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
14 use self::ResolveReason::*;
18 use middle::def_id::DefId;
20 use middle::ty::{self, Ty, MethodCall, MethodCallee};
21 use middle::ty_fold::{TypeFolder,TypeFoldable};
23 use write_substs_to_tcx;
29 use syntax::codemap::{DUMMY_SP, Span};
30 use rustc_front::print::pprust::pat_to_string;
31 use rustc_front::visit;
32 use rustc_front::visit::Visitor;
33 use rustc_front::util as hir_util;
36 ///////////////////////////////////////////////////////////////////////////
37 // Entry point functions
39 pub fn resolve_type_vars_in_expr(fcx: &FnCtxt, e: &hir::Expr) {
40 assert_eq!(fcx.writeback_errors.get(), false);
41 let mut wbcx = WritebackCx::new(fcx);
43 wbcx.visit_upvar_borrow_map();
44 wbcx.visit_closures();
47 pub fn resolve_type_vars_in_fn(fcx: &FnCtxt,
50 assert_eq!(fcx.writeback_errors.get(), false);
51 let mut wbcx = WritebackCx::new(fcx);
52 wbcx.visit_block(blk);
53 for arg in &decl.inputs {
54 wbcx.visit_node_id(ResolvingPattern(arg.pat.span), arg.id);
55 wbcx.visit_pat(&*arg.pat);
57 // Privacy needs the type for the whole pattern, not just each binding
58 if !pat_util::pat_is_binding(&fcx.tcx().def_map, &*arg.pat) {
59 wbcx.visit_node_id(ResolvingPattern(arg.pat.span),
63 wbcx.visit_upvar_borrow_map();
64 wbcx.visit_closures();
67 ///////////////////////////////////////////////////////////////////////////
68 // The Writerback context. This visitor walks the AST, checking the
69 // fn-specific tables to find references to types or regions. It
70 // resolves those regions to remove inference variables and writes the
71 // final result back into the master tables in the tcx. Here and
72 // there, it applies a few ad-hoc checks that were not convenient to
75 struct WritebackCx<'cx, 'tcx: 'cx> {
76 fcx: &'cx FnCtxt<'cx, 'tcx>,
79 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
80 fn new(fcx: &'cx FnCtxt<'cx, 'tcx>) -> WritebackCx<'cx, 'tcx> {
81 WritebackCx { fcx: fcx }
84 fn tcx(&self) -> &'cx ty::ctxt<'tcx> {
88 // Hacky hack: During type-checking, we treat *all* operators
89 // as potentially overloaded. But then, during writeback, if
90 // we observe that something like `a+b` is (known to be)
91 // operating on scalars, we clear the overload.
92 fn fix_scalar_binary_expr(&mut self, e: &hir::Expr) {
93 if let hir::ExprBinary(ref op, ref lhs, ref rhs) = e.node {
94 let lhs_ty = self.fcx.node_ty(lhs.id);
95 let lhs_ty = self.fcx.infcx().resolve_type_vars_if_possible(&lhs_ty);
97 let rhs_ty = self.fcx.node_ty(rhs.id);
98 let rhs_ty = self.fcx.infcx().resolve_type_vars_if_possible(&rhs_ty);
100 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
101 self.fcx.inh.tables.borrow_mut().method_map.remove(&MethodCall::expr(e.id));
103 // weird but true: the by-ref binops put an
104 // adjustment on the lhs but not the rhs; the
105 // adjustment for rhs is kind of baked into the
107 if !hir_util::is_by_value_binop(op.node) {
108 self.fcx.inh.tables.borrow_mut().adjustments.remove(&lhs.id);
115 ///////////////////////////////////////////////////////////////////////////
116 // Impl of Visitor for Resolver
118 // This is the master code which walks the AST. It delegates most of
119 // the heavy lifting to the generic visit and resolve functions
120 // below. In general, a function is made into a `visitor` if it must
121 // traffic in node-ids or update tables in the type context etc.
