pub trait HasTypingEnv<'tcx> {
// Required method
fn typing_env(&self) -> TypingEnv<'tcx>;
// Provided method
fn param_env(&self) -> ParamEnv<'tcx> { ... }
}
pub trait HasTypingEnv<'tcx> {
// Required method
fn typing_env(&self) -> TypingEnv<'tcx>;
// Provided method
fn param_env(&self) -> ParamEnv<'tcx> { ... }
}