1 // Copyright 2012-2015 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.
15 Within the check phase of type check, we check each item one at a time
16 (bodies of function expressions are checked as part of the containing
17 function). Inference is used to supply types wherever they are
20 By far the most complex case is checking the body of a function. This
21 can be broken down into several distinct phases:
23 - gather: creates type variables to represent the type of each local
24 variable and pattern binding.
26 - main: the main pass does the lion's share of the work: it
27 determines the types of all expressions, resolves
28 methods, checks for most invalid conditions, and so forth. In
29 some cases, where a type is unknown, it may create a type or region
30 variable and use that as the type of an expression.
32 In the process of checking, various constraints will be placed on
33 these type variables through the subtyping relationships requested
34 through the `demand` module. The `infer` module is in charge
35 of resolving those constraints.
37 - regionck: after main is complete, the regionck pass goes over all
38 types looking for regions and making sure that they did not escape
39 into places they are not in scope. This may also influence the
40 final assignments of the various region variables if there is some
43 - vtable: find and records the impls to use for each trait bound that
44 appears on a type parameter.
46 - writeback: writes the final types within a function body, replacing
47 type variables with their final inferred types. These final types
48 are written into the `tcx.node_types` table, which should *never* contain
49 any reference to a type variable.
53 While type checking a function, the intermediate types for the
54 expressions, blocks, and so forth contained within the function are
55 stored in `fcx.node_types` and `fcx.item_substs`. These types
56 may contain unresolved type variables. After type checking is
57 complete, the functions in the writeback module are used to take the
58 types from this table, resolve them, and then write them into their
59 permanent home in the type context `ccx.tcx`.
61 This means that during inferencing you should use `fcx.write_ty()`
62 and `fcx.expr_ty()` / `fcx.node_ty()` to write/obtain the types of
63 nodes within the function.
65 The types of top-level items, which never contain unbound type
66 variables, are stored directly into the `tcx` tables.
68 n.b.: A type variable is not the same thing as a type parameter. A
69 type variable is rather an "instance" of a type parameter: that is,
70 given a generic function `fn foo<T>(t: T)`: while checking the
71 function `foo`, the type `ty_param(0)` refers to the type `T`, which
72 is treated in abstract. When `foo()` is called, however, `T` will be
73 substituted for a fresh type variable `N`. This variable will
74 eventually be resolved to some concrete type (which might itself be
79 pub use self::Expectation::*;
80 pub use self::compare_method::{compare_impl_method, compare_const_impl};
81 use self::TupleArgumentsFlag::*;
83 use astconv::{self, ast_region_to_region, ast_ty_to_ty, AstConv, PathParamMode};
84 use check::_match::pat_ctxt;
85 use dep_graph::DepNode;
86 use fmt_macros::{Parser, Piece, Position};
87 use middle::astconv_util::prohibit_type_params;
88 use middle::cstore::LOCAL_CRATE;
89 use middle::def::{self, Def};
90 use middle::def_id::DefId;
92 use middle::infer::{TypeOrigin, type_variable};
93 use middle::pat_util::{self, pat_id_map};
94 use middle::subst::{self, Subst, Substs, VecPerParamSpace, ParamSpace};
95 use middle::traits::{self, report_fulfillment_errors};
96 use middle::ty::{GenericPredicates, TypeScheme};
97 use middle::ty::{Disr, ParamTy, ParameterEnvironment};
98 use middle::ty::{LvaluePreference, NoPreference, PreferMutLvalue};
99 use middle::ty::{self, ToPolyTraitRef, Ty, TyCtxt};
100 use middle::ty::{MethodCall, MethodCallee};
101 use middle::ty::adjustment;
102 use middle::ty::error::TypeError;
103 use middle::ty::fold::{TypeFolder, TypeFoldable};
104 use middle::ty::util::Representability;
105 use require_c_abi_if_variadic;
106 use rscope::{ElisionFailureInfo, RegionScope};
107 use session::{Session, CompileResult};
108 use {CrateCtxt, lookup_full_def};
111 use util::common::{block_query, ErrorReported, indenter, loop_query};
112 use util::nodemap::{DefIdMap, FnvHashMap, NodeMap};
114 use std::cell::{Cell, Ref, RefCell};
115 use std::collections::{HashSet};
116 use std::mem::replace;
117 use syntax::abi::Abi;
120 use syntax::attr::AttrMetaMethods;
121 use syntax::codemap::{self, Span, Spanned};
122 use syntax::errors::DiagnosticBuilder;
123 use syntax::parse::token::{self, InternedString, special_idents};
125 use syntax::util::lev_distance::find_best_match_for_name;
127 use rustc_front::intravisit::{self, Visitor};
128 use rustc_front::hir;
129 use rustc_front::hir::{Visibility, PatKind};
130 use rustc_front::print::pprust;
131 use rustc_back::slice;
150 /// closures defined within the function. For example:
153 /// bar(move|| { ... })
156 /// Here, the function `foo()` and the closure passed to
157 /// `bar()` will each have their own `FnCtxt`, but they will
158 /// share the inherited fields.
159 pub struct Inherited<'a, 'tcx: 'a> {
160 infcx: infer::InferCtxt<'a, 'tcx>,
161 locals: RefCell<NodeMap<Ty<'tcx>>>,
163 fulfillment_cx: RefCell<traits::FulfillmentContext<'tcx>>,
165 tables: &'a RefCell<ty::Tables<'tcx>>,
167 // When we process a call like `c()` where `c` is a closure type,
168 // we may not have decided yet whether `c` is a `Fn`, `FnMut`, or
169 // `FnOnce` closure. In that case, we defer full resolution of the
170 // call until upvar inference can kick in and make the
171 // decision. We keep these deferred resolutions grouped by the
172 // def-id of the closure, so that once we decide, we can easily go
173 // back and process them.
174 deferred_call_resolutions: RefCell<DefIdMap<Vec<DeferredCallResolutionHandler<'tcx>>>>,
176 deferred_cast_checks: RefCell<Vec<cast::CastCheck<'tcx>>>,
179 trait DeferredCallResolution<'tcx> {
180 fn resolve<'a>(&mut self, fcx: &FnCtxt<'a,'tcx>);
183 type DeferredCallResolutionHandler<'tcx> = Box<DeferredCallResolution<'tcx>+'tcx>;
185 /// When type-checking an expression, we propagate downward
186 /// whatever type hint we are able in the form of an `Expectation`.
187 #[derive(Copy, Clone, Debug)]
188 pub enum Expectation<'tcx> {
189 /// We know nothing about what type this expression should have.
192 /// This expression should have the type given (or some subtype)
193 ExpectHasType(Ty<'tcx>),
195 /// This expression will be cast to the `Ty`
196 ExpectCastableToType(Ty<'tcx>),
198 /// This rvalue expression will be wrapped in `&` or `Box` and coerced
199 /// to `&Ty` or `Box<Ty>`, respectively. `Ty` is `[A]` or `Trait`.
200 ExpectRvalueLikeUnsized(Ty<'tcx>),
203 impl<'tcx> Expectation<'tcx> {
204 // Disregard "castable to" expectations because they
205 // can lead us astray. Consider for example `if cond
206 // {22} else {c} as u8` -- if we propagate the
207 // "castable to u8" constraint to 22, it will pick the
208 // type 22u8, which is overly constrained (c might not
209 // be a u8). In effect, the problem is that the
210 // "castable to" expectation is not the tightest thing
211 // we can say, so we want to drop it in this case.
212 // The tightest thing we can say is "must unify with
213 // else branch". Note that in the case of a "has type"
214 // constraint, this limitation does not hold.
216 // If the expected type is just a type variable, then don't use
217 // an expected type. Otherwise, we might write parts of the type
218 // when checking the 'then' block which are incompatible with the
220 fn adjust_for_branches<'a>(&self, fcx: &FnCtxt<'a, 'tcx>) -> Expectation<'tcx> {
222 ExpectHasType(ety) => {
223 let ety = fcx.infcx().shallow_resolve(ety);
224 if !ety.is_ty_var() {
230 ExpectRvalueLikeUnsized(ety) => {
231 ExpectRvalueLikeUnsized(ety)
238 #[derive(Copy, Clone)]
239 pub struct UnsafetyState {
240 pub def: ast::NodeId,
241 pub unsafety: hir::Unsafety,
242 pub unsafe_push_count: u32,
247 pub fn function(unsafety: hir::Unsafety, def: ast::NodeId) -> UnsafetyState {
248 UnsafetyState { def: def, unsafety: unsafety, unsafe_push_count: 0, from_fn: true }
251 pub fn recurse(&mut self, blk: &hir::Block) -> UnsafetyState {
252 match self.unsafety {
253 // If this unsafe, then if the outer function was already marked as
254 // unsafe we shouldn't attribute the unsafe'ness to the block. This
255 // way the block can be warned about instead of ignoring this
256 // extraneous block (functions are never warned about).
257 hir::Unsafety::Unsafe if self.from_fn => *self,
260 let (unsafety, def, count) = match blk.rules {
261 hir::PushUnsafeBlock(..) =>
262 (unsafety, blk.id, self.unsafe_push_count.checked_add(1).unwrap()),
263 hir::PopUnsafeBlock(..) =>
264 (unsafety, blk.id, self.unsafe_push_count.checked_sub(1).unwrap()),
265 hir::UnsafeBlock(..) =>
266 (hir::Unsafety::Unsafe, blk.id, self.unsafe_push_count),
267 hir::DefaultBlock | hir::PushUnstableBlock | hir:: PopUnstableBlock =>
268 (unsafety, self.def, self.unsafe_push_count),
270 UnsafetyState{ def: def,
272 unsafe_push_count: count,
280 pub struct FnCtxt<'a, 'tcx: 'a> {
281 body_id: ast::NodeId,
283 // This flag is set to true if, during the writeback phase, we encounter
284 // a type error in this function.
285 writeback_errors: Cell<bool>,
287 // Number of errors that had been reported when we started
288 // checking this function. On exit, if we find that *more* errors
289 // have been reported, we will skip regionck and other work that
290 // expects the types within the function to be consistent.
291 err_count_on_creation: usize,
293 ret_ty: ty::FnOutput<'tcx>,
295 ps: RefCell<UnsafetyState>,
297 inh: &'a Inherited<'a, 'tcx>,
299 ccx: &'a CrateCtxt<'a, 'tcx>,
302 impl<'a, 'tcx> Inherited<'a, 'tcx> {
303 fn new(tcx: &'a TyCtxt<'tcx>,
304 tables: &'a RefCell<ty::Tables<'tcx>>,
305 param_env: ty::ParameterEnvironment<'a, 'tcx>)
306 -> Inherited<'a, 'tcx> {
309 infcx: infer::new_infer_ctxt(tcx, tables, Some(param_env)),
310 fulfillment_cx: RefCell::new(traits::FulfillmentContext::new()),
311 locals: RefCell::new(NodeMap()),
313 deferred_call_resolutions: RefCell::new(DefIdMap()),
314 deferred_cast_checks: RefCell::new(Vec::new()),
318 fn normalize_associated_types_in<T>(&self,
320 body_id: ast::NodeId,
323 where T : TypeFoldable<'tcx>
325 assoc::normalize_associated_types_in(&self.infcx,
326 &mut self.fulfillment_cx.borrow_mut(),
334 // Used by check_const and check_enum_variants
335 pub fn blank_fn_ctxt<'a, 'tcx>(ccx: &'a CrateCtxt<'a, 'tcx>,
336 inh: &'a Inherited<'a, 'tcx>,
337 rty: ty::FnOutput<'tcx>,
338 body_id: ast::NodeId)
339 -> FnCtxt<'a, 'tcx> {
342 writeback_errors: Cell::new(false),
343 err_count_on_creation: ccx.tcx.sess.err_count(),
345 ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal, 0)),
351 fn static_inherited_fields<'a, 'tcx>(ccx: &'a CrateCtxt<'a, 'tcx>,
352 tables: &'a RefCell<ty::Tables<'tcx>>)
353 -> Inherited<'a, 'tcx> {
354 // It's kind of a kludge to manufacture a fake function context
355 // and statement context, but we might as well do write the code only once
356 let param_env = ccx.tcx.empty_parameter_environment();
357 Inherited::new(ccx.tcx, &tables, param_env)
360 struct CheckItemTypesVisitor<'a, 'tcx: 'a> { ccx: &'a CrateCtxt<'a, 'tcx> }
361 struct CheckItemBodiesVisitor<'a, 'tcx: 'a> { ccx: &'a CrateCtxt<'a, 'tcx> }
363 impl<'a, 'tcx> Visitor<'tcx> for CheckItemTypesVisitor<'a, 'tcx> {
364 fn visit_item(&mut self, i: &'tcx hir::Item) {
365 check_item_type(self.ccx, i);
366 intravisit::walk_item(self, i);
369 fn visit_ty(&mut self, t: &'tcx hir::Ty) {
371 hir::TyFixedLengthVec(_, ref expr) => {
372 check_const_in_type(self.ccx, &expr, self.ccx.tcx.types.usize);
377 intravisit::walk_ty(self, t);
381 impl<'a, 'tcx> Visitor<'tcx> for CheckItemBodiesVisitor<'a, 'tcx> {
382 fn visit_item(&mut self, i: &'tcx hir::Item) {
383 check_item_body(self.ccx, i);
387 pub fn check_wf_new(ccx: &CrateCtxt) -> CompileResult {
388 ccx.tcx.sess.track_errors(|| {
389 let mut visit = wfcheck::CheckTypeWellFormedVisitor::new(ccx);
390 ccx.tcx.visit_all_items_in_krate(DepNode::WfCheck, &mut visit);
394 pub fn check_item_types(ccx: &CrateCtxt) -> CompileResult {
395 ccx.tcx.sess.track_errors(|| {
396 let mut visit = CheckItemTypesVisitor { ccx: ccx };
397 ccx.tcx.visit_all_items_in_krate(DepNode::TypeckItemType, &mut visit);
401 pub fn check_item_bodies(ccx: &CrateCtxt) -> CompileResult {
402 ccx.tcx.sess.track_errors(|| {
403 let mut visit = CheckItemBodiesVisitor { ccx: ccx };
404 ccx.tcx.visit_all_items_in_krate(DepNode::TypeckItemBody, &mut visit);
408 pub fn check_drop_impls(ccx: &CrateCtxt) -> CompileResult {
409 ccx.tcx.sess.track_errors(|| {
410 let _task = ccx.tcx.dep_graph.in_task(DepNode::Dropck);
411 let drop_trait = match ccx.tcx.lang_items.drop_trait() {
412 Some(id) => ccx.tcx.lookup_trait_def(id), None => { return }
414 drop_trait.for_each_impl(ccx.tcx, |drop_impl_did| {
415 let _task = ccx.tcx.dep_graph.in_task(DepNode::DropckImpl(drop_impl_did));
416 if drop_impl_did.is_local() {
417 match dropck::check_drop_impl(ccx.tcx, drop_impl_did) {
420 assert!(ccx.tcx.sess.has_errors());
428 fn check_bare_fn<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
429 decl: &'tcx hir::FnDecl,
430 body: &'tcx hir::Block,
434 param_env: ty::ParameterEnvironment<'a, 'tcx>)
437 ty::TyBareFn(_, ref fn_ty) => {
438 let tables = RefCell::new(ty::Tables::empty());
439 let inh = Inherited::new(ccx.tcx, &tables, param_env);
441 // Compute the fty from point of view of inside fn.
442 let fn_scope = ccx.tcx.region_maps.call_site_extent(fn_id, body.id);
444 fn_ty.sig.subst(ccx.tcx, &inh.infcx.parameter_environment.free_substs);
446 ccx.tcx.liberate_late_bound_regions(fn_scope, &fn_sig);
448 inh.normalize_associated_types_in(body.span,
452 let fcx = check_fn(ccx, fn_ty.unsafety, fn_id, &fn_sig,
453 decl, fn_id, body, &inh);
455 fcx.select_all_obligations_and_apply_defaults();
456 upvar::closure_analyze_fn(&fcx, fn_id, decl, body);
457 fcx.select_obligations_where_possible();
459 fcx.select_all_obligations_or_error(); // Casts can introduce new obligations.
461 regionck::regionck_fn(&fcx, fn_id, fn_span, decl, body);
462 writeback::resolve_type_vars_in_fn(&fcx, decl, body);
464 _ => ccx.tcx.sess.impossible_case(body.span,
465 "check_bare_fn: function type expected")
469 struct GatherLocalsVisitor<'a, 'tcx: 'a> {
470 fcx: &'a FnCtxt<'a, 'tcx>
473 impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> {
474 fn assign(&mut self, _span: Span, nid: ast::NodeId, ty_opt: Option<Ty<'tcx>>) -> Ty<'tcx> {
477 // infer the variable's type
478 let var_ty = self.fcx.infcx().next_ty_var();
479 self.fcx.inh.locals.borrow_mut().insert(nid, var_ty);
483 // take type that the user specified
484 self.fcx.inh.locals.borrow_mut().insert(nid, typ);
491 impl<'a, 'tcx> Visitor<'tcx> for GatherLocalsVisitor<'a, 'tcx> {
492 // Add explicitly-declared locals.
493 fn visit_local(&mut self, local: &'tcx hir::Local) {
494 let o_ty = match local.ty {
495 Some(ref ty) => Some(self.fcx.to_ty(&ty)),
498 self.assign(local.span, local.id, o_ty);
499 debug!("Local variable {:?} is assigned type {}",
501 self.fcx.infcx().ty_to_string(
502 self.fcx.inh.locals.borrow().get(&local.id).unwrap().clone()));
503 intravisit::walk_local(self, local);
506 // Add pattern bindings.
507 fn visit_pat(&mut self, p: &'tcx hir::Pat) {
508 if let PatKind::Ident(_, ref path1, _) = p.node {
509 if pat_util::pat_is_binding(&self.fcx.ccx.tcx.def_map.borrow(), p) {
510 let var_ty = self.assign(p.span, p.id, None);
512 self.fcx.require_type_is_sized(var_ty, p.span,
513 traits::VariableType(p.id));
515 debug!("Pattern binding {} is assigned to {} with type {:?}",
517 self.fcx.infcx().ty_to_string(
518 self.fcx.inh.locals.borrow().get(&p.id).unwrap().clone()),
522 intravisit::walk_pat(self, p);
525 fn visit_block(&mut self, b: &'tcx hir::Block) {
526 // non-obvious: the `blk` variable maps to region lb, so
527 // we have to keep this up-to-date. This
528 // is... unfortunate. It'd be nice to not need this.
529 intravisit::walk_block(self, b);
532 // Since an expr occurs as part of the type fixed size arrays we
533 // need to record the type for that node
534 fn visit_ty(&mut self, t: &'tcx hir::Ty) {
536 hir::TyFixedLengthVec(ref ty, ref count_expr) => {
538 check_expr_with_hint(self.fcx, &count_expr, self.fcx.tcx().types.usize);
540 hir::TyBareFn(ref function_declaration) => {
541 intravisit::walk_fn_decl_nopat(self, &function_declaration.decl);
542 walk_list!(self, visit_lifetime_def, &function_declaration.lifetimes);
544 _ => intravisit::walk_ty(self, t)
548 // Don't descend into the bodies of nested closures
549 fn visit_fn(&mut self, _: intravisit::FnKind<'tcx>, _: &'tcx hir::FnDecl,
550 _: &'tcx hir::Block, _: Span, _: ast::NodeId) { }
553 /// Helper used by check_bare_fn and check_expr_fn. Does the grungy work of checking a function
554 /// body and returns the function context used for that purpose, since in the case of a fn item
555 /// there is still a bit more to do.
