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proc-macro-srv: Fix unnecessary subtree wrapping in protocol #21154

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Merged
merged 1 commit into from
Nov 28, 2025
+42 −40
Merged

proc-macro-srv: Fix unnecessary subtree wrapping in protocol #21154

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80 changes: 41 additions & 39 deletions crates/proc-macro-api/src/legacy_protocol/msg/flat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -216,16 +216,7 @@ impl FlatTree {
text: Vec::new(),
version,
};
let group = proc_macro_srv::Group {
delimiter: proc_macro_srv::Delimiter::None,
stream: Some(tokenstream),
span: proc_macro_srv::DelimSpan {
open: call_site,
close: call_site,
entire: call_site,
},
};
w.write_tokenstream(&group);
w.write_tokenstream(call_site, &tokenstream);

FlatTree {
subtree: if version >= ENCODE_CLOSE_SPAN_VERSION {
Expand Down Expand Up @@ -267,16 +258,7 @@ impl FlatTree {
text: Vec::new(),
version,
};
let group = proc_macro_srv::Group {
delimiter: proc_macro_srv::Delimiter::None,
stream: Some(tokenstream),
span: proc_macro_srv::DelimSpan {
open: call_site,
close: call_site,
entire: call_site,
},
};
w.write_tokenstream(&group);
w.write_tokenstream(call_site, &tokenstream);

FlatTree {
subtree: if version >= ENCODE_CLOSE_SPAN_VERSION {
Expand Down Expand Up @@ -491,7 +473,7 @@ impl SpanTransformer for Span {
}

struct Writer<'a, 'span, S: SpanTransformer, W> {
work: VecDeque<(usize, W)>,
work: VecDeque<(usize, usize, W)>,
string_table: FxHashMap<std::borrow::Cow<'a, str>, u32>,
span_data_table: &'span mut S::Table,
version: u32,
Expand All @@ -508,14 +490,13 @@ impl<'a, T: SpanTransformer> Writer<'a, '_, T, tt::iter::TtIter<'a, T::Span>> {
fn write_subtree(&mut self, root: tt::SubtreeView<'a, T::Span>) {
let subtree = root.top_subtree();
self.enqueue(subtree, root.iter());
while let Some((idx, subtree)) = self.work.pop_front() {
self.subtree(idx, subtree);
while let Some((idx, len, subtree)) = self.work.pop_front() {
self.subtree(idx, len, subtree);
}
}

fn subtree(&mut self, idx: usize, subtree: tt::iter::TtIter<'a, T::Span>) {
fn subtree(&mut self, idx: usize, n_tt: usize, subtree: tt::iter::TtIter<'a, T::Span>) {
let mut first_tt = self.token_tree.len();
let n_tt = subtree.clone().count(); // FIXME: `count()` walks over the entire iterator.
self.token_tree.resize(first_tt + n_tt, !0);

self.subtree[idx].tt = [first_tt as u32, (first_tt + n_tt) as u32];
Expand Down Expand Up @@ -594,7 +575,8 @@ impl<'a, T: SpanTransformer> Writer<'a, '_, T, tt::iter::TtIter<'a, T::Span>> {
let close = self.token_id_of(subtree.delimiter.close);
let delimiter_kind = subtree.delimiter.kind;
self.subtree.push(SubtreeRepr { open, close, kind: delimiter_kind, tt: [!0, !0] });
self.work.push_back((idx, contents));
// FIXME: `count()` walks over the entire iterator.
self.work.push_back((idx, contents.clone().count(), contents));
idx as u32
}
}
Expand Down Expand Up @@ -624,26 +606,43 @@ impl<'a, T: SpanTransformer, U> Writer<'a, '_, T, U> {
}

#[cfg(feature = "sysroot-abi")]
impl<'a, T: SpanTransformer> Writer<'a, '_, T, &'a proc_macro_srv::Group<T::Span>> {
fn write_tokenstream(&mut self, root: &'a proc_macro_srv::Group<T::Span>) {
self.enqueue_group(root);

while let Some((idx, group)) = self.work.pop_front() {
self.group(idx, group);
impl<'a, T: SpanTransformer>
Writer<'a, '_, T, Option<proc_macro_srv::TokenStreamIter<'a, T::Span>>>
{
fn write_tokenstream(
&mut self,
call_site: T::Span,
root: &'a proc_macro_srv::TokenStream<T::Span>,
) {
let call_site = self.token_id_of(call_site);
self.subtree.push(SubtreeRepr {
open: call_site,
close: call_site,
kind: tt::DelimiterKind::Invisible,
tt: [!0, !0],
});
self.work.push_back((0, root.len(), Some(root.iter())));

while let Some((idx, len, group)) = self.work.pop_front() {
self.group(idx, len, group);
}
}

fn group(&mut self, idx: usize, group: &'a proc_macro_srv::Group<T::Span>) {
fn group(
&mut self,
idx: usize,
n_tt: usize,
group: Option<proc_macro_srv::TokenStreamIter<'a, T::Span>>,
) {
let mut first_tt = self.token_tree.len();
let n_tt = group.stream.as_ref().map_or(0, |it| it.len());
self.token_tree.resize(first_tt + n_tt, !0);

self.subtree[idx].tt = [first_tt as u32, (first_tt + n_tt) as u32];

for tt in group.stream.iter().flat_map(|it| it.iter()) {
for tt in group.into_iter().flatten() {
let idx_tag = match tt {
proc_macro_srv::TokenTree::Group(group) => {
let idx = self.enqueue_group(group);
let idx = self.enqueue(group);
idx << 2
}
proc_macro_srv::TokenTree::Literal(lit) => {
Expand Down Expand Up @@ -706,7 +705,7 @@ impl<'a, T: SpanTransformer> Writer<'a, '_, T, &'a proc_macro_srv::Group<T::Span
}
}

fn enqueue_group(&mut self, group: &'a proc_macro_srv::Group<T::Span>) -> u32 {
fn enqueue(&mut self, group: &'a proc_macro_srv::Group<T::Span>) -> u32 {
let idx = self.subtree.len();
let open = self.token_id_of(group.span.open);
let close = self.token_id_of(group.span.close);
Expand All @@ -717,7 +716,11 @@ impl<'a, T: SpanTransformer> Writer<'a, '_, T, &'a proc_macro_srv::Group<T::Span
proc_macro_srv::Delimiter::None => tt::DelimiterKind::Invisible,
};
self.subtree.push(SubtreeRepr { open, close, kind: delimiter_kind, tt: [!0, !0] });
self.work.push_back((idx, group));
self.work.push_back((
idx,
group.stream.as_ref().map_or(0, |stream| stream.len()),
group.stream.as_ref().map(|ts| ts.iter()),
));
idx as u32
}
}
Expand Down Expand Up @@ -959,7 +962,6 @@ impl<T: SpanTransformer> Reader<'_, T> {
};
res[i] = Some(g);
}
// FIXME: double check this
proc_macro_srv::TokenStream::new(vec![proc_macro_srv::TokenTree::Group(
res[0].take().unwrap(),
)])
Expand Down
2 changes: 1 addition & 1 deletion crates/proc-macro-srv/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ pub use proc_macro::Delimiter;

pub use crate::bridge::*;
pub use crate::server_impl::literal_from_str;
pub use crate::token_stream::{TokenStream, literal_to_string};
pub use crate::token_stream::{TokenStream, TokenStreamIter, literal_to_string};

#[derive(Copy, Clone, Eq, PartialEq, Debug)]
pub enum ProcMacroKind {
Expand Down