use crate::ty::subst::SubstsRef;
use crate::ty::{self, AdtKind, List, Ty, TyCtxt};
+use rustc_ast::ast;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_span::{Span, DUMMY_SP};
use smallvec::SmallVec;
-use syntax::ast;
use std::borrow::Cow;
use std::fmt::Debug;