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::TyFnDef(_, _, 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 /// Registers an obligation for checking later, during regionck, that the type `ty` must
1626 /// outlive the region `r`.
1627 pub fn register_region_obligation(&self,
1630 cause: traits::ObligationCause<'tcx>)
1632 let mut fulfillment_cx = self.inh.fulfillment_cx.borrow_mut();
1633 fulfillment_cx.register_region_obligation(ty, region, cause);
1636 /// Registers an obligation for checking later, during regionck, that the type `ty` must
1637 /// outlive the region `r`.
1638 pub fn register_wf_obligation(&self,
1641 code: traits::ObligationCauseCode<'tcx>)
1643 // WF obligations never themselves fail, so no real need to give a detailed cause:
1644 let cause = traits::ObligationCause::new(span, self.body_id, code);
1645 self.register_predicate(traits::Obligation::new(cause, ty::Predicate::WellFormed(ty)));
1648 pub fn register_old_wf_obligation(&self,
1651 code: traits::ObligationCauseCode<'tcx>)
1653 // Registers an "old-style" WF obligation that uses the
1654 // implicator code. This is basically a buggy version of
1655 // `register_wf_obligation` that is being kept around
1656 // temporarily just to help with phasing in the newer rules.
1658 // FIXME(#27579) all uses of this should be migrated to register_wf_obligation eventually
1659 let cause = traits::ObligationCause::new(span, self.body_id, code);
1660 self.register_region_obligation(ty, ty::ReEmpty, cause);
1663 /// Registers obligations that all types appearing in `substs` are well-formed.
1664 pub fn add_wf_bounds(&self, substs: &Substs<'tcx>, expr: &hir::Expr)
1666 for &ty in &substs.types {
1667 self.register_wf_obligation(ty, expr.span, traits::MiscObligation);
1671 /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each
1672 /// type/region parameter was instantiated (`substs`), creates and registers suitable
1673 /// trait/region obligations.
1675 /// For example, if there is a function:
1678 /// fn foo<'a,T:'a>(...)
1681 /// and a reference:
1687 /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a`
1688 /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally.
1689 pub fn add_obligations_for_parameters(&self,
1690 cause: traits::ObligationCause<'tcx>,
1691 predicates: &ty::InstantiatedPredicates<'tcx>)
1693 assert!(!predicates.has_escaping_regions());
1695 debug!("add_obligations_for_parameters(predicates={:?})",
1698 for obligation in traits::predicates_for_generics(cause, predicates) {
1699 self.register_predicate(obligation);
1703 // FIXME(arielb1): use this instead of field.ty everywhere
1704 // Only for fields! Returns <none> for methods>
1705 // Indifferent to privacy flags
1706 pub fn field_ty(&self,
1708 field: ty::FieldDef<'tcx>,
1709 substs: &Substs<'tcx>)
1712 self.normalize_associated_types_in(span,
1713 