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use rustc::hir;
use rustc::hir::def::Res;
use rustc::ty::{self, ParamEnv, TyCtxt};
use smallvec::SmallVec;
use syntax::ast::*;
use syntax::mut_visit::{self, MutVisitor};
use syntax::ptr::P;
use crate::ast_manip::MutVisit;
use crate::RefactorCtxt;
fn types_approx_equal<'tcx>(
tcx: TyCtxt<'tcx>,
ty1: ty::Ty<'tcx>,
ty2: ty::Ty<'tcx>,
) -> bool {
// Normalizing and erasing regions fixes a few cases where `illtyped` would otherwise falsely
// report a type error. Specifically:
//
// - On a method call `x.f()`, the autoref adjustment on `x` uses a specific region, while the
// signature returned by `opt_callee_fn_sig` has regions erased (because `opt_callee_info`
// itself calls `normalize_erasing_regions`). Erasing regions fixes this issue, though at
// the cost of ignoring most borrow checker errors.
// - On array expressions, often one side has the length expression fully evaluated, while the
// other does not. Normalizing makes sure both sides are evaluated, so no error is reported
// (assuming the lengths do, in fact, match).
let ty1 = tcx.normalize_erasing_regions(ParamEnv::empty(), ty1);
let ty2 = tcx.normalize_erasing_regions(ParamEnv::empty(), ty2);
ty1 == ty2
}
pub trait IlltypedFolder<'tcx> {
/// Called on each expr `e` whose `actual` type doesn't match the `expected` type propagated
/// down from its parent. Implementations should attempt to correct `e` to an expr that has
/// type `expected`.
#[allow(unused)]
fn fix_expr(&mut self, e: &mut P<Expr>, actual: ty::Ty<'tcx>, expected: ty::Ty<'tcx>) {}
/// Called on each expr `e` that is the subject of an invalid cast: `e` has type `actual`,
/// which cannot be cast to `target`. Implementations should attempt to correct `e` to an expr
/// that has a type castable to `target`.
///
/// The default implementation dispatches to `fix_expr`, since fixing `e` to have type exactly
/// `target` will certainly make the cast succeed.
fn fix_expr_cast(&mut self, e: &mut P<Expr>, actual: ty::Ty<'tcx>, target: ty::Ty<'tcx>) {
self.fix_expr(e, actual, target)
}
/// Called on each expr `e` that contains a subexpr whose actual type doesn't match the
/// expected type propagated down from `e`.
fn fix_expr_parent(&mut self, _e: &mut P<Expr>) {}
}
impl<'a, 'tcx, F: IlltypedFolder<'tcx>> IlltypedFolder<'tcx> for &'a mut F {
fn fix_expr(&mut self, e: &mut P<Expr>, actual: ty::Ty<'tcx>, expected: ty::Ty<'tcx>) {
<F as IlltypedFolder>::fix_expr(self, e, actual, expected)
}
fn fix_expr_cast(&mut self, e: &mut P<Expr>, actual: ty::Ty<'tcx>, target: ty::Ty<'tcx>) {
<F as IlltypedFolder>::fix_expr_cast(self, e, actual, target)
}
fn fix_expr_parent(&mut self, e: &mut P<Expr>) {
<F as IlltypedFolder>::fix_expr_parent(self, e)
}
}
struct FoldIlltyped<'a, 'tcx, F> {
cx: &'a RefactorCtxt<'a, 'tcx>,
inner: F,
}
impl<'a, 'tcx, F: IlltypedFolder<'tcx>> FoldIlltyped<'a, 'tcx, F> {
/// Attempt to ensure that `expr` has the type `expected_ty`. Return true if
/// retyping was needed.
fn ensure(&mut self, expr: &mut P<Expr>, expected_ty: ty::Ty<'tcx>) -> bool {
if let Some(actual_ty) = self.cx.opt_adjusted_node_type(expr.id) {
if !types_approx_equal(self.cx.ty_ctxt(), actual_ty, expected_ty) {
self.inner.fix_expr(expr, actual_ty, expected_ty);
return true;
}
}
false
}
/// Attempt to ensure that `expr` has the type `expected_ty`, inserting
/// casts if needed. Return true if retyping was needed.
