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_type_nodes();
47 wbcx.visit_cast_types();
49 wbcx.visit_free_region_map();
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 // Mapping from free regions of the function to the
76 // early-bound versions of them, visible from the
77 // outside of the function. This is needed by, and
78 // only populated if there are any `impl Trait`.
79 free_to_bound_regions: DefIdMap<&'gcx ty::Region>,
81 body: &'gcx hir::Body,
84 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
85 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, body: &'gcx hir::Body)
86 -> WritebackCx<'cx, 'gcx, 'tcx> {
87 let mut wbcx = WritebackCx {
89 tables: ty::TypeckTables::empty(),
90 free_to_bound_regions: DefIdMap(),
94 // Only build the reverse mapping if `impl Trait` is used.
95 if fcx.anon_types.borrow().is_empty() {
99 let gcx = fcx.tcx.global_tcx();
100 let free_substs = fcx.parameter_environment.free_substs;
101 for (i, k) in free_substs.iter().enumerate() {
102 let r = if let Some(r) = k.as_region() {
108 ty::ReFree(ty::FreeRegion {
109 bound_region: ty::BoundRegion::BrNamed(def_id, name), ..
111 let bound_region = gcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
115 wbcx.free_to_bound_regions.insert(def_id, bound_region);
118 bug!("{:?} is not a free region for an early-bound lifetime", r);
126 fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
130 fn write_ty_to_tables(&mut self, node_id: ast::NodeId, ty: Ty<'gcx>) {
131 debug!("write_ty_to_tables({}, {:?})", node_id, ty);
132 assert!(!ty.needs_infer());
133 self.tables.node_types.insert(node_id, ty);
136 // Hacky hack: During type-checking, we treat *all* operators
137 // as potentially overloaded. But then, during writeback, if
138 // we observe that something like `a+b` is (known to be)
139 // operating on scalars, we clear the overload.
140 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
142 hir::ExprUnary(hir::UnNeg, ref inner) |
143 hir::ExprUnary(hir::UnNot, ref inner) => {
144 let inner_ty = self.fcx.node_ty(inner.id);
145 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
147 if inner_ty.is_scalar() {
148 self.fcx.tables.borrow_mut().method_map.remove(&MethodCall::expr(e.id));
151 hir::ExprBinary(ref op, ref lhs, ref rhs) |
152 hir::ExprAssignOp(ref op, ref lhs, ref rhs) => {
153 let lhs_ty = self.fcx.node_ty(lhs.id);
154 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
156 let rhs_ty = self.fcx.node_ty(rhs.id);
157 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
159 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
160 self.fcx.tables.borrow_mut().method_map.remove(&MethodCall::expr(e.id));
162 // weird but true: the by-ref binops put an
163 // adjustment on the lhs but not the rhs; the
164 // adjustment for rhs is kind of baked into the
167 hir::ExprBinary(..) => {
168 if !op.node.is_by_value() {
169 self.fcx.tables.borrow_mut().adjustments.remove(&lhs.id);
172 hir::ExprAssignOp(..) => {
173 self.fcx.tables.borrow_mut().adjustments.remove(&lhs.id);
184 ///////////////////////////////////////////////////////////////////////////
185 // Impl of Visitor for Resolver
187 // This is the master code which walks the AST. It delegates most of
188 // the heavy lifting to the generic visit and resolve functions
189 // below. In general, a function is made into a `visitor` if it must
190 // traffic in node-ids or update tables in the type context etc.
