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;
30 use syntax::codemap::{DUMMY_SP, Span};
31 use syntax::print::pprust::pat_to_string;
33 use syntax::visit::Visitor;
35 ///////////////////////////////////////////////////////////////////////////
36 // Entry point functions
38 pub fn resolve_type_vars_in_expr(fcx: &FnCtxt, e: &ast::Expr) {
39 assert_eq!(fcx.writeback_errors.get(), false);
40 let mut wbcx = WritebackCx::new(fcx);
42 wbcx.visit_upvar_borrow_map();
43 wbcx.visit_closures();
46 pub fn resolve_type_vars_in_fn(fcx: &FnCtxt,
49 assert_eq!(fcx.writeback_errors.get(), false);
50 let mut wbcx = WritebackCx::new(fcx);
51 wbcx.visit_block(blk);
52 for arg in &decl.inputs {
53 wbcx.visit_node_id(ResolvingPattern(arg.pat.span), arg.id);
54 wbcx.visit_pat(&*arg.pat);
56 // Privacy needs the type for the whole pattern, not just each binding
57 if !pat_util::pat_is_binding(&fcx.tcx().def_map, &*arg.pat) {
58 wbcx.visit_node_id(ResolvingPattern(arg.pat.span),
62 wbcx.visit_upvar_borrow_map();
63 wbcx.visit_closures();
66 ///////////////////////////////////////////////////////////////////////////
67 // The Writerback context. This visitor walks the AST, checking the
68 // fn-specific tables to find references to types or regions. It
69 // resolves those regions to remove inference variables and writes the
70 // final result back into the master tables in the tcx. Here and
71 // there, it applies a few ad-hoc checks that were not convenient to
74 struct WritebackCx<'cx, 'tcx: 'cx> {
75 fcx: &'cx FnCtxt<'cx, 'tcx>,
78 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
79 fn new(fcx: &'cx FnCtxt<'cx, 'tcx>) -> WritebackCx<'cx, 'tcx> {
80 WritebackCx { fcx: fcx }
83 fn tcx(&self) -> &'cx ty::ctxt<'tcx> {
87 // Hacky hack: During type-checking, we treat *all* operators
88 // as potentially overloaded. But then, during writeback, if
89 // we observe that something like `a+b` is (known to be)
90 // operating on scalars, we clear the overload.
91 fn fix_scalar_binary_expr(&mut self, e: &ast::Expr) {
92 if let ast::ExprBinary(ref op, ref lhs, ref rhs) = e.node {
93 let lhs_ty = self.fcx.node_ty(lhs.id);
94 let lhs_ty = self.fcx.infcx().resolve_type_vars_if_possible(&lhs_ty);
96 let rhs_ty = self.fcx.node_ty(rhs.id);
97 let rhs_ty = self.fcx.infcx().resolve_type_vars_if_possible(&rhs_ty);
99 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
100 self.fcx.inh.tables.borrow_mut().method_map.remove(&MethodCall::expr(e.id));
102 // weird but true: the by-ref binops put an
103 // adjustment on the lhs but not the rhs; the
104 // adjustment for rhs is kind of baked into the
106 if !ast_util::is_by_value_binop(op.node) {
107 self.fcx.inh.tables.borrow_mut().adjustments.remove(&lhs.id);
114 ///////////////////////////////////////////////////////////////////////////
115 // Impl of Visitor for Resolver
117 // This is the master code which walks the AST. It delegates most of
118 // the heavy lifting to the generic visit and resolve functions
119 // below. In general, a function is made into a `visitor` if it must
120 // traffic in node-ids or update tables in the type context etc.
