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.

2 files changed, 29 insertions, 1 deletions

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);