192 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
193 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
194 NestedVisitorMap::None
197 fn visit_stmt(&mut self, s: &'gcx hir::Stmt) {
198 self.visit_node_id(s.span, s.node.id());
199 intravisit::walk_stmt(self, s);
202 fn visit_expr(&mut self, e: &'gcx hir::Expr) {
203 self.fix_scalar_builtin_expr(e);
205 self.visit_node_id(e.span, e.id);
206 self.visit_method_map_entry(e.span, MethodCall::expr(e.id));
208 if let hir::ExprClosure(_, _, body, _) = e.node {
209 let body = self.fcx.tcx.hir.body(body);
210 for arg in &body.arguments {
211 self.visit_node_id(e.span, arg.id);
214 self.visit_body(body);
217 intravisit::walk_expr(self, e);
220 fn visit_block(&mut self, b: &'gcx hir::Block) {
221 self.visit_node_id(b.span, b.id);
222 intravisit::walk_block(self, b);
225 fn visit_pat(&mut self, p: &'gcx hir::Pat) {
226 self.visit_node_id(p.span, p.id);
227 intravisit::walk_pat(self, p);
230 fn visit_local(&mut self, l: &'gcx hir::Local) {
231 intravisit::walk_local(self, l);
232 let var_ty = self.fcx.local_ty(l.span, l.id);
233 let var_ty = self.resolve(&var_ty, &l.span);
234 self.write_ty_to_tables(l.id, var_ty);
238 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
239 fn visit_upvar_borrow_map(&mut self) {
240 for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
241 let new_upvar_capture = match *upvar_capture {
242 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
243 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
244 let r = upvar_borrow.region;
245 let r = self.resolve(&r, &upvar_id.var_id);
246 ty::UpvarCapture::ByRef(
247 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
250 debug!("Upvar capture for {:?} resolved to {:?}",
253 self.tables.upvar_capture_map.insert(*upvar_id, new_upvar_capture);
257 fn visit_closures(&mut self) {
258 for (&id, closure_ty) in self.fcx.tables.borrow().closure_tys.iter() {
259 let closure_ty = self.resolve(closure_ty, &id);
260 self.tables.closure_tys.insert(id, closure_ty);
263 for (&id, &closure_kind) in self.fcx.tables.borrow().closure_kinds.iter() {
264 self.tables.closure_kinds.insert(id, closure_kind);
268 fn visit_cast_types(&mut self) {
269 self.tables.cast_kinds.extend(
270 self.fcx.tables.borrow().cast_kinds.iter().map(|(&key, &value)| (key, value)));
273 fn visit_lints(&mut self) {
274 self.fcx.tables.borrow_mut().lints.transfer(&mut self.tables.lints);
277 fn visit_free_region_map(&mut self) {
278 self.tables.free_region_map = self.fcx.tables.borrow().free_region_map.clone();
281 fn visit_anon_types(&mut self) {
282 let gcx = self.tcx().global_tcx();
283 for (&node_id, &concrete_ty) in self.fcx.anon_types.borrow().iter() {
284 let inside_ty = self.resolve(&concrete_ty, &node_id);
286 // Convert the type from the function into a type valid outside
287 // the function, by replacing free regions with early-bound ones.
288 let outside_ty = gcx.fold_regions(&inside_ty, &mut false, |r, _| {
290 // 'static is valid everywhere.
292 ty::ReEmpty => gcx.mk_region(*r),
294 // Free regions that come from early-bound regions are valid.
295 ty::ReFree(ty::FreeRegion {
296 bound_region: ty::BoundRegion::BrNamed(def_id, ..), ..
297 }) if self.free_to_bound_regions.contains_key(&def_id) => {
298 self.free_to_bound_regions[&def_id]
302 ty::ReEarlyBound(_) |
303 ty::ReLateBound(..) |
305 ty::ReSkolemized(..) => {
306 let span = node_id.to_span(&self.fcx.tcx);
307 span_err!(self.tcx().sess, span, E0564,
308 "only named lifetimes are allowed in `impl Trait`, \
309 but `{}` was found in the type `{}`", r, inside_ty);
310 gcx.mk_region(ty::ReStatic)
315 let span = node_id.to_span(&self.fcx.tcx);
316 span_bug!(span, "invalid region in impl Trait: {:?}", r);
321 self.tables.node_types.insert(node_id, outside_ty);
325 fn visit_node_id(&mut self, span: Span, node_id: ast::NodeId) {
326 // Export associated path extensions.
327 if let Some(def) = self.fcx.tables.borrow_mut().type_relative_path_defs.remove(&node_id) {
328 self.tables.type_relative_path_defs.insert(node_id, def);
331 // Resolve any borrowings for the node with id `node_id`
332 self.visit_adjustments(span, node_id);
334 // Resolve the type of the node with id `node_id`
335 let n_ty = self.fcx.node_ty(node_id);
336 let n_ty = self.resolve(&n_ty, &span);
337 self.write_ty_to_tables(node_id, n_ty);
338 debug!("Node {} has type {:?}", node_id, n_ty);
340 // Resolve any substitutions
341 self.fcx.opt_node_ty_substs(node_id, |item_substs| {
342 let item_substs = self.resolve(item_substs, &span);
343 if !item_substs.is_noop() {
344 debug!("write_substs_to_tcx({}, {:?})", node_id, item_substs);
345 assert!(!item_substs.substs.needs_infer());
346 self.tables.item_substs.insert(node_id, item_substs);
351 fn visit_adjustments(&mut self, span: Span, node_id: ast::NodeId) {