123 impl<'cx, 'tcx, 'v> Visitor<'v> for WritebackCx<'cx, 'tcx> {
124 fn visit_item(&mut self, _: &hir::Item) {
128 fn visit_stmt(&mut self, s: &hir::Stmt) {
129 if self.fcx.writeback_errors.get() {
133 self.visit_node_id(ResolvingExpr(s.span), hir_util::stmt_id(s));
134 visit::walk_stmt(self, s);
137 fn visit_expr(&mut self, e: &hir::Expr) {
138 if self.fcx.writeback_errors.get() {
142 self.fix_scalar_binary_expr(e);
144 self.visit_node_id(ResolvingExpr(e.span), e.id);
145 self.visit_method_map_entry(ResolvingExpr(e.span),
146 MethodCall::expr(e.id));
148 if let hir::ExprClosure(_, ref decl, _) = e.node {
149 for input in &decl.inputs {
150 self.visit_node_id(ResolvingExpr(e.span), input.id);
154 visit::walk_expr(self, e);
157 fn visit_block(&mut self, b: &hir::Block) {
158 if self.fcx.writeback_errors.get() {
162 self.visit_node_id(ResolvingExpr(b.span), b.id);
163 visit::walk_block(self, b);
166 fn visit_pat(&mut self, p: &hir::Pat) {
167 if self.fcx.writeback_errors.get() {
171 self.visit_node_id(ResolvingPattern(p.span), p.id);
173 debug!("Type for pattern binding {} (id {}) resolved to {:?}",
176 self.tcx().node_id_to_type(p.id));
178 visit::walk_pat(self, p);
181 fn visit_local(&mut self, l: &hir::Local) {
182 if self.fcx.writeback_errors.get() {
186 let var_ty = self.fcx.local_ty(l.span, l.id);
187 let var_ty = self.resolve(&var_ty, ResolvingLocal(l.span));
188 write_ty_to_tcx(self.tcx(), l.id, var_ty);
189 visit::walk_local(self, l);
192 fn visit_ty(&mut self, t: &hir::Ty) {
194 hir::TyFixedLengthVec(ref ty, ref count_expr) => {
195 self.visit_ty(&**ty);
196 write_ty_to_tcx(self.tcx(), count_expr.id, self.tcx().types.usize);
198 _ => visit::walk_ty(self, t)
203 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
204 fn visit_upvar_borrow_map(&self) {
205 if self.fcx.writeback_errors.get() {
209 for (upvar_id, upvar_capture) in self.fcx.inh.tables.borrow().upvar_capture_map.iter() {
210 let new_upvar_capture = match *upvar_capture {
211 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
212 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
213 let r = upvar_borrow.region;
214 let r = self.resolve(&r, ResolvingUpvar(*upvar_id));
215 ty::UpvarCapture::ByRef(
216 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
219 debug!("Upvar capture for {:?} resolved to {:?}",
226 .insert(*upvar_id, new_upvar_capture);
230 fn visit_closures(&self) {
231 if self.fcx.writeback_errors.get() {
235 for (def_id, closure_ty) in self.fcx.inh.tables.borrow().closure_tys.iter() {
236 let closure_ty = self.resolve(closure_ty, ResolvingClosure(*def_id));
237 self.fcx.tcx().tables.borrow_mut().closure_tys.insert(*def_id, closure_ty);
240 for (def_id, &closure_kind) in self.fcx.inh.tables.borrow().closure_kinds.iter() {
241 self.fcx.tcx().tables.borrow_mut().closure_kinds.insert(*def_id, closure_kind);
245 fn visit_node_id(&self, reason: ResolveReason, id: ast::NodeId) {
246 // Resolve any borrowings for the node with id `id`
247 self.visit_adjustments(reason, id);
249 // Resolve the type of the node with id `id`
250 let n_ty = self.fcx.node_ty(id);
251 let n_ty = self.resolve(&n_ty, reason);
252 write_ty_to_tcx(self.tcx(), id, n_ty);
253 debug!("Node {} has type {:?}", id, n_ty);
255 // Resolve any substitutions
256 self.fcx.opt_node_ty_substs(id, |item_substs| {
257 write_substs_to_tcx(self.tcx(), id,
258 self.resolve(item_substs, reason));
262 fn visit_adjustments(&self, reason: ResolveReason, id: ast::NodeId) {
263 let adjustments = self.fcx.inh.tables.borrow_mut().adjustments.remove(&id);
266 debug!("No adjustments for node {}", id);
269 Some(adjustment) => {
270 let resolved_adjustment = match adjustment {
271 ty::AdjustReifyFnPointer => ty::AdjustReifyFnPointer,
273 ty::AdjustUnsafeFnPointer => {
274 ty::AdjustUnsafeFnPointer
277 ty::AdjustDerefRef(adj) => {
278 for autoderef in 0..adj.autoderefs {
279 let method_call = MethodCall::autoderef(id, autoderef as u32);
280 self.visit_method_map_entry(reason, method_call);
283 ty::AdjustDerefRef(ty::AutoDerefRef {
284 autoderefs: adj.autoderefs,
285 autoref: self.resolve(&adj.autoref, reason),
286 unsize: self.resolve(&adj.unsize, reason),
290 debug!("Adjustments for node {}: {:?}", id, resolved_adjustment);
291 self.tcx().tables.borrow_mut().adjustments.insert(
292 id, resolved_adjustment);
297 fn visit_method_map_entry(&self,
298 reason: ResolveReason,
299 method_call: MethodCall) {
300 // Resolve any method map entry
301 let new_method = match self.fcx.inh.tables.borrow_mut().method_map.remove(&method_call) {
303 debug!("writeback::resolve_method_map_entry(call={:?}, entry={:?})",
306 let new_method = MethodCallee {
307 def_id: method.def_id,
308 ty: self.resolve(&method.ty, reason),
309 substs: self.tcx().mk_substs(self.resolve(method.substs, reason)),
317 //NB(jroesch): We need to match twice to avoid a double borrow which would cause an ICE
320 self.tcx().tables.borrow_mut().method_map.insert(
328 fn resolve<T:TypeFoldable<'tcx>>(&self, t: &T, reason: ResolveReason) -> T {
329 t.fold_with(&mut Resolver::new(self.fcx, reason))
333 ///////////////////////////////////////////////////////////////////////////
334 // Resolution reason.
