From a35499268eeda40d9a9c9388f54df548d0dd405e Mon Sep 17 00:00:00 2001
From: binarycat <binarycat@envs.net>
Date: Sat, 18 Oct 2025 15:13:36 -0500
Subject: [PATCH] rustdoc search: relax rules for identifiers

---
 src/librustdoc/html/static/js/search.js  |  5 ++++-
 tests/rustdoc-js-std/parser-errors.js    |  2 +-
 tests/rustdoc-js-std/search-by-number.js | 19 +++++++++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 tests/rustdoc-js-std/search-by-number.js

diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 0929d351463cc..337c973a2c84f 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -149,7 +149,10 @@ const ROOT_PATH = typeof window !== "undefined" ? window.rootPath : "../";
 const UNBOXING_LIMIT = 5;
 
 // used for search query verification
-const REGEX_IDENT = /\p{ID_Start}\p{ID_Continue}*|_\p{ID_Continue}+/uy;
+// because searches are often performed using substrings of identifiers,
+// and not just full identiferes, we allow them to start with chars that otherwise
+// can only appear in the middle of identifiers
+const REGEX_IDENT = /\p{ID_Continue}+/uy;
 const REGEX_INVALID_TYPE_FILTER = /[^a-z]/ui;
 
 const MAX_RESULTS = 200;
diff --git a/tests/rustdoc-js-std/parser-errors.js b/tests/rustdoc-js-std/parser-errors.js
index 6e11dda8532fa..612118607b5cc 100644
--- a/tests/rustdoc-js-std/parser-errors.js
+++ b/tests/rustdoc-js-std/parser-errors.js
@@ -165,7 +165,7 @@ const PARSED = [
         foundElems: 0,
         userQuery: "_:",
         returned: [],
-        error: "Unexpected `_` (not a valid identifier)",
+        error: "Unexpected `_` in type filter (before `:`)",
     },
     {
         query: "ab:",
diff --git a/tests/rustdoc-js-std/search-by-number.js b/tests/rustdoc-js-std/search-by-number.js
new file mode 100644
index 0000000000000..9d1cb5314dcaa
--- /dev/null
+++ b/tests/rustdoc-js-std/search-by-number.js
@@ -0,0 +1,19 @@
+// regression test for https://github.com/rust-lang/rust/issues/147763
+//
+// identifiers in search queries should not be required to follow the
+// same strict rules around ID_Start that identifers in rust code follow,
+// as searches frequently use substrings of identifers.
+//
+// for example, identifiers cannot start with digits,
+// but they can contain them, so we allow search idents to start with digits.
+
+const EXPECTED = {
+    'query': '8',
+    'others': [
+        {
+            'path': 'std',
+            'name': 'i8',
+            'href': '../std/primitive.i8.html',
+        },
+    ]
+};