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, MethodCall, MethodCallee};
20 use rustc::ty::adjustment;
21 use rustc::ty::fold::{TypeFolder,TypeFoldable};
22 use rustc::util::nodemap::{DefIdMap, 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.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();
48 wbcx.visit_free_region_map();
50 let used_trait_imports = mem::replace(&mut self.tables.borrow_mut().used_trait_imports,
52 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
53 wbcx.tables.used_trait_imports = used_trait_imports;
55 wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
57 self.tcx.alloc_tables(wbcx.tables)
61 ///////////////////////////////////////////////////////////////////////////
62 // The Writerback context. This visitor walks the AST, checking the
63 // fn-specific tables to find references to types or regions. It
64 // resolves those regions to remove inference variables and writes the
65 // final result back into the master tables in the tcx. Here and
66 // there, it applies a few ad-hoc checks that were not convenient to
69 struct WritebackCx<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
70 fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
72 tables: ty::TypeckTables<'gcx>,
74 // Mapping from free regions of the function to the
75 // early-bound versions of them, visible from the
76 // outside of the function. This is needed by, and
77 // only populated if there are any `impl Trait`.
78 free_to_bound_regions: DefIdMap<ty::Region<'gcx>>,
80 body: &'gcx hir::Body,
83 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
84 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, body: &'gcx hir::Body)
85 -> WritebackCx<'cx, 'gcx, 'tcx> {
86 let mut wbcx = WritebackCx {
88 tables: ty::TypeckTables::empty(),
89 free_to_bound_regions: DefIdMap(),
93 // Only build the reverse mapping if `impl Trait` is used.
94 if fcx.anon_types.borrow().is_empty() {
98 let gcx = fcx.tcx.global_tcx();
99 let free_substs = fcx.parameter_environment.free_substs;
100 for (i, k) in free_substs.iter().enumerate() {
101 let r = if let Some(r) = k.as_region() {
107 ty::ReFree(ty::FreeRegion {
108 bound_region: ty::BoundRegion::BrNamed(def_id, name), ..
110 let bound_region = gcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
114 wbcx.free_to_bound_regions.insert(def_id, bound_region);
117 bug!("{:?} is not a free region for an early-bound lifetime", r);
125 fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
129 fn write_ty_to_tables(&mut self, node_id: ast::NodeId, ty: Ty<'gcx>) {
130 debug!("write_ty_to_tables({}, {:?})", node_id, ty);
131 assert!(!ty.needs_infer());
132 self.tables.node_types.insert(node_id, ty);
135 // Hacky hack: During type-checking, we treat *all* operators
136 // as potentially overloaded. But then, during writeback, if
137 // we observe that something like `a+b` is (known to be)
138 // operating on scalars, we clear the overload.
139 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
141 hir::ExprUnary(hir::UnNeg, ref inner) |
142 hir::ExprUnary(hir::UnNot, ref inner) => {
143 let inner_ty = self.fcx.node_ty(inner.id);
144 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
146 if inner_ty.is_scalar() {
147 self.fcx.tables.borrow_mut().method_map.remove(&MethodCall::expr(e.id));
150 hir::ExprBinary(ref op, ref lhs, ref rhs) |
151 hir::ExprAssignOp(ref op, ref lhs, ref rhs) => {
152 let lhs_ty = self.fcx.node_ty(lhs.id);
153 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
155 let rhs_ty = self.fcx.node_ty(rhs.id);
156 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
158 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
159 self.fcx.tables.borrow_mut().method_map.remove(&MethodCall::expr(e.id));
161 // weird but true: the by-ref binops put an
162 // adjustment on the lhs but not the rhs; the
163 // adjustment for rhs is kind of baked into the
166 hir::ExprBinary(..) => {
167 if !op.node.is_by_value() {
168 self.fcx.tables.borrow_mut().adjustments.remove(&lhs.id);
171 hir::ExprAssignOp(..) => {
172 self.fcx.tables.borrow_mut().adjustments.remove(&lhs.id);
183 ///////////////////////////////////////////////////////////////////////////
184 // Impl of Visitor for Resolver
186 // This is the master code which walks the AST. It delegates most of
187 // the heavy lifting to the generic visit and resolve functions
188 // below. In general, a function is made into a `visitor` if it must
189 // traffic in node-ids or update tables in the type context etc.
