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::util::nodemap::DefIdSet;
27 ///////////////////////////////////////////////////////////////////////////
30 impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
31 pub fn resolve_type_vars_in_body(&self, body: &'gcx hir::Body)
32 -> &'gcx ty::TypeckTables<'gcx> {
33 let item_id = self.tcx.hir.body_owner(body.id());
34 let item_def_id = self.tcx.hir.local_def_id(item_id);
36 let mut wbcx = WritebackCx::new(self, body);
37 for arg in &body.arguments {
38 wbcx.visit_node_id(arg.pat.span, arg.hir_id);
40 wbcx.visit_body(body);
41 wbcx.visit_upvar_borrow_map();
42 wbcx.visit_closures();
43 wbcx.visit_liberated_fn_sigs();
44 wbcx.visit_fru_field_types();
45 wbcx.visit_anon_types();
46 wbcx.visit_cast_types();
47 wbcx.visit_free_region_map();
48 wbcx.visit_generator_sigs();
49 wbcx.visit_generator_interiors();
51 let used_trait_imports = mem::replace(&mut self.tables.borrow_mut().used_trait_imports,
53 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
54 wbcx.tables.used_trait_imports = used_trait_imports;
56 wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
58 self.tcx.alloc_tables(wbcx.tables)
62 ///////////////////////////////////////////////////////////////////////////
63 // The Writerback context. This visitor walks the AST, checking the
64 // fn-specific tables to find references to types or regions. It
65 // resolves those regions to remove inference variables and writes the
66 // final result back into the master tables in the tcx. Here and
67 // there, it applies a few ad-hoc checks that were not convenient to
70 struct WritebackCx<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
71 fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
73 tables: ty::TypeckTables<'gcx>,
75 body: &'gcx hir::Body,
78 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
79 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, body: &'gcx hir::Body)
80 -> WritebackCx<'cx, 'gcx, 'tcx>
82 let owner = fcx.tcx.hir.definitions().node_to_hir_id(body.id().node_id);
86 tables: ty::TypeckTables::empty(Some(DefId::local(owner.owner))),
91 fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
95 fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'gcx>) {
96 debug!("write_ty_to_tables({:?}, {:?})", hir_id, ty);
97 assert!(!ty.needs_infer());
98 self.tables.node_types_mut().insert(hir_id, ty);
101 // Hacky hack: During type-checking, we treat *all* operators
102 // as potentially overloaded. But then, during writeback, if
103 // we observe that something like `a+b` is (known to be)
104 // operating on scalars, we clear the overload.
105 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
107 hir::ExprUnary(hir::UnNeg, ref inner) |
108 hir::ExprUnary(hir::UnNot, ref inner) => {
109 let inner_ty = self.fcx.node_ty(inner.hir_id);
110 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
112 if inner_ty.is_scalar() {
113 let mut tables = self.fcx.tables.borrow_mut();
114 tables.type_dependent_defs_mut().remove(e.hir_id);
115 tables.node_substs_mut().remove(e.hir_id);
118 hir::ExprBinary(ref op, ref lhs, ref rhs) |
119 hir::ExprAssignOp(ref op, ref lhs, ref rhs) => {
120 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
121 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
123 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
124 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
126 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
127 let mut tables = self.fcx.tables.borrow_mut();
128 tables.type_dependent_defs_mut().remove(e.hir_id);
129 tables.node_substs_mut().remove(e.hir_id);
132 hir::ExprBinary(..) => {
133 if !op.node.is_by_value() {
134 let mut adjustments = tables.adjustments_mut();
135 adjustments.get_mut(lhs.hir_id).map(|a| a.pop());
136 adjustments.get_mut(rhs.hir_id).map(|a| a.pop());
139 hir::ExprAssignOp(..) => {
140 tables.adjustments_mut().get_mut(lhs.hir_id).map(|a| a.pop());
151 ///////////////////////////////////////////////////////////////////////////
152 // Impl of Visitor for Resolver
154 // This is the master code which walks the AST. It delegates most of
155 // the heavy lifting to the generic visit and resolve functions
156 // below. In general, a function is made into a `visitor` if it must
157 // traffic in node-ids or update tables in the type context etc.
