Log item for which layout retrieval fails

bindgen/codegen/mod.rs

@@ -2143,7 +2143,7 @@ impl CodeGenerator for CompInfo {
         } else if is_union && !forward_decl {
             // TODO(emilio): It'd be nice to unify this with the struct path
             // above somehow.
-            let layout = layout.expect("Unable to get layout information?");
+            let layout = layout.unwrap_or_else(|| panic!("Unable to get layout information for item\n{:#?}", item));
             if struct_layout.requires_explicit_align(layout) {
                 explicit_align = Some(layout.align);
             }