558 /// * inherited: other fields inherited from the enclosing fn (if any)
559 fn check_fn<'a, 'tcx>(ccx: &'a CrateCtxt<'a, 'tcx>,
560 unsafety: hir::Unsafety,
561 unsafety_id: ast::NodeId,
562 fn_sig: &ty::FnSig<'tcx>,
563 decl: &'tcx hir::FnDecl,
565 body: &'tcx hir::Block,
566 inherited: &'a Inherited<'a, 'tcx>)
570 let err_count_on_creation = tcx.sess.err_count();
572 let arg_tys = &fn_sig.inputs;
573 let ret_ty = fn_sig.output;
575 debug!("check_fn(arg_tys={:?}, ret_ty={:?}, fn_id={})",
580 // Create the function context. This is either derived from scratch or,
581 // in the case of function expressions, based on the outer context.
584 writeback_errors: Cell::new(false),
585 err_count_on_creation: err_count_on_creation,
587 ps: RefCell::new(UnsafetyState::function(unsafety, unsafety_id)),
592 if let ty::FnConverging(ret_ty) = ret_ty {
593 fcx.require_type_is_sized(ret_ty, decl.output.span(), traits::ReturnType);
596 debug!("fn-sig-map: fn_id={} fn_sig={:?}", fn_id, fn_sig);
598 inherited.tables.borrow_mut().liberated_fn_sigs.insert(fn_id, fn_sig.clone());
601 let mut visit = GatherLocalsVisitor { fcx: &fcx, };
603 // Add formal parameters.
604 for (arg_ty, input) in arg_tys.iter().zip(&decl.inputs) {
605 // The type of the argument must be well-formed.
607 // NB -- this is now checked in wfcheck, but that
608 // currently only results in warnings, so we issue an
609 // old-style WF obligation here so that we still get the
610 // errors that we used to get.
611 fcx.register_old_wf_obligation(arg_ty, input.ty.span, traits::MiscObligation);
613 // Create type variables for each argument.
614 pat_util::pat_bindings(
617 |_bm, pat_id, sp, _path| {
618 let var_ty = visit.assign(sp, pat_id, None);
619 fcx.require_type_is_sized(var_ty, sp,
620 traits::VariableType(pat_id));
623 // Check the pattern.
626 map: pat_id_map(&tcx.def_map, &input.pat),
628 _match::check_pat(&pcx, &input.pat, *arg_ty);
631 visit.visit_block(body);
634 check_block_with_expected(&fcx, body, match ret_ty {
635 ty::FnConverging(result_type) => ExpectHasType(result_type),
636 ty::FnDiverging => NoExpectation
639 for (input, arg) in decl.inputs.iter().zip(arg_tys) {
640 fcx.write_ty(input.id, arg);
646 pub fn check_struct(ccx: &CrateCtxt, id: ast::NodeId, span: Span) {
649 check_representable(tcx, span, id, "struct");
651 if tcx.lookup_simd(ccx.tcx.map.local_def_id(id)) {
652 check_simd(tcx, span, id);
656 pub fn check_item_type<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>, it: &'tcx hir::Item) {
657 debug!("check_item_type(it.id={}, it.name={})",
659 ccx.tcx.item_path_str(ccx.tcx.map.local_def_id(it.id)));
660 let _indenter = indenter();
662 // Consts can play a role in type-checking, so they are included here.
663 hir::ItemStatic(_, _, ref e) |
664 hir::ItemConst(_, ref e) => check_const(ccx, it.span, &e, it.id),
665 hir::ItemEnum(ref enum_definition, _) => {
666 check_enum_variants(ccx,
668 &enum_definition.variants,
671 hir::ItemFn(..) => {} // entirely within check_item_body
672 hir::ItemImpl(_, _, _, _, _, ref impl_items) => {
673 debug!("ItemImpl {} with id {}", it.name, it.id);
674 match ccx.tcx.impl_trait_ref(ccx.tcx.map.local_def_id(it.id)) {
675 Some(impl_trait_ref) => {
676 check_impl_items_against_trait(ccx,
684 hir::ItemTrait(_, ref generics, _, _) => {
685 check_trait_on_unimplemented(ccx, generics, it);
687 hir::ItemStruct(..) => {
688 check_struct(ccx, it.id, it.span);
690 hir::ItemTy(_, ref generics) => {
691 let pty_ty = ccx.tcx.node_id_to_type(it.id);
692 check_bounds_are_used(ccx, &generics.ty_params, pty_ty);
694 hir::ItemForeignMod(ref m) => {
695 if m.abi == Abi::RustIntrinsic {
696 for item in &m.items {
697 intrinsic::check_intrinsic_type(ccx, item);
699 } else if m.abi == Abi::PlatformIntrinsic {
700 for item in &m.items {
701 intrinsic::check_platform_intrinsic_type(ccx, item);
704 for item in &m.items {
705 let pty = ccx.tcx.lookup_item_type(ccx.tcx.map.local_def_id(item.id));
706 if !pty.generics.types.is_empty() {
707 let mut err = struct_span_err!(ccx.tcx.sess, item.span, E0044,
708 "foreign items may not have type parameters");
709 span_help!(&mut err, item.span,
710 "consider using specialization instead of \
715 if let hir::ForeignItemFn(ref fn_decl, _) = item.node {
716 require_c_abi_if_variadic(ccx.tcx, fn_decl, m.abi, item.span);
721 _ => {/* nothing to do */ }
725 pub fn check_item_body<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>, it: &'tcx hir::Item) {
726 debug!("check_item_body(it.id={}, it.name={})",
728 ccx.tcx.item_path_str(ccx.tcx.map.local_def_id(it.id)));
729 let _indenter = indenter();
731 hir::ItemFn(ref decl, _, _, _, _, ref body) => {
732 let fn_pty = ccx.tcx.lookup_item_type(ccx.tcx.map.local_def_id(it.id));
733 let param_env = ParameterEnvironment::for_item(ccx.tcx, it.id);
734 check_bare_fn(ccx, &decl, &body, it.id, it.span, fn_pty.ty, param_env);
736 hir::ItemImpl(_, _, _, _, _, ref impl_items) => {
737 debug!("ItemImpl {} with id {}", it.name, it.id);
739 let impl_pty = ccx.tcx.lookup_item_type(ccx.tcx.map.local_def_id(it.id));
741 for impl_item in impl_items {
742 match impl_item.node {
743 hir::ImplItemKind::Const(_, ref expr) => {
744 check_const(ccx, impl_item.span, &expr, impl_item.id)
746 hir::ImplItemKind::Method(ref sig, ref body) => {
747 check_method_body(ccx, &impl_pty.generics, sig, body,
748 impl_item.id, impl_item.span);
750 hir::ImplItemKind::Type(_) => {
751 // Nothing to do here.
756 hir::ItemTrait(_, _, _, ref trait_items) => {
757 let trait_def = ccx.tcx.lookup_trait_def(ccx.tcx.map.local_def_id(it.id));
758 for trait_item in trait_items {
759 match trait_item.node {
760 hir::ConstTraitItem(_, Some(ref expr)) => {
761 check_const(ccx, trait_item.span, &expr, trait_item.id)
763 hir::MethodTraitItem(ref sig, Some(ref body)) => {
764 check_trait_fn_not_const(ccx, trait_item.span, sig.constness);
766 check_method_body(ccx, &trait_def.generics, sig, body,
767 trait_item.id, trait_item.span);
769 hir::MethodTraitItem(ref sig, None) => {
770 check_trait_fn_not_const(ccx, trait_item.span, sig.constness);
772 hir::ConstTraitItem(_, None) |
773 hir::TypeTraitItem(..) => {
779 _ => {/* nothing to do */ }
783 fn check_trait_fn_not_const<'a,'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
785 constness: hir::Constness)
788 hir::Constness::NotConst => {
791 hir::Constness::Const => {
792 span_err!(ccx.tcx.sess, span, E0379, "trait fns cannot be declared const");
797 fn check_trait_on_unimplemented<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
798 generics: &hir::Generics,
800 if let Some(ref attr) = item.attrs.iter().find(|a| {
801 a.check_name("rustc_on_unimplemented")
803 if let Some(ref istring) = attr.value_str() {
804 let parser = Parser::new(&istring);
805 let types = &generics.ty_params;
806 for token in parser {
808 Piece::String(_) => (), // Normal string, no need to check it
809 Piece::NextArgument(a) => match a.position {
810 // `{Self}` is allowed
811 Position::ArgumentNamed(s) if s == "Self" => (),
812 // So is `{A}` if A is a type parameter
813 Position::ArgumentNamed(s) => match types.iter().find(|t| {
818 span_err!(ccx.tcx.sess, attr.span, E0230,
819 "there is no type parameter \
824 // `{:1}` and `{}` are not to be used
825 Position::ArgumentIs(_) | Position::ArgumentNext => {
826 span_err!(ccx.tcx.sess, attr.span, E0231,
827 "only named substitution \
828 parameters are allowed");
834 span_err!(ccx.tcx.sess, attr.span, E0232,
835 "this attribute must have a value, \
836 eg `#[rustc_on_unimplemented = \"foo\"]`")
841 /// Type checks a method body.
845 /// * `item_generics`: generics defined on the impl/trait that contains
847 /// * `self_bound`: bound for the `Self` type parameter, if any
848 /// * `method`: the method definition
849 fn check_method_body<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
850 item_generics: &ty::Generics<'tcx>,
851 sig: &'tcx hir::MethodSig,
852 body: &'tcx hir::Block,
853 id: ast::NodeId, span: Span) {
854 debug!("check_method_body(item_generics={:?}, id={})",
856 let param_env = ParameterEnvironment::for_item(ccx.tcx, id);
858 let fty = ccx.tcx.node_id_to_type(id);
859 debug!("check_method_body: fty={:?}", fty);
861 check_bare_fn(ccx, &sig.decl, body, id, span, fty, param_env);
864 fn check_impl_items_against_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
866 impl_trait_ref: &ty::TraitRef<'tcx>,
867 impl_items: &[hir::ImplItem]) {
868 // Locate trait methods
870 let trait_items = tcx.trait_items(impl_trait_ref.def_id);
871 let mut overridden_associated_type = None;
873 // Check existing impl methods to see if they are both present in trait
874 // and compatible with trait signature
875 for impl_item in impl_items {
876 let ty_impl_item = ccx.tcx.impl_or_trait_item(ccx.tcx.map.local_def_id(impl_item.id));
877 let ty_trait_item = trait_items.iter()
878 .find(|ac| ac.name() == ty_impl_item.name());
880 if let Some(ty_trait_item) = ty_trait_item {
881 match impl_item.node {
882 hir::ImplItemKind::Const(..) => {
883 let impl_const = match ty_impl_item {
884 ty::ConstTraitItem(ref cti) => cti,
885 _ => tcx.sess.span_bug(impl_item.span, "non-const impl-item for const")
888 // Find associated const definition.
889 if let &ty::ConstTraitItem(ref trait_const) = ty_trait_item {
890 compare_const_impl(ccx.tcx,
896 span_err!(tcx.sess, impl_item.span, E0323,
897 "item `{}` is an associated const, \
898 which doesn't match its trait `{:?}`",
903 hir::ImplItemKind::Method(ref sig, ref body) => {
904 check_trait_fn_not_const(ccx, impl_item.span, sig.constness);
906 let impl_method = match ty_impl_item {
907 ty::MethodTraitItem(ref mti) => mti,
908 _ => tcx.sess.span_bug(impl_item.span, "non-method impl-item for method")
911 if let &ty::MethodTraitItem(ref trait_method) = ty_trait_item {
912 compare_impl_method(ccx.tcx,
919 span_err!(tcx.sess, impl_item.span, E0324,
920 "item `{}` is an associated method, \
921 which doesn't match its trait `{:?}`",
926 hir::ImplItemKind::Type(_) => {
927 let impl_type = match ty_impl_item {
928 ty::TypeTraitItem(ref tti) => tti,
929 _ => tcx.sess.span_bug(impl_item.span, "non-type impl-item for type")
932 if let &ty::TypeTraitItem(ref at) = ty_trait_item {
933 if let Some(_) = at.ty {
934 overridden_associated_type = Some(impl_item);
937 span_err!(tcx.sess, impl_item.span, E0325,
938 "item `{}` is an associated type, \
939 which doesn't match its trait `{:?}`",
948 // Check for missing items from trait
949 let provided_methods = tcx.provided_trait_methods(impl_trait_ref.def_id);
950 let mut missing_items = Vec::new();
951 let mut invalidated_items = Vec::new();
952 let associated_type_overridden = overridden_associated_type.is_some();
953 for trait_item in trait_items.iter() {
955 ty::ConstTraitItem(ref associated_const) => {
956 let is_implemented = impl_items.iter().any(|ii| {
958 hir::ImplItemKind::Const(..) => {
959 ii.name == associated_const.name
964 let is_provided = associated_const.has_value;
968 missing_items.push(associated_const.name);
969 } else if associated_type_overridden {
970 invalidated_items.push(associated_const.name);
974 ty::MethodTraitItem(ref trait_method) => {
976 impl_items.iter().any(|ii| {
978 hir::ImplItemKind::Method(..) => {
979 ii.name == trait_method.name
985 provided_methods.iter().any(|m| m.name == trait_method.name);
988 missing_items.push(trait_method.name);
989 } else if associated_type_overridden {
990 invalidated_items.push(trait_method.name);
994 ty::TypeTraitItem(ref associated_type) => {
995 let is_implemented = impl_items.iter().any(|ii| {
997 hir::ImplItemKind::Type(_) => {
998 ii.name == associated_type.name
1003 let is_provided = associated_type.ty.is_some();
1004 if !is_implemented {
1006 missing_items.push(associated_type.name);
1007 } else if associated_type_overridden {
1008 invalidated_items.push(associated_type.name);
1015 if !missing_items.is_empty() {
1016 span_err!(tcx.sess, impl_span, E0046,
1017 "not all trait items implemented, missing: `{}`",
1018 missing_items.iter()
1019 .map(|name| name.to_string())
1020 .collect::<Vec<_>>().join("`, `"))
1023 if !invalidated_items.is_empty() {
1024 let invalidator = overridden_associated_type.unwrap();
1025 span_err!(tcx.sess, invalidator.span, E0399,
1026 "the following trait items need to be reimplemented \
1027 as `{}` was overridden: `{}`",
1029 invalidated_items.iter()
1030 .map(|name| name.to_string())
1031 .collect::<Vec<_>>().join("`, `"))
1035 fn report_cast_to_unsized_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
1042 if t_cast.references_error() || t_expr.references_error() {
1045 let tstr = fcx.infcx().ty_to_string(t_cast);
1046 let mut err = fcx.type_error_struct(span, |actual| {
1047 format!("cast to unsized type: `{}` as `{}`", actual, tstr)
1050 ty::TyRef(_, ty::TypeAndMut { mutbl: mt, .. }) => {
1051 let mtstr = match mt {
1052 hir::MutMutable => "mut ",
1053 hir::MutImmutable => ""
1055 if t_cast.is_trait() {
1056 match fcx.tcx().sess.codemap().span_to_snippet(t_span) {
1058 err.span_suggestion(t_span,
1059 "try casting to a reference instead:",
1060 format!("&{}{}", mtstr, s));
1063 span_help!(err, t_span,
1064 "did you mean `&{}{}`?", mtstr, tstr),
1067 span_help!(err, span,
1068 "consider using an implicit coercion to `&{}{}` instead",
1073 match fcx.tcx().sess.codemap().span_to_snippet(t_span) {
1075 err.span_suggestion(t_span,
1076 "try casting to a `Box` instead:",
1077 format!("Box<{}>", s));
1080 span_help!(err, t_span, "did you mean `Box<{}>`?", tstr),
1084 span_help!(err, e_span,
1085 "consider using a box or reference as appropriate");
1089 fcx.write_error(id);
1093 impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
1094 fn tcx(&self) -> &TyCtxt<'tcx> { self.ccx.tcx }
1096 fn get_item_type_scheme(&self, _: Span, id: DefId)
1097 -> Result<ty::TypeScheme<'tcx>, ErrorReported>
1099 Ok(self.tcx().lookup_item_type(id))
1102 fn get_trait_def(&self, _: Span, id: DefId)
1103 -> Result<&'tcx ty::TraitDef<'tcx>, ErrorReported>
1105 Ok(self.tcx().lookup_trait_def(id))
1108 fn ensure_super_predicates(&self, _: Span, _: DefId) -> Result<(), ErrorReported> {
1109 // all super predicates are ensured during collect pass
1113 fn get_free_substs(&self) -> Option<&Substs<'tcx>> {
1114 Some(&self.inh.infcx.parameter_environment.free_substs)
1117 fn get_type_parameter_bounds(&self,
1119 node_id: ast::NodeId)
1120 -> Result<Vec<ty::PolyTraitRef<'tcx>>, ErrorReported>
1122 let def = self.tcx().type_parameter_def(node_id);
1123 let r = self.inh.infcx.parameter_environment
1126 .filter_map(|predicate| {
1128 ty::Predicate::Trait(ref data) => {
1129 if data.0.self_ty().is_param(def.space, def.index) {
1130 Some(data.to_poly_trait_ref())
1144 fn trait_defines_associated_type_named(&self,
1145 trait_def_id: DefId,
1146 assoc_name: ast::Name)
1149 let trait_def = self.ccx.tcx.lookup_trait_def(trait_def_id);
1150 trait_def.associated_type_names.contains(&assoc_name)
1154 ty_param_def: Option<ty::TypeParameterDef<'tcx>>,
1155 substs: Option<&mut subst::Substs<'tcx>>,
1156 space: Option<subst::ParamSpace>,
1157 span: Span) -> Ty<'tcx> {
1158 // Grab the default doing subsitution
1159 let default = ty_param_def.and_then(|def| {
1160 def.default.map(|ty| type_variable::Default {
1161 ty: ty.subst_spanned(self.tcx(), substs.as_ref().unwrap(), Some(span)),
1163 def_id: def.default_def_id
1167 let ty_var = self.infcx().next_ty_var_with_default(default);
1169 // Finally we add the type variable to the substs
1172 Some(substs) => { substs.types.push(space.unwrap(), ty_var); ty_var }
1176 fn projected_ty_from_poly_trait_ref(&self,
1178 poly_trait_ref: ty::PolyTraitRef<'tcx>,
1179 item_name: ast::Name)
1182 let (trait_ref, _) =
1183 self.infcx().replace_late_bound_regions_with_fresh_var(
1185 infer::LateBoundRegionConversionTime::AssocTypeProjection(item_name),
1188 self.normalize_associated_type(span, trait_ref, item_name)
1191 fn projected_ty(&self,
1193 trait_ref: ty::TraitRef<'tcx>,
1194 item_name: ast::Name)
1197 self.normalize_associated_type(span, trait_ref, item_name)
1201 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
1202 fn tcx(&self) -> &TyCtxt<'tcx> { self.ccx.tcx }
1204 pub fn infcx(&self) -> &infer::InferCtxt<'a,'tcx> {
1208 pub fn param_env(&self) -> &ty::ParameterEnvironment<'a,'tcx> {
1209 &self.inh.infcx.parameter_environment
1212 pub fn sess(&self) -> &Session {
1216 pub fn err_count_since_creation(&self) -> usize {
1217 self.ccx.tcx.sess.err_count() - self.err_count_on_creation
1220 /// Resolves type variables in `ty` if possible. Unlike the infcx
1221 /// version, this version will also select obligations if it seems
1222 /// useful, in an effort to get more type information.
