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rustdoc_json: Remove one call to std::mem::take in after_krate.

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This patch removes one call to `std::mem::take` to save two
`memcpy`s: `JsonRenderer::index` can be quite large as noted
https://github.com/rust-lang/rust/pull/142335. `self.index` can be
passed directly to `types::Crate`. This removal makes `self` immutable.

The private `serialize_and_write` method is moved as a function: the
`self` argument is replaced by `sess: &Session`. This `&Session` was
fetched earlier in `after_krate` in all cases. This change allows to
call `serialize_and_write` after `output_crate` is created, without
having a conflict around the move of `self`: the borrow checker is now
happy.
This commit is contained in:
Ivan Enderlin 2026-01-09 08:55:02 +01:00
parent 3fda0e426c
commit b9ae4f7bf7
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1 changed files with 24 additions and 24 deletions
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48
src/librustdoc/json/mod.rs
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@ -104,22 +104,6 @@ impl<'tcx> JsonRenderer<'tcx> {
})
.unwrap_or_default()
}
fn serialize_and_write<T: Write>(
&self,
output_crate: types::Crate,
mut writer: BufWriter<T>,
path: &str,
) -> Result<(), Error> {
self.sess().time("rustdoc_json_serialize_and_write", || {
try_err!(
serde_json::ser::to_writer(&mut writer, &output_crate).map_err(|e| e.to_string()),
path
);
try_err!(writer.flush(), path);
Ok(())
})
}
}
impl<'tcx> JsonRenderer<'tcx> {
@ -252,26 +236,23 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
unreachable!("RUN_ON_MODULE = false, should never call mod_item_in")
}
fn after_krate(mut self) -> Result<(), Error> {
fn after_krate(self) -> Result<(), Error> {
debug!("Done with crate");
let e = ExternalCrate { crate_num: LOCAL_CRATE };
// We've finished using the index, and don't want to clone it, because it is big.
let index = std::mem::take(&mut self.index);
let sess = self.sess();
// Note that tcx.rust_target_features is inappropriate here because rustdoc tries to run for
// multiple targets: https://github.com/rust-lang/rust/pull/137632
//
// We want to describe a single target, so pass tcx.sess rather than tcx.
let target = conversions::target(self.tcx.sess);
let target = conversions::target(sess);
debug!("Constructing Output");
let output_crate = types::Crate {
root: self.id_from_item_default(e.def_id().into()),
crate_version: self.cache.crate_version.clone(),
includes_private: self.cache.document_private,
index,
paths: self
.cache
.paths
@ -313,6 +294,8 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
)
})
.collect(),
// Be careful to not clone the `index`, it is big.
index: self.index,
target,
format_version: types::FORMAT_VERSION,
};
@ -323,17 +306,34 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
p.push(output_crate.index.get(&output_crate.root).unwrap().name.clone().unwrap());
p.set_extension("json");
self.serialize_and_write(
serialize_and_write(
sess,
output_crate,
try_err!(File::create_buffered(&p), p),
&p.display().to_string(),
)
} else {
self.serialize_and_write(output_crate, BufWriter::new(stdout().lock()), "<stdout>")
serialize_and_write(sess, output_crate, BufWriter::new(stdout().lock()), "<stdout>")
}
}
}
fn serialize_and_write<T: Write>(
sess: &Session,
output_crate: types::Crate,
mut writer: BufWriter<T>,
path: &str,
) -> Result<(), Error> {
sess.time("rustdoc_json_serialize_and_write", || {
try_err!(
serde_json::ser::to_writer(&mut writer, &output_crate).map_err(|e| e.to_string()),
path
);
try_err!(writer.flush(), path);
Ok(())
})
}
// Some nodes are used a lot. Make sure they don't unintentionally get bigger.
//
// These assertions are here, not in `src/rustdoc-json-types/lib.rs` where the types are defined,