Add regression test for missing item from private mod in JSON output

Author: GuillaumeGomez

src/librustdoc/passes/stripper.rs

@@ -161,7 +161,7 @@ impl<'a> ImplStripper<'a> {
         } else if self.is_json_output {
             // If the "for" item is exported and the impl block isn't `#[doc(hidden)]`, then we
             // need to keep it.
-            self.cache.access_levels.is_exported(for_def_id)
+            self.cache.effective_visibilities.is_exported(for_def_id)
                 && !item.attrs.lists(sym::doc).has_word(sym::hidden)
         } else {
             false

src/test/rustdoc-json/reexport/reexport_method_from_private_module.rs

@@ -0,0 +1,28 @@
+// Regression test for <https://github.com/rust-lang/rust/issues/102583>.
+
+// @set impl_S = "$.index[*][?(@.docs=='impl S')].id"
+// @has "$.index[*][?(@.name=='S')].inner.impls[*]" $impl_S
+// @set is_present = "$.index[*][?(@.name=='is_present')].id"
+// @is "$.index[*][?(@.docs=='impl S')].inner.items[*]" $is_present
+// @!has "$.index[*][?(@.name=='hidden_impl')]"
+// @!has "$.index[*][?(@.name=='hidden_fn')]"
+
+#![no_std]
+
+mod private_mod {
+    pub struct S;
+
+    /// impl S
+    impl S {
+        pub fn is_present() {}
+        #[doc(hidden)]
+        pub fn hidden_fn() {}
+    }
+
+    #[doc(hidden)]
+    impl S {
+        pub fn hidden_impl() {}
+    }
+}
+
+pub use private_mod::*;