Rollup merge of rust-lang#129124 - aDotInTheVoid:rdj-hashmap-3, r=GuillaumeGomez

rustdoc-json: Use FxHashMap from rustdoc_json_types

Alternative to rust-lang#110051 and rust-lang#127456.

This lets us avoid rehashing the json index after building it by using the same hashmap type in construction and in rustdoc_json_types. The above PR's tried to do this by having rustdoc_json_types get the same hashmap that rustdoc has via rustc_data_structures. However, this can be made simpler if we change rustdoc instead.

For the rustdoc-type republish on crates.io, It will filter out the `pub use`, and not change source at all. rust-lang/rustdoc-types#30. That code [already replaces the hashmap](https://github.com/aDotInTheVoid/rustdoc-types/blob/8d6528669ec64c2af43d1c79a228b7711cefdad7/update.sh#L11) to use the one in `std::collections` (instead of `FxHashMap`)

try-job: dist-arm-linux

r? `@GuillaumeGomez`

Author: GuillaumeGomez

src/librustdoc/json/mod.rs

@@ -13,12 +13,15 @@ use std::io::{stdout, BufWriter, Write};
 use std::path::PathBuf;
 use std::rc::Rc;
 
-use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::{DefId, DefIdSet};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustdoc_json_types as types;
+// It's important to use the FxHashMap from rustdoc_json_types here, instead of
+// the one from rustc_data_structures, as they're different types due to sysroots.
+// See #110051 and #127456 for details
+use rustdoc_json_types::FxHashMap;
 
 use crate::clean::types::{ExternalCrate, ExternalLocation};
 use crate::clean::ItemKind;
@@ -234,14 +237,11 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
         let index = (*self.index).clone().into_inner();
 
         debug!("Constructing Output");
-        // This needs to be the default HashMap for compatibility with the public interface for
-        // rustdoc-json-types
-        #[allow(rustc::default_hash_types)]
         let output = types::Crate {
             root: types::Id(format!("0:0:{}", e.name(self.tcx).as_u32())),
             crate_version: self.cache.crate_version.clone(),
             includes_private: self.cache.document_private,
-            index: index.into_iter().collect(),
+            index,
             paths: self
                 .cache
                 .paths

src/rustdoc-json-types/lib.rs

@@ -5,7 +5,7 @@
 
 use std::path::PathBuf;
 
-use rustc_hash::FxHashMap;
+pub use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
 
 /// The version of JSON output that this crate represents.