge::client::Literal,
         >,
@@ -365,8 +365,8 @@ pub mod token_stream {
     pub struct IntoIter(
         std::vec::IntoIter<
             bridge::TokenTree<
+                bridge::client::TokenStream,
                 bridge::client::Span,
-                bridge::client::Group,
                 bridge::client::Ident,
                 bridge::client::Literal,
             >,
@@ -788,7 +788,7 @@ impl fmt::Display for TokenTree {
 /// A `Group` internally contains a `TokenStream` which is surrounded by `Delimiter`s.
 #[derive(Clone)]
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
-pub struct Group(bridge::client::Group);
+pub struct Group(bridge::Group<bridge::client::TokenStream, bridge::client::Span>);
 
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
 impl !Send for Group {}
@@ -825,13 +825,17 @@ impl Group {
     /// method below.
     #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
     pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
-        Group(bridge::client::Group::new(delimiter, stream.0))
+        Group(bridge::Group {
+            delimiter,
+            stream: stream.0,
+            span: bridge::DelimSpan::from_single(Span::call_site().0),
+        })
     }
 
     /// Returns the delimiter of this `Group`
     #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
     pub fn delimiter(&self) -> Delimiter {
-        self.0.delimiter()
+        self.0.delimiter
     }
 
     /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
@@ -840,7 +844,7 @@ impl Group {
     /// returned above.
     #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
     pub fn stream(&self) -> TokenStream {
-        TokenStream(Some(self.0.stream()))
+        TokenStream(self.0.stream.clone())
     }
 
     /// Returns the span for the delimiters of this token stream, spanning the
@@ -852,7 +856,7 @@ impl Group {
     /// ```
     #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
     pub fn span(&self) -> Span {
-        Span(self.0.span())
+        Span(self.0.span.entire)
     }
 
     /// Returns the span pointing to the opening delimiter of this group.
@@ -863,7 +867,7 @@ impl Group {
     /// ```
     #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
     pub fn span_open(&self) -> Span {
-        Span(self.0.span_open())
+        Span(self.0.span.open)
     }
 
     /// Returns the span pointing to the closing delimiter of this group.
@@ -874,7 +878,7 @@ impl Group {
     /// ```
     #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
     pub fn span_close(&self) -> Span {
-        Span(self.0.span_close())
+        Span(self.0.span.close)
     }
 
     /// Configures the span for this `Group`'s delimiters, but not its internal
@@ -885,7 +889,7 @@ impl Group {
     /// tokens at the level of the `Group`.
     #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
     pub fn set_span(&mut self, span: Span) {
-        self.0.set_span(span.0);
+        self.0.span = bridge::DelimSpan::from_single(span.0);
     }
 }