Uniformly handle HIR literals in visitors and lints

compiler/rustc_lint/src/late.rs

@@ -152,6 +152,10 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
         hir_visit::walk_pat(self, p);
     }
 
+    fn visit_lit(&mut self, hir_id: HirId, lit: &'tcx hir::Lit, negated: bool) {
+        lint_callback!(self, check_lit, hir_id, lit, negated);
+    }
+
     fn visit_expr_field(&mut self, field: &'tcx hir::ExprField<'tcx>) {
         self.with_lint_attrs(field.hir_id, |cx| hir_visit::walk_expr_field(cx, field))
     }