191 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
192 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
193 NestedVisitorMap::None
196 fn visit_stmt(&mut self, s: &'gcx hir::Stmt) {
197 self.visit_node_id(s.span, s.node.id());
198 intravisit::walk_stmt(self, s);
201 fn visit_expr(&mut self, e: &'gcx hir::Expr) {
202 self.fix_scalar_builtin_expr(e);
204 self.visit_node_id(e.span, e.id);
205 self.visit_method_map_entry(e.span, MethodCall::expr(e.id));
207 if let hir::ExprClosure(_, _, body, _) = e.node {
208 let body = self.fcx.tcx.hir.body(body);
209 for arg in &body.arguments {
210 self.visit_node_id(e.span, arg.id);
213 self.visit_body(body);
216 intravisit::walk_expr(self, e);
219 fn visit_block(&mut self, b: &'gcx hir::Block) {
220 self.visit_node_id(b.span, b.id);
221 intravisit::walk_block(self, b);
224 fn visit_pat(&mut self, p: &'gcx hir::Pat) {
225 self.visit_node_id(p.span, p.id);
226 intravisit::walk_pat(self, p);
229 fn visit_local(&mut self, l: &'gcx hir::Local) {
230 intravisit::walk_local(self, l);
231 let var_ty = self.fcx.local_ty(l.span, l.id);
232 let var_ty = self.resolve(&var_ty, &l.span);
233 self.write_ty_to_tables(l.id, var_ty);
237 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
238 fn visit_upvar_borrow_map(&mut self) {
239 for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
240 let new_upvar_capture = match *upvar_capture {
241 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
242 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
243 let r = upvar_borrow.region;
244 let r = self.resolve(&r, &upvar_id.var_id);
245 ty::UpvarCapture::ByRef(
246 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
249 debug!("Upvar capture for {:?} resolved to {:?}",
252 self.tables.upvar_capture_map.insert(*upvar_id, new_upvar_capture);
256 fn visit_closures(&mut self) {
257 for (&id, closure_ty) in self.fcx.tables.borrow().closure_tys.iter() {
258 let closure_ty = self.resolve(closure_ty, &id);
259 self.tables.closure_tys.insert(id, closure_ty);
262 for (&id, &closure_kind) in self.fcx.tables.borrow().closure_kinds.iter() {
263 self.tables.closure_kinds.insert(id, closure_kind);
267 fn visit_cast_types(&mut self) {
268 self.tables.cast_kinds.extend(
269 self.fcx.tables.borrow().cast_kinds.iter().map(|(&key, &value)| (key, value)));
272 fn visit_lints(&mut self) {
273 self.fcx.tables.borrow_mut().lints.transfer(&mut self.tables.lints);
276 fn visit_free_region_map(&mut self) {
277 let free_region_map = self.tcx().lift_to_global(&self.fcx.tables.borrow().free_region_map);
278 let free_region_map = free_region_map.expect("all regions in free-region-map are global");
279 self.tables.free_region_map = free_region_map;
282 fn visit_anon_types(&mut self) {
283 let gcx = self.tcx().global_tcx();
284 for (&node_id, &concrete_ty) in self.fcx.anon_types.borrow().iter() {
285 let inside_ty = self.resolve(&concrete_ty, &node_id);
287 // Convert the type from the function into a type valid outside
288 // the function, by replacing free regions with early-bound ones.
289 let outside_ty = gcx.fold_regions(&inside_ty, &mut false, |r, _| {
291 // 'static is valid everywhere.
292 ty::ReStatic => gcx.types.re_static,
293 ty::ReEmpty => gcx.types.re_empty,
295 // Free regions that come from early-bound regions are valid.
296 ty::ReFree(ty::FreeRegion {
297 bound_region: ty::BoundRegion::BrNamed(def_id, ..), ..
298 }) if self.free_to_bound_regions.contains_key(&def_id) => {
299 self.free_to_bound_regions[&def_id]
303 ty::ReEarlyBound(_) |
304 ty::ReLateBound(..) |
306 ty::ReSkolemized(..) => {
307 let span = node_id.to_span(&self.fcx.tcx);
308 span_err!(self.tcx().sess, span, E0564,
309 "only named lifetimes are allowed in `impl Trait`, \
310 but `{}` was found in the type `{}`", r, inside_ty);
316 let span = node_id.to_span(&self.fcx.tcx);
317 span_bug!(span, "invalid region in impl Trait: {:?}", r);
322 self.tables.node_types.insert(node_id, outside_ty);
326 fn visit_node_id(&mut self, span: Span, node_id: ast::NodeId) {
327 // Export associated path extensions.