1223 fn resolve_type_vars_if_possible(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
1224 debug!("resolve_type_vars_if_possible(ty={:?})", ty);
1226 // No TyInfer()? Nothing needs doing.
1227 if !ty.has_infer_types() {
1228 debug!("resolve_type_vars_if_possible: ty={:?}", ty);
1232 // If `ty` is a type variable, see whether we already know what it is.
1233 ty = self.infcx().resolve_type_vars_if_possible(&ty);
1234 if !ty.has_infer_types() {
1235 debug!("resolve_type_vars_if_possible: ty={:?}", ty);
1239 // If not, try resolving pending obligations as much as
1240 // possible. This can help substantially when there are
1241 // indirect dependencies that don't seem worth tracking
1243 self.select_obligations_where_possible();
1244 ty = self.infcx().resolve_type_vars_if_possible(&ty);
1246 debug!("resolve_type_vars_if_possible: ty={:?}", ty);
1250 fn record_deferred_call_resolution(&self,
1251 closure_def_id: DefId,
1252 r: DeferredCallResolutionHandler<'tcx>) {
1253 let mut deferred_call_resolutions = self.inh.deferred_call_resolutions.borrow_mut();
1254 deferred_call_resolutions.entry(closure_def_id).or_insert(vec![]).push(r);
1257 fn remove_deferred_call_resolutions(&self,
1258 closure_def_id: DefId)
1259 -> Vec<DeferredCallResolutionHandler<'tcx>>
1261 let mut deferred_call_resolutions = self.inh.deferred_call_resolutions.borrow_mut();
1262 deferred_call_resolutions.remove(&closure_def_id).unwrap_or(Vec::new())
1265 pub fn tag(&self) -> String {
1266 let self_ptr: *const FnCtxt = self;
1267 format!("{:?}", self_ptr)
1270 pub fn local_ty(&self, span: Span, nid: ast::NodeId) -> Ty<'tcx> {
1271 match self.inh.locals.borrow().get(&nid) {
1274 span_err!(self.tcx().sess, span, E0513,
1275 "no type for local variable {}",
1277 self.tcx().types.err
1283 pub fn write_ty(&self, node_id: ast::NodeId, ty: Ty<'tcx>) {
1284 debug!("write_ty({}, {:?}) in fcx {}",
1285 node_id, ty, self.tag());
1286 self.inh.tables.borrow_mut().node_types.insert(node_id, ty);
1289 pub fn write_substs(&self, node_id: ast::NodeId, substs: ty::ItemSubsts<'tcx>) {
1290 if !substs.substs.is_noop() {
1291 debug!("write_substs({}, {:?}) in fcx {}",
1296 self.inh.tables.borrow_mut().item_substs.insert(node_id, substs);
1300 pub fn write_autoderef_adjustment(&self,
1301 node_id: ast::NodeId,
1303 self.write_adjustment(
1305 adjustment::AdjustDerefRef(adjustment::AutoDerefRef {
1313 pub fn write_adjustment(&self,
1314 node_id: ast::NodeId,
1315 adj: adjustment::AutoAdjustment<'tcx>) {
1316 debug!("write_adjustment(node_id={}, adj={:?})", node_id, adj);
1318 if adj.is_identity() {
1322 self.inh.tables.borrow_mut().adjustments.insert(node_id, adj);
1325 /// Basically whenever we are converting from a type scheme into
1326 /// the fn body space, we always want to normalize associated
1327 /// types as well. This function combines the two.
1328 fn instantiate_type_scheme<T>(&self,
1330 substs: &Substs<'tcx>,
1333 where T : TypeFoldable<'tcx>
1335 let value = value.subst(self.tcx(), substs);
1336 let result = self.normalize_associated_types_in(span, &value);
1337 debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}",
1344 /// As `instantiate_type_scheme`, but for the bounds found in a
1345 /// generic type scheme.
1346 fn instantiate_bounds(&self,
1348 substs: &Substs<'tcx>,
1349 bounds: &ty::GenericPredicates<'tcx>)
1350 -> ty::InstantiatedPredicates<'tcx>
1352 ty::InstantiatedPredicates {
1353 predicates: self.instantiate_type_scheme(span, substs, &bounds.predicates)
1358 fn normalize_associated_types_in<T>(&self, span: Span, value: &T) -> T
1359 where T : TypeFoldable<'tcx>
1361 self.inh.normalize_associated_types_in(span, self.body_id, value)
1364 fn normalize_associated_type(&self,
1366 trait_ref: ty::TraitRef<'tcx>,
1367 item_name: ast::Name)
1370 let cause = traits::ObligationCause::new(span,
1372 traits::ObligationCauseCode::MiscObligation);
1376 .normalize_projection_type(self.infcx(),
1378 trait_ref: trait_ref,
1379 item_name: item_name,
1384 /// Instantiates the type in `did` with the generics in `path` and returns
1385 /// it (registering the necessary trait obligations along the way).
1387 /// Note that this function is only intended to be used with type-paths,
1388 /// not with value-paths.
1389 pub fn instantiate_type(&self,
1394 debug!("instantiate_type(did={:?}, path={:?})", did, path);
1396 self.tcx().lookup_item_type(did);
1397 let type_predicates =
1398 self.tcx().lookup_predicates(did);
1399 let substs = astconv::ast_path_substs_for_ty(self, self,
1401 PathParamMode::Optional,
1402 &type_scheme.generics,
1403 path.segments.last().unwrap());
1404 debug!("instantiate_type: ty={:?} substs={:?}", &type_scheme.ty, &substs);
1406 self.instantiate_bounds(path.span, &substs, &type_predicates);
1407 self.add_obligations_for_parameters(
1408 traits::ObligationCause::new(
1411 traits::ItemObligation(did)),
1414 self.instantiate_type_scheme(path.span, &substs, &type_scheme.ty)
1417 /// Return the dict-like variant corresponding to a given `Def`.
1418 pub fn def_struct_variant(&self,
1421 -> Option<(ty::AdtDef<'tcx>, ty::VariantDef<'tcx>)>
1423 let (adt, variant) = match def {
1424 Def::Variant(enum_id, variant_id) => {
1425 let adt = self.tcx().lookup_adt_def(enum_id);
1426 (adt, adt.variant_with_id(variant_id))
1428 Def::Struct(did) | Def::TyAlias(did) => {
1429 let typ = self.tcx().lookup_item_type(did);
1430 if let ty::TyStruct(adt, _) = typ.ty.sty {
1431 (adt, adt.struct_variant())
1439 let var_kind = variant.kind();
1440 if var_kind == ty::VariantKind::Struct {
1441 Some((adt, variant))
1442 } else if var_kind == ty::VariantKind::Unit {
1443 Some((adt, variant))
1449 pub fn write_nil(&self, node_id: ast::NodeId) {
1450 self.write_ty(node_id, self.tcx().mk_nil());
1452 pub fn write_error(&self, node_id: ast::NodeId) {
1453 self.write_ty(node_id, self.tcx().types.err);
1456 pub fn require_type_meets(&self,
1459 code: traits::ObligationCauseCode<'tcx>,
1460 bound: ty::BuiltinBound)
1462 self.register_builtin_bound(
1465 traits::ObligationCause::new(span, self.body_id, code));
1468 pub fn require_type_is_sized(&self,
1471 code: traits::ObligationCauseCode<'tcx>)
1473 self.require_type_meets(ty, span, code, ty::BoundSized);
1476 pub fn require_expr_have_sized_type(&self,
1478 code: traits::ObligationCauseCode<'tcx>)
1480 self.require_type_is_sized(self.expr_ty(expr), expr.span, code);
1483 pub fn type_is_known_to_be_sized(&self,
1488 traits::type_known_to_meet_builtin_bound(self.infcx(),
1494 pub fn register_builtin_bound(&self,
1496 builtin_bound: ty::BuiltinBound,
1497 cause: traits::ObligationCause<'tcx>)
1499 self.inh.fulfillment_cx.borrow_mut()
1500 .register_builtin_bound(self.infcx(), ty, builtin_bound, cause);
1503 pub fn register_predicate(&self,
1504 obligation: traits::PredicateObligation<'tcx>)
1506 debug!("register_predicate({:?})",
1508 self.inh.fulfillment_cx
1510 .register_predicate_obligation(self.infcx(), obligation);
1513 pub fn to_ty(&self, ast_t: &hir::Ty) -> Ty<'tcx> {
1514 let t = ast_ty_to_ty(self, self, ast_t);
1515 self.register_wf_obligation(t, ast_t.span, traits::MiscObligation);
1519 pub fn expr_ty(&self, ex: &hir::Expr) -> Ty<'tcx> {
1520 match self.inh.tables.borrow().node_types.get(&ex.id) {
1523 self.tcx().sess.bug(&format!("no type for expr in fcx {}",
1529 /// Apply `adjustment` to the type of `expr`
1530 pub fn adjust_expr_ty(&self,
1532 adjustment: Option<&adjustment::AutoAdjustment<'tcx>>)
1535 let raw_ty = self.expr_ty(expr);
1536 let raw_ty = self.infcx().shallow_resolve(raw_ty);
1537 let resolve_ty = |ty: Ty<'tcx>| self.infcx().resolve_type_vars_if_possible(&ty);
1538 raw_ty.adjust(self.tcx(), expr.span, expr.id, adjustment, |method_call| {
1539 self.inh.tables.borrow().method_map.get(&method_call)
1540 .map(|method| resolve_ty(method.ty))
1544 pub fn node_ty(&self, id: ast::NodeId) -> Ty<'tcx> {
1545 match self.inh.tables.borrow().node_types.get(&id) {
1547 None if self.err_count_since_creation() != 0 => self.tcx().types.err,
1549 self.tcx().sess.bug(
1550 &format!("no type for node {}: {} in fcx {}",
1551 id, self.tcx().map.node_to_string(id),
1557 pub fn item_substs(&self) -> Ref<NodeMap<ty::ItemSubsts<'tcx>>> {
1558 // NOTE: @jroesch this is hack that appears to be fixed on nightly, will monitor if
1559 // it changes when we upgrade the snapshot compiler
1560 fn project_item_susbts<'a, 'tcx>(tables: &'a ty::Tables<'tcx>)
1561 -> &'a NodeMap<ty::ItemSubsts<'tcx>> {
1565 Ref::map(self.inh.tables.borrow(), project_item_susbts)
1568 pub fn opt_node_ty_substs<F>(&self,
1571 F: FnOnce(&ty::ItemSubsts<'tcx>),
1573 match self.inh.tables.borrow().item_substs.get(&id) {
1579 pub fn mk_subty(&self,
1580 a_is_expected: bool,
1584 -> Result<(), TypeError<'tcx>> {
1585 infer::mk_subty(self.infcx(), a_is_expected, origin, sub, sup)
1588 pub fn mk_eqty(&self,
1589 a_is_expected: bool,
1593 -> Result<(), TypeError<'tcx>> {
1594 infer::mk_eqty(self.infcx(), a_is_expected, origin, sub, sup)
1597 pub fn mk_subr(&self,
1598 origin: infer::SubregionOrigin<'tcx>,
1601 infer::mk_subr(self.infcx(), origin, sub, sup)
1604 pub fn type_error_message<M>(&self,
1607 actual_ty: Ty<'tcx>,
1608 err: Option<&TypeError<'tcx>>)
1609 where M: FnOnce(String) -> String,
1611 self.infcx().type_error_message(sp, mk_msg, actual_ty, err);
1614 pub fn type_error_struct<M>(&self,
1617 actual_ty: Ty<'tcx>,
1618 err: Option<&TypeError<'tcx>>)
1619 -> DiagnosticBuilder<'tcx>
1620 where M: FnOnce(String) -> String,
1622 self.infcx().type_error_struct(sp, mk_msg, actual_ty, err)
1625 pub fn report_mismatched_types(&self,
1629 err: &TypeError<'tcx>) {
1630 self.infcx().report_mismatched_types(sp, e, a, err)
1633 /// Registers an obligation for checking later, during regionck, that the type `ty` must
1634 /// outlive the region `r`.
1635 pub fn register_region_obligation(&self,
1638 cause: traits::ObligationCause<'tcx>)
1640 let mut fulfillment_cx = self.inh.fulfillment_cx.borrow_mut();
1641 fulfillment_cx.register_region_obligation(ty, region, cause);
1644 /// Registers an obligation for checking later, during regionck, that the type `ty` must
1645 /// outlive the region `r`.
1646 pub fn register_wf_obligation(&self,
1649 code: traits::ObligationCauseCode<'tcx>)
1651 // WF obligations never themselves fail, so no real need to give a detailed cause:
1652 let cause = traits::ObligationCause::new(span, self.body_id, code);
1653 self.register_predicate(traits::Obligation::new(cause, ty::Predicate::WellFormed(ty)));
1656 pub fn register_old_wf_obligation(&self,
1659 code: traits::ObligationCauseCode<'tcx>)
1661 // Registers an "old-style" WF obligation that uses the
1662 // implicator code. This is basically a buggy version of
1663 // `register_wf_obligation` that is being kept around
1664 // temporarily just to help with phasing in the newer rules.
1666 // FIXME(#27579) all uses of this should be migrated to register_wf_obligation eventually
1667 let cause = traits::ObligationCause::new(span, self.body_id, code);
1668 self.register_region_obligation(ty, ty::ReEmpty, cause);
1671 /// Registers obligations that all types appearing in `substs` are well-formed.
1672 pub fn add_wf_bounds(&self, substs: &Substs<'tcx>, expr: &hir::Expr)
1674 for &ty in &substs.types {
1675 self.register_wf_obligation(ty, expr.span, traits::MiscObligation);
1679 /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each
1680 /// type/region parameter was instantiated (`substs`), creates and registers suitable
1681 /// trait/region obligations.
1683 /// For example, if there is a function:
1686 /// fn foo<'a,T:'a>(...)
1689 /// and a reference:
1695 /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a`
1696 /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally.
1697 pub fn add_obligations_for_parameters(&self,
1698 cause: traits::ObligationCause<'tcx>,
1699 predicates: &ty::InstantiatedPredicates<'tcx>)
1701 assert!(!predicates.has_escaping_regions());
1703 debug!("add_obligations_for_parameters(predicates={:?})",
1706 for obligation in traits::predicates_for_generics(cause, predicates) {
1707 self.register_predicate(obligation);
1711 // FIXME(arielb1): use this instead of field.ty everywhere
1712 pub fn field_ty(&self,
1714 field: ty::FieldDef<'tcx>,
1715 substs: &Substs<'tcx>)
1718 self.normalize_associated_types_in(span,
1719 &field.ty(self.tcx(), substs))
1722 // Only for fields! Returns <none> for methods>
1723 // Indifferent to privacy flags
1724 fn check_casts(&self) {
1725 let mut deferred_cast_checks = self.inh.deferred_cast_checks.borrow_mut();
1726 for cast in deferred_cast_checks.drain(..) {
1731 /// Apply "fallbacks" to some types
1732 /// ! gets replaced with (), unconstrained ints with i32, and unconstrained floats with f64.
1733 fn default_type_parameters(&self) {
1734 use middle::ty::error::UnconstrainedNumeric::Neither;
1735 use middle::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
1736 for ty in &self.infcx().unsolved_variables() {
1737 let resolved = self.infcx().resolve_type_vars_if_possible(ty);
1738 if self.infcx().type_var_diverges(resolved) {
1739 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1741 match self.infcx().type_is_unconstrained_numeric(resolved) {
1742 UnconstrainedInt => {
1743 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.i32)
1745 UnconstrainedFloat => {
1746 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.f64)
1754 fn select_all_obligations_and_apply_defaults(&self) {
1755 if self.tcx().sess.features.borrow().default_type_parameter_fallback {
1756 self.new_select_all_obligations_and_apply_defaults();
1758 self.old_select_all_obligations_and_apply_defaults();
1762 // Implements old type inference fallback algorithm
1763 fn old_select_all_obligations_and_apply_defaults(&self) {
1764 self.select_obligations_where_possible();
1765 self.default_type_parameters();
1766 self.select_obligations_where_possible();
1769 fn new_select_all_obligations_and_apply_defaults(&self) {
1770 use middle::ty::error::UnconstrainedNumeric::Neither;
1771 use middle::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
1773 // For the time being this errs on the side of being memory wasteful but provides better
1775 // let type_variables = self.infcx().type_variables.clone();
1777 // There is a possibility that this algorithm will have to run an arbitrary number of times
1778 // to terminate so we bound it by the compiler's recursion limit.
1779 for _ in 0..self.tcx().sess.recursion_limit.get() {
1780 // First we try to solve all obligations, it is possible that the last iteration
1781 // has made it possible to make more progress.
1782 self.select_obligations_where_possible();
1784 let mut conflicts = Vec::new();
1786 // Collect all unsolved type, integral and floating point variables.
1787 let unsolved_variables = self.inh.infcx.unsolved_variables();
1789 // We must collect the defaults *before* we do any unification. Because we have
1790 // directly attached defaults to the type variables any unification that occurs
1791 // will erase defaults causing conflicting defaults to be completely ignored.
1792 let default_map: FnvHashMap<_, _> =
1795 .filter_map(|t| self.infcx().default(t).map(|d| (t, d)))
1798 let mut unbound_tyvars = HashSet::new();
1800 debug!("select_all_obligations_and_apply_defaults: defaults={:?}", default_map);
1802 // We loop over the unsolved variables, resolving them and if they are
1803 // and unconstrainted numeric type we add them to the set of unbound
1804 // variables. We do this so we only apply literal fallback to type
1805 // variables without defaults.
1806 for ty in &unsolved_variables {
1807 let resolved = self.infcx().resolve_type_vars_if_possible(ty);
1808 if self.infcx().type_var_diverges(resolved) {
1809 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1811 match self.infcx().type_is_unconstrained_numeric(resolved) {
1812 UnconstrainedInt | UnconstrainedFloat => {
1813 unbound_tyvars.insert(resolved);
1820 // We now remove any numeric types that also have defaults, and instead insert
1821 // the type variable with a defined fallback.
1822 for ty in &unsolved_variables {
1823 if let Some(_default) = default_map.get(ty) {
1824 let resolved = self.infcx().resolve_type_vars_if_possible(ty);
1826 debug!("select_all_obligations_and_apply_defaults: ty: {:?} with default: {:?}",
1829 match resolved.sty {
1830 ty::TyInfer(ty::TyVar(_)) => {
1831 unbound_tyvars.insert(ty);
1834 ty::TyInfer(ty::IntVar(_)) | ty::TyInfer(ty::FloatVar(_)) => {
1835 unbound_tyvars.insert(ty);
1836 if unbound_tyvars.contains(resolved) {
1837 unbound_tyvars.remove(resolved);
1846 // If there are no more fallbacks to apply at this point we have applied all possible
1847 // defaults and type inference will proceed as normal.
1848 if unbound_tyvars.is_empty() {
1852 // Finally we go through each of the unbound type variables and unify them with
1853 // the proper fallback, reporting a conflicting default error if any of the
1854 // unifications fail. We know it must be a conflicting default because the
1855 // variable would only be in `unbound_tyvars` and have a concrete value if
1856 // it had been solved by previously applying a default.
1858 // We wrap this in a transaction for error reporting, if we detect a conflict
1859 // we will rollback the inference context to its prior state so we can probe
1860 // for conflicts and correctly report them.
