1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Type resolution: the phase that finds all the types in the AST with
12 // unresolved type variables and replaces "ty_var" types with their
17 use rustc::hir::def_id::{DefId, DefIndex};
18 use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
19 use rustc::infer::{InferCtxt};
20 use rustc::ty::{self, Ty, TyCtxt};
21 use rustc::ty::fold::{TypeFolder, TypeFoldable};
22 use rustc::ty::subst::{Kind, Substs};
23 use rustc::util::nodemap::{DefIdSet, FxHashMap};
29 ///////////////////////////////////////////////////////////////////////////
32 impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
33 pub fn resolve_type_vars_in_body(&self, body: &'gcx hir::Body)
34 -> &'gcx ty::TypeckTables<'gcx> {
35 let item_id = self.tcx.hir.body_owner(body.id());
36 let item_def_id = self.tcx.hir.local_def_id(item_id);
38 let mut wbcx = WritebackCx::new(self, body);
39 for arg in &body.arguments {
40 wbcx.visit_node_id(arg.pat.span, arg.hir_id);
42 wbcx.visit_body(body);
43 wbcx.visit_upvar_borrow_map();
44 wbcx.visit_closures();
45 wbcx.visit_liberated_fn_sigs();
46 wbcx.visit_fru_field_types();
47 wbcx.visit_anon_types();
48 wbcx.visit_cast_types();
49 wbcx.visit_free_region_map();
50 wbcx.visit_generator_sigs();
51 wbcx.visit_generator_interiors();
53 let used_trait_imports = mem::replace(&mut self.tables.borrow_mut().used_trait_imports,
55 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
56 wbcx.tables.used_trait_imports = used_trait_imports;
58 wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
60 self.tcx.alloc_tables(wbcx.tables)
64 ///////////////////////////////////////////////////////////////////////////
65 // The Writerback context. This visitor walks the AST, checking the
66 // fn-specific tables to find references to types or regions. It
67 // resolves those regions to remove inference variables and writes the
68 // final result back into the master tables in the tcx. Here and
69 // there, it applies a few ad-hoc checks that were not convenient to
72 struct WritebackCx<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
73 fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
75 tables: ty::TypeckTables<'gcx>,
77 body: &'gcx hir::Body,
80 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
81 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, body: &'gcx hir::Body)
82 -> WritebackCx<'cx, 'gcx, 'tcx>
84 let owner = fcx.tcx.hir.definitions().node_to_hir_id(body.id().node_id);
88 tables: ty::TypeckTables::empty(Some(DefId::local(owner.owner))),
93 fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
97 fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'gcx>) {
98 debug!("write_ty_to_tables({:?}, {:?})", hir_id, ty);
99 assert!(!ty.needs_infer());
100 self.tables.node_types_mut().insert(hir_id, ty);
103 // Hacky hack: During type-checking, we treat *all* operators
104 // as potentially overloaded. But then, during writeback, if
105 // we observe that something like `a+b` is (known to be)
106 // operating on scalars, we clear the overload.
107 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
109 hir::ExprUnary(hir::UnNeg, ref inner) |
110 hir::ExprUnary(hir::UnNot, ref inner) => {
111 let inner_ty = self.fcx.node_ty(inner.hir_id);
112 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
114 if inner_ty.is_scalar() {
115 let mut tables = self.fcx.tables.borrow_mut();
116 tables.type_dependent_defs_mut().remove(e.hir_id);
117 tables.node_substs_mut().remove(e.hir_id);
120 hir::ExprBinary(ref op, ref lhs, ref rhs) |
121 hir::ExprAssignOp(ref op, ref lhs, ref rhs) => {
122 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
123 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
125 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
126 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
128 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
129 let mut tables = self.fcx.tables.borrow_mut();
130 tables.type_dependent_defs_mut().remove(e.hir_id);
131 tables.node_substs_mut().remove(e.hir_id);
134 hir::ExprBinary(..) => {
135 if !op.node.is_by_value() {
136 let mut adjustments = tables.adjustments_mut();
137 adjustments.get_mut(lhs.hir_id).map(|a| a.pop());
138 adjustments.get_mut(rhs.hir_id).map(|a| a.pop());
141 hir::ExprAssignOp(..) => {
142 tables.adjustments_mut().get_mut(lhs.hir_id).map(|a| a.pop());
153 ///////////////////////////////////////////////////////////////////////////
154 // Impl of Visitor for Resolver
156 // This is the master code which walks the AST. It delegates most of
157 // the heavy lifting to the generic visit and resolve functions
158 // below. In general, a function is made into a `visitor` if it must
159 // traffic in node-ids or update tables in the type context etc.