336 #[derive(Copy, Clone)]
339 ResolvingLocal(Span),
340 ResolvingPattern(Span),
341 ResolvingUpvar(ty::UpvarId),
342 ResolvingClosure(DefId),
346 fn span(&self, tcx: &ty::ctxt) -> Span {
348 ResolvingExpr(s) => s,
349 ResolvingLocal(s) => s,
350 ResolvingPattern(s) => s,
351 ResolvingUpvar(upvar_id) => {
352 tcx.expr_span(upvar_id.closure_expr_id)
354 ResolvingClosure(did) => {
356 tcx.expr_span(did.node)
365 ///////////////////////////////////////////////////////////////////////////
366 // The Resolver. This is the type folding engine that detects
367 // unresolved types and so forth.
369 struct Resolver<'cx, 'tcx: 'cx> {
370 tcx: &'cx ty::ctxt<'tcx>,
371 infcx: &'cx infer::InferCtxt<'cx, 'tcx>,
372 writeback_errors: &'cx Cell<bool>,
373 reason: ResolveReason,
376 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
377 fn new(fcx: &'cx FnCtxt<'cx, 'tcx>,
378 reason: ResolveReason)
379 -> Resolver<'cx, 'tcx>
381 Resolver::from_infcx(fcx.infcx(), &fcx.writeback_errors, reason)
384 fn from_infcx(infcx: &'cx infer::InferCtxt<'cx, 'tcx>,
385 writeback_errors: &'cx Cell<bool>,
386 reason: ResolveReason)
387 -> Resolver<'cx, 'tcx>
389 Resolver { infcx: infcx,
391 writeback_errors: writeback_errors,
395 fn report_error(&self, e: infer::FixupError) {
396 self.writeback_errors.set(true);
397 if !self.tcx.sess.has_errors() {
399 ResolvingExpr(span) => {
400 span_err!(self.tcx.sess, span, E0101,
401 "cannot determine a type for this expression: {}",
402 infer::fixup_err_to_string(e));
405 ResolvingLocal(span) => {
406 span_err!(self.tcx.sess, span, E0102,
407 "cannot determine a type for this local variable: {}",
408 infer::fixup_err_to_string(e));
411 ResolvingPattern(span) => {
412 span_err!(self.tcx.sess, span, E0103,
413 "cannot determine a type for this pattern binding: {}",
414 infer::fixup_err_to_string(e));
417 ResolvingUpvar(upvar_id) => {
418 let span = self.reason.span(self.tcx);
419 span_err!(self.tcx.sess, span, E0104,
420 "cannot resolve lifetime for captured variable `{}`: {}",
421 self.tcx.local_var_name_str(upvar_id.var_id).to_string(),
422 infer::fixup_err_to_string(e));
425 ResolvingClosure(_) => {
426 let span = self.reason.span(self.tcx);
427 span_err!(self.tcx.sess, span, E0196,
428 "cannot determine a type for this closure")
435 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
436 fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> {
440 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
441 match self.infcx.fully_resolve(&t) {
444 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
446 self.report_error(e);
452 fn fold_region(&mut self, r: ty::Region) -> ty::Region {
453 match self.infcx.fully_resolve(&r) {
456 self.report_error(e);
463 ///////////////////////////////////////////////////////////////////////////
464 // During type check, we store promises with the result of trait
465 // lookup rather than the actual results (because the results are not
466 // necessarily available immediately). These routines unwind the
467 // promises. It is expected that we will have already reported any
468 // errors that may be encountered, so if the promises store an error,
469 // a dummy result is returned.