1863 let _ = self.infcx().commit_if_ok(|_: &infer::CombinedSnapshot| {
1864 for ty in &unbound_tyvars {
1865 if self.infcx().type_var_diverges(ty) {
1866 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1868 match self.infcx().type_is_unconstrained_numeric(ty) {
1869 UnconstrainedInt => {
1870 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.i32)
1872 UnconstrainedFloat => {
1873 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.f64)
1876 if let Some(default) = default_map.get(ty) {
1877 let default = default.clone();
1878 match infer::mk_eqty(self.infcx(), false,
1879 TypeOrigin::Misc(default.origin_span),
1883 conflicts.push((*ty, default));
1892 // If there are conflicts we rollback, otherwise commit
1893 if conflicts.len() > 0 {
1900 if conflicts.len() > 0 {
1901 // Loop through each conflicting default, figuring out the default that caused
1902 // a unification failure and then report an error for each.
1903 for (conflict, default) in conflicts {
1904 let conflicting_default =
1905 self.find_conflicting_default(&unbound_tyvars, &default_map, conflict)
1906 .unwrap_or(type_variable::Default {
1907 ty: self.infcx().next_ty_var(),
1908 origin_span: codemap::DUMMY_SP,
1909 def_id: self.tcx().map.local_def_id(0) // what do I put here?
1912 // This is to ensure that we elimnate any non-determinism from the error
1913 // reporting by fixing an order, it doesn't matter what order we choose
1914 // just that it is consistent.
1915 let (first_default, second_default) =
1916 if default.def_id < conflicting_default.def_id {
1917 (default, conflicting_default)
1919 (conflicting_default, default)
1923 self.infcx().report_conflicting_default_types(
1924 first_default.origin_span,
1931 self.select_obligations_where_possible();
1934 // For use in error handling related to default type parameter fallback. We explicitly
1935 // apply the default that caused conflict first to a local version of the type variable
1936 // table then apply defaults until we find a conflict. That default must be the one
1937 // that caused conflict earlier.
1938 fn find_conflicting_default(&self,
1939 unbound_vars: &HashSet<Ty<'tcx>>,
1940 default_map: &FnvHashMap<&Ty<'tcx>, type_variable::Default<'tcx>>,
1942 -> Option<type_variable::Default<'tcx>> {
1943 use middle::ty::error::UnconstrainedNumeric::Neither;
1944 use middle::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
1946 // Ensure that we apply the conflicting default first
1947 let mut unbound_tyvars = Vec::with_capacity(unbound_vars.len() + 1);
1948 unbound_tyvars.push(conflict);
1949 unbound_tyvars.extend(unbound_vars.iter());
1951 let mut result = None;
1952 // We run the same code as above applying defaults in order, this time when
1953 // we find the conflict we just return it for error reporting above.
1955 // We also run this inside snapshot that never commits so we can do error
1956 // reporting for more then one conflict.
1957 for ty in &unbound_tyvars {
1958 if self.infcx().type_var_diverges(ty) {
1959 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1961 match self.infcx().type_is_unconstrained_numeric(ty) {
1962 UnconstrainedInt => {
1963 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.i32)
1965 UnconstrainedFloat => {
1966 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.f64)
1969 if let Some(default) = default_map.get(ty) {
1970 let default = default.clone();
1971 match infer::mk_eqty(self.infcx(), false,
1972 TypeOrigin::Misc(default.origin_span),
1976 result = Some(default);
1988 fn select_all_obligations_or_error(&self) {
1989 debug!("select_all_obligations_or_error");
1991 // upvar inference should have ensured that all deferred call
1992 // resolutions are handled by now.
1993 assert!(self.inh.deferred_call_resolutions.borrow().is_empty());
1995 self.select_all_obligations_and_apply_defaults();
1997 let mut fulfillment_cx = self.inh.fulfillment_cx.borrow_mut();
1998 match fulfillment_cx.select_all_or_error(self.infcx()) {
2000 Err(errors) => { report_fulfillment_errors(self.infcx(), &errors); }
2004 /// Select as many obligations as we can at present.
2005 fn select_obligations_where_possible(&self) {
2007 self.inh.fulfillment_cx
2009 .select_where_possible(self.infcx())
2012 Err(errors) => { report_fulfillment_errors(self.infcx(), &errors); }
2016 fn private_item_is_visible(&self, def_id: DefId) -> bool {
2017 match self.tcx().map.as_local_node_id(def_id) {
2018 Some(node_id) => self.tcx().map.private_item_is_visible_from(node_id, self.body_id),
2019 None => false, // Private items from other crates are never visible
2024 impl<'a, 'tcx> RegionScope for FnCtxt<'a, 'tcx> {
2025 fn object_lifetime_default(&self, span: Span) -> Option<ty::Region> {
2026 Some(self.base_object_lifetime_default(span))
2029 fn base_object_lifetime_default(&self, span: Span) -> ty::Region {
2030 // RFC #599 specifies that object lifetime defaults take
2031 // precedence over other defaults. But within a fn body we
2032 // don't have a *default* region, rather we use inference to
2033 // find the *correct* region, which is strictly more general
2034 // (and anyway, within a fn body the right region may not even
2035 // be something the user can write explicitly, since it might
2036 // be some expression).
2037 self.infcx().next_region_var(infer::MiscVariable(span))
2040 fn anon_regions(&self, span: Span, count: usize)
2041 -> Result<Vec<ty::Region>, Option<Vec<ElisionFailureInfo>>> {
2042 Ok((0..count).map(|_| {
2043 self.infcx().next_region_var(infer::MiscVariable(span))
2048 /// Whether `autoderef` requires types to resolve.
2049 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
2050 pub enum UnresolvedTypeAction {
2051 /// Produce an error and return `TyError` whenever a type cannot
2052 /// be resolved (i.e. it is `TyInfer`).
2054 /// Go on without emitting any errors, and return the unresolved
2055 /// type. Useful for probing, e.g. in coercions.
2059 /// Executes an autoderef loop for the type `t`. At each step, invokes `should_stop` to decide
2060 /// whether to terminate the loop. Returns the final type and number of derefs that it performed.
2062 /// Note: this method does not modify the adjustments table. The caller is responsible for
2063 /// inserting an AutoAdjustment record into the `fcx` using one of the suitable methods.
2064 pub fn autoderef<'a, 'tcx, T, F>(fcx: &FnCtxt<'a, 'tcx>,
2067 opt_expr: Option<&hir::Expr>,
2068 unresolved_type_action: UnresolvedTypeAction,
2069 mut lvalue_pref: LvaluePreference,
2071 -> (Ty<'tcx>, usize, Option<T>)
2072 where F: FnMut(Ty<'tcx>, usize) -> Option<T>,
2074 debug!("autoderef(base_ty={:?}, opt_expr={:?}, lvalue_pref={:?})",
2079 let mut t = base_ty;
2080 for autoderefs in 0..fcx.tcx().sess.recursion_limit.get() {
2081 let resolved_t = match unresolved_type_action {
2082 UnresolvedTypeAction::Error => {
2083 structurally_resolved_type(fcx, sp, t)
2085 UnresolvedTypeAction::Ignore => {
2086 // We can continue even when the type cannot be resolved
2087 // (i.e. it is an inference variable) because `Ty::builtin_deref`
2088 // and `try_overloaded_deref` both simply return `None`
2089 // in such a case without producing spurious errors.
2090 fcx.resolve_type_vars_if_possible(t)
2093 if resolved_t.references_error() {
2094 return (resolved_t, autoderefs, None);
2097 match should_stop(resolved_t, autoderefs) {
2098 Some(x) => return (resolved_t, autoderefs, Some(x)),
2102 // Otherwise, deref if type is derefable:
2103 let mt = match resolved_t.builtin_deref(false, lvalue_pref) {
2104 Some(mt) => Some(mt),
2107 opt_expr.map(|expr| MethodCall::autoderef(expr.id, autoderefs as u32));
2109 // Super subtle: it might seem as though we should
2110 // pass `opt_expr` to `try_overloaded_deref`, so that
2111 // the (implicit) autoref of using an overloaded deref
2112 // would get added to the adjustment table. However we
2113 // do not do that, because it's kind of a
2114 // "meta-adjustment" -- instead, we just leave it
2115 // unrecorded and know that there "will be" an
2116 // autoref. regionck and other bits of the code base,
2117 // when they encounter an overloaded autoderef, have
2118 // to do some reconstructive surgery. This is a pretty
2119 // complex mess that is begging for a proper MIR.
2120 try_overloaded_deref(fcx, sp, method_call, None, resolved_t, lvalue_pref)
2126 if mt.mutbl == hir::MutImmutable {
2127 lvalue_pref = NoPreference;
2130 None => return (resolved_t, autoderefs, None)
2134 // We've reached the recursion limit, error gracefully.
2135 span_err!(fcx.tcx().sess, sp, E0055,
2136 "reached the recursion limit while auto-dereferencing {:?}",
2138 (fcx.tcx().types.err, 0, None)
2141 fn try_overloaded_deref<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2143 method_call: Option<MethodCall>,
2144 base_expr: Option<&hir::Expr>,
2146 lvalue_pref: LvaluePreference)
2147 -> Option<ty::TypeAndMut<'tcx>>
2149 // Try DerefMut first, if preferred.
2150 let method = match (lvalue_pref, fcx.tcx().lang_items.deref_mut_trait()) {
2151 (PreferMutLvalue, Some(trait_did)) => {
2152 method::lookup_in_trait(fcx, span, base_expr,
2153 token::intern("deref_mut"), trait_did,
2159 // Otherwise, fall back to Deref.
2160 let method = match (method, fcx.tcx().lang_items.deref_trait()) {
2161 (None, Some(trait_did)) => {
2162 method::lookup_in_trait(fcx, span, base_expr,
2163 token::intern("deref"), trait_did,
2166 (method, _) => method
2169 make_overloaded_lvalue_return_type(fcx, method_call, method)
2172 /// For the overloaded lvalue expressions (`*x`, `x[3]`), the trait returns a type of `&T`, but the
2173 /// actual type we assign to the *expression* is `T`. So this function just peels off the return
2174 /// type by one layer to yield `T`. It also inserts the `method-callee` into the method map.
2175 fn make_overloaded_lvalue_return_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2176 method_call: Option<MethodCall>,
2177 method: Option<MethodCallee<'tcx>>)
2178 -> Option<ty::TypeAndMut<'tcx>>
2182 // extract method return type, which will be &T;
2183 // all LB regions should have been instantiated during method lookup
2184 let ret_ty = method.ty.fn_ret();
2185 let ret_ty = fcx.tcx().no_late_bound_regions(&ret_ty).unwrap().unwrap();
2187 if let Some(method_call) = method_call {
2188 fcx.inh.tables.borrow_mut().method_map.insert(method_call, method);
2191 // method returns &T, but the type as visible to user is T, so deref
2192 ret_ty.builtin_deref(true, NoPreference)
2198 fn lookup_indexing<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2200 base_expr: &'tcx hir::Expr,
2203 lvalue_pref: LvaluePreference)
2204 -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)>
2206 // FIXME(#18741) -- this is almost but not quite the same as the
2207 // autoderef that normal method probing does. They could likely be
2210 let (ty, autoderefs, final_mt) = autoderef(fcx,
2214 UnresolvedTypeAction::Error,
2217 try_index_step(fcx, MethodCall::expr(expr.id), expr, base_expr,
2218 adj_ty, idx, false, lvalue_pref, idx_ty)
2221 if final_mt.is_some() {
2225 // After we have fully autoderef'd, if the resulting type is [T; n], then
2226 // do a final unsized coercion to yield [T].
2227 if let ty::TyArray(element_ty, _) = ty.sty {
2228 let adjusted_ty = fcx.tcx().mk_slice(element_ty);
2229 try_index_step(fcx, MethodCall::expr(expr.id), expr, base_expr,
2230 adjusted_ty, autoderefs, true, lvalue_pref, idx_ty)
2236 /// To type-check `base_expr[index_expr]`, we progressively autoderef (and otherwise adjust)
2237 /// `base_expr`, looking for a type which either supports builtin indexing or overloaded indexing.
2238 /// This loop implements one step in that search; the autoderef loop is implemented by
2239 /// `lookup_indexing`.
2240 fn try_index_step<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2241 method_call: MethodCall,
2243 base_expr: &'tcx hir::Expr,
2244 adjusted_ty: Ty<'tcx>,
2247 lvalue_pref: LvaluePreference,
2249 -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)>
2251 let tcx = fcx.tcx();
2252 debug!("try_index_step(expr={:?}, base_expr.id={:?}, adjusted_ty={:?}, \
2253 autoderefs={}, unsize={}, index_ty={:?})",
2261 let input_ty = fcx.infcx().next_ty_var();
2263 // First, try built-in indexing.
2264 match (adjusted_ty.builtin_index(), &index_ty.sty) {
2265 (Some(ty), &ty::TyUint(ast::UintTy::Us)) | (Some(ty), &ty::TyInfer(ty::IntVar(_))) => {
2266 debug!("try_index_step: success, using built-in indexing");
2267 // If we had `[T; N]`, we should've caught it before unsizing to `[T]`.
2269 fcx.write_autoderef_adjustment(base_expr.id, autoderefs);
2270 return Some((tcx.types.usize, ty));
2275 // Try `IndexMut` first, if preferred.
2276 let method = match (lvalue_pref, tcx.lang_items.index_mut_trait()) {
2277 (PreferMutLvalue, Some(trait_did)) => {
2278 method::lookup_in_trait_adjusted(fcx,
2281 token::intern("index_mut"),
2286 Some(vec![input_ty]))
2291 // Otherwise, fall back to `Index`.
2292 let method = match (method, tcx.lang_items.index_trait()) {
2293 (None, Some(trait_did)) => {
2294 method::lookup_in_trait_adjusted(fcx,
2297 token::intern("index"),
2302 Some(vec![input_ty]))
2304 (method, _) => method,
2307 // If some lookup succeeds, write callee into table and extract index/element
2308 // type from the method signature.
2309 // If some lookup succeeded, install method in table
2310 method.and_then(|method| {
2311 debug!("try_index_step: success, using overloaded indexing");
2312 make_overloaded_lvalue_return_type(fcx, Some(method_call), Some(method)).
2313 map(|ret| (input_ty, ret.ty))
2317 fn check_method_argument_types<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2319 method_fn_ty: Ty<'tcx>,
2320 callee_expr: &'tcx hir::Expr,
2321 args_no_rcvr: &'tcx [P<hir::Expr>],
2322 tuple_arguments: TupleArgumentsFlag,
2323 expected: Expectation<'tcx>)
2324 -> ty::FnOutput<'tcx> {
2325 if method_fn_ty.references_error() {
2326 let err_inputs = err_args(fcx.tcx(), args_no_rcvr.len());
2328 let err_inputs = match tuple_arguments {
2329 DontTupleArguments => err_inputs,
2330 TupleArguments => vec![fcx.tcx().mk_tup(err_inputs)],
2333 check_argument_types(fcx,
2340 ty::FnConverging(fcx.tcx().types.err)
2342 match method_fn_ty.sty {
2343 ty::TyBareFn(_, ref fty) => {
2344 // HACK(eddyb) ignore self in the definition (see above).
2345 let expected_arg_tys = expected_types_for_fn_args(fcx,
2349 &fty.sig.0.inputs[1..]);
2350 check_argument_types(fcx,
2352 &fty.sig.0.inputs[1..],
2353 &expected_arg_tys[..],
2360 fcx.tcx().sess.span_bug(callee_expr.span,
2361 "method without bare fn type");
2367 /// Generic function that factors out common logic from function calls, method calls and overloaded
2369 fn check_argument_types<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2371 fn_inputs: &[Ty<'tcx>],
2372 expected_arg_tys: &[Ty<'tcx>],
2373 args: &'tcx [P<hir::Expr>],
2375 tuple_arguments: TupleArgumentsFlag) {
2376 let tcx = fcx.ccx.tcx;
2378 // Grab the argument types, supplying fresh type variables
2379 // if the wrong number of arguments were supplied
2380 let supplied_arg_count = if tuple_arguments == DontTupleArguments {
2386 // All the input types from the fn signature must outlive the call
2387 // so as to validate implied bounds.
2388 for &fn_input_ty in fn_inputs {
2389 fcx.register_wf_obligation(fn_input_ty, sp, traits::MiscObligation);
2392 let mut expected_arg_tys = expected_arg_tys;
2393 let expected_arg_count = fn_inputs.len();
2394 let formal_tys = if tuple_arguments == TupleArguments {
2395 let tuple_type = structurally_resolved_type(fcx, sp, fn_inputs[0]);
2396 match tuple_type.sty {
2397 ty::TyTuple(ref arg_types) => {
2398 if arg_types.len() != args.len() {
2399 span_err!(tcx.sess, sp, E0057,
2400 "this function takes {} parameter{} but {} parameter{} supplied",
2402 if arg_types.len() == 1 {""} else {"s"},
2404 if args.len() == 1 {" was"} else {"s were"});
2405 expected_arg_tys = &[];
2406 err_args(fcx.tcx(), args.len())
2408 expected_arg_tys = match expected_arg_tys.get(0) {
2409 Some(&ty) => match ty.sty {
2410 ty::TyTuple(ref tys) => &tys,
2415 (*arg_types).clone()
2419 span_err!(tcx.sess, sp, E0059,
2420 "cannot use call notation; the first type parameter \
2421 for the function trait is neither a tuple nor unit");
2422 expected_arg_tys = &[];
2423 err_args(fcx.tcx(), args.len())
2426 } else if expected_arg_count == supplied_arg_count {
2428 } else if variadic {
2429 if supplied_arg_count >= expected_arg_count {
2432 span_err!(tcx.sess, sp, E0060,
2433 "this function takes at least {} parameter{} \
2434 but {} parameter{} supplied",
2436 if expected_arg_count == 1 {""} else {"s"},
2438 if supplied_arg_count == 1 {" was"} else {"s were"});
2439 expected_arg_tys = &[];
2440 err_args(fcx.tcx(), supplied_arg_count)
2443 span_err!(tcx.sess, sp, E0061,
2444 "this function takes {} parameter{} but {} parameter{} supplied",
2446 if expected_arg_count == 1 {""} else {"s"},
2448 if supplied_arg_count == 1 {" was"} else {"s were"});
2449 expected_arg_tys = &[];
2450 err_args(fcx.tcx(), supplied_arg_count)
2453 debug!("check_argument_types: formal_tys={:?}",
2454 formal_tys.iter().map(|t| fcx.infcx().ty_to_string(*t)).collect::<Vec<String>>());
2456 // Check the arguments.
2457 // We do this in a pretty awful way: first we typecheck any arguments
2458 // that are not anonymous functions, then we typecheck the anonymous
2459 // functions. This is so that we have more information about the types
2460 // of arguments when we typecheck the functions. This isn't really the
2461 // right way to do this.
2462 let xs = [false, true];
2463 let mut any_diverges = false; // has any of the arguments diverged?
2464 let mut warned = false; // have we already warned about unreachable code?
2465 for check_blocks in &xs {
2466 let check_blocks = *check_blocks;
2467 debug!("check_blocks={}", check_blocks);
2469 // More awful hacks: before we check argument types, try to do
2470 // an "opportunistic" vtable resolution of any trait bounds on
2471 // the call. This helps coercions.
2473 fcx.select_obligations_where_possible();
2476 // For variadic functions, we don't have a declared type for all of
2477 // the arguments hence we only do our usual type checking with
2478 // the arguments who's types we do know.