161 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
162 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
163 NestedVisitorMap::None
166 fn visit_expr(&mut self, e: &'gcx hir::Expr) {
167 self.fix_scalar_builtin_expr(e);
169 self.visit_node_id(e.span, e.hir_id);
171 if let hir::ExprClosure(_, _, body, _, _) = e.node {
172 let body = self.fcx.tcx.hir.body(body);
173 for arg in &body.arguments {
174 self.visit_node_id(e.span, arg.hir_id);
177 self.visit_body(body);
180 intravisit::walk_expr(self, e);
183 fn visit_block(&mut self, b: &'gcx hir::Block) {
184 self.visit_node_id(b.span, b.hir_id);
185 intravisit::walk_block(self, b);
188 fn visit_pat(&mut self, p: &'gcx hir::Pat) {
190 hir::PatKind::Binding(..) => {
196 .expect("missing binding mode");
197 self.tables.pat_binding_modes_mut().insert(p.hir_id, bm);
202 self.visit_pat_adjustments(p.span, p.hir_id);
204 self.visit_node_id(p.span, p.hir_id);
205 intravisit::walk_pat(self, p);
208 fn visit_local(&mut self, l: &'gcx hir::Local) {
209 intravisit::walk_local(self, l);
210 let var_ty = self.fcx.local_ty(l.span, l.id);
211 let var_ty = self.resolve(&var_ty, &l.span);
212 self.write_ty_to_tables(l.hir_id, var_ty);
215 fn visit_ty(&mut self, hir_ty: &'gcx hir::Ty) {
216 intravisit::walk_ty(self, hir_ty);
217 let ty = self.fcx.node_ty(hir_ty.hir_id);
218 let ty = self.resolve(&ty, &hir_ty.span);
219 self.write_ty_to_tables(hir_ty.hir_id, ty);
223 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
224 fn visit_upvar_borrow_map(&mut self) {
225 for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
226 let new_upvar_capture = match *upvar_capture {
227 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
228 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
229 let r = upvar_borrow.region;
230 let r = self.resolve(&r, &upvar_id.var_id);
231 ty::UpvarCapture::ByRef(
232 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
235 debug!("Upvar capture for {:?} resolved to {:?}",
238 self.tables.upvar_capture_map.insert(*upvar_id, new_upvar_capture);
242 fn visit_closures(&mut self) {
243 let fcx_tables = self.fcx.tables.borrow();
244 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
245 let common_local_id_root = fcx_tables.local_id_root.unwrap();
247 for (&id, closure_ty) in fcx_tables.closure_tys().iter() {
248 let hir_id = hir::HirId {
249 owner: common_local_id_root.index,
252 let closure_ty = self.resolve(closure_ty, &hir_id);
253 self.tables.closure_tys_mut().insert(hir_id, closure_ty);
256 for (&id, &closure_kind) in fcx_tables.closure_kinds().iter() {
257 let hir_id = hir::HirId {
258 owner: common_local_id_root.index,
261 self.tables.closure_kinds_mut().insert(hir_id, closure_kind);
265 fn visit_cast_types(&mut self) {
266 let fcx_tables = self.fcx.tables.borrow();
267 let fcx_cast_kinds = fcx_tables.cast_kinds();
268 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
269 let mut self_cast_kinds = self.tables.cast_kinds_mut();
270 let common_local_id_root = fcx_tables.local_id_root.unwrap();
272 for (&local_id, &cast_kind) in fcx_cast_kinds.iter() {
273 let hir_id = hir::HirId {
274 owner: common_local_id_root.index,
277 self_cast_kinds.insert(hir_id, cast_kind);
281 fn visit_free_region_map(&mut self) {
282 let free_region_map = self.tcx().lift_to_global(&self.fcx.tables.borrow().free_region_map);
283 let free_region_map = free_region_map.expect("all regions in free-region-map are global");
284 self.tables.free_region_map = free_region_map;
287 fn visit_anon_types(&mut self) {
288 let gcx = self.tcx().global_tcx();
289 for (&def_id, anon_defn) in self.fcx.anon_types.borrow().iter() {
290 let node_id = gcx.hir.as_local_node_id(def_id).unwrap();
291 let inside_ty = self.resolve(&anon_defn.concrete_ty, &node_id);
293 // Use substs to build up a reverse map from regions
294 // to their identity mappings.