159 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
160 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
161 NestedVisitorMap::None
164 fn visit_expr(&mut self, e: &'gcx hir::Expr) {
165 self.fix_scalar_builtin_expr(e);
167 self.visit_node_id(e.span, e.hir_id);
169 if let hir::ExprClosure(_, _, body, _, _) = e.node {
170 let body = self.fcx.tcx.hir.body(body);
171 for arg in &body.arguments {
172 self.visit_node_id(e.span, arg.hir_id);
175 self.visit_body(body);
178 intravisit::walk_expr(self, e);
181 fn visit_block(&mut self, b: &'gcx hir::Block) {
182 self.visit_node_id(b.span, b.hir_id);
183 intravisit::walk_block(self, b);
186 fn visit_pat(&mut self, p: &'gcx hir::Pat) {
188 hir::PatKind::Binding(..) => {
194 .expect("missing binding mode");
195 self.tables.pat_binding_modes_mut().insert(p.hir_id, bm);
200 self.visit_node_id(p.span, p.hir_id);
201 intravisit::walk_pat(self, p);
204 fn visit_local(&mut self, l: &'gcx hir::Local) {
205 intravisit::walk_local(self, l);
206 let var_ty = self.fcx.local_ty(l.span, l.id);
207 let var_ty = self.resolve(&var_ty, &l.span);
208 self.write_ty_to_tables(l.hir_id, var_ty);
211 fn visit_ty(&mut self, hir_ty: &'gcx hir::Ty) {
212 intravisit::walk_ty(self, hir_ty);
213 let ty = self.fcx.node_ty(hir_ty.hir_id);
214 let ty = self.resolve(&ty, &hir_ty.span);
215 self.write_ty_to_tables(hir_ty.hir_id, ty);
219 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
220 fn visit_upvar_borrow_map(&mut self) {
221 for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
222 let new_upvar_capture = match *upvar_capture {
223 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
224 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
225 let r = upvar_borrow.region;
226 let r = self.resolve(&r, &upvar_id.var_id);
227 ty::UpvarCapture::ByRef(
228 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
231 debug!("Upvar capture for {:?} resolved to {:?}",
234 self.tables.upvar_capture_map.insert(*upvar_id, new_upvar_capture);
238 fn visit_closures(&mut self) {
239 let fcx_tables = self.fcx.tables.borrow();
240 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
241 let common_local_id_root = fcx_tables.local_id_root.unwrap();
243 for (&id, closure_ty) in fcx_tables.closure_tys().iter() {
244 let hir_id = hir::HirId {
245 owner: common_local_id_root.index,
248 let closure_ty = self.resolve(closure_ty, &hir_id);
249 self.tables.closure_tys_mut().insert(hir_id, closure_ty);
252 for (&id, &closure_kind) in fcx_tables.closure_kinds().iter() {
253 let hir_id = hir::HirId {
254 owner: common_local_id_root.index,
257 self.tables.closure_kinds_mut().insert(hir_id, closure_kind);
261 fn visit_cast_types(&mut self) {
262 let fcx_tables = self.fcx.tables.borrow();
263 let fcx_cast_kinds = fcx_tables.cast_kinds();
264 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
265 let mut self_cast_kinds = self.tables.cast_kinds_mut();
266 let common_local_id_root = fcx_tables.local_id_root.unwrap();
268 for (&local_id, &cast_kind) in fcx_cast_kinds.iter() {
269 let hir_id = hir::HirId {
270 owner: common_local_id_root.index,
273 self_cast_kinds.insert(hir_id, cast_kind);
277 fn visit_free_region_map(&mut self) {
278 let free_region_map = self.tcx().lift_to_global(&self.fcx.tables.borrow().free_region_map);
279 let free_region_map = free_region_map.expect("all regions in free-region-map are global");
280 self.tables.free_region_map = free_region_map;
283 fn visit_anon_types(&mut self) {
284 let gcx = self.tcx().global_tcx();
285 for (&node_id, &concrete_ty) in self.fcx.anon_types.borrow().iter() {
286 let inside_ty = self.resolve(&concrete_ty, &node_id);
288 // Convert the type from the function into a type valid outside
289 // the function, by replacing invalid regions with 'static,
290 // after producing an error for each of them.
291 let outside_ty = gcx.fold_regions(&inside_ty, &mut false, |r, _| {
293 // 'static and early-bound regions are valid.
295 ty::ReEarlyBound(_) |
299 ty::ReLateBound(..) |
301 ty::ReSkolemized(..) => {
302 let span = node_id.to_span(&self.fcx.tcx);
303 span_err!(self.tcx().sess, span, E0564,
304 "only named lifetimes are allowed in `impl Trait`, \
305 but `{}` was found in the type `{}`", r, inside_ty);
311 let span = node_id.to_span(&self.fcx.tcx);
312 span_bug!(span, "invalid region in impl Trait: {:?}", r);
317 let hir_id = self.tcx().hir.node_to_hir_id(node_id);
318 self.tables.node_types_mut().insert(hir_id, outside_ty);
322 fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
323 // Export associated path extensions and method resultions.
