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::intravisit::{self, Visitor, NestedVisitorMap};
18 use rustc::infer::{InferCtxt};
19 use rustc::ty::{self, Ty, TyCtxt};
20 use rustc::ty::fold::{TypeFolder,TypeFoldable};
21 use rustc::util::nodemap::DefIdSet;
26 ///////////////////////////////////////////////////////////////////////////
29 impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
30 pub fn resolve_type_vars_in_body(&self, body: &'gcx hir::Body)
31 -> &'gcx ty::TypeckTables<'gcx> {
32 let item_id = self.tcx.hir.body_owner(body.id());
33 let item_def_id = self.tcx.hir.local_def_id(item_id);
35 let mut wbcx = WritebackCx::new(self, body);
36 for arg in &body.arguments {
37 wbcx.visit_node_id(arg.pat.span, arg.id);
39 wbcx.visit_body(body);
40 wbcx.visit_upvar_borrow_map();
41 wbcx.visit_closures();
42 wbcx.visit_liberated_fn_sigs();
43 wbcx.visit_fru_field_types();
44 wbcx.visit_anon_types();
45 wbcx.visit_cast_types();
47 wbcx.visit_free_region_map();
49 let used_trait_imports = mem::replace(&mut self.tables.borrow_mut().used_trait_imports,
51 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
52 wbcx.tables.used_trait_imports = used_trait_imports;
54 wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
56 self.tcx.alloc_tables(wbcx.tables)
60 ///////////////////////////////////////////////////////////////////////////
61 // The Writerback context. This visitor walks the AST, checking the
62 // fn-specific tables to find references to types or regions. It
63 // resolves those regions to remove inference variables and writes the
64 // final result back into the master tables in the tcx. Here and
65 // there, it applies a few ad-hoc checks that were not convenient to
68 struct WritebackCx<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
69 fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
71 tables: ty::TypeckTables<'gcx>,
73 body: &'gcx hir::Body,
76 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
77 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, body: &'gcx hir::Body)
78 -> WritebackCx<'cx, 'gcx, 'tcx> {
81 tables: ty::TypeckTables::empty(),
86 fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
90 fn write_ty_to_tables(&mut self, node_id: ast::NodeId, ty: Ty<'gcx>) {
91 debug!("write_ty_to_tables({}, {:?})", node_id, ty);
92 assert!(!ty.needs_infer());
93 self.tables.node_types.insert(node_id, ty);
96 // Hacky hack: During type-checking, we treat *all* operators
97 // as potentially overloaded. But then, during writeback, if
98 // we observe that something like `a+b` is (known to be)
99 // operating on scalars, we clear the overload.
100 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
102 hir::ExprUnary(hir::UnNeg, ref inner) |
103 hir::ExprUnary(hir::UnNot, ref inner) => {
104 let inner_ty = self.fcx.node_ty(inner.id);
105 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
107 if inner_ty.is_scalar() {
108 let mut tables = self.fcx.tables.borrow_mut();
109 tables.type_dependent_defs.remove(&e.id);
110 tables.node_substs.remove(&e.id);
113 hir::ExprBinary(ref op, ref lhs, ref rhs) |
114 hir::ExprAssignOp(ref op, ref lhs, ref rhs) => {
115 let lhs_ty = self.fcx.node_ty(lhs.id);
116 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
118 let rhs_ty = self.fcx.node_ty(rhs.id);
119 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
121 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
122 let mut tables = self.fcx.tables.borrow_mut();
123 tables.type_dependent_defs.remove(&e.id);
124 tables.node_substs.remove(&e.id);
127 hir::ExprBinary(..) => {
128 if !op.node.is_by_value() {
129 tables.adjustments.get_mut(&lhs.id).map(|a| a.pop());
130 tables.adjustments.get_mut(&rhs.id).map(|a| a.pop());
133 hir::ExprAssignOp(..) => {
134 tables.adjustments.get_mut(&lhs.id).map(|a| a.pop());
145 ///////////////////////////////////////////////////////////////////////////
146 // Impl of Visitor for Resolver
148 // This is the master code which walks the AST. It delegates most of
149 // the heavy lifting to the generic visit and resolve functions
150 // below. In general, a function is made into a `visitor` if it must
151 // traffic in node-ids or update tables in the type context etc.
