Function check_must_use_def 

fn check_must_use_def(
    cx: &LateContext<'_>,
    def_id: DefId,
    span: Span,
    descr_pre_path: &str,
    descr_post_path: &str,
    expr_is_from_block: bool,
) -> bool

Returns whether further errors should be suppressed because a lint has been emitted.