rustdoc-search: add unbox flag to Result aliases

Fixes #139665

compiler/rustc_passes/src/check_attr.rs

@@ -1109,6 +1109,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             ItemKind::Trait(_, _, _, generics, _, items)
                 if generics.params.len() != 0
                     || items.iter().any(|item| matches!(item.kind, AssocItemKind::Type)) => {}
+            ItemKind::TyAlias(_, _, generics) if generics.params.len() != 0 => {}
             _ => {
                 self.dcx().emit_err(errors::DocSearchUnboxInvalid { span: meta.span() });
             }

library/std/src/io/error.rs

@@ -48,6 +48,7 @@ use crate::{error, fmt, result, sys};
 /// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(bootstrap), doc(search_unbox))]
 pub type Result<T> = result::Result<T, Error>;
 
 /// The error type for I/O operations of the [`Read`], [`Write`], [`Seek`], and

library/std/src/thread/mod.rs

@@ -1676,6 +1676,7 @@ impl fmt::Debug for Thread {
 /// [`Result`]: crate::result::Result
 /// [`std::panic::resume_unwind`]: crate::panic::resume_unwind
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(bootstrap), doc(search_unbox))]
 pub type Result<T> = crate::result::Result<T, Box<dyn Any + Send + 'static>>;
 
 // This packet is used to communicate the return value between the spawned

tests/rustdoc-js-std/unbox-type-result.js

@@ -0,0 +1,20 @@
+// exact-check
+
+// Test case for https://github.com/rust-lang/rust/issues/139665
+// make sure that std::io::Result and std::thread::Result get unboxed
+
+const EXPECTED = [
+    {
+        query: "File -> Metadata",
+        others: [
+            { path: "std::fs::File", name: "metadata" },
+            { path: "std::fs::File", name: "metadata_at" },
+        ]
+    },
+    {
+        query: "JoinHandle<T> -> T",
+        others: [
+            { path: "std::thread::JoinHandle", name: "join" },
+        ]
+    },
+];

tests/rustdoc-js/generics-unbox.js

@@ -31,4 +31,10 @@ const EXPECTED = [
             { 'path': 'generics_unbox', 'name': 'beta' },
         ],
     },
+    {
+        'query': '-> Sigma',
+        'others': [
+            { 'path': 'generics_unbox', 'name': 'delta' },
+        ],
+    },
 ];

tests/rustdoc-js/generics-unbox.rs

@@ -42,3 +42,15 @@ pub fn beta<T, U>(_: Inside<T>) -> Out<Out3<T, U>, Out4<U, T>> {
 pub fn gamma<T, U>(_: Inside<T>) -> Out<Out3<U, T>, Out4<T, U>> {
     loop {}
 }
+
+pub fn delta(_: i32) -> Epsilon<Sigma> {
+    loop {}
+}
+
+#[doc(search_unbox)]
+pub struct Theta<T>(T);
+
+#[doc(search_unbox)]
+pub type Epsilon<T> = Theta<T>;
+
+pub struct Sigma;