2479 let t = if variadic {
2481 } else if tuple_arguments == TupleArguments {
2486 for (i, arg) in args.iter().take(t).enumerate() {
2487 if any_diverges && !warned {
2491 .add_lint(lint::builtin::UNREACHABLE_CODE,
2494 "unreachable expression".to_string());
2497 let is_block = match arg.node {
2498 hir::ExprClosure(..) => true,
2502 if is_block == check_blocks {
2503 debug!("checking the argument");
2504 let formal_ty = formal_tys[i];
2506 // The special-cased logic below has three functions:
2507 // 1. Provide as good of an expected type as possible.
2508 let expected = expected_arg_tys.get(i).map(|&ty| {
2509 Expectation::rvalue_hint(fcx.tcx(), ty)
2512 check_expr_with_unifier(fcx,
2514 expected.unwrap_or(ExpectHasType(formal_ty)),
2516 // 2. Coerce to the most detailed type that could be coerced
2517 // to, which is `expected_ty` if `rvalue_hint` returns an
2518 // `ExprHasType(expected_ty)`, or the `formal_ty` otherwise.
2519 let coerce_ty = expected.and_then(|e| e.only_has_type(fcx));
2520 demand::coerce(fcx, arg.span, coerce_ty.unwrap_or(formal_ty), &arg);
2522 // 3. Relate the expected type and the formal one,
2523 // if the expected type was used for the coercion.
2524 coerce_ty.map(|ty| demand::suptype(fcx, arg.span, formal_ty, ty));
2528 if let Some(&arg_ty) = fcx.inh.tables.borrow().node_types.get(&arg.id) {
2529 any_diverges = any_diverges || fcx.infcx().type_var_diverges(arg_ty);
2532 if any_diverges && !warned {
2533 let parent = fcx.ccx.tcx.map.get_parent_node(args[0].id);
2537 .add_lint(lint::builtin::UNREACHABLE_CODE,
2540 "unreachable call".to_string());
2546 // We also need to make sure we at least write the ty of the other
2547 // arguments which we skipped above.
2549 for arg in args.iter().skip(expected_arg_count) {
2550 check_expr(fcx, &arg);
2552 // There are a few types which get autopromoted when passed via varargs
2553 // in C but we just error out instead and require explicit casts.
2554 let arg_ty = structurally_resolved_type(fcx, arg.span,
2557 ty::TyFloat(ast::FloatTy::F32) => {
2558 fcx.type_error_message(arg.span,
2560 format!("can't pass an {} to variadic \
2561 function, cast to c_double", t)
2564 ty::TyInt(ast::IntTy::I8) | ty::TyInt(ast::IntTy::I16) | ty::TyBool => {
2565 fcx.type_error_message(arg.span, |t| {
2566 format!("can't pass {} to variadic \
2567 function, cast to c_int",
2571 ty::TyUint(ast::UintTy::U8) | ty::TyUint(ast::UintTy::U16) => {
2572 fcx.type_error_message(arg.span, |t| {
2573 format!("can't pass {} to variadic \
2574 function, cast to c_uint",
2584 // FIXME(#17596) Ty<'tcx> is incorrectly invariant w.r.t 'tcx.
2585 fn err_args<'tcx>(tcx: &TyCtxt<'tcx>, len: usize) -> Vec<Ty<'tcx>> {
2586 (0..len).map(|_| tcx.types.err).collect()
2589 fn write_call<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2590 call_expr: &hir::Expr,
2591 output: ty::FnOutput<'tcx>) {
2592 fcx.write_ty(call_expr.id, match output {
2593 ty::FnConverging(output_ty) => output_ty,
2594 ty::FnDiverging => fcx.infcx().next_diverging_ty_var()
2598 // AST fragment checking
2599 fn check_lit<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2601 expected: Expectation<'tcx>)
2604 let tcx = fcx.ccx.tcx;
2607 ast::LitKind::Str(..) => tcx.mk_static_str(),
2608 ast::LitKind::ByteStr(ref v) => {
2609 tcx.mk_imm_ref(tcx.mk_region(ty::ReStatic),
2610 tcx.mk_array(tcx.types.u8, v.len()))
2612 ast::LitKind::Byte(_) => tcx.types.u8,
2613 ast::LitKind::Char(_) => tcx.types.char,
2614 ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t),
2615 ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t),
2616 ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => {
2617 let opt_ty = expected.to_option(fcx).and_then(|ty| {
2619 ty::TyInt(_) | ty::TyUint(_) => Some(ty),
2620 ty::TyChar => Some(tcx.types.u8),
2621 ty::TyRawPtr(..) => Some(tcx.types.usize),
2622 ty::TyBareFn(..) => Some(tcx.types.usize),
2626 opt_ty.unwrap_or_else(
2627 || tcx.mk_int_var(fcx.infcx().next_int_var_id()))
2629 ast::LitKind::Float(_, t) => tcx.mk_mach_float(t),
2630 ast::LitKind::FloatUnsuffixed(_) => {
2631 let opt_ty = expected.to_option(fcx).and_then(|ty| {
2633 ty::TyFloat(_) => Some(ty),
2637 opt_ty.unwrap_or_else(
2638 || tcx.mk_float_var(fcx.infcx().next_float_var_id()))
2640 ast::LitKind::Bool(_) => tcx.types.bool
2644 fn check_expr_eq_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2645 expr: &'tcx hir::Expr,
2646 expected: Ty<'tcx>) {
2647 check_expr_with_unifier(
2648 fcx, expr, ExpectHasType(expected), NoPreference,
2649 || demand::eqtype(fcx, expr.span, expected, fcx.expr_ty(expr)));
2652 pub fn check_expr_has_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2653 expr: &'tcx hir::Expr,
2654 expected: Ty<'tcx>) {
2655 check_expr_with_unifier(
2656 fcx, expr, ExpectHasType(expected), NoPreference,
2657 || demand::suptype(fcx, expr.span, expected, fcx.expr_ty(expr)));
2660 fn check_expr_coercable_to_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2661 expr: &'tcx hir::Expr,
2662 expected: Ty<'tcx>) {
2663 check_expr_with_unifier(
2664 fcx, expr, ExpectHasType(expected), NoPreference,
2665 || demand::coerce(fcx, expr.span, expected, expr));
2668 fn check_expr_with_hint<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>, expr: &'tcx hir::Expr,
2669 expected: Ty<'tcx>) {
2670 check_expr_with_unifier(
2671 fcx, expr, ExpectHasType(expected), NoPreference,
2675 fn check_expr_with_expectation<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2676 expr: &'tcx hir::Expr,
2677 expected: Expectation<'tcx>) {
2678 check_expr_with_unifier(
2679 fcx, expr, expected, NoPreference,
2683 fn check_expr_with_expectation_and_lvalue_pref<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2684 expr: &'tcx hir::Expr,
2685 expected: Expectation<'tcx>,
2686 lvalue_pref: LvaluePreference)
2688 check_expr_with_unifier(fcx, expr, expected, lvalue_pref, || ())
2691 fn check_expr<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, expr: &'tcx hir::Expr) {
2692 check_expr_with_unifier(fcx, expr, NoExpectation, NoPreference, || ())
2695 fn check_expr_with_lvalue_pref<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, expr: &'tcx hir::Expr,
2696 lvalue_pref: LvaluePreference) {
2697 check_expr_with_unifier(fcx, expr, NoExpectation, lvalue_pref, || ())
2700 // determine the `self` type, using fresh variables for all variables
2701 // declared on the impl declaration e.g., `impl<A,B> for Vec<(A,B)>`
2702 // would return ($0, $1) where $0 and $1 are freshly instantiated type
2704 pub fn impl_self_ty<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2705 span: Span, // (potential) receiver for this impl
2707 -> TypeAndSubsts<'tcx> {
2708 let tcx = fcx.tcx();
2710 let ity = tcx.lookup_item_type(did);
2711 let (tps, rps, raw_ty) =
2712 (ity.generics.types.get_slice(subst::TypeSpace),
2713 ity.generics.regions.get_slice(subst::TypeSpace),
2716 debug!("impl_self_ty: tps={:?} rps={:?} raw_ty={:?}", tps, rps, raw_ty);
2718 let rps = fcx.inh.infcx.region_vars_for_defs(span, rps);
2719 let mut substs = subst::Substs::new(
2720 VecPerParamSpace::empty(),
2721 VecPerParamSpace::new(rps, Vec::new(), Vec::new()));
2722 fcx.inh.infcx.type_vars_for_defs(span, ParamSpace::TypeSpace, &mut substs, tps);
2723 let substd_ty = fcx.instantiate_type_scheme(span, &substs, &raw_ty);
2725 TypeAndSubsts { substs: substs, ty: substd_ty }
2728 /// Controls whether the arguments are tupled. This is used for the call
2731 /// Tupling means that all call-side arguments are packed into a tuple and
2732 /// passed as a single parameter. For example, if tupling is enabled, this
2735 /// fn f(x: (isize, isize))
2737 /// Can be called as:
2744 #[derive(Clone, Eq, PartialEq)]
2745 enum TupleArgumentsFlag {
2750 /// Unifies the return type with the expected type early, for more coercions
2751 /// and forward type information on the argument expressions.
2752 fn expected_types_for_fn_args<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2754 expected_ret: Expectation<'tcx>,
2755 formal_ret: ty::FnOutput<'tcx>,
2756 formal_args: &[Ty<'tcx>])
2758 let expected_args = expected_ret.only_has_type(fcx).and_then(|ret_ty| {
2759 if let ty::FnConverging(formal_ret_ty) = formal_ret {
2760 fcx.infcx().commit_regions_if_ok(|| {
2761 // Attempt to apply a subtyping relationship between the formal
2762 // return type (likely containing type variables if the function
2763 // is polymorphic) and the expected return type.
2764 // No argument expectations are produced if unification fails.
2765 let origin = TypeOrigin::Misc(call_span);
2766 let ures = fcx.infcx().sub_types(false, origin, formal_ret_ty, ret_ty);
2767 // FIXME(#15760) can't use try! here, FromError doesn't default
2768 // to identity so the resulting type is not constrained.
2769 if let Err(e) = ures {
2773 // Record all the argument types, with the substitutions
2774 // produced from the above subtyping unification.
2775 Ok(formal_args.iter().map(|ty| {
2776 fcx.infcx().resolve_type_vars_if_possible(ty)
2782 }).unwrap_or(vec![]);
2783 debug!("expected_types_for_fn_args(formal={:?} -> {:?}, expected={:?} -> {:?})",
2784 formal_args, formal_ret,
2785 expected_args, expected_ret);
2790 /// If an expression has any sub-expressions that result in a type error,
2791 /// inspecting that expression's type with `ty.references_error()` will return
2792 /// true. Likewise, if an expression is known to diverge, inspecting its
2793 /// type with `ty::type_is_bot` will return true (n.b.: since Rust is
2794 /// strict, _|_ can appear in the type of an expression that does not,
2795 /// itself, diverge: for example, fn() -> _|_.)
2796 /// Note that inspecting a type's structure *directly* may expose the fact
2797 /// that there are actually multiple representations for `TyError`, so avoid
2798 /// that when err needs to be handled differently.
2799 fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
2800 expr: &'tcx hir::Expr,
2801 expected: Expectation<'tcx>,
2802 lvalue_pref: LvaluePreference,
2806 debug!(">> typechecking: expr={:?} expected={:?}",
2809 // Checks a method call.
2810 fn check_method_call<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2811 expr: &'tcx hir::Expr,
2812 method_name: Spanned<ast::Name>,
2813 args: &'tcx [P<hir::Expr>],
2815 expected: Expectation<'tcx>,
2816 lvalue_pref: LvaluePreference) {
2817 let rcvr = &args[0];
2818 check_expr_with_lvalue_pref(fcx, &rcvr, lvalue_pref);
2820 // no need to check for bot/err -- callee does that
2821 let expr_t = structurally_resolved_type(fcx,
2823 fcx.expr_ty(&rcvr));
2825 let tps = tps.iter().map(|ast_ty| fcx.to_ty(&ast_ty)).collect::<Vec<_>>();
2826 let fn_ty = match method::lookup(fcx,
2834 let method_ty = method.ty;
2835 let method_call = MethodCall::expr(expr.id);
2836 fcx.inh.tables.borrow_mut().method_map.insert(method_call, method);
2840 if method_name.node != special_idents::invalid.name {
2841 method::report_error(fcx, method_name.span, expr_t,
2842 method_name.node, Some(rcvr), error);
2844 fcx.write_error(expr.id);
2849 // Call the generic checker.
2850 let ret_ty = check_method_argument_types(fcx,
2858 write_call(fcx, expr, ret_ty);
2861 // A generic function for checking the then and else in an if
2863 fn check_then_else<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2864 cond_expr: &'tcx hir::Expr,
2865 then_blk: &'tcx hir::Block,
2866 opt_else_expr: Option<&'tcx hir::Expr>,
2869 expected: Expectation<'tcx>) {
2870 check_expr_has_type(fcx, cond_expr, fcx.tcx().types.bool);
2872 let expected = expected.adjust_for_branches(fcx);
2873 check_block_with_expected(fcx, then_blk, expected);
2874 let then_ty = fcx.node_ty(then_blk.id);
2876 let branches_ty = match opt_else_expr {
2877 Some(ref else_expr) => {
2878 check_expr_with_expectation(fcx, &else_expr, expected);
2879 let else_ty = fcx.expr_ty(&else_expr);
2880 infer::common_supertype(fcx.infcx(),
2881 TypeOrigin::IfExpression(sp),
2887 infer::common_supertype(fcx.infcx(),
2888 TypeOrigin::IfExpressionWithNoElse(sp),
2895 let cond_ty = fcx.expr_ty(cond_expr);
2896 let if_ty = if cond_ty.references_error() {
2902 fcx.write_ty(id, if_ty);
2905 // Check field access expressions
2906 fn check_field<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
2907 expr: &'tcx hir::Expr,
2908 lvalue_pref: LvaluePreference,
2909 base: &'tcx hir::Expr,
2910 field: &Spanned<ast::Name>) {
2911 check_expr_with_lvalue_pref(fcx, base, lvalue_pref);
2912 let expr_t = structurally_resolved_type(fcx, expr.span,
2914 // FIXME(eddyb) #12808 Integrate privacy into this auto-deref loop.
2915 let (_, autoderefs, field_ty) = autoderef(fcx,
2919 UnresolvedTypeAction::Error,
2923 ty::TyStruct(base_def, substs) => {
2924 debug!("struct named {:?}", base_t);
2925 base_def.struct_variant()
2926 .find_field_named(field.node)
2927 .map(|f| fcx.field_ty(expr.span, f, substs))
2934 fcx.write_ty(expr.id, field_ty);
2935 fcx.write_autoderef_adjustment(base.id, autoderefs);
2941 if field.node == special_idents::invalid.name {
2942 fcx.write_error(expr.id);
2946 if method::exists(fcx, field.span, field.node, expr_t, expr.id) {
2947 fcx.type_error_struct(field.span,
2949 format!("attempted to take value of method `{}` on type \
2950 `{}`", field.node, actual)
2953 .fileline_help(field.span,
2954 "maybe a `()` to call it is missing? \
2955 If not, try an anonymous function")
2958 let mut err = fcx.type_error_struct(
2961 format!("attempted access of field `{}` on \
2962 type `{}`, but no field with that \
2968 if let ty::TyStruct(def, _) = expr_t.sty {
2969 suggest_field_names(&mut err, def.struct_variant(), field, vec![]);
2974 fcx.write_error(expr.id);
2977 // displays hints about the closest matches in field names
2978 fn suggest_field_names<'tcx>(err: &mut DiagnosticBuilder,
2979 variant: ty::VariantDef<'tcx>,
2980 field: &Spanned<ast::Name>,
2981 skip : Vec<InternedString>) {
2982 let name = field.node.as_str();
2983 let names = variant.fields
2985 .filter_map(|ref field| {
2986 // ignore already set fields and private fields from non-local crates
2987 if skip.iter().any(|x| *x == field.name.as_str()) ||
2988 (variant.did.krate != LOCAL_CRATE && field.vis != Visibility::Public) {
2995 // only find fits with at least one matching letter
2996 if let Some(name) = find_best_match_for_name(names, &name, Some(name.len())) {
2997 err.span_help(field.span,
2998 &format!("did you mean `{}`?", name));
3002 // Check tuple index expressions
3003 fn check_tup_field<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
3004 expr: &'tcx hir::Expr,
3005 lvalue_pref: LvaluePreference,
3006 base: &'tcx hir::Expr,
3007 idx: codemap::Spanned<usize>) {
3008 check_expr_with_lvalue_pref(fcx, base, lvalue_pref);
3009 let expr_t = structurally_resolved_type(fcx, expr.span,
3011 let mut tuple_like = false;
3012 // FIXME(eddyb) #12808 Integrate privacy into this auto-deref loop.
3013 let (_, autoderefs, field_ty) = autoderef(fcx,
3017 UnresolvedTypeAction::Error,
3021 ty::TyStruct(base_def, substs) => {
3022 tuple_like = base_def.struct_variant().is_tuple_struct();
3024 debug!("tuple struct named {:?}", base_t);
3025 base_def.struct_variant()
3028 .map(|f| fcx.field_ty(expr.span, f, substs))
3033 ty::TyTuple(ref v) => {
3035 if idx.node < v.len() { Some(v[idx.node]) } else { None }
3042 fcx.write_ty(expr.id, field_ty);
3043 fcx.write_autoderef_adjustment(base.id, autoderefs);
3048 fcx.type_error_message(
3052 format!("attempted out-of-bounds tuple index `{}` on \
3057 format!("attempted tuple index `{}` on type `{}`, but the \
3058 type was not a tuple or tuple struct",
3065 fcx.write_error(expr.id);
3068 fn report_unknown_field<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3070 variant: ty::VariantDef<'tcx>,
3072 skip_fields: &[hir::Field]) {
3073 let mut err = fcx.type_error_struct(
3075 |actual| if let ty::TyEnum(..) = ty.sty {
3076 format!("struct variant `{}::{}` has no field named `{}`",
3077 actual, variant.name.as_str(), field.name.node)
3079 format!("structure `{}` has no field named `{}`",
3080 actual, field.name.node)
3084 // prevent all specified fields from being suggested
3085 let skip_fields = skip_fields.iter().map(|ref x| x.name.node.as_str());
3086 suggest_field_names(&mut err, variant, &field.name, skip_fields.collect());
3090 fn check_expr_struct_fields<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3093 variant: ty::VariantDef<'tcx>,
3094 ast_fields: &'tcx [hir::Field],
3095 check_completeness: bool) {
3096 let tcx = fcx.ccx.tcx;
3097 let substs = match adt_ty.sty {
3098 ty::TyStruct(_, substs) | ty::TyEnum(_, substs) => substs,
3099 _ => tcx.sess.span_bug(span, "non-ADT passed to check_expr_struct_fields")
3102 let mut remaining_fields = FnvHashMap();
3103 for field in &variant.fields {
3104 remaining_fields.insert(field.name, field);
3107 let mut error_happened = false;
3109 // Typecheck each field.
