Add regression test for rust-lang#98006

Author: GuillaumeGomez

src/test/rustdoc-json/primitive_overloading.rs

@@ -0,0 +1,17 @@
+// compile-flags: --document-private-items
+
+// Regression test for <https://github.com/rust-lang/rust/issues/98006>.
+
+#![feature(rustdoc_internals)]
+#![feature(no_core)]
+
+#![no_core]
+
+// @has primitive_overloading.json
+// @has - "$.index[*][?(@.name=='usize')]"
+// @has - "$.index[*][?(@.name=='prim')]"
+
+#[doc(primitive = "usize")]
+/// This is the built-in type `usize`.
+mod prim {
+}