Remove needless use of `Into`

src/librustdoc/clean/inline.rs

@@ -327,7 +327,7 @@ fn merge_attrs(
 /// Inline an `impl`, inherent or of a trait. The `did` must be for an `impl`.
 crate fn build_impl(
     cx: &mut DocContext<'_>,
-    parent_module: impl Into<Option<DefId>>,
+    parent_module: Option<DefId>,
     did: DefId,
     attrs: Option<Attrs<'_>>,
     ret: &mut Vec<clean::Item>,
@@ -478,7 +478,7 @@ fn merge_attrs(
         record_extern_trait(cx, did);
     }
 
-    let (merged_attrs, cfg) = merge_attrs(cx, parent_module.into(), load_attrs(cx, did), attrs);
+    let (merged_attrs, cfg) = merge_attrs(cx, parent_module, load_attrs(cx, did), attrs);
     trace!("merged_attrs={:?}", merged_attrs);
 
     trace!(