Fix errors on blanket impls by ignoring the children of generated impls

src/librustdoc/json/mod.rs

@@ -171,8 +171,21 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
     /// the hashmap because certain items (traits and types) need to have their mappings for trait
     /// implementations filled out before they're inserted.
     fn item(&mut self, item: clean::Item) -> Result<(), Error> {
+        let local_blanket_impl = match item.def_id {
+            clean::ItemId::Blanket { impl_id, .. } => impl_id.is_local(),
+            clean::ItemId::Auto { .. }
+            | clean::ItemId::DefId(_)
+            | clean::ItemId::Primitive(_, _) => false,
+        };
+
         // Flatten items that recursively store other items
-        item.kind.inner_items().for_each(|i| self.item(i.clone()).unwrap());
+        // FIXME(CraftSpider): We skip children of local blanket implementations, as we'll have
+        //     already seen the actual generic impl, and the generated ones don't need documenting.
+        //     This is necessary due to the visibility, return type, and self arg of the generated
+        //     impls not quite matching, and will no longer be necessary when the mismatch is fixed.
+        if !local_blanket_impl {
+            item.kind.inner_items().for_each(|i| self.item(i.clone()).unwrap());
+        }
 
         let id = item.def_id;
         if let Some(mut new_item) = self.convert_item(item) {

src/test/rustdoc-json/impls/blanket_with_local.rs

@@ -0,0 +1,14 @@
+// Test for the ICE in rust/83718
+// A blanket impl plus a local type together shouldn't result in mismatched ID issues
+
+// @has blanket_with_local.json "$.index[*][?(@.name=='Load')]"
+pub trait Load {
+    fn load() {}
+}
+
+impl<P> Load for P {
+    fn load() {}
+}
+
+// @has - "$.index[*][?(@.name=='Wrapper')]"
+pub struct Wrapper {}