3110 for field in ast_fields {
3111 let expected_field_type;
3113 if let Some(v_field) = remaining_fields.remove(&field.name.node) {
3114 expected_field_type = fcx.field_ty(field.span, v_field, substs);
3116 error_happened = true;
3117 expected_field_type = tcx.types.err;
3118 if let Some(_) = variant.find_field_named(field.name.node) {
3119 span_err!(fcx.tcx().sess, field.name.span, E0062,
3120 "field `{}` specified more than once",
3123 report_unknown_field(fcx, adt_ty, variant, field, ast_fields);
3127 // Make sure to give a type to the field even if there's
3128 // an error, so we can continue typechecking
3129 check_expr_coercable_to_type(fcx, &field.expr, expected_field_type);
3132 // Make sure the programmer specified all the fields.
3133 if check_completeness &&
3135 !remaining_fields.is_empty()
3137 span_err!(tcx.sess, span, E0063,
3138 "missing field{} {} in initializer of `{}`",
3139 if remaining_fields.len() == 1 {""} else {"s"},
3140 remaining_fields.keys()
3141 .map(|n| format!("`{}`", n))
3142 .collect::<Vec<_>>()
3149 fn check_struct_fields_on_error<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
3151 fields: &'tcx [hir::Field],
3152 base_expr: &'tcx Option<P<hir::Expr>>) {
3153 // Make sure to still write the types
3154 // otherwise we might ICE
3155 fcx.write_error(id);
3156 for field in fields {
3157 check_expr(fcx, &field.expr);
3160 Some(ref base) => check_expr(fcx, &base),
3165 fn check_expr_struct<'a, 'tcx>(fcx: &FnCtxt<'a,'tcx>,
3168 fields: &'tcx [hir::Field],
3169 base_expr: &'tcx Option<P<hir::Expr>>)
3171 let tcx = fcx.tcx();
3173 // Find the relevant variant
3174 let def = lookup_full_def(tcx, path.span, expr.id);
3175 if def == Def::Err {
3176 check_struct_fields_on_error(fcx, expr.id, fields, base_expr);
3179 let variant = match fcx.def_struct_variant(def, path.span) {
3180 Some((_, variant)) => variant,
3182 span_err!(fcx.tcx().sess, path.span, E0071,
3183 "`{}` does not name a structure",
3184 pprust::path_to_string(path));
3185 check_struct_fields_on_error(fcx, expr.id, fields, base_expr);
3190 let expr_ty = fcx.instantiate_type(def.def_id(), path);
3191 fcx.write_ty(expr.id, expr_ty);
3193 check_expr_struct_fields(fcx, expr_ty, expr.span, variant, fields,
3194 base_expr.is_none());
3195 if let &Some(ref base_expr) = base_expr {
3196 check_expr_has_type(fcx, base_expr, expr_ty);
3198 ty::TyStruct(adt, substs) => {
3199 fcx.inh.tables.borrow_mut().fru_field_types.insert(
3201 adt.struct_variant().fields.iter().map(|f| {
3202 fcx.normalize_associated_types_in(
3203 expr.span, &f.ty(tcx, substs)
3209 span_err!(tcx.sess, base_expr.span, E0436,
3210 "functional record update syntax requires a struct");
3216 type ExprCheckerWithTy = fn(&FnCtxt, &hir::Expr, Ty);
3218 let tcx = fcx.ccx.tcx;
3221 hir::ExprBox(ref subexpr) => {
3222 let expected_inner = expected.to_option(fcx).map_or(NoExpectation, |ty| {
3224 ty::TyBox(ty) => Expectation::rvalue_hint(tcx, ty),
3228 check_expr_with_expectation(fcx, subexpr, expected_inner);
3229 let referent_ty = fcx.expr_ty(&subexpr);
3230 fcx.write_ty(id, tcx.mk_box(referent_ty));
3233 hir::ExprLit(ref lit) => {
3234 let typ = check_lit(fcx, &lit, expected);
3235 fcx.write_ty(id, typ);
3237 hir::ExprBinary(op, ref lhs, ref rhs) => {
3238 op::check_binop(fcx, expr, op, lhs, rhs);
3240 hir::ExprAssignOp(op, ref lhs, ref rhs) => {
3241 op::check_binop_assign(fcx, expr, op, lhs, rhs);
3243 hir::ExprUnary(unop, ref oprnd) => {
3244 let expected_inner = match unop {
3245 hir::UnNot | hir::UnNeg => {
3252 let lvalue_pref = match unop {
3253 hir::UnDeref => lvalue_pref,
3256 check_expr_with_expectation_and_lvalue_pref(
3257 fcx, &oprnd, expected_inner, lvalue_pref);
3258 let mut oprnd_t = fcx.expr_ty(&oprnd);
3260 if !oprnd_t.references_error() {
3263 oprnd_t = structurally_resolved_type(fcx, expr.span, oprnd_t);
3264 oprnd_t = match oprnd_t.builtin_deref(true, NoPreference) {
3266 None => match try_overloaded_deref(fcx, expr.span,
3267 Some(MethodCall::expr(expr.id)),
3268 Some(&oprnd), oprnd_t, lvalue_pref) {
3271 fcx.type_error_message(expr.span, |actual| {
3272 format!("type `{}` cannot be \
3273 dereferenced", actual)
3281 oprnd_t = structurally_resolved_type(fcx, oprnd.span,
3283 if !(oprnd_t.is_integral() || oprnd_t.sty == ty::TyBool) {
3284 oprnd_t = op::check_user_unop(fcx, "!", "not",
3285 tcx.lang_items.not_trait(),
3286 expr, &oprnd, oprnd_t, unop);
3290 oprnd_t = structurally_resolved_type(fcx, oprnd.span,
3292 if !(oprnd_t.is_integral() || oprnd_t.is_fp()) {
3293 oprnd_t = op::check_user_unop(fcx, "-", "neg",
3294 tcx.lang_items.neg_trait(),
3295 expr, &oprnd, oprnd_t, unop);
3300 fcx.write_ty(id, oprnd_t);
3302 hir::ExprAddrOf(mutbl, ref oprnd) => {
3303 let hint = expected.only_has_type(fcx).map_or(NoExpectation, |ty| {
3305 ty::TyRef(_, ref mt) | ty::TyRawPtr(ref mt) => {
3306 if fcx.tcx().expr_is_lval(&oprnd) {
3307 // Lvalues may legitimately have unsized types.
3308 // For example, dereferences of a fat pointer and
3309 // the last field of a struct can be unsized.
3310 ExpectHasType(mt.ty)
3312 Expectation::rvalue_hint(tcx, mt.ty)
3318 let lvalue_pref = LvaluePreference::from_mutbl(mutbl);
3319 check_expr_with_expectation_and_lvalue_pref(fcx,
3324 let tm = ty::TypeAndMut { ty: fcx.expr_ty(&oprnd), mutbl: mutbl };
3325 let oprnd_t = if tm.ty.references_error() {
3328 // Note: at this point, we cannot say what the best lifetime
3329 // is to use for resulting pointer. We want to use the
3330 // shortest lifetime possible so as to avoid spurious borrowck
3331 // errors. Moreover, the longest lifetime will depend on the
3332 // precise details of the value whose address is being taken
3333 // (and how long it is valid), which we don't know yet until type
3334 // inference is complete.
3336 // Therefore, here we simply generate a region variable. The
3337 // region inferencer will then select the ultimate value.
3338 // Finally, borrowck is charged with guaranteeing that the
3339 // value whose address was taken can actually be made to live
3340 // as long as it needs to live.
3341 let region = fcx.infcx().next_region_var(infer::AddrOfRegion(expr.span));
3342 tcx.mk_ref(tcx.mk_region(region), tm)
3344 fcx.write_ty(id, oprnd_t);
3346 hir::ExprPath(ref maybe_qself, ref path) => {
3347 let opt_self_ty = maybe_qself.as_ref().map(|qself| {
3348 fcx.to_ty(&qself.ty)
3351 let path_res = if let Some(&d) = tcx.def_map.borrow().get(&id) {
3353 } else if let Some(hir::QSelf { position: 0, .. }) = *maybe_qself {
3354 // Create some fake resolution that can't possibly be a type.
3355 def::PathResolution {
3356 base_def: Def::Mod(tcx.map.local_def_id(ast::CRATE_NODE_ID)),
3357 depth: path.segments.len()
3360 tcx.sess.span_bug(expr.span,
3361 &format!("unbound path {:?}", expr))
3364 if let Some((opt_ty, segments, def)) =
3365 resolve_ty_and_def_ufcs(fcx, path_res, opt_self_ty, path,
3366 expr.span, expr.id) {
3367 if def != Def::Err {
3368 let (scheme, predicates) = type_scheme_and_predicates_for_def(fcx,
3371 instantiate_path(fcx,
3380 fcx.write_ty(id, fcx.tcx().types.err);
3384 // We always require that the type provided as the value for
3385 // a type parameter outlives the moment of instantiation.
3386 fcx.opt_node_ty_substs(expr.id, |item_substs| {
3387 fcx.add_wf_bounds(&item_substs.substs, expr);
3390 hir::ExprInlineAsm(ref ia) => {
3391 for &(_, ref input) in &ia.inputs {
3392 check_expr(fcx, &input);
3394 for out in &ia.outputs {
3395 check_expr(fcx, &out.expr);
3399 hir::ExprBreak(_) => { fcx.write_ty(id, fcx.infcx().next_diverging_ty_var()); }
3400 hir::ExprAgain(_) => { fcx.write_ty(id, fcx.infcx().next_diverging_ty_var()); }
3401 hir::ExprRet(ref expr_opt) => {
3403 ty::FnConverging(result_type) => {
3406 if let Err(_) = fcx.mk_eqty(false, TypeOrigin::Misc(expr.span),
3407 result_type, fcx.tcx().mk_nil()) {
3408 span_err!(tcx.sess, expr.span, E0069,
3409 "`return;` in a function whose return type is \
3413 check_expr_coercable_to_type(fcx, &e, result_type);
3417 ty::FnDiverging => {
3418 if let Some(ref e) = *expr_opt {
3419 check_expr(fcx, &e);
3421 span_err!(tcx.sess, expr.span, E0166,
3422 "`return` in a function declared as diverging");
3425 fcx.write_ty(id, fcx.infcx().next_diverging_ty_var());
3427 hir::ExprAssign(ref lhs, ref rhs) => {
3428 check_expr_with_lvalue_pref(fcx, &lhs, PreferMutLvalue);
3430 let tcx = fcx.tcx();
3431 if !tcx.expr_is_lval(&lhs) {
3432 span_err!(tcx.sess, expr.span, E0070,
3433 "invalid left-hand side expression");
3436 let lhs_ty = fcx.expr_ty(&lhs);
3437 check_expr_coercable_to_type(fcx, &rhs, lhs_ty);
3438 let rhs_ty = fcx.expr_ty(&rhs);
3440 fcx.require_expr_have_sized_type(&lhs, traits::AssignmentLhsSized);
3442 if lhs_ty.references_error() || rhs_ty.references_error() {
3443 fcx.write_error(id);
3448 hir::ExprIf(ref cond, ref then_blk, ref opt_else_expr) => {
3449 check_then_else(fcx, &cond, &then_blk, opt_else_expr.as_ref().map(|e| &**e),
3450 id, expr.span, expected);
3452 hir::ExprWhile(ref cond, ref body, _) => {
3453 check_expr_has_type(fcx, &cond, tcx.types.bool);
3454 check_block_no_value(fcx, &body);
3455 let cond_ty = fcx.expr_ty(&cond);
3456 let body_ty = fcx.node_ty(body.id);
3457 if cond_ty.references_error() || body_ty.references_error() {
3458 fcx.write_error(id);
3464 hir::ExprLoop(ref body, _) => {
3465 check_block_no_value(fcx, &body);
3466 if !may_break(tcx, expr.id, &body) {
3467 fcx.write_ty(id, fcx.infcx().next_diverging_ty_var());
3472 hir::ExprMatch(ref discrim, ref arms, match_src) => {
3473 _match::check_match(fcx, expr, &discrim, arms, expected, match_src);
3475 hir::ExprClosure(capture, ref decl, ref body) => {
3476 closure::check_expr_closure(fcx, expr, capture, &decl, &body, expected);
3478 hir::ExprBlock(ref b) => {
3479 check_block_with_expected(fcx, &b, expected);
3480 fcx.write_ty(id, fcx.node_ty(b.id));
3482 hir::ExprCall(ref callee, ref args) => {
3483 callee::check_call(fcx, expr, &callee, &args[..], expected);
3485 // we must check that return type of called functions is WF:
3486 let ret_ty = fcx.expr_ty(expr);
3487 fcx.register_wf_obligation(ret_ty, expr.span, traits::MiscObligation);
3489 hir::ExprMethodCall(name, ref tps, ref args) => {
3490 check_method_call(fcx, expr, name, &args[..], &tps[..], expected, lvalue_pref);
3491 let arg_tys = args.iter().map(|a| fcx.expr_ty(&a));
3492 let args_err = arg_tys.fold(false, |rest_err, a| rest_err || a.references_error());
3494 fcx.write_error(id);
3497 hir::ExprCast(ref e, ref t) => {
3498 if let hir::TyFixedLengthVec(_, ref count_expr) = t.node {
3499 check_expr_with_hint(fcx, &count_expr, tcx.types.usize);
3502 // Find the type of `e`. Supply hints based on the type we are casting to,
3504 let t_cast = fcx.to_ty(t);
3505 let t_cast = structurally_resolved_type(fcx, expr.span, t_cast);
3506 check_expr_with_expectation(fcx, e, ExpectCastableToType(t_cast));
3507 let t_expr = fcx.expr_ty(e);
3508 let t_cast = fcx.infcx().resolve_type_vars_if_possible(&t_cast);
3510 // Eagerly check for some obvious errors.
3511 if t_expr.references_error() || t_cast.references_error() {
3512 fcx.write_error(id);
3513 } else if !fcx.type_is_known_to_be_sized(t_cast, expr.span) {
3514 report_cast_to_unsized_type(fcx, expr.span, t.span, e.span, t_cast, t_expr, id);
3516 // Write a type for the whole expression, assuming everything is going
3518 fcx.write_ty(id, t_cast);
3520 // Defer other checks until we're done type checking.
3521 let mut deferred_cast_checks = fcx.inh.deferred_cast_checks.borrow_mut();
3522 let cast_check = cast::CastCheck::new((**e).clone(), t_expr, t_cast, expr.span);
3523 deferred_cast_checks.push(cast_check);
3526 hir::ExprType(ref e, ref t) => {
3527 let typ = fcx.to_ty(&t);
3528 check_expr_eq_type(fcx, &e, typ);
3529 fcx.write_ty(id, typ);
3531 hir::ExprVec(ref args) => {
3532 let uty = expected.to_option(fcx).and_then(|uty| {
3534 ty::TyArray(ty, _) | ty::TySlice(ty) => Some(ty),
3539 let typ = match uty {
3542 check_expr_coercable_to_type(fcx, &e, uty);
3547 let t: Ty = fcx.infcx().next_ty_var();
3549 check_expr_has_type(fcx, &e, t);
3554 let typ = tcx.mk_array(typ, args.len());
3555 fcx.write_ty(id, typ);
3557 hir::ExprRepeat(ref element, ref count_expr) => {
3558 check_expr_has_type(fcx, &count_expr, tcx.types.usize);
3559 let count = fcx.tcx().eval_repeat_count(&count_expr);
3561 let uty = match expected {
3562 ExpectHasType(uty) => {
3564 ty::TyArray(ty, _) | ty::TySlice(ty) => Some(ty),
3571 let (element_ty, t) = match uty {
3573 check_expr_coercable_to_type(fcx, &element, uty);
3577 let t: Ty = fcx.infcx().next_ty_var();
3578 check_expr_has_type(fcx, &element, t);
3579 (fcx.expr_ty(&element), t)
3584 // For [foo, ..n] where n > 1, `foo` must have
3586 fcx.require_type_meets(
3593 if element_ty.references_error() {
3594 fcx.write_error(id);
3596 let t = tcx.mk_array(t, count);
3597 fcx.write_ty(id, t);
3600 hir::ExprTup(ref elts) => {
3601 let flds = expected.only_has_type(fcx).and_then(|ty| {
3603 ty::TyTuple(ref flds) => Some(&flds[..]),
3607 let mut err_field = false;
3609 let elt_ts = elts.iter().enumerate().map(|(i, e)| {
3610 let t = match flds {
3611 Some(ref fs) if i < fs.len() => {
3613 check_expr_coercable_to_type(fcx, &e, ety);
3617 check_expr_with_expectation(fcx, &e, NoExpectation);
3621 err_field = err_field || t.references_error();
3625 fcx.write_error(id);
3627 let typ = tcx.mk_tup(elt_ts);
3628 fcx.write_ty(id, typ);
3631 hir::ExprStruct(ref path, ref fields, ref base_expr) => {
3632 check_expr_struct(fcx, expr, path, fields, base_expr);
3634 fcx.require_expr_have_sized_type(expr, traits::StructInitializerSized);
3636 hir::ExprField(ref base, ref field) => {
3637 check_field(fcx, expr, lvalue_pref, &base, field);
3639 hir::ExprTupField(ref base, idx) => {
3640 check_tup_field(fcx, expr, lvalue_pref, &base, idx);
3642 hir::ExprIndex(ref base, ref idx) => {
3643 check_expr_with_lvalue_pref(fcx, &base, lvalue_pref);
3644 check_expr(fcx, &idx);
3646 let base_t = fcx.expr_ty(&base);
3647 let idx_t = fcx.expr_ty(&idx);
3649 if base_t.references_error() {
3650 fcx.write_ty(id, base_t);
3651 } else if idx_t.references_error() {
3652 fcx.write_ty(id, idx_t);
3654 let base_t = structurally_resolved_type(fcx, expr.span, base_t);
3655 match lookup_indexing(fcx, expr, base, base_t, idx_t, lvalue_pref) {
3656 Some((index_ty, element_ty)) => {
3657 let idx_expr_ty = fcx.expr_ty(idx);
3658 demand::eqtype(fcx, expr.span, index_ty, idx_expr_ty);
3659 fcx.write_ty(id, element_ty);
3662 check_expr_has_type(fcx, &idx, fcx.tcx().types.err);
3663 fcx.type_error_message(
3666 format!("cannot index a value of type `{}`",
3671 fcx.write_ty(id, fcx.tcx().types.err);
3676 hir::ExprRange(ref start, ref end) => {
3677 let t_start = start.as_ref().map(|e| {
3678 check_expr(fcx, &e);
3681 let t_end = end.as_ref().map(|e| {
3682 check_expr(fcx, &e);
3686 let idx_type = match (t_start, t_end) {
3687 (Some(ty), None) | (None, Some(ty)) => {
3690 (Some(t_start), Some(t_end)) if (t_start.references_error() ||
3691 t_end.references_error()) => {
3692 Some(fcx.tcx().types.err)
3694 (Some(t_start), Some(t_end)) => {
3695 Some(infer::common_supertype(fcx.infcx(),
3696 TypeOrigin::RangeExpression(expr.span),
3704 // Note that we don't check the type of start/end satisfy any
3705 // bounds because right now the range structs do not have any. If we add
3706 // some bounds, then we'll need to check `t_start` against them here.
3708 let range_type = match idx_type {
3709 Some(idx_type) if idx_type.references_error() => {
3713 // Find the did from the appropriate lang item.
