Rollup merge of #141658 - lolbinarycat:rustdoc-search-stability-rank-138067, r=GuillaumeGomez

rustdoc search: prefer stable items in search results

fixes https://github.com/rust-lang/rust/issues/138067

this does add a new field to the search index, but since we're only listing unstable items instead of adding a boolean flag to every item, it should only increase the search index size of sysroot crates, since those are the only ones using the `staged_api` feature, at least as far as the rust project is concerned.

5 files changed, 37 insertions, 1 deletions

diff --git a/src/librustdoc/formats/cache.rs b/src/librustdoc/formats/cache.rs
index 80399cf3842..918b292466d 100644
--- a/src/librustdoc/formats/cache.rs
+++ b/src/librustdoc/formats/cache.rs
@@ -602,6 +602,7 @@ fn add_item_to_search_index(tcx: TyCtxt<'_>, cache: &mut Cache, item: &clean::It
         search_type,
         aliases,
         deprecation,
+        is_unstable: item.stability(tcx).map(|x| x.is_unstable()).unwrap_or(false),
     };
     cache.search_index.push(index_item);
 }
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index a46253237db..95259847075 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -139,6 +139,7 @@ pub(crate) struct IndexItem {
     pub(crate) search_type: Option<IndexItemFunctionType>,
     pub(crate) aliases: Box<[Symbol]>,
     pub(crate) deprecation: Option<Deprecation>,
+    pub(crate) is_unstable: bool,
 }
 
 /// A type used for the search index.
diff --git a/src/librustdoc/html/render/search_index.rs b/src/librustdoc/html/render/search_index.rs
index e2f86b8a854..93c9df8c049 100644
--- a/src/librustdoc/html/render/search_index.rs
+++ b/src/librustdoc/html/render/search_index.rs
@@ -93,6 +93,7 @@ pub(crate) fn build_index(
                 ),
                 aliases: item.attrs.get_doc_aliases(),
                 deprecation: item.deprecation(tcx),
+                is_unstable: item.stability(tcx).is_some_and(|x| x.is_unstable()),
             });
         }
     }
@@ -655,6 +656,7 @@ pub(crate) fn build_index(
             let mut parents_backref_queue = VecDeque::new();
             let mut functions = String::with_capacity(self.items.len());
             let mut deprecated = Vec::with_capacity(self.items.len());
+            let mut unstable = Vec::with_capacity(self.items.len());
 
             let mut type_backref_queue = VecDeque::new();
 
@@ -711,6 +713,9 @@ pub(crate) fn build_index(
                     // bitmasks always use 1-indexing for items, with 0 as the crate itself
                     deprecated.push(u32::try_from(index + 1).unwrap());
                 }
+                if item.is_unstable {
+                    unstable.push(u32::try_from(index + 1).unwrap());
+                }
             }
 
             for (index, path) in &revert_extra_paths {
@@ -749,6 +754,7 @@ pub(crate) fn build_index(
             crate_data.serialize_field("r", &re_exports)?;
             crate_data.serialize_field("b", &self.associated_item_disambiguators)?;
             crate_data.serialize_field("c", &bitmap_to_string(&deprecated))?;
+            crate_data.serialize_field("u", &bitmap_to_string(&unstable))?;
             crate_data.serialize_field("e", &bitmap_to_string(&self.empty_desc))?;
             crate_data.serialize_field("P", &param_names)?;
             if has_aliases {
diff --git a/src/librustdoc/html/static/js/rustdoc.d.ts b/src/librustdoc/html/static/js/rustdoc.d.ts
index a9589764547..b082b65ab57 100644
--- a/src/librustdoc/html/static/js/rustdoc.d.ts
+++ b/src/librustdoc/html/static/js/rustdoc.d.ts
@@ -449,6 +449,8 @@ declare namespace rustdoc {
      * of `p`) but is used for modules items like free functions.
      *
      * `c` is an array of item indices that are deprecated.
+     *
+     * `u` is an array of item indices that are unstable.
      */
     type RawSearchIndexCrate = {
     doc: string,
@@ -463,6 +465,7 @@ declare namespace rustdoc {
     p: Array<[number, string] | [number, string, number] | [number, string, number, number] | [number, string, number, number, string]>,
     b: Array<[number, String]>,
     c: string,
+    u: string,
     r: Array<[number, number]>,
     P: Array<[number, string]>,
     };
diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 2caf214ff73..9e422040db0 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -1465,6 +1465,11 @@ class DocSearch {
          */
         this.searchIndexEmptyDesc = new Map();
         /**
+         * @type {Map<String, RoaringBitmap>}
+         */
+        this.searchIndexUnstable = new Map();
+
+        /**
          *  @type {Uint32Array}
          */
         this.functionTypeFingerprint = new Uint32Array(0);
@@ -2052,9 +2057,10 @@ class DocSearch {
             };
             const descShardList = [descShard];
 
-            // Deprecated items and items with no description
+            // Deprecated and unstable items and items with no description
             this.searchIndexDeprecated.set(crate, new RoaringBitmap(crateCorpus.c));
             this.searchIndexEmptyDesc.set(crate, new RoaringBitmap(crateCorpus.e));
+            this.searchIndexUnstable.set(crate, new RoaringBitmap(crateCorpus.u));
             let descIndex = 0;
 
             /**
@@ -3326,6 +3332,25 @@ class DocSearch {
                     return a - b;
                 }
 
+                // sort unstable items later
+                // FIXME: there is some doubt if this is the most effecient way to implement this.
+                // alternative options include:
+                // * put is_unstable on each item when the index is built.
+                //   increases memory usage but avoids a hashmap lookup.
+                // * put is_unstable on each item before sorting.
+                //   better worst case performance but worse average case performance.
+                a = Number(
+                    // @ts-expect-error
+                    this.searchIndexUnstable.get(aaa.item.crate).contains(aaa.item.bitIndex),
+                );
+                b = Number(
+                    // @ts-expect-error
+                    this.searchIndexUnstable.get(bbb.item.crate).contains(bbb.item.bitIndex),
+                );
+                if (a !== b) {
+                    return a - b;
+                }
+
                 // sort by crate (current crate comes first)
                 a = Number(aaa.item.crate !== preferredCrate);
                 b = Number(bbb.item.crate !== preferredCrate);