Rollup merge of #95769 - fmease:fix-issue-95717, r=GuillaumeGomez

Hide cross-crate `#[doc(hidden)]` associated items in trait impls

Fixes #95717.

r? ```@GuillaumeGomez```
This is the bug I ran into in #95316.

```@rustbot``` label T-rustdoc A-cross-crate-reexports

2 files changed, 42 insertions, 0 deletions

diff --git a/src/test/rustdoc/auxiliary/cross-crate-hidden-assoc-trait-items.rs b/src/test/rustdoc/auxiliary/cross-crate-hidden-assoc-trait-items.rs
new file mode 100644
index 00000000000..3baf8a6c07e
--- /dev/null
+++ b/src/test/rustdoc/auxiliary/cross-crate-hidden-assoc-trait-items.rs
@@ -0,0 +1,19 @@
+pub trait Tr {
+    type VisibleAssoc;
+    #[doc(hidden)]
+    type HiddenAssoc;
+
+    const VISIBLE_ASSOC: ();
+    #[doc(hidden)]
+    const HIDDEN_ASSOC: ();
+}
+
+pub struct Ty;
+
+impl Tr for Ty {
+    type VisibleAssoc = ();
+    type HiddenAssoc = ();
+
+    const VISIBLE_ASSOC: () = ();
+    const HIDDEN_ASSOC: () = ();
+}
diff --git a/src/test/rustdoc/cross-crate-hidden-assoc-trait-items.rs b/src/test/rustdoc/cross-crate-hidden-assoc-trait-items.rs
new file mode 100644
index 00000000000..d02bc4fe712
--- /dev/null
+++ b/src/test/rustdoc/cross-crate-hidden-assoc-trait-items.rs
@@ -0,0 +1,23 @@
+// Regression test for issue #95717
+// Hide cross-crate `#[doc(hidden)]` associated items in trait impls.
+
+#![crate_name = "dependent"]
+// edition:2021
+// aux-crate:dependency=cross-crate-hidden-assoc-trait-items.rs
+
+// The trait `Tr` contains 2 hidden and 2 visisible associated items.
+// Instead of checking for the absence of the hidden items, check for the presence of the
+// visible items instead and assert that there are *exactly two* associated items
+// (by counting the number of `section`s). This is more robust and future-proof.
+
+// @has dependent/struct.Ty.html
+// @has - '//*[@id="associatedtype.VisibleAssoc"]' 'type VisibleAssoc = ()'
+// @has - '//*[@id="associatedconstant.VISIBLE_ASSOC"]' 'const VISIBLE_ASSOC: ()'
+// @count - '//*[@class="impl-items"]/section' 2
+
+// @has dependent/trait.Tr.html
+// @has - '//*[@id="associatedtype.VisibleAssoc-1"]' 'type VisibleAssoc = ()'
+// @has - '//*[@id="associatedconstant.VISIBLE_ASSOC-1"]' 'const VISIBLE_ASSOC: ()'
+// @count - '//*[@class="impl-items"]/section' 2
+
+pub use dependency::{Tr, Ty};