122 impl<'cx, 'tcx, 'v> Visitor<'v> for WritebackCx<'cx, 'tcx> {
123 fn visit_item(&mut self, _: &ast::Item) {
127 fn visit_stmt(&mut self, s: &ast::Stmt) {
128 if self.fcx.writeback_errors.get() {
132 self.visit_node_id(ResolvingExpr(s.span), ast_util::stmt_id(s));
133 visit::walk_stmt(self, s);
136 fn visit_expr(&mut self, e: &ast::Expr) {
137 if self.fcx.writeback_errors.get() {
141 self.fix_scalar_binary_expr(e);
143 self.visit_node_id(ResolvingExpr(e.span), e.id);
144 self.visit_method_map_entry(ResolvingExpr(e.span),
145 MethodCall::expr(e.id));
147 if let ast::ExprClosure(_, ref decl, _) = e.node {
148 for input in &decl.inputs {
149 self.visit_node_id(ResolvingExpr(e.span), input.id);
153 visit::walk_expr(self, e);
156 fn visit_block(&mut self, b: &ast::Block) {
157 if self.fcx.writeback_errors.get() {
161 self.visit_node_id(ResolvingExpr(b.span), b.id);
162 visit::walk_block(self, b);
165 fn visit_pat(&mut self, p: &ast::Pat) {
166 if self.fcx.writeback_errors.get() {
170 self.visit_node_id(ResolvingPattern(p.span), p.id);
172 debug!("Type for pattern binding {} (id {}) resolved to {:?}",
175 self.tcx().node_id_to_type(p.id));
177 visit::walk_pat(self, p);
180 fn visit_local(&mut self, l: &ast::Local) {
181 if self.fcx.writeback_errors.get() {
185 let var_ty = self.fcx.local_ty(l.span, l.id);
186 let var_ty = self.resolve(&var_ty, ResolvingLocal(l.span));
187 write_ty_to_tcx(self.tcx(), l.id, var_ty);
188 visit::walk_local(self, l);
191 fn visit_ty(&mut self, t: &ast::Ty) {
193 ast::TyFixedLengthVec(ref ty, ref count_expr) => {
194 self.visit_ty(&**ty);
195 write_ty_to_tcx(self.tcx(), count_expr.id, self.tcx().types.usize);
197 _ => visit::walk_ty(self, t)
202 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
203 fn visit_upvar_borrow_map(&self) {
204 if self.fcx.writeback_errors.get() {
208 for (upvar_id, upvar_capture) in self.fcx.inh.tables.borrow().upvar_capture_map.iter() {
209 let new_upvar_capture = match *upvar_capture {
210 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
211 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
212 let r = upvar_borrow.region;
213 let r = self.resolve(&r, ResolvingUpvar(*upvar_id));
214 ty::UpvarCapture::ByRef(
215 ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
218 debug!("Upvar capture for {:?} resolved to {:?}",
225 .insert(*upvar_id, new_upvar_capture);
229 fn visit_closures(&self) {
230 if self.fcx.writeback_errors.get() {
234 for (def_id, closure_ty) in self.fcx.inh.tables.borrow().closure_tys.iter() {
235 let closure_ty = self.resolve(closure_ty, ResolvingClosure(*def_id));
236 self.fcx.tcx().tables.borrow_mut().closure_tys.insert(*def_id, closure_ty);
239 for (def_id, &closure_kind) in self.fcx.inh.tables.borrow().closure_kinds.iter() {
240 self.fcx.tcx().tables.borrow_mut().closure_kinds.insert(*def_id, closure_kind);
244 fn visit_node_id(&self, reason: ResolveReason, id: ast::NodeId) {
245 // Resolve any borrowings for the node with id `id`
246 self.visit_adjustments(reason, id);
248 // Resolve the type of the node with id `id`
249 let n_ty = self.fcx.node_ty(id);
250 let n_ty = self.resolve(&n_ty, reason);
251 write_ty_to_tcx(self.tcx(), id, n_ty);
252 debug!("Node {} has type {:?}", id, n_ty);
254 // Resolve any substitutions
255 self.fcx.opt_node_ty_substs(id, |item_substs| {
256 write_substs_to_tcx(self.tcx(), id,
257 self.resolve(item_substs, reason));
261 fn visit_adjustments(&self, reason: ResolveReason, id: ast::NodeId) {
262 let adjustments = self.fcx.inh.tables.borrow_mut().adjustments.remove(&id);
265 debug!("No adjustments for node {}", id);
268 Some(adjustment) => {
269 let resolved_adjustment = match adjustment {
270 ty::AdjustReifyFnPointer => ty::AdjustReifyFnPointer,
272 ty::AdjustUnsafeFnPointer => {
273 ty::AdjustUnsafeFnPointer
276 ty::AdjustDerefRef(adj) => {
277 for autoderef in 0..adj.autoderefs {
278 let method_call = MethodCall::autoderef(id, autoderef as u32);
279 self.visit_method_map_entry(reason, method_call);
282 ty::AdjustDerefRef(ty::AutoDerefRef {
283 autoderefs: adj.autoderefs,
284 autoref: self.resolve(&adj.autoref, reason),
285 unsize: self.resolve(&adj.unsize, reason),
289 debug!("Adjustments for node {}: {:?}", id, resolved_adjustment);
290 self.tcx().tables.borrow_mut().adjustments.insert(
291 id, resolved_adjustment);
296 fn visit_method_map_entry(&self,
297 reason: ResolveReason,
298 method_call: MethodCall) {
299 // Resolve any method map entry
300 let new_method = match self.fcx.inh.tables.borrow_mut().method_map.remove(&method_call) {
302 debug!("writeback::resolve_method_map_entry(call={:?}, entry={:?})",
305 let new_method = MethodCallee {
306 def_id: method.def_id,
307 ty: self.resolve(&method.ty, reason),
308 substs: self.tcx().mk_substs(self.resolve(method.substs, reason)),
316 //NB(jroesch): We need to match twice to avoid a double borrow which would cause an ICE
319 self.tcx().tables.borrow_mut().method_map.insert(
327 fn resolve<T:TypeFoldable<'tcx>>(&self, t: &T, reason: ResolveReason) -> T {
328 t.fold_with(&mut Resolver::new(self.fcx, reason))
332 ///////////////////////////////////////////////////////////////////////////
333 // Resolution reason.