3714 let did = match (start, end) {
3715 (&Some(_), &Some(_)) => tcx.lang_items.range_struct(),
3716 (&Some(_), &None) => tcx.lang_items.range_from_struct(),
3717 (&None, &Some(_)) => tcx.lang_items.range_to_struct(),
3719 tcx.sess.span_bug(expr.span, "full range should be dealt with above")
3723 if let Some(did) = did {
3724 let def = tcx.lookup_adt_def(did);
3725 let predicates = tcx.lookup_predicates(did);
3726 let substs = Substs::new_type(vec![idx_type], vec![]);
3727 let bounds = fcx.instantiate_bounds(expr.span, &substs, &predicates);
3728 fcx.add_obligations_for_parameters(
3729 traits::ObligationCause::new(expr.span,
3731 traits::ItemObligation(did)),
3734 tcx.mk_struct(def, tcx.mk_substs(substs))
3736 span_err!(tcx.sess, expr.span, E0236, "no lang item for range syntax");
3741 // Neither start nor end => RangeFull
3742 if let Some(did) = tcx.lang_items.range_full_struct() {
3744 tcx.lookup_adt_def(did),
3745 tcx.mk_substs(Substs::empty())
3748 span_err!(tcx.sess, expr.span, E0237, "no lang item for range syntax");
3754 fcx.write_ty(id, range_type);
3759 debug!("type of expr({}) {} is...", expr.id,
3760 pprust::expr_to_string(expr));
3761 debug!("... {:?}, expected is {:?}",
3768 pub fn resolve_ty_and_def_ufcs<'a, 'b, 'tcx>(fcx: &FnCtxt<'b, 'tcx>,
3769 path_res: def::PathResolution,
3770 opt_self_ty: Option<Ty<'tcx>>,
3771 path: &'a hir::Path,
3773 node_id: ast::NodeId)
3774 -> Option<(Option<Ty<'tcx>>,
3775 &'a [hir::PathSegment],
3779 // If fully resolved already, we don't have to do anything.
3780 if path_res.depth == 0 {
3781 Some((opt_self_ty, &path.segments, path_res.base_def))
3783 let mut def = path_res.base_def;
3784 let ty_segments = path.segments.split_last().unwrap().1;
3785 let base_ty_end = path.segments.len() - path_res.depth;
3786 let ty = astconv::finish_resolving_def_to_ty(fcx, fcx, span,
3787 PathParamMode::Optional,
3790 &ty_segments[..base_ty_end],
3791 &ty_segments[base_ty_end..]);
3792 let item_segment = path.segments.last().unwrap();
3793 let item_name = item_segment.identifier.name;
3794 match method::resolve_ufcs(fcx, span, item_name, ty, node_id) {
3796 // Write back the new resolution.
3797 fcx.ccx.tcx.def_map.borrow_mut()
3798 .insert(node_id, def::PathResolution {
3802 Some((Some(ty), slice::ref_slice(item_segment), def))
3805 if item_name != special_idents::invalid.name {
3806 method::report_error(fcx, span, ty, item_name, None, error);
3808 fcx.write_error(node_id);
3815 impl<'tcx> Expectation<'tcx> {
3816 /// Provide an expectation for an rvalue expression given an *optional*
3817 /// hint, which is not required for type safety (the resulting type might
3818 /// be checked higher up, as is the case with `&expr` and `box expr`), but
3819 /// is useful in determining the concrete type.
3821 /// The primary use case is where the expected type is a fat pointer,
3822 /// like `&[isize]`. For example, consider the following statement:
3824 /// let x: &[isize] = &[1, 2, 3];
3826 /// In this case, the expected type for the `&[1, 2, 3]` expression is
3827 /// `&[isize]`. If however we were to say that `[1, 2, 3]` has the
3828 /// expectation `ExpectHasType([isize])`, that would be too strong --
3829 /// `[1, 2, 3]` does not have the type `[isize]` but rather `[isize; 3]`.
3830 /// It is only the `&[1, 2, 3]` expression as a whole that can be coerced
3831 /// to the type `&[isize]`. Therefore, we propagate this more limited hint,
3832 /// which still is useful, because it informs integer literals and the like.
3833 /// See the test case `test/run-pass/coerce-expect-unsized.rs` and #20169
3834 /// for examples of where this comes up,.
3835 fn rvalue_hint(tcx: &TyCtxt<'tcx>, ty: Ty<'tcx>) -> Expectation<'tcx> {
3836 match tcx.struct_tail(ty).sty {
3837 ty::TySlice(_) | ty::TyStr | ty::TyTrait(..) => {
3838 ExpectRvalueLikeUnsized(ty)
3840 _ => ExpectHasType(ty)
3844 // Resolves `expected` by a single level if it is a variable. If
3845 // there is no expected type or resolution is not possible (e.g.,
3846 // no constraints yet present), just returns `None`.
3847 fn resolve<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Expectation<'tcx> {
3852 ExpectCastableToType(t) => {
3853 ExpectCastableToType(
3854 fcx.infcx().resolve_type_vars_if_possible(&t))
3856 ExpectHasType(t) => {
3858 fcx.infcx().resolve_type_vars_if_possible(&t))
3860 ExpectRvalueLikeUnsized(t) => {
3861 ExpectRvalueLikeUnsized(
3862 fcx.infcx().resolve_type_vars_if_possible(&t))
3867 fn to_option<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
3868 match self.resolve(fcx) {
3869 NoExpectation => None,
3870 ExpectCastableToType(ty) |
3872 ExpectRvalueLikeUnsized(ty) => Some(ty),
3876 fn only_has_type<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
3877 match self.resolve(fcx) {
3878 ExpectHasType(ty) => Some(ty),
3884 pub fn check_decl_initializer<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
3885 local: &'tcx hir::Local,
3886 init: &'tcx hir::Expr)
3888 let ref_bindings = fcx.tcx().pat_contains_ref_binding(&local.pat);
3890 let local_ty = fcx.local_ty(init.span, local.id);
3891 if let Some(m) = ref_bindings {
3892 // Somewhat subtle: if we have a `ref` binding in the pattern,
3893 // we want to avoid introducing coercions for the RHS. This is
3894 // both because it helps preserve sanity and, in the case of
3895 // ref mut, for soundness (issue #23116). In particular, in
3896 // the latter case, we need to be clear that the type of the
3897 // referent for the reference that results is *equal to* the
3898 // type of the lvalue it is referencing, and not some
3899 // supertype thereof.
3900 check_expr_with_lvalue_pref(fcx, init, LvaluePreference::from_mutbl(m));
3901 let init_ty = fcx.expr_ty(init);
3902 demand::eqtype(fcx, init.span, init_ty, local_ty);
3904 check_expr_coercable_to_type(fcx, init, local_ty)
3908 pub fn check_decl_local<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, local: &'tcx hir::Local) {
3909 let tcx = fcx.ccx.tcx;
3911 let t = fcx.local_ty(local.span, local.id);
3912 fcx.write_ty(local.id, t);
3914 if let Some(ref init) = local.init {
3915 check_decl_initializer(fcx, local, &init);
3916 let init_ty = fcx.expr_ty(&init);
3917 if init_ty.references_error() {
3918 fcx.write_ty(local.id, init_ty);
3922 let pcx = pat_ctxt {
3924 map: pat_id_map(&tcx.def_map, &local.pat),
3926 _match::check_pat(&pcx, &local.pat, t);
3927 let pat_ty = fcx.node_ty(local.pat.id);
3928 if pat_ty.references_error() {
3929 fcx.write_ty(local.id, pat_ty);
3933 pub fn check_stmt<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, stmt: &'tcx hir::Stmt) {
3935 let mut saw_bot = false;
3936 let mut saw_err = false;
3938 hir::StmtDecl(ref decl, id) => {
3941 hir::DeclLocal(ref l) => {
3942 check_decl_local(fcx, &l);
3943 let l_t = fcx.node_ty(l.id);
3944 saw_bot = saw_bot || fcx.infcx().type_var_diverges(l_t);
3945 saw_err = saw_err || l_t.references_error();
3947 hir::DeclItem(_) => {/* ignore for now */ }
3950 hir::StmtExpr(ref expr, id) => {
3952 // Check with expected type of ()
3953 check_expr_has_type(fcx, &expr, fcx.tcx().mk_nil());
3954 let expr_ty = fcx.expr_ty(&expr);
3955 saw_bot = saw_bot || fcx.infcx().type_var_diverges(expr_ty);
3956 saw_err = saw_err || expr_ty.references_error();
3958 hir::StmtSemi(ref expr, id) => {
3960 check_expr(fcx, &expr);
3961 let expr_ty = fcx.expr_ty(&expr);
3962 saw_bot |= fcx.infcx().type_var_diverges(expr_ty);
3963 saw_err |= expr_ty.references_error();
3967 fcx.write_ty(node_id, fcx.infcx().next_diverging_ty_var());
3970 fcx.write_error(node_id);
3973 fcx.write_nil(node_id)
3977 pub fn check_block_no_value<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, blk: &'tcx hir::Block) {
3978 check_block_with_expected(fcx, blk, ExpectHasType(fcx.tcx().mk_nil()));
3979 let blkty = fcx.node_ty(blk.id);
3980 if blkty.references_error() {
3981 fcx.write_error(blk.id);
3983 let nilty = fcx.tcx().mk_nil();
3984 demand::suptype(fcx, blk.span, nilty, blkty);
3988 fn check_block_with_expected<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3989 blk: &'tcx hir::Block,
3990 expected: Expectation<'tcx>) {
3992 let mut fcx_ps = fcx.ps.borrow_mut();
3993 let unsafety_state = fcx_ps.recurse(blk);
3994 replace(&mut *fcx_ps, unsafety_state)
3997 let mut warned = false;
3998 let mut any_diverges = false;
3999 let mut any_err = false;
4000 for s in &blk.stmts {
4002 let s_id = ::rustc_front::util::stmt_id(s);
4003 let s_ty = fcx.node_ty(s_id);
4004 if any_diverges && !warned && match s.node {
4005 hir::StmtDecl(ref decl, _) => {
4007 hir::DeclLocal(_) => true,
4011 hir::StmtExpr(_, _) | hir::StmtSemi(_, _) => true,
4016 .add_lint(lint::builtin::UNREACHABLE_CODE,
4019 "unreachable statement".to_string());
4022 any_diverges = any_diverges || fcx.infcx().type_var_diverges(s_ty);
4023 any_err = any_err || s_ty.references_error();
4026 None => if any_err {
4027 fcx.write_error(blk.id);
4028 } else if any_diverges {
4029 fcx.write_ty(blk.id, fcx.infcx().next_diverging_ty_var());
4031 fcx.write_nil(blk.id);
4034 if any_diverges && !warned {
4038 .add_lint(lint::builtin::UNREACHABLE_CODE,
4041 "unreachable expression".to_string());
4043 let ety = match expected {
4044 ExpectHasType(ety) => {
4045 check_expr_coercable_to_type(fcx, &e, ety);
4049 check_expr_with_expectation(fcx, &e, expected);
4055 fcx.write_error(blk.id);
4056 } else if any_diverges {
4057 fcx.write_ty(blk.id, fcx.infcx().next_diverging_ty_var());
4059 fcx.write_ty(blk.id, ety);
4064 *fcx.ps.borrow_mut() = prev;
4067 /// Checks a constant appearing in a type. At the moment this is just the
4068 /// length expression in a fixed-length vector, but someday it might be
4069 /// extended to type-level numeric literals.
4070 fn check_const_in_type<'a,'tcx>(ccx: &'a CrateCtxt<'a,'tcx>,
4071 expr: &'tcx hir::Expr,
4072 expected_type: Ty<'tcx>) {
4073 let tables = RefCell::new(ty::Tables::empty());
4074 let inh = static_inherited_fields(ccx, &tables);
4075 let fcx = blank_fn_ctxt(ccx, &inh, ty::FnConverging(expected_type), expr.id);
4076 check_const_with_ty(&fcx, expr.span, expr, expected_type);
4079 fn check_const<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
4083 let tables = RefCell::new(ty::Tables::empty());
4084 let inh = static_inherited_fields(ccx, &tables);
4085 let rty = ccx.tcx.node_id_to_type(id);
4086 let fcx = blank_fn_ctxt(ccx, &inh, ty::FnConverging(rty), e.id);
4087 let declty = fcx.ccx.tcx.lookup_item_type(ccx.tcx.map.local_def_id(id)).ty;
4088 check_const_with_ty(&fcx, sp, e, declty);
4091 fn check_const_with_ty<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4095 // Gather locals in statics (because of block expressions).
4096 // This is technically unnecessary because locals in static items are forbidden,
4097 // but prevents type checking from blowing up before const checking can properly
4099 GatherLocalsVisitor { fcx: fcx }.visit_expr(e);
4101 check_expr_with_hint(fcx, e, declty);
4102 demand::coerce(fcx, e.span, declty, e);
4104 fcx.select_all_obligations_and_apply_defaults();
4105 upvar::closure_analyze_const(&fcx, e);
4106 fcx.select_obligations_where_possible();
4108 fcx.select_all_obligations_or_error();
4110 regionck::regionck_expr(fcx, e);
4111 writeback::resolve_type_vars_in_expr(fcx, e);
4114 /// Checks whether a type can be represented in memory. In particular, it
4115 /// identifies types that contain themselves without indirection through a
4116 /// pointer, which would mean their size is unbounded.
4117 pub fn check_representable(tcx: &TyCtxt,
4119 item_id: ast::NodeId,
4120 _designation: &str) -> bool {
4121 let rty = tcx.node_id_to_type(item_id);
4123 // Check that it is possible to represent this type. This call identifies
4124 // (1) types that contain themselves and (2) types that contain a different
4125 // recursive type. It is only necessary to throw an error on those that
4126 // contain themselves. For case 2, there must be an inner type that will be
4127 // caught by case 1.
4128 match rty.is_representable(tcx, sp) {
4129 Representability::SelfRecursive => {
4130 let item_def_id = tcx.map.local_def_id(item_id);
4131 traits::recursive_type_with_infinite_size_error(tcx, item_def_id).emit();
4134 Representability::Representable | Representability::ContainsRecursive => (),
4139 pub fn check_simd(tcx: &TyCtxt, sp: Span, id: ast::NodeId) {
4140 let t = tcx.node_id_to_type(id);
4142 ty::TyStruct(def, substs) => {
4143 let fields = &def.struct_variant().fields;
4144 if fields.is_empty() {
4145 span_err!(tcx.sess, sp, E0075, "SIMD vector cannot be empty");
4148 let e = fields[0].ty(tcx, substs);
4149 if !fields.iter().all(|f| f.ty(tcx, substs) == e) {
4150 span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous");
4154 ty::TyParam(_) => { /* struct<T>(T, T, T, T) is ok */ }
4155 _ if e.is_machine() => { /* struct(u8, u8, u8, u8) is ok */ }
4157 span_err!(tcx.sess, sp, E0077,
4158 "SIMD vector element type should be machine type");
4167 pub fn check_enum_variants<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
4169 vs: &'tcx [hir::Variant],
4171 // disr_in_range should be removed once we have forced type hints for consts
4172 fn disr_in_range(ccx: &CrateCtxt,
4174 disr: ty::Disr) -> bool {
4175 fn uint_in_range(ccx: &CrateCtxt, ty: ast::UintTy, disr: ty::Disr) -> bool {
4177 ast::UintTy::U8 => disr as u8 as Disr == disr,
4178 ast::UintTy::U16 => disr as u16 as Disr == disr,
4179 ast::UintTy::U32 => disr as u32 as Disr == disr,
4180 ast::UintTy::U64 => disr as u64 as Disr == disr,
4181 ast::UintTy::Us => uint_in_range(ccx, ccx.tcx.sess.target.uint_type, disr)
4184 fn int_in_range(ccx: &CrateCtxt, ty: ast::IntTy, disr: ty::Disr) -> bool {
4186 ast::IntTy::I8 => disr as i8 as Disr == disr,
4187 ast::IntTy::I16 => disr as i16 as Disr == disr,
4188 ast::IntTy::I32 => disr as i32 as Disr == disr,
4189 ast::IntTy::I64 => disr as i64 as Disr == disr,
4190 ast::IntTy::Is => int_in_range(ccx, ccx.tcx.sess.target.int_type, disr)
4194 attr::UnsignedInt(ty) => uint_in_range(ccx, ty, disr),
4195 attr::SignedInt(ty) => int_in_range(ccx, ty, disr)
4199 fn do_check<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
4200 vs: &'tcx [hir::Variant],
4202 hint: attr::ReprAttr) {
4203 #![allow(trivial_numeric_casts)]
4205 let rty = ccx.tcx.node_id_to_type(id);
4206 let mut disr_vals: Vec<ty::Disr> = Vec::new();
4208 let tables = RefCell::new(ty::Tables::empty());
4209 let inh = static_inherited_fields(ccx, &tables);
4210 let fcx = blank_fn_ctxt(ccx, &inh, ty::FnConverging(rty), id);
4212 let (_, repr_type_ty) = ccx.tcx.enum_repr_type(Some(&hint));
4214 if let Some(ref e) = v.node.disr_expr {
4215 check_const_with_ty(&fcx, e.span, e, repr_type_ty);
4219 let def_id = ccx.tcx.map.local_def_id(id);
4221 let variants = &ccx.tcx.lookup_adt_def(def_id).variants;
4222 for (v, variant) in vs.iter().zip(variants.iter()) {
4223 let current_disr_val = variant.disr_val;
4225 // Check for duplicate discriminant values
4226 match disr_vals.iter().position(|&x| x == current_disr_val) {
4228 let mut err = struct_span_err!(ccx.tcx.sess, v.span, E0081,
4229 "discriminant value `{}` already exists", disr_vals[i]);
4230 let variant_i_node_id = ccx.tcx.map.as_local_node_id(variants[i].did).unwrap();
4231 span_note!(&mut err, ccx.tcx.map.span(variant_i_node_id),
4232 "conflicting discriminant here");
4237 // Check for unrepresentable discriminant values
4239 attr::ReprAny | attr::ReprExtern => {
4240 disr_vals.push(current_disr_val);
4242 attr::ReprInt(sp, ity) => {
4243 if !disr_in_range(ccx, ity, current_disr_val) {
4244 let mut err = struct_span_err!(ccx.tcx.sess, v.span, E0082,
4245 "discriminant value outside specified type");
4246 span_note!(&mut err, sp,
4247 "discriminant type specified here");
4251 // Error reported elsewhere.
4252 attr::ReprSimd | attr::ReprPacked => {}
4257 let def_id = ccx.tcx.map.local_def_id(id);
4258 let hint = *ccx.tcx.lookup_repr_hints(def_id).get(0).unwrap_or(&attr::ReprAny);
4260 if hint != attr::ReprAny && vs.is_empty() {
4261 span_err!(ccx.tcx.sess, sp, E0084,
4262 "unsupported representation for zero-variant enum");
4265 do_check(ccx, vs, id, hint);
4267 check_representable(ccx.tcx, sp, id, "enum");
4270 // Returns the type parameter count and the type for the given definition.
4271 fn type_scheme_and_predicates_for_def<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4274 -> (TypeScheme<'tcx>, GenericPredicates<'tcx>) {
4276 Def::Local(_, nid) | Def::Upvar(_, nid, _, _) => {
4277 let typ = fcx.local_ty(sp, nid);
4278 (ty::TypeScheme { generics: ty::Generics::empty(), ty: typ },
4279 ty::GenericPredicates::empty())
4281 Def::Fn(id) | Def::Method(id) |
4282 Def::Static(id, _) | Def::Variant(_, id) |
4283 Def::Struct(id) | Def::Const(id) | Def::AssociatedConst(id) => {
4284 (fcx.tcx().lookup_item_type(id), fcx.tcx().lookup_predicates(id))
4289 Def::AssociatedTy(..) |
4293 Def::ForeignMod(..) |
4297 fcx.ccx.tcx.sess.span_bug(sp, &format!("expected value, found {:?}", defn));
4302 // Instantiates the given path, which must refer to an item with the given
4303 // number of type parameters and type.