// TODO: Use this when checking casts
#[allow(dead_code)]
fn ensure_cast(&mut self, sub_e: &mut P<Expr>, target_ty: ty::Ty<'tcx>) -> bool {
if let Some(actual_ty) = self.cx.opt_adjusted_node_type(sub_e.id) {
self.inner.fix_expr_cast(sub_e, actual_ty, target_ty);
return true;
}
false
}
/// Attempt to ensure that the last statement in a block
/// (if it's a `StmtKind::Expr`) has the expected type.
fn ensure_block(&mut self, block: &mut P<Block>, expected_ty: ty::Ty<'tcx>) -> bool {
let last_stmt_kind = block.stmts.last_mut().map(|stmt| &mut stmt.kind);
if let Some(StmtKind::Expr(ref mut e)) = last_stmt_kind {
self.ensure(e, expected_ty)
} else {
false
}
}
}
impl<'a, 'tcx, F: IlltypedFolder<'tcx>> MutVisitor for FoldIlltyped<'a, 'tcx, F> {
fn visit_expr(&mut self, e: &mut P<Expr>) {
let mut illtyped = false;
mut_visit::noop_visit_expr(e, self);
let ty = match self.cx.opt_node_type(e.id) {
Some(x) => x,
None => return,
};
if let ty::TyKind::Error = ty.kind {
return;
}
// We need the whole `Expr` to do this lookup, so it can't happen inside the match.
let opt_fn_sig = self.cx.opt_callee_fn_sig(&e);
let tcx = self.cx.ty_ctxt();
let id = e.id;
match &mut e.kind {
ExprKind::Box(content) => {
illtyped |= self.ensure(content, ty.boxed_ty());
}
ExprKind::Array(elems) => {
let expected_elem_ty = ty.builtin_index().unwrap();
for e in elems {
illtyped |= self.ensure(e, expected_elem_ty);
}
}
ExprKind::Repeat(elem, _count) => {
let expected_elem_ty = ty.builtin_index().unwrap();
illtyped |= self.ensure(elem, expected_elem_ty);
}
ExprKind::Tup(elems) => {
let elem_tys = expect!([ty.kind] ty::TyKind::Tuple(elem_tys) => elem_tys);
for (elem, elem_ty) in elems.iter_mut().zip(elem_tys.types()) {
illtyped |= self.ensure(elem, elem_ty);
}
}
ExprKind::Call(_callee, args) => {
if let Some(fn_sig) = opt_fn_sig {
for (i, arg) in args.iter_mut().enumerate() {
if let Some(&ty) = fn_sig.inputs().get(i) {
illtyped |= self.ensure(arg, ty);
}
}
}
}
ExprKind::MethodCall(_seg, args) => {
if let Some(fn_sig) = opt_fn_sig {
for (i, arg) in args.iter_mut().enumerate() {
if let Some(&ty) = fn_sig.inputs().get(i) {
illtyped |= self.ensure(arg, ty);
}
}
}
}
ExprKind::Binary(binop, lhs, rhs) => {
use syntax::ast::BinOpKind::*;
// TODO: check for overloads
match binop.node {
Add | Sub | Mul | Div | Rem | BitXor | BitAnd | BitOr => {
illtyped |= self.ensure(lhs, ty);
illtyped |= self.ensure(rhs, ty);
}
Eq | Lt | Le | Ne | Ge | Gt => {
if let Some(lhs_ty) = self.cx.opt_node_type(lhs.id) {
illtyped |= self.ensure(rhs, lhs_ty);
} else if let Some(rhs_ty) = self.cx.opt_node_type(rhs.id) {
illtyped |= self.ensure(lhs, rhs_ty);
}
}
Shl | Shr => {
illtyped |= self.ensure(lhs, ty);
}
And | Or => {
illtyped |= self.ensure(lhs, ty);
illtyped |= self.ensure(rhs, ty);
}
}
}
ExprKind::Unary(unop, ohs) => {
// TODO: need case for deref, and a check for overloads
use syntax::ast::UnOp::*;
match unop {
Not | Neg => {
illtyped |= self.ensure(ohs, ty);
}
Deref => {} // TODO
}
}
ExprKind::Lit(_l) => {} // TODO
ExprKind::Cast(_sub_e, _target) => {
// Check if the cast is erroneous. We do this by looking up the subexpression
// (yes, the subexpression) in the `cast_kinds` table - if there's nothing
// there, it's not a valid cast.
// Updating to nightly-2019-04-08 note: cast_kinds is gone now,
// and cast checking only marks coercion casts. We don't need to
// implement the logic for coercions, but it looks like we need
// to implement logic for real cast typechecking.