153 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
154 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
155 NestedVisitorMap::None
158 fn visit_expr(&mut self, e: &'gcx hir::Expr) {
159 self.fix_scalar_builtin_expr(e);
161 self.visit_node_id(e.span, e.id);
163 if let hir::ExprClosure(_, _, body, _) = e.node {
164 let body = self.fcx.tcx.hir.body(body);
165 for arg in &body.arguments {
166 self.visit_node_id(e.span, arg.id);
169 self.visit_body(body);
172 intravisit::walk_expr(self, e);
175 fn visit_block(&mut self, b: &'gcx hir::Block) {
176 self.visit_node_id(b.span, b.id);
177 intravisit::walk_block(self, b);
180 fn visit_pat(&mut self, p: &'gcx hir::Pat) {
181 self.visit_node_id(p.span, p.id);
182 intravisit::walk_pat(self, p);
185 fn visit_local(&mut self, l: &'gcx hir::Local) {
186 intravisit::walk_local(self, l);
187 let var_ty = self.fcx.local_ty(l.span, l.id);
188 let var_ty = self.resolve(&var_ty, &l.span);
189 self.write_ty_to_tables(l.id, var_ty);
193 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
194 fn visit_upvar_borrow_map(&mut self) {
195 for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
196 let new_upvar_capture = match *upvar_capture {
197 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
198 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
199 let r = upvar_borrow.region;
200 let r = self.resolve(&r, &upvar_id.var_id);
201 ty::UpvarCapture::ByRef(
202 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
205 debug!("Upvar capture for {:?} resolved to {:?}",
208 self.tables.upvar_capture_map.insert(*upvar_id, new_upvar_capture);
212 fn visit_closures(&mut self) {
213 for (&id, closure_ty) in self.fcx.tables.borrow().closure_tys.iter() {
214 let closure_ty = self.resolve(closure_ty, &id);
215 self.tables.closure_tys.insert(id, closure_ty);
218 for (&id, &closure_kind) in self.fcx.tables.borrow().closure_kinds.iter() {
219 self.tables.closure_kinds.insert(id, closure_kind);
223 fn visit_cast_types(&mut self) {
224 self.tables.cast_kinds.extend(
225 self.fcx.tables.borrow().cast_kinds.iter().map(|(&key, &value)| (key, value)));
228 fn visit_lints(&mut self) {
229 self.fcx.tables.borrow_mut().lints.transfer(&mut self.tables.lints);
232 fn visit_free_region_map(&mut self) {
233 let free_region_map = self.tcx().lift_to_global(&self.fcx.tables.borrow().free_region_map);
234 let free_region_map = free_region_map.expect("all regions in free-region-map are global");
235 self.tables.free_region_map = free_region_map;
238 fn visit_anon_types(&mut self) {
239 let gcx = self.tcx().global_tcx();
240 for (&node_id, &concrete_ty) in self.fcx.anon_types.borrow().iter() {
241 let inside_ty = self.resolve(&concrete_ty, &node_id);
243 // Convert the type from the function into a type valid outside
244 // the function, by replacing invalid regions with 'static,
245 // after producing an error for each of them.
246 let outside_ty = gcx.fold_regions(&inside_ty, &mut false, |r, _| {
248 // 'static and early-bound regions are valid.
250 ty::ReEarlyBound(_) |
254 ty::ReLateBound(..) |
256 ty::ReSkolemized(..) => {
257 let span = node_id.to_span(&self.fcx.tcx);
258 span_err!(self.tcx().sess, span, E0564,
259 "only named lifetimes are allowed in `impl Trait`, \
260 but `{}` was found in the type `{}`", r, inside_ty);
266 let span = node_id.to_span(&self.fcx.tcx);
267 span_bug!(span, "invalid region in impl Trait: {:?}", r);
272 self.tables.node_types.insert(node_id, outside_ty);
276 fn visit_node_id(&mut self, span: Span, node_id: ast::NodeId) {
277 // Export associated path extensions and method resultions.