328 if let Some(def) = self.fcx.tables.borrow_mut().type_relative_path_defs.remove(&node_id) {
329 self.tables.type_relative_path_defs.insert(node_id, def);
332 // Resolve any borrowings for the node with id `node_id`
333 self.visit_adjustments(span, node_id);
335 // Resolve the type of the node with id `node_id`
336 let n_ty = self.fcx.node_ty(node_id);
337 let n_ty = self.resolve(&n_ty, &span);
338 self.write_ty_to_tables(node_id, n_ty);
339 debug!("Node {} has type {:?}", node_id, n_ty);
341 // Resolve any substitutions
342 self.fcx.opt_node_ty_substs(node_id, |item_substs| {
343 let item_substs = self.resolve(item_substs, &span);
344 if !item_substs.is_noop() {
345 debug!("write_substs_to_tcx({}, {:?})", node_id, item_substs);
346 assert!(!item_substs.substs.needs_infer());
347 self.tables.item_substs.insert(node_id, item_substs);
352 fn visit_adjustments(&mut self, span: Span, node_id: ast::NodeId) {
353 let adjustments = self.fcx.tables.borrow_mut().adjustments.remove(&node_id);
356 debug!("No adjustments for node {}", node_id);
359 Some(adjustment) => {
360 let resolved_adjustment = match adjustment.kind {
361 adjustment::Adjust::NeverToAny => {
362 adjustment::Adjust::NeverToAny
365 adjustment::Adjust::ReifyFnPointer => {
366 adjustment::Adjust::ReifyFnPointer
369 adjustment::Adjust::MutToConstPointer => {
370 adjustment::Adjust::MutToConstPointer
373 adjustment::Adjust::ClosureFnPointer => {
374 adjustment::Adjust::ClosureFnPointer
377 adjustment::Adjust::UnsafeFnPointer => {
378 adjustment::Adjust::UnsafeFnPointer
381 adjustment::Adjust::DerefRef { autoderefs, autoref, unsize } => {
382 for autoderef in 0..autoderefs {
383 let method_call = MethodCall::autoderef(node_id, autoderef as u32);
384 self.visit_method_map_entry(span, method_call);
387 adjustment::Adjust::DerefRef {
388 autoderefs: autoderefs,
389 autoref: self.resolve(&autoref, &span),
394 let resolved_adjustment = adjustment::Adjustment {
395 kind: resolved_adjustment,
396 target: self.resolve(&adjustment.target, &span)
398 debug!("Adjustments for node {}: {:?}", node_id, resolved_adjustment);
399 self.tables.adjustments.insert(node_id, resolved_adjustment);
404 fn visit_method_map_entry(&mut self,
406 method_call: MethodCall) {
407 // Resolve any method map entry
408 let new_method = match self.fcx.tables.borrow_mut().method_map.remove(&method_call) {
410 debug!("writeback::resolve_method_map_entry(call={:?}, entry={:?})",
413 let new_method = MethodCallee {
414 def_id: method.def_id,
415 ty: self.resolve(&method.ty, &method_span),
416 substs: self.resolve(&method.substs, &method_span),
424 //NB(jroesch): We need to match twice to avoid a double borrow which would cause an ICE
425 if let Some(method) = new_method {
426 self.tables.method_map.insert(method_call, method);
430 fn visit_liberated_fn_sigs(&mut self) {
431 for (&node_id, fn_sig) in self.fcx.tables.borrow().liberated_fn_sigs.iter() {
432 let fn_sig = self.resolve(fn_sig, &node_id);
433 self.tables.liberated_fn_sigs.insert(node_id, fn_sig.clone());
437 fn visit_fru_field_types(&mut self) {
438 for (&node_id, ftys) in self.fcx.tables.borrow().fru_field_types.iter() {
439 let ftys = self.resolve(ftys, &node_id);
440 self.tables.fru_field_types.insert(node_id, ftys);
444 fn resolve<T>(&self, x: &T, span: &Locatable) -> T::Lifted
445 where T: TypeFoldable<'tcx> + ty::Lift<'gcx>
447 let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
448 if let Some(lifted) = self.tcx().lift_to_global(&x) {
451 span_bug!(span.to_span(&self.fcx.tcx),
452 "writeback: `{:?}` missing from the global type context",
459 fn to_span(&self, tcx: &TyCtxt) -> Span;
462 impl Locatable for Span {
463 fn to_span(&self, _: &TyCtxt) -> Span { *self }
466 impl Locatable for ast::NodeId {
467 fn to_span(&self, tcx: &TyCtxt) -> Span { tcx.hir.span(*self) }
470 ///////////////////////////////////////////////////////////////////////////
471 // The Resolver. This is the type folding engine that detects
472 // unresolved types and so forth.
474 struct Resolver<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
475 tcx: TyCtxt<'cx, 'gcx, 'tcx>,
476 infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
477 span: &'cx Locatable,
478 body: &'gcx hir::Body,
481 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
482 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, span: &'cx Locatable, body: &'gcx hir::Body)
483 -> Resolver<'cx, 'gcx, 'tcx>
493 fn report_error(&self, t: Ty<'tcx>) {
494 if !self.tcx.sess.has_errors() {
495 self.infcx.need_type_info(self.body.id(), self.span.to_span(&self.tcx), t);
500 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
501 fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
505 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
506 match self.infcx.fully_resolve(&t) {
509 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
511 self.report_error(t);
517 // FIXME This should be carefully checked
518 // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
519 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
520 match self.infcx.fully_resolve(&r) {
523 self.tcx.types.re_static
529 ///////////////////////////////////////////////////////////////////////////
530 // During type check, we store promises with the result of trait
531 // lookup rather than the actual results (because the results are not
532 // necessarily available immediately). These routines unwind the
533 // promises. It is expected that we will have already reported any
534 // errors that may be encountered, so if the promises store an error,
535 // a dummy result is returned.