352 let adjustments = self.fcx.tables.borrow_mut().adjustments.remove(&node_id);
355 debug!("No adjustments for node {}", node_id);
358 Some(adjustment) => {
359 let resolved_adjustment = match adjustment.kind {
360 adjustment::Adjust::NeverToAny => {
361 adjustment::Adjust::NeverToAny
364 adjustment::Adjust::ReifyFnPointer => {
365 adjustment::Adjust::ReifyFnPointer
368 adjustment::Adjust::MutToConstPointer => {
369 adjustment::Adjust::MutToConstPointer
372 adjustment::Adjust::ClosureFnPointer => {
373 adjustment::Adjust::ClosureFnPointer
376 adjustment::Adjust::UnsafeFnPointer => {
377 adjustment::Adjust::UnsafeFnPointer
380 adjustment::Adjust::DerefRef { autoderefs, autoref, unsize } => {
381 for autoderef in 0..autoderefs {
382 let method_call = MethodCall::autoderef(node_id, autoderef as u32);
383 self.visit_method_map_entry(span, method_call);
386 adjustment::Adjust::DerefRef {
387 autoderefs: autoderefs,
388 autoref: self.resolve(&autoref, &span),
393 let resolved_adjustment = adjustment::Adjustment {
394 kind: resolved_adjustment,
395 target: self.resolve(&adjustment.target, &span)
397 debug!("Adjustments for node {}: {:?}", node_id, resolved_adjustment);
398 self.tables.adjustments.insert(node_id, resolved_adjustment);
403 fn visit_method_map_entry(&mut self,
405 method_call: MethodCall) {
406 // Resolve any method map entry
407 let new_method = match self.fcx.tables.borrow_mut().method_map.remove(&method_call) {
409 debug!("writeback::resolve_method_map_entry(call={:?}, entry={:?})",
412 let new_method = MethodCallee {
413 def_id: method.def_id,
414 ty: self.resolve(&method.ty, &method_span),
415 substs: self.resolve(&method.substs, &method_span),
423 //NB(jroesch): We need to match twice to avoid a double borrow which would cause an ICE
424 if let Some(method) = new_method {
425 self.tables.method_map.insert(method_call, method);
429 fn visit_liberated_fn_sigs(&mut self) {
430 for (&node_id, fn_sig) in self.fcx.tables.borrow().liberated_fn_sigs.iter() {
431 let fn_sig = self.resolve(fn_sig, &node_id);
432 self.tables.liberated_fn_sigs.insert(node_id, fn_sig.clone());
436 fn visit_fru_field_types(&mut self) {
437 for (&node_id, ftys) in self.fcx.tables.borrow().fru_field_types.iter() {
438 let ftys = self.resolve(ftys, &node_id);
439 self.tables.fru_field_types.insert(node_id, ftys);
443 fn visit_type_nodes(&self) {
444 for (&id, ty) in self.fcx.ast_ty_to_ty_cache.borrow().iter() {
445 let ty = self.resolve(ty, &id);
446 self.fcx.tcx.ast_ty_to_ty_cache.borrow_mut().insert(id, ty);
450 fn resolve<T>(&self, x: &T, span: &Locatable) -> T::Lifted
451 where T: TypeFoldable<'tcx> + ty::Lift<'gcx>
453 let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
454 if let Some(lifted) = self.tcx().lift_to_global(&x) {
457 span_bug!(span.to_span(&self.fcx.tcx),
458 "writeback: `{:?}` missing from the global type context",
465 fn to_span(&self, tcx: &TyCtxt) -> Span;
468 impl Locatable for Span {
469 fn to_span(&self, _: &TyCtxt) -> Span { *self }
472 impl Locatable for ast::NodeId {
473 fn to_span(&self, tcx: &TyCtxt) -> Span { tcx.hir.span(*self) }
476 ///////////////////////////////////////////////////////////////////////////
477 // The Resolver. This is the type folding engine that detects
478 // unresolved types and so forth.
480 struct Resolver<'cx, 'gcx: 'cx+'tcx, 'tcx: 'cx> {
481 tcx: TyCtxt<'cx, 'gcx, 'tcx>,
482 infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
483 span: &'cx Locatable,
484 body: &'gcx hir::Body,
487 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
488 fn new(fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>, span: &'cx Locatable, body: &'gcx hir::Body)
489 -> Resolver<'cx, 'gcx, 'tcx>
499 fn report_error(&self, t: Ty<'tcx>) {
500 if !self.tcx.sess.has_errors() {
501 self.infcx.need_type_info(self.body.id(), self.span.to_span(&self.tcx), t);
506 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
507 fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
511 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
512 match self.infcx.fully_resolve(&t) {
515 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
517 self.report_error(t);
523 // FIXME This should be carefully checked
524 // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
525 fn fold_region(&mut self, r: &'tcx ty::Region) -> &'tcx ty::Region {
526 match self.infcx.fully_resolve(&r) {
529 self.tcx.mk_region(ty::ReStatic)
535 ///////////////////////////////////////////////////////////////////////////
536 // During type check, we store promises with the result of trait
537 // lookup rather than the actual results (because the results are not
538 // necessarily available immediately). These routines unwind the
539 // promises. It is expected that we will have already reported any
540 // errors that may be encountered, so if the promises store an error,
541 // a dummy result is returned.