Don't wrap struct padding in __bindgen_marker_Opaque

bindgen/codegen/mod.rs

@@ -2362,12 +2362,9 @@ impl CodeGenerator for CompInfo {
 
             if has_address {
                 let layout = Layout::new(1, 1);
-                // Normally for opaque data we use helpers::blob,
-                // which may wrap it in __bindgen_marker_Opaque<T>.
-                // Downstream tools may then use this as a sign that
-                // the type is complex or can't be stack-allocated,
-                // etc. But in this case this one-byte field is harmless
-                // so we'll just represent it without that extra marker.
+                // Don't use __bindgen_marker_Opaque for this harmless one-byte
+                // field. See StructLayoutTracker::padding_field() for a longer
+                // explanation of blob_inner() vs blob().
                 let ty = helpers::blob_inner(ctx, Layout::new(1, 1), false);
                 struct_layout.saw_field_with_layout(
                     "_address",

bindgen/codegen/struct_layout.rs

@@ -393,7 +393,12 @@ impl<'a> StructLayoutTracker<'a> {
     }
 
     fn padding_field(&mut self, layout: Layout) -> proc_macro2::TokenStream {
-        let ty = helpers::blob(self.ctx, layout, false);
+        // Normally for opaque data we use helpers::blob(), which may wrap it
+        // __bindgen_marker_Opaque<T>. Downstream tools may then use this as a
+        // sign that the type is complex or can't be stack-allocated, etc. But
+        // in this case the padding is just plain data, so we want to represent
+        // it without the extra marker.
+        let ty = helpers::blob_inner(self.ctx, layout, false);
         let padding_count = self.padding_count;
 
         self.padding_count += 1;