335 #[derive(Copy, Clone)]
338 ResolvingLocal(Span),
339 ResolvingPattern(Span),
340 ResolvingUpvar(ty::UpvarId),
341 ResolvingClosure(DefId),
345 fn span(&self, tcx: &ty::ctxt) -> Span {
347 ResolvingExpr(s) => s,
348 ResolvingLocal(s) => s,
349 ResolvingPattern(s) => s,
350 ResolvingUpvar(upvar_id) => {
351 tcx.expr_span(upvar_id.closure_expr_id)
353 ResolvingClosure(did) => {
355 tcx.expr_span(did.node)
364 ///////////////////////////////////////////////////////////////////////////
365 // The Resolver. This is the type folding engine that detects
366 // unresolved types and so forth.
368 struct Resolver<'cx, 'tcx: 'cx> {
369 tcx: &'cx ty::ctxt<'tcx>,
370 infcx: &'cx infer::InferCtxt<'cx, 'tcx>,
371 writeback_errors: &'cx Cell<bool>,
372 reason: ResolveReason,
375 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
376 fn new(fcx: &'cx FnCtxt<'cx, 'tcx>,
377 reason: ResolveReason)
378 -> Resolver<'cx, 'tcx>
380 Resolver::from_infcx(fcx.infcx(), &fcx.writeback_errors, reason)
383 fn from_infcx(infcx: &'cx infer::InferCtxt<'cx, 'tcx>,
384 writeback_errors: &'cx Cell<bool>,
385 reason: ResolveReason)
386 -> Resolver<'cx, 'tcx>
388 Resolver { infcx: infcx,
390 writeback_errors: writeback_errors,
394 fn report_error(&self, e: infer::FixupError) {
395 self.writeback_errors.set(true);
396 if !self.tcx.sess.has_errors() {
398 ResolvingExpr(span) => {
399 span_err!(self.tcx.sess, span, E0101,
400 "cannot determine a type for this expression: {}",
401 infer::fixup_err_to_string(e));
404 ResolvingLocal(span) => {
405 span_err!(self.tcx.sess, span, E0102,
406 "cannot determine a type for this local variable: {}",
407 infer::fixup_err_to_string(e));
410 ResolvingPattern(span) => {
411 span_err!(self.tcx.sess, span, E0103,
412 "cannot determine a type for this pattern binding: {}",
413 infer::fixup_err_to_string(e));
416 ResolvingUpvar(upvar_id) => {
417 let span = self.reason.span(self.tcx);
418 span_err!(self.tcx.sess, span, E0104,
419 "cannot resolve lifetime for captured variable `{}`: {}",
420 self.tcx.local_var_name_str(upvar_id.var_id).to_string(),
421 infer::fixup_err_to_string(e));
424 ResolvingClosure(_) => {
425 let span = self.reason.span(self.tcx);
426 span_err!(self.tcx.sess, span, E0196,
427 "cannot determine a type for this closure")
434 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
435 fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> {
439 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
440 match self.infcx.fully_resolve(&t) {
443 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable",
445 self.report_error(e);
451 fn fold_region(&mut self, r: ty::Region) -> ty::Region {
452 match self.infcx.fully_resolve(&r) {
455 self.report_error(e);
462 ///////////////////////////////////////////////////////////////////////////
463 // During type check, we store promises with the result of trait
464 // lookup rather than the actual results (because the results are not
465 // necessarily available immediately). These routines unwind the
466 // promises. It is expected that we will have already reported any
467 // errors that may be encountered, so if the promises store an error,
468 // a dummy result is returned.