From c8b2a9af2b10295436828e6678c466536bada981 Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Wed, 5 Nov 2025 23:37:51 -0700
Subject: [PATCH] rustdoc-search: remove broken index special case

---
 src/librustdoc/html/render/search_index.rs | 35 ++++++++----------
 tests/rustdoc-js/auxiliary/emptytype.rs    | 41 ++++++++++++++++++++++
 tests/rustdoc-js/empty-type.js             |  8 +++++
 tests/rustdoc-js/empty-type.rs             |  8 +++++
 4 files changed, 71 insertions(+), 21 deletions(-)
 create mode 100644 tests/rustdoc-js/auxiliary/emptytype.rs
 create mode 100644 tests/rustdoc-js/empty-type.js
 create mode 100644 tests/rustdoc-js/empty-type.rs

diff --git a/src/librustdoc/html/render/search_index.rs b/src/librustdoc/html/render/search_index.rs
index 96e941b598ad1..9c072eed51aec 100644
--- a/src/librustdoc/html/render/search_index.rs
+++ b/src/librustdoc/html/render/search_index.rs
@@ -1051,28 +1051,21 @@ impl Serialize for TypeData {
     where
         S: Serializer,
     {
-        if self.search_unbox
-            || !self.inverted_function_inputs_index.is_empty()
-            || !self.inverted_function_output_index.is_empty()
-        {
-            let mut seq = serializer.serialize_seq(None)?;
-            let mut buf = Vec::new();
-            encode::write_postings_to_string(&self.inverted_function_inputs_index, &mut buf);
-            let mut serialized_result = Vec::new();
-            stringdex_internals::encode::write_base64_to_bytes(&buf, &mut serialized_result);
-            seq.serialize_element(&str::from_utf8(&serialized_result).unwrap())?;
-            buf.clear();
-            serialized_result.clear();
-            encode::write_postings_to_string(&self.inverted_function_output_index, &mut buf);
-            stringdex_internals::encode::write_base64_to_bytes(&buf, &mut serialized_result);
-            seq.serialize_element(&str::from_utf8(&serialized_result).unwrap())?;
-            if self.search_unbox {
-                seq.serialize_element(&1)?;
-            }
-            seq.end()
-        } else {
-            None::<()>.serialize(serializer)
+        let mut seq = serializer.serialize_seq(None)?;
+        let mut buf = Vec::new();
+        encode::write_postings_to_string(&self.inverted_function_inputs_index, &mut buf);
+        let mut serialized_result = Vec::new();
+        stringdex_internals::encode::write_base64_to_bytes(&buf, &mut serialized_result);
+        seq.serialize_element(&str::from_utf8(&serialized_result).unwrap())?;
+        buf.clear();
+        serialized_result.clear();
+        encode::write_postings_to_string(&self.inverted_function_output_index, &mut buf);
+        stringdex_internals::encode::write_base64_to_bytes(&buf, &mut serialized_result);
+        seq.serialize_element(&str::from_utf8(&serialized_result).unwrap())?;
+        if self.search_unbox {
+            seq.serialize_element(&1)?;
         }
+        seq.end()
     }
 }
 
diff --git a/tests/rustdoc-js/auxiliary/emptytype.rs b/tests/rustdoc-js/auxiliary/emptytype.rs
new file mode 100644
index 0000000000000..2a06b4ec9f8ca
--- /dev/null
+++ b/tests/rustdoc-js/auxiliary/emptytype.rs
@@ -0,0 +1,41 @@
+// https://github.com/rust-lang/rust/issues/148431
+
+// This test is designed to hit a case where, thanks to the
+// recursion limit, the where clause gets generated, but not
+// used, because we run out of fuel.
+//
+// This results in a reverse index with nothing in it, which
+// used to crash when we parsed it.
+pub fn foobar1<A: T1<B>, B: T2<C>, C: T3<D>, D: T4<A>>(a: A) {}
+
+pub trait T1<T: ?Sized> {}
+pub trait T2<T: ?Sized> {}
+pub trait T3<T: ?Sized> {}
+pub trait T4<T: ?Sized> {}
+
+// foobar1 is the version that worked at the time this test was written
+// the rest are here to try to make the test at least a little more
+// robust, in the sense that it actually tests the code and isn't magically
+// fixed by the recursion limit changing
+pub fn foobar2<A: U1<B>, B: U2<C>, C: U3<D>, D: U4<E>, E: U5<A>>(a: A) {}
+
+pub trait U1<T: ?Sized> {}
+pub trait U2<T: ?Sized> {}
+pub trait U3<T: ?Sized> {}
+pub trait U4<T: ?Sized> {}
+pub trait U5<T: ?Sized> {}
+
+pub fn foobar3<A: V1<B>, B: V2<C>, C: V3<D>, D: V4<E>, E: V5<F>, F: V6<A>>(a: A) {}
+
+pub trait V1<T: ?Sized> {}
+pub trait V2<T: ?Sized> {}
+pub trait V3<T: ?Sized> {}
+pub trait V4<T: ?Sized> {}
+pub trait V5<T: ?Sized> {}
+pub trait V6<T: ?Sized> {}
+
+pub fn foobar4<A: W1<B>, B: W2<C>, C: W3<A>>(a: A) {}
+
+pub trait W1<T: ?Sized> {}
+pub trait W2<T: ?Sized> {}
+pub trait W3<T: ?Sized> {}
diff --git a/tests/rustdoc-js/empty-type.js b/tests/rustdoc-js/empty-type.js
new file mode 100644
index 0000000000000..e4c8f9954cb7f
--- /dev/null
+++ b/tests/rustdoc-js/empty-type.js
@@ -0,0 +1,8 @@
+const EXPECTED = [
+    {
+        query: 'baz',
+        others: [
+            { name: 'baz' }
+        ],
+    },
+];
diff --git a/tests/rustdoc-js/empty-type.rs b/tests/rustdoc-js/empty-type.rs
new file mode 100644
index 0000000000000..87ea73709b6bb
--- /dev/null
+++ b/tests/rustdoc-js/empty-type.rs
@@ -0,0 +1,8 @@
+//@ aux-crate:emptytype=emptytype.rs
+//@ compile-flags: --extern emptytype
+//@ aux-build:emptytype.rs
+//@ build-aux-docs
+
+extern crate emptytype;
+
+pub fn baz() {}