295 // This is necessary because of `impl Trait` lifetimes
296 // are computed by replacing existing lifetimes with 'static
297 // and remapping only those used in the `impl Trait` return type,
298 // resulting in the parameters shifting.
299 let id_substs = Substs::identity_for_item(gcx, def_id);
300 let map: FxHashMap<Kind<'tcx>, Kind<'gcx>> =
304 .map(|(index, subst)| (*subst, id_substs[index]))
307 // Convert the type from the function into a type valid outside
308 // the function, by replacing invalid regions with 'static,
309 // after producing an error for each of them.
310 let outside_ty = gcx.fold_regions(&inside_ty, &mut false, |r, _| {
312 // 'static and early-bound regions are valid.
316 // All other regions, we map them appropriately to their adjusted
317 // indices, erroring if we find any lifetimes that were not mapped
319 _ => if let Some(r1) =
320 map.get(&Kind::from(r)).and_then(|k| k.as_region()) { r1 } else
322 // No mapping was found. This means that
323 // it is either a disallowed lifetime,
324 // which will be caught by regionck, or it
325 // is a region in a non-upvar closure
326 // generic, which is explicitly
327 // allowed. If that surprises you, read
330 // The case of closure is a somewhat
331 // subtle (read: hacky) consideration. The
332 // problem is that our closure types
333 // currently include all the lifetime
334 // parameters declared on the enclosing
335 // function, even if they are unused by
336 // the closure itself. We can't readily
337 // filter them out, so here we replace
338 // those values with `'empty`. This can't
339 // really make a difference to the rest of
340 // the compiler; those regions are ignored
341 // for the outlives relation, and hence
342 // don't affect trait selection or auto
343 // traits, and they are erased during
350 let hir_id = self.tcx().hir.node_to_hir_id(node_id);
351 self.tables.node_types_mut().insert(hir_id, outside_ty);
355 fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
356 // Export associated path extensions and method resultions.
357 if let Some(def) = self.fcx
360 .type_dependent_defs_mut()
362 self.tables.type_dependent_defs_mut().insert(hir_id, def);
365 // Resolve any borrowings for the node with id `node_id`
366 self.visit_adjustments(span, hir_id);
368 // Resolve the type of the node with id `node_id`
369 let n_ty = self.fcx.node_ty(hir_id);
370 let n_ty = self.resolve(&n_ty, &span);
371 self.write_ty_to_tables(hir_id, n_ty);
372 debug!("Node {:?} has type {:?}", hir_id, n_ty);
374 // Resolve any substitutions
375 if let Some(substs) = self.fcx.tables.borrow().node_substs_opt(hir_id) {
376 let substs = self.resolve(&substs, &span);
377 debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
378 assert!(!substs.needs_infer());
379 self.tables.node_substs_mut().insert(hir_id, substs);
383 fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
384 let adjustment = self.fcx
391 debug!("No adjustments for node {:?}", hir_id);
394 Some(adjustment) => {
395 let resolved_adjustment = self.resolve(&adjustment, &span);
396 debug!("Adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
397 self.tables.adjustments_mut().insert(hir_id, resolved_adjustment);
402 fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
403 let adjustment = self.fcx
406 .pat_adjustments_mut()
410 debug!("No pat_adjustments for node {:?}", hir_id);
413 Some(adjustment) => {
414 let resolved_adjustment = self.resolve(&adjustment, &span);
415 debug!("pat_adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
416 self.tables.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
421 fn visit_generator_interiors(&mut self) {
422 let common_local_id_root = self.fcx.tables.borrow().local_id_root.unwrap();
423 for (&id, interior) in self.fcx.tables.borrow().generator_interiors().iter() {
424 let hir_id = hir::HirId {
425 owner: common_local_id_root.index,
428 let interior = self.resolve(interior, &hir_id);
429 self.tables.generator_interiors_mut().insert(hir_id, interior);
433 fn visit_generator_sigs(&mut self) {
