Function rustc_builtin_macros::deriving::generic::combine_substructure

source · 
pub fn combine_substructure(
    f: Box<dyn FnMut(&ExtCtxt<'_>, Span, &Substructure<'_>) -> BlockOrExpr + '_>
) -> RefCell<Box<dyn FnMut(&ExtCtxt<'_>, Span, &Substructure<'_>) -> BlockOrExpr + '_>>