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Merged
rust-bors merged 3 commits into from
Jan 27, 2026
+34 −30
Merged

Rustdoc performance improvements #151368

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3757ce6
Remove a string comparison and reduce number of clones in `Hierarchy:…
GuillaumeGomez Jan 19, 2026
dd42a9f
Replace regex with find calls
GuillaumeGomez Jan 19, 2026
bd45311
Improve code
GuillaumeGomez Jan 26, 2026
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64 changes: 34 additions & 30 deletions src/librustdoc/html/render/write_shared.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,6 @@ use std::str::FromStr;
use std::{fmt, fs};

use indexmap::IndexMap;
use regex::Regex;
use rustc_ast::join_path_syms;
use rustc_data_structures::flock;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
Expand Down Expand Up @@ -376,12 +375,15 @@ fn hack_get_external_crate_names(
};
// this is only run once so it's fine not to cache it
// !dot_matches_new_line: all crates on same line. greedy: match last bracket
let regex = Regex::new(r"\[.*\]").unwrap();
let Some(content) = regex.find(&content) else {
return Err(Error::new("could not find crates list in crates.js", path));
};
let content: Vec<String> = try_err!(serde_json::from_str(content.as_str()), &path);
Ok(content)
if let Some(start) = content.find('[')
&& let Some(end) = content[start..].find(']')
{
let content: Vec<String> =
try_err!(serde_json::from_str(&content[start..=start + end]), &path);
Ok(content)
} else {
Err(Error::new("could not find crates list in crates.js", path))
}
}

#[derive(Serialize, Deserialize, Clone, Default, Debug)]
Expand Down Expand Up @@ -504,33 +506,35 @@ impl Hierarchy {

fn add_path(self: &Rc<Self>, path: &Path) {
let mut h = Rc::clone(self);
let mut elems = path
let mut components = path
.components()
.filter_map(|s| match s {
Component::Normal(s) => Some(s.to_owned()),
Component::ParentDir => Some(OsString::from("..")),
_ => None,
})
.filter(|component| matches!(component, Component::Normal(_) | Component::ParentDir))
.peekable();
loop {
let cur_elem = elems.next().expect("empty file path");
if cur_elem == ".." {
if let Some(parent) = h.parent.upgrade() {

assert!(components.peek().is_some(), "empty file path");
while let Some(component) = components.next() {
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@yotamofek yotamofek Jan 26, 2026

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just noticed there's a very small change in behavior here.
previous version would panic if path.components() doesn't yield any items.
not sure if it's worth preserving? (you could add a assert!(components.peek().is_some()) before the loop)

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@GuillaumeGomez GuillaumeGomez Jan 26, 2026

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Good catch. Yeah let's go with an assert.

match component {
Component::Normal(s) => {
if components.peek().is_none() {
h.elems.borrow_mut().insert(s.to_owned());
break;
}
h = {
let mut children = h.children.borrow_mut();

if let Some(existing) = children.get(s) {
Rc::clone(existing)
} else {
let new_node = Rc::new(Self::with_parent(s.to_owned(), &h));
children.insert(s.to_owned(), Rc::clone(&new_node));
new_node
}
};
}
Component::ParentDir if let Some(parent) = h.parent.upgrade() => {
h = parent;
}
continue;
}
if elems.peek().is_none() {
h.elems.borrow_mut().insert(cur_elem);
break;
} else {
let entry = Rc::clone(
h.children
.borrow_mut()
.entry(cur_elem.clone())
.or_insert_with(|| Rc::new(Self::with_parent(cur_elem, &h))),
);
h = entry;
_ => {}
}
}
}
Expand Down
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