// TODO: Implement
// let parent = self.cx.hir_map().get_parent_did(sub_e.id);
// let tables = self.cx.ty_ctxt().typeck_tables_of(parent);
// let hir_id = self.cx.hir_map().node_to_hir_id(sub_e.id);
// if tables.cast_kinds().get(hir_id).is_none() {
// illtyped |= self.ensure_cast(sub_e, ty);
// }
}
ExprKind::AddrOf(_, _m, _ohs) => {} // TODO
ExprKind::If(cond, _tr, _fl) => {
// TODO: do something clever with tr + fl
illtyped |= self.ensure(cond, tcx.mk_bool());
}
ExprKind::Let(pat, expr) => {
if let Some(pat_ty) = self.cx.opt_node_type(pat.id) {
illtyped |= self.ensure(expr, pat_ty);
}
}
ExprKind::While(cond, _body, _opt_label) => {
illtyped |= self.ensure(cond, tcx.mk_bool());
}
ExprKind::Match(expr, arms) => {
if let Some(pat_ty) = arms
.get(0)
.and_then(|arm| self.cx.opt_node_type(arm.pat.id))
{
illtyped |= self.ensure(expr, pat_ty);
}
// TODO: self.ensure arm bodies match ty
}
ExprKind::Block(blk, _opt_label) => {
// TODO: check returns from opt_label
illtyped |= self.ensure_block(blk, ty);
}
ExprKind::Assign(el, er) => {
let lhs_ty = self.cx.node_type(el.id);
illtyped |= self.ensure(er, lhs_ty);
}
ExprKind::AssignOp(_op, el, er) => {
// TODO: need cases for arith/bitwise, shift, &&/||, and a check for overloads
let lhs_ty = self.cx.node_type(el.id);
illtyped |= self.ensure(er, lhs_ty);
}
ExprKind::Index(_el, er) => {
// TODO: check for overloads
illtyped |= self.ensure(er, tcx.mk_mach_uint(UintTy::Usize));
}
ExprKind::Range(_e1, _e2, _lim) => {
// TODO: e1 & e2 should have the same type if both present
}
ExprKind::Struct(_path, fields, maybe_expr) => {
handle_struct(self.cx, id, ty, fields, maybe_expr, |e, ty| {
illtyped |= self.ensure(e, ty)
});
}
// TODO: handle ExprKind::Paren???
_ => {}
};
if illtyped {
self.inner.fix_expr_parent(e)
}
}
fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
let mut items = mut_visit::noop_flat_map_item(i, self);
for i in items.iter_mut() {
let id = i.id;
match &mut i.kind {
ItemKind::Static(_ty, _mutbl, expr) => {
let did = self.cx.node_def_id(id);
let expected_ty = self.cx.ty_ctxt().type_of(did);
info!("STATIC: expected ty {:?}, expr {:?}", expected_ty, expr);
let tcx = self.cx.ty_ctxt();
let node_id = tcx.hir().as_local_hir_id(did).unwrap();
match tcx.hir().get(node_id) {
hir::Node::Item(item) => match item.kind {
hir::ItemKind::Static(ref t, ..) => info!(" - ty hir = {:?}", t),
_ => {}
},
_ => {}
}
self.ensure(expr, expected_ty);
}
ItemKind::Const(_ty, expr) => {
let did = self.cx.node_def_id(id);
let expected_ty = self.cx.ty_ctxt().type_of(did);
self.ensure(expr, expected_ty);
}
_ => {}
}
}
items
}
}
fn handle_struct<'tcx, F>(
cx: &RefactorCtxt<'_, 'tcx>,
expr_id: NodeId,
ty: ty::Ty<'tcx>,
fields: &mut Vec<Field>,
maybe_expr: &mut Option<P<Expr>>,
mut ensure: F,
) where
F: FnMut(&mut P<Expr>, ty::Ty<'tcx>),
{
let (adt_def, substs) = match ty.kind {
ty::TyKind::Adt(a, s) => (a, s),
_ => return,
};
// Get the variant def using the resolution of the path.
let variant_hir_res = match_or!([resolve_struct_path(cx, expr_id)] Some(x) => x;
return);
let vdef = adt_def.variant_of_res(variant_hir_res);
mut_visit::visit_vec(fields, |f| {
let idx = match_or!([cx.ty_ctxt().find_field_index(f.ident, vdef)] Some(x) => x; return);
let fdef = &vdef.fields[idx];
let field_ty = fdef.ty(cx.ty_ctxt(), substs);
ensure(&mut f.expr, field_ty);
});
mut_visit::visit_opt(maybe_expr, |e| ensure(e, ty));
}
fn resolve_struct_path(cx: &RefactorCtxt, id: NodeId) -> Option<Res> {
let node = match_or!([cx.hir_map().find(id)] Some(x) => x; return None);
let expr = match_or!([node] hir::Node::Expr(e) => e; return None);
let qpath: &hir::QPath =
match_or!([expr.kind] hir::ExprKind::Struct(ref q, ..) => q; return None);
let path = match_or!([qpath] hir::QPath::Resolved(_, ref path) => path; return None);
Some(path.res)
}
pub fn fold_illtyped<'tcx, F, T>(cx: &RefactorCtxt<'_, 'tcx>, x: &mut T, f: F)
where
F: IlltypedFolder<'tcx>,
T: MutVisit,
{
let mut f2 = FoldIlltyped { cx, inner: f };
x.visit(&mut f2)
}