434 let common_local_id_root = self.fcx.tables.borrow().local_id_root.unwrap();
435 for (&id, gen_sig) in self.fcx.tables.borrow().generator_sigs().iter() {
436 let hir_id = hir::HirId {
437 owner: common_local_id_root.index,
440 let gen_sig = gen_sig.map(|s| ty::GenSig {
441 yield_ty: self.resolve(&s.yield_ty, &hir_id),
442 return_ty: self.resolve(&s.return_ty, &hir_id),
444 self.tables.generator_sigs_mut().insert(hir_id, gen_sig);
448 fn visit_liberated_fn_sigs(&mut self) {
449 let fcx_tables = self.fcx.tables.borrow();
450 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
451 let common_local_id_root = fcx_tables.local_id_root.unwrap();
453 for (&local_id, fn_sig) in fcx_tables.liberated_fn_sigs().iter() {
454 let hir_id = hir::HirId {
455 owner: common_local_id_root.index,
458 let fn_sig = self.resolve(fn_sig, &hir_id);
459 self.tables.liberated_fn_sigs_mut().insert(hir_id, fn_sig.clone());
463 fn visit_fru_field_types(&mut self) {
464 let fcx_tables = self.fcx.tables.borrow();
465 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
466 let common_local_id_root = fcx_tables.local_id_root.unwrap();
468 for (&local_id, ftys) in fcx_tables.fru_field_types().iter() {
469 let hir_id = hir::HirId {
470 owner: common_local_id_root.index,
473 let ftys = self.resolve(ftys, &hir_id);
474 self.tables.fru_field_types_mut().insert(hir_id, ftys);
478 fn resolve<T>(&self, x: &T, span: &Locatable) -> T::Lifted
479 where T: TypeFoldable<'tcx> + ty::Lift<'gcx>
481 let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
482 if let Some(lifted) = self.tcx().lift_to_global(&x) {
485 span_bug!(span.to_span(&self.fcx.tcx),
486 "writeback: `{:?}` missing from the global type context",
493 fn to_span(&self, tcx: &TyCtxt) -> Span;
496 impl Locatable for Span {
497 fn to_span(&self, _: &TyCtxt) -> Span { *self }
500 impl Locatable for ast::NodeId {
501 fn to_span(&self, tcx: &TyCtxt) -> Span { tcx.hir.span(*self) }
504 impl Locatable for DefIndex {
505 fn to_span(&self, tcx: &TyCtxt) -> Span {
506 let node_id = tcx.hir.def_index_to_node_id(*self);
507 tcx.hir.span(node_id)
511 impl Locatable for hir::HirId {
512 fn to_span(&self, tcx: &TyCtxt) -> Span {
513 let node_id = tcx.hir.definitions().find_node_for_hir_id(*self);
514 tcx.hir.span(node_id)
518 ///////////////////////////////////////////////////////////////////////////
519 // The Resolver. This is the type folding engine that detects
520 // unresolved types and so forth.
522 struct Resolver<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
523 tcx: TyCtxt<'cx, 'gcx, 'tcx>,
524 infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
525 span: &'cx Locatable,
526 body: &'gcx hir::Body,
529 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
530 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, span: &'cx Locatable, body: &'gcx hir::Body)
531 -> Resolver<'cx, 'gcx, 'tcx>
541 fn report_error(&self, t: Ty<'tcx>) {
542 if !self.tcx.sess.has_errors() {
543 self.infcx.need_type_info(Some(self.body.id()), self.span.to_span(&self.tcx), t);
548 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
549 fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
553 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
554 match self.infcx.fully_resolve(&t) {
557 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
559 self.report_error(t);
565 // FIXME This should be carefully checked
566 // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
567 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
568 match self.infcx.fully_resolve(&r) {
571 self.tcx.types.re_static
577 ///////////////////////////////////////////////////////////////////////////
578 // During type check, we store promises with the result of trait
579 // lookup rather than the actual results (because the results are not
580 // necessarily available immediately). These routines unwind the
581 // promises. It is expected that we will have already reported any
582 // errors that may be encountered, so if the promises store an error,
583 // a dummy result is returned.