4304 pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4305 segments: &[hir::PathSegment],
4306 type_scheme: TypeScheme<'tcx>,
4307 type_predicates: &ty::GenericPredicates<'tcx>,
4308 opt_self_ty: Option<Ty<'tcx>>,
4311 node_id: ast::NodeId) {
4312 debug!("instantiate_path(path={:?}, def={:?}, node_id={}, type_scheme={:?})",
4318 // We need to extract the type parameters supplied by the user in
4319 // the path `path`. Due to the current setup, this is a bit of a
4320 // tricky-process; the problem is that resolve only tells us the
4321 // end-point of the path resolution, and not the intermediate steps.
4322 // Luckily, we can (at least for now) deduce the intermediate steps
4323 // just from the end-point.
4325 // There are basically four cases to consider:
4327 // 1. Reference to a *type*, such as a struct or enum:
4329 // mod a { struct Foo<T> { ... } }
4331 // Because we don't allow types to be declared within one
4332 // another, a path that leads to a type will always look like
4333 // `a::b::Foo<T>` where `a` and `b` are modules. This implies
4334 // that only the final segment can have type parameters, and
4335 // they are located in the TypeSpace.
4337 // *Note:* Generally speaking, references to types don't
4338 // actually pass through this function, but rather the
4339 // `ast_ty_to_ty` function in `astconv`. However, in the case
4340 // of struct patterns (and maybe literals) we do invoke
4341 // `instantiate_path` to get the general type of an instance of
4342 // a struct. (In these cases, there are actually no type
4343 // parameters permitted at present, but perhaps we will allow
4344 // them in the future.)
4346 // 1b. Reference to an enum variant or tuple-like struct:
4348 // struct foo<T>(...)
4349 // enum E<T> { foo(...) }
4351 // In these cases, the parameters are declared in the type
4354 // 2. Reference to a *fn item*:
4358 // In this case, the path will again always have the form
4359 // `a::b::foo::<T>` where only the final segment should have
4360 // type parameters. However, in this case, those parameters are
4361 // declared on a value, and hence are in the `FnSpace`.
4363 // 3. Reference to a *method*:
4365 // impl<A> SomeStruct<A> {
4369 // Here we can have a path like
4370 // `a::b::SomeStruct::<A>::foo::<B>`, in which case parameters
4371 // may appear in two places. The penultimate segment,
4372 // `SomeStruct::<A>`, contains parameters in TypeSpace, and the
4373 // final segment, `foo::<B>` contains parameters in fn space.
4375 // 4. Reference to an *associated const*:
4377 // impl<A> AnotherStruct<A> {
4378 // const FOO: B = BAR;
4381 // The path in this case will look like
4382 // `a::b::AnotherStruct::<A>::FOO`, so the penultimate segment
4383 // only will have parameters in TypeSpace.
4385 // The first step then is to categorize the segments appropriately.
4387 assert!(!segments.is_empty());
4389 let mut ufcs_associated = None;
4390 let mut segment_spaces: Vec<_>;
4392 // Case 1 and 1b. Reference to a *type* or *enum variant*.
4398 Def::AssociatedTy(..) |
4401 Def::TyParam(..) => {
4402 // Everything but the final segment should have no
4403 // parameters at all.
4404 segment_spaces = vec![None; segments.len() - 1];
4405 segment_spaces.push(Some(subst::TypeSpace));
4408 // Case 2. Reference to a top-level value.
4411 Def::Static(..) => {
4412 segment_spaces = vec![None; segments.len() - 1];
4413 segment_spaces.push(Some(subst::FnSpace));
4416 // Case 3. Reference to a method.
4417 Def::Method(def_id) => {
4418 let container = fcx.tcx().impl_or_trait_item(def_id).container();
4420 ty::TraitContainer(trait_did) => {
4421 callee::check_legal_trait_for_method_call(fcx.ccx, span, trait_did)
4423 ty::ImplContainer(_) => {}
4426 if segments.len() >= 2 {
4427 segment_spaces = vec![None; segments.len() - 2];
4428 segment_spaces.push(Some(subst::TypeSpace));
4429 segment_spaces.push(Some(subst::FnSpace));
4431 // `<T>::method` will end up here, and so can `T::method`.
4432 let self_ty = opt_self_ty.expect("UFCS sugared method missing Self");
4433 segment_spaces = vec![Some(subst::FnSpace)];
4434 ufcs_associated = Some((container, self_ty));
4438 Def::AssociatedConst(def_id) => {
4439 let container = fcx.tcx().impl_or_trait_item(def_id).container();
4441 ty::TraitContainer(trait_did) => {
4442 callee::check_legal_trait_for_method_call(fcx.ccx, span, trait_did)
4444 ty::ImplContainer(_) => {}
4447 if segments.len() >= 2 {
4448 segment_spaces = vec![None; segments.len() - 2];
4449 segment_spaces.push(Some(subst::TypeSpace));
4450 segment_spaces.push(None);
4452 // `<T>::CONST` will end up here, and so can `T::CONST`.
4453 let self_ty = opt_self_ty.expect("UFCS sugared const missing Self");
4454 segment_spaces = vec![None];
4455 ufcs_associated = Some((container, self_ty));
4459 // Other cases. Various nonsense that really shouldn't show up
4460 // here. If they do, an error will have been reported
4461 // elsewhere. (I hope)
4463 Def::ForeignMod(..) |
4468 segment_spaces = vec![None; segments.len()];
4471 assert_eq!(segment_spaces.len(), segments.len());
4473 // In `<T as Trait<A, B>>::method`, `A` and `B` are mandatory, but
4474 // `opt_self_ty` can also be Some for `Foo::method`, where Foo's
4475 // type parameters are not mandatory.
4476 let require_type_space = opt_self_ty.is_some() && ufcs_associated.is_none();
4478 debug!("segment_spaces={:?}", segment_spaces);
4480 // Next, examine the definition, and determine how many type
4481 // parameters we expect from each space.
4482 let type_defs = &type_scheme.generics.types;
4483 let region_defs = &type_scheme.generics.regions;
4485 // Now that we have categorized what space the parameters for each
4486 // segment belong to, let's sort out the parameters that the user
4487 // provided (if any) into their appropriate spaces. We'll also report
4488 // errors if type parameters are provided in an inappropriate place.
4489 let mut substs = Substs::empty();
4490 for (opt_space, segment) in segment_spaces.iter().zip(segments) {
4493 prohibit_type_params(fcx.tcx(), slice::ref_slice(segment));
4497 push_explicit_parameters_from_segment_to_substs(fcx,
4507 if let Some(self_ty) = opt_self_ty {
4508 if type_defs.len(subst::SelfSpace) == 1 {
4509 substs.types.push(subst::SelfSpace, self_ty);
4513 // Now we have to compare the types that the user *actually*
4514 // provided against the types that were *expected*. If the user
4515 // did not provide any types, then we want to substitute inference
4516 // variables. If the user provided some types, we may still need
4517 // to add defaults. If the user provided *too many* types, that's
4519 for &space in &[subst::SelfSpace, subst::TypeSpace, subst::FnSpace] {
4520 adjust_type_parameters(fcx, span, space, type_defs,
4521 require_type_space, &mut substs);
4522 assert_eq!(substs.types.len(space), type_defs.len(space));
4524 adjust_region_parameters(fcx, span, space, region_defs, &mut substs);
4525 assert_eq!(substs.regions().len(space), region_defs.len(space));
4528 // The things we are substituting into the type should not contain
4529 // escaping late-bound regions, and nor should the base type scheme.
4530 assert!(!substs.has_regions_escaping_depth(0));
4531 assert!(!type_scheme.has_escaping_regions());
4533 // Add all the obligations that are required, substituting and
4534 // normalized appropriately.
4535 let bounds = fcx.instantiate_bounds(span, &substs, &type_predicates);
4536 fcx.add_obligations_for_parameters(
4537 traits::ObligationCause::new(span, fcx.body_id, traits::ItemObligation(def.def_id())),
4540 // Substitute the values for the type parameters into the type of
4541 // the referenced item.
4542 let ty_substituted = fcx.instantiate_type_scheme(span, &substs, &type_scheme.ty);
4545 if let Some((ty::ImplContainer(impl_def_id), self_ty)) = ufcs_associated {
4546 // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
4547 // is inherent, there is no `Self` parameter, instead, the impl needs
4548 // type parameters, which we can infer by unifying the provided `Self`
4549 // with the substituted impl type.
4550 let impl_scheme = fcx.tcx().lookup_item_type(impl_def_id);
4551 assert_eq!(substs.types.len(subst::TypeSpace),
4552 impl_scheme.generics.types.len(subst::TypeSpace));
4553 assert_eq!(substs.regions().len(subst::TypeSpace),
4554 impl_scheme.generics.regions.len(subst::TypeSpace));
4556 let impl_ty = fcx.instantiate_type_scheme(span, &substs, &impl_scheme.ty);
4557 if fcx.mk_subty(false, TypeOrigin::Misc(span), self_ty, impl_ty).is_err() {
4558 fcx.tcx().sess.span_bug(span,
4560 "instantiate_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
4566 debug!("instantiate_path: type of {:?} is {:?}",
4569 fcx.write_ty(node_id, ty_substituted);
4570 fcx.write_substs(node_id, ty::ItemSubsts { substs: substs });
4573 /// Finds the parameters that the user provided and adds them to `substs`. If too many
4574 /// parameters are provided, then reports an error and clears the output vector.
4576 /// We clear the output vector because that will cause the `adjust_XXX_parameters()` later to
4577 /// use inference variables. This seems less likely to lead to derived errors.
4579 /// Note that we *do not* check for *too few* parameters here. Due to the presence of defaults
4580 /// etc that is more complicated. I wanted however to do the reporting of *too many* parameters
4581 /// here because we can easily use the precise span of the N+1'th parameter.
4582 fn push_explicit_parameters_from_segment_to_substs<'a, 'tcx>(
4583 fcx: &FnCtxt<'a, 'tcx>,
4584 space: subst::ParamSpace,
4586 type_defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4587 region_defs: &VecPerParamSpace<ty::RegionParameterDef>,
4588 segment: &hir::PathSegment,
4589 substs: &mut Substs<'tcx>)
4591 match segment.parameters {
4592 hir::AngleBracketedParameters(ref data) => {
4593 push_explicit_angle_bracketed_parameters_from_segment_to_substs(
4594 fcx, space, type_defs, region_defs, data, substs);
4597 hir::ParenthesizedParameters(ref data) => {
4598 span_err!(fcx.tcx().sess, span, E0238,
4599 "parenthesized parameters may only be used with a trait");
4600 push_explicit_parenthesized_parameters_from_segment_to_substs(
4601 fcx, space, span, type_defs, data, substs);
4606 fn push_explicit_angle_bracketed_parameters_from_segment_to_substs<'a, 'tcx>(
4607 fcx: &FnCtxt<'a, 'tcx>,
4608 space: subst::ParamSpace,
4609 type_defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4610 region_defs: &VecPerParamSpace<ty::RegionParameterDef>,
4611 data: &hir::AngleBracketedParameterData,
4612 substs: &mut Substs<'tcx>)
4615 let type_count = type_defs.len(space);
4616 assert_eq!(substs.types.len(space), 0);
4617 for (i, typ) in data.types.iter().enumerate() {
4618 let t = fcx.to_ty(&typ);
4620 substs.types.push(space, t);
4621 } else if i == type_count {
4622 span_err!(fcx.tcx().sess, typ.span, E0087,
4623 "too many type parameters provided: \
4624 expected at most {} parameter{}, \
4625 found {} parameter{}",
4627 if type_count == 1 {""} else {"s"},
4629 if data.types.len() == 1 {""} else {"s"});
4630 substs.types.truncate(space, 0);
4636 if !data.bindings.is_empty() {
4637 span_err!(fcx.tcx().sess, data.bindings[0].span, E0182,
4638 "unexpected binding of associated item in expression path \
4639 (only allowed in type paths)");
4643 let region_count = region_defs.len(space);
4644 assert_eq!(substs.regions().len(space), 0);
4645 for (i, lifetime) in data.lifetimes.iter().enumerate() {
4646 let r = ast_region_to_region(fcx.tcx(), lifetime);
4647 if i < region_count {
4648 substs.mut_regions().push(space, r);
4649 } else if i == region_count {
4650 span_err!(fcx.tcx().sess, lifetime.span, E0088,
4651 "too many lifetime parameters provided: \
4652 expected {} parameter{}, found {} parameter{}",
4654 if region_count == 1 {""} else {"s"},
4655 data.lifetimes.len(),
4656 if data.lifetimes.len() == 1 {""} else {"s"});
4657 substs.mut_regions().truncate(space, 0);
4665 /// `push_explicit_angle_bracketed_parameters_from_segment_to_substs`,
4666 /// but intended for `Foo(A,B) -> C` form. This expands to
4667 /// roughly the same thing as `Foo<(A,B),C>`. One important
4668 /// difference has to do with the treatment of anonymous
4669 /// regions, which are translated into bound regions (NYI).
4670 fn push_explicit_parenthesized_parameters_from_segment_to_substs<'a, 'tcx>(
4671 fcx: &FnCtxt<'a, 'tcx>,
4672 space: subst::ParamSpace,
4674 type_defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4675 data: &hir::ParenthesizedParameterData,
4676 substs: &mut Substs<'tcx>)
4678 let type_count = type_defs.len(space);
4680 span_err!(fcx.tcx().sess, span, E0167,
4681 "parenthesized form always supplies 2 type parameters, \
4682 but only {} parameter(s) were expected",
4686 let input_tys: Vec<Ty> =
4687 data.inputs.iter().map(|ty| fcx.to_ty(&ty)).collect();
4689 let tuple_ty = fcx.tcx().mk_tup(input_tys);
4691 if type_count >= 1 {
4692 substs.types.push(space, tuple_ty);
4695 let output_ty: Option<Ty> =
4696 data.output.as_ref().map(|ty| fcx.to_ty(&ty));
4699 output_ty.unwrap_or(fcx.tcx().mk_nil());
4701 if type_count >= 2 {
4702 substs.types.push(space, output_ty);
4706 fn adjust_type_parameters<'a, 'tcx>(
4707 fcx: &FnCtxt<'a, 'tcx>,
4710 defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4711 require_type_space: bool,
4712 substs: &mut Substs<'tcx>)
4714 let provided_len = substs.types.len(space);
4715 let desired = defs.get_slice(space);
4716 let required_len = desired.iter()
4717 .take_while(|d| d.default.is_none())
4720 debug!("adjust_type_parameters(space={:?}, \
4729 // Enforced by `push_explicit_parameters_from_segment_to_substs()`.
4730 assert!(provided_len <= desired.len());
4732 // Nothing specified at all: supply inference variables for
4734 if provided_len == 0 && !(require_type_space && space == subst::TypeSpace) {
4735 substs.types.replace(space, Vec::new());
4736 fcx.infcx().type_vars_for_defs(span, space, substs, &desired[..]);
4740 // Too few parameters specified: report an error and use Err
4742 if provided_len < required_len {
4744 if desired.len() != required_len { "at least " } else { "" };
4745 span_err!(fcx.tcx().sess, span, E0089,
4746 "too few type parameters provided: expected {}{} parameter{}, \
4747 found {} parameter{}",
4748 qualifier, required_len,
4749 if required_len == 1 {""} else {"s"},
4751 if provided_len == 1 {""} else {"s"});
4752 substs.types.replace(space, vec![fcx.tcx().types.err; desired.len()]);
4756 // Otherwise, add in any optional parameters that the user
4757 // omitted. The case of *too many* parameters is handled
4759 // push_explicit_parameters_from_segment_to_substs(). Note
4760 // that the *default* type are expressed in terms of all prior
4761 // parameters, so we have to substitute as we go with the
4762 // partial substitution that we have built up.
4763 for i in provided_len..desired.len() {
4764 let default = desired[i].default.unwrap();
4765 let default = default.subst_spanned(fcx.tcx(), substs, Some(span));
4766 substs.types.push(space, default);
4768 assert_eq!(substs.types.len(space), desired.len());
4770 debug!("Final substs: {:?}", substs);
4773 fn adjust_region_parameters(
4777 defs: &VecPerParamSpace<ty::RegionParameterDef>,
4778 substs: &mut Substs)
4780 let provided_len = substs.mut_regions().len(space);
4781 let desired = defs.get_slice(space);
4783 // Enforced by `push_explicit_parameters_from_segment_to_substs()`.
4784 assert!(provided_len <= desired.len());
4786 // If nothing was provided, just use inference variables.
4787 if provided_len == 0 {
4788 substs.mut_regions().replace(
4790 fcx.infcx().region_vars_for_defs(span, desired));
4794 // If just the right number were provided, everybody is happy.
4795 if provided_len == desired.len() {
4799 // Otherwise, too few were provided. Report an error and then
4800 // use inference variables.
4801 span_err!(fcx.tcx().sess, span, E0090,
4802 "too few lifetime parameters provided: expected {} parameter{}, \
4803 found {} parameter{}",
4805 if desired.len() == 1 {""} else {"s"},
4807 if provided_len == 1 {""} else {"s"});
4809 substs.mut_regions().replace(
4811 fcx.infcx().region_vars_for_defs(span, desired));
4815 fn structurally_resolve_type_or_else<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
4819 where F: Fn() -> Ty<'tcx>
4821 let mut ty = fcx.resolve_type_vars_if_possible(ty);
4824 let alternative = f();
4827 if alternative.is_ty_var() || alternative.references_error() {
4828 fcx.type_error_message(sp, |_actual| {
4829 "the type of this value must be known in this context".to_string()
4831 demand::suptype(fcx, sp, fcx.tcx().types.err, ty);
4832 ty = fcx.tcx().types.err;
4834 demand::suptype(fcx, sp, alternative, ty);
4842 // Resolves `typ` by a single level if `typ` is a type variable. If no
4843 // resolution is possible, then an error is reported.
4844 pub fn structurally_resolved_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4849 structurally_resolve_type_or_else(fcx, sp, ty, || {
4854 // Returns true if b contains a break that can exit from b
4855 pub fn may_break(cx: &TyCtxt, id: ast::NodeId, b: &hir::Block) -> bool {
4856 // First: is there an unlabeled break immediately
4858 (loop_query(&b, |e| {
4860 hir::ExprBreak(None) => true,
4864 // Second: is there a labeled break with label
4865 // <id> nested anywhere inside the loop?
4866 (block_query(b, |e| {
4867 if let hir::ExprBreak(Some(_)) = e.node {
4868 lookup_full_def(cx, e.span, e.id) == Def::Label(id)
4875 pub fn check_bounds_are_used<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
4876 tps: &[hir::TyParam],
4878 debug!("check_bounds_are_used(n_tps={}, ty={:?})",
4881 // make a vector of booleans initially false, set to true when used
4882 if tps.is_empty() { return; }
4883 let mut tps_used = vec![false; tps.len()];
4885 for leaf_ty in ty.walk() {
4886 if let ty::TyParam(ParamTy {idx, ..}) = leaf_ty.sty {
4887 debug!("Found use of ty param num {}", idx);
4888 tps_used[idx as usize] = true;
4892 for (i, b) in tps_used.iter().enumerate() {
4894 span_err!(ccx.tcx.sess, tps[i].span, E0091,
4895 "type parameter `{}` is unused",