278 if let Some(def) = self.fcx.tables.borrow_mut().type_dependent_defs.remove(&node_id) {
279 self.tables.type_dependent_defs.insert(node_id, def);
282 // Resolve any borrowings for the node with id `node_id`
283 self.visit_adjustments(span, node_id);
285 // Resolve the type of the node with id `node_id`
286 let n_ty = self.fcx.node_ty(node_id);
287 let n_ty = self.resolve(&n_ty, &span);
288 self.write_ty_to_tables(node_id, n_ty);
289 debug!("Node {} has type {:?}", node_id, n_ty);
291 // Resolve any substitutions
292 if let Some(&substs) = self.fcx.tables.borrow().node_substs.get(&node_id) {
293 let substs = self.resolve(&substs, &span);
294 debug!("write_substs_to_tcx({}, {:?})", node_id, substs);
295 assert!(!substs.needs_infer());
296 self.tables.node_substs.insert(node_id, substs);
300 fn visit_adjustments(&mut self, span: Span, node_id: ast::NodeId) {
301 let adjustment = self.fcx.tables.borrow_mut().adjustments.remove(&node_id);
304 debug!("No adjustments for node {}", node_id);
307 Some(adjustment) => {
308 let resolved_adjustment = self.resolve(&adjustment, &span);
309 debug!("Adjustments for node {}: {:?}", node_id, resolved_adjustment);
310 self.tables.adjustments.insert(node_id, resolved_adjustment);
315 fn visit_liberated_fn_sigs(&mut self) {
316 for (&node_id, fn_sig) in self.fcx.tables.borrow().liberated_fn_sigs.iter() {
317 let fn_sig = self.resolve(fn_sig, &node_id);
318 self.tables.liberated_fn_sigs.insert(node_id, fn_sig.clone());
322 fn visit_fru_field_types(&mut self) {
323 for (&node_id, ftys) in self.fcx.tables.borrow().fru_field_types.iter() {
324 let ftys = self.resolve(ftys, &node_id);
325 self.tables.fru_field_types.insert(node_id, ftys);
329 fn resolve<T>(&self, x: &T, span: &Locatable) -> T::Lifted
330 where T: TypeFoldable<'tcx> + ty::Lift<'gcx>
332 let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
333 if let Some(lifted) = self.tcx().lift_to_global(&x) {
336 span_bug!(span.to_span(&self.fcx.tcx),
337 "writeback: `{:?}` missing from the global type context",
344 fn to_span(&self, tcx: &TyCtxt) -> Span;
347 impl Locatable for Span {
348 fn to_span(&self, _: &TyCtxt) -> Span { *self }
351 impl Locatable for ast::NodeId {
352 fn to_span(&self, tcx: &TyCtxt) -> Span { tcx.hir.span(*self) }
355 ///////////////////////////////////////////////////////////////////////////
356 // The Resolver. This is the type folding engine that detects
357 // unresolved types and so forth.
359 struct Resolver<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
360 tcx: TyCtxt<'cx, 'gcx, 'tcx>,
361 infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
362 span: &'cx Locatable,
363 body: &'gcx hir::Body,
366 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
367 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, span: &'cx Locatable, body: &'gcx hir::Body)
368 -> Resolver<'cx, 'gcx, 'tcx>
378 fn report_error(&self, t: Ty<'tcx>) {
379 if !self.tcx.sess.has_errors() {
380 self.infcx.need_type_info(self.body.id(), self.span.to_span(&self.tcx), t);
385 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
386 fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
390 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
391 match self.infcx.fully_resolve(&t) {
394 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
396 self.report_error(t);
402 // FIXME This should be carefully checked
403 // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
404 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
405 match self.infcx.fully_resolve(&r) {
408 self.tcx.types.re_static
414 ///////////////////////////////////////////////////////////////////////////
415 // During type check, we store promises with the result of trait
416 // lookup rather than the actual results (because the results are not
417 // necessarily available immediately). These routines unwind the
418 // promises. It is expected that we will have already reported any
419 // errors that may be encountered, so if the promises store an error,
420 // a dummy result is returned.