324 if let Some(def) = self.fcx
327 .type_dependent_defs_mut()
329 self.tables.type_dependent_defs_mut().insert(hir_id, def);
332 // Resolve any borrowings for the node with id `node_id`
333 self.visit_adjustments(span, hir_id);
335 // Resolve the type of the node with id `node_id`
336 let n_ty = self.fcx.node_ty(hir_id);
337 let n_ty = self.resolve(&n_ty, &span);
338 self.write_ty_to_tables(hir_id, n_ty);
339 debug!("Node {:?} has type {:?}", hir_id, n_ty);
341 // Resolve any substitutions
342 if let Some(substs) = self.fcx.tables.borrow().node_substs_opt(hir_id) {
343 let substs = self.resolve(&substs, &span);
344 debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
345 assert!(!substs.needs_infer());
346 self.tables.node_substs_mut().insert(hir_id, substs);
350 fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
351 let adjustment = self.fcx
358 debug!("No adjustments for node {:?}", hir_id);
361 Some(adjustment) => {
362 let resolved_adjustment = self.resolve(&adjustment, &span);
363 debug!("Adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
364 self.tables.adjustments_mut().insert(hir_id, resolved_adjustment);
369 fn visit_generator_interiors(&mut self) {
370 let common_local_id_root = self.fcx.tables.borrow().local_id_root.unwrap();
371 for (&id, interior) in self.fcx.tables.borrow().generator_interiors().iter() {
372 let hir_id = hir::HirId {
373 owner: common_local_id_root.index,
376 let interior = self.resolve(interior, &hir_id);
377 self.tables.generator_interiors_mut().insert(hir_id, interior);
381 fn visit_generator_sigs(&mut self) {
382 let common_local_id_root = self.fcx.tables.borrow().local_id_root.unwrap();
383 for (&id, gen_sig) in self.fcx.tables.borrow().generator_sigs().iter() {
384 let hir_id = hir::HirId {
385 owner: common_local_id_root.index,
388 let gen_sig = gen_sig.map(|s| ty::GenSig {
389 yield_ty: self.resolve(&s.yield_ty, &hir_id),
390 return_ty: self.resolve(&s.return_ty, &hir_id),
392 self.tables.generator_sigs_mut().insert(hir_id, gen_sig);
396 fn visit_liberated_fn_sigs(&mut self) {
397 let fcx_tables = self.fcx.tables.borrow();
398 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
399 let common_local_id_root = fcx_tables.local_id_root.unwrap();
401 for (&local_id, fn_sig) in fcx_tables.liberated_fn_sigs().iter() {
402 let hir_id = hir::HirId {
403 owner: common_local_id_root.index,
406 let fn_sig = self.resolve(fn_sig, &hir_id);
407 self.tables.liberated_fn_sigs_mut().insert(hir_id, fn_sig.clone());
411 fn visit_fru_field_types(&mut self) {
412 let fcx_tables = self.fcx.tables.borrow();
413 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
414 let common_local_id_root = fcx_tables.local_id_root.unwrap();
416 for (&local_id, ftys) in fcx_tables.fru_field_types().iter() {
417 let hir_id = hir::HirId {
418 owner: common_local_id_root.index,
421 let ftys = self.resolve(ftys, &hir_id);
422 self.tables.fru_field_types_mut().insert(hir_id, ftys);
426 fn resolve<T>(&self, x: &T, span: &Locatable) -> T::Lifted
427 where T: TypeFoldable<'tcx> + ty::Lift<'gcx>
429 let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
430 if let Some(lifted) = self.tcx().lift_to_global(&x) {
433 span_bug!(span.to_span(&self.fcx.tcx),
434 "writeback: `{:?}` missing from the global type context",
441 fn to_span(&self, tcx: &TyCtxt) -> Span;
444 impl Locatable for Span {
445 fn to_span(&self, _: &TyCtxt) -> Span { *self }
448 impl Locatable for ast::NodeId {
449 fn to_span(&self, tcx: &TyCtxt) -> Span { tcx.hir.span(*self) }
452 impl Locatable for DefIndex {
453 fn to_span(&self, tcx: &TyCtxt) -> Span {
454 let node_id = tcx.hir.def_index_to_node_id(*self);
455 tcx.hir.span(node_id)
459 impl Locatable for hir::HirId {
460 fn to_span(&self, tcx: &TyCtxt) -> Span {
461 let node_id = tcx.hir.definitions().find_node_for_hir_id(*self);
462 tcx.hir.span(node_id)
466 ///////////////////////////////////////////////////////////////////////////
467 // The Resolver. This is the type folding engine that detects
468 // unresolved types and so forth.
470 struct Resolver<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
471 tcx: TyCtxt<'cx, 'gcx, 'tcx>,
472 infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
473 span: &'cx Locatable,
474 body: &'gcx hir::Body,
477 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
478 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, span: &'cx Locatable, body: &'gcx hir::Body)
479 -> Resolver<'cx, 'gcx, 'tcx>
489 fn report_error(&self, t: Ty<'tcx>) {
490 if !self.tcx.sess.has_errors() {
491 self.infcx.need_type_info(Some(self.body.id()), self.span.to_span(&self.tcx), t);
496 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
497 fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
501 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
502 match self.infcx.fully_resolve(&t) {
505 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
507 self.report_error(t);
513 // FIXME This should be carefully checked
514 // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
515 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
516 match self.infcx.fully_resolve(&r) {
519 self.tcx.types.re_static
525 ///////////////////////////////////////////////////////////////////////////
526 // During type check, we store promises with the result of trait
527 // lookup rather than the actual results (because the results are not
528 // necessarily available immediately). These routines unwind the
529 // promises. It is expected that we will have already reported any
530 // errors that may be encountered, so if the promises store an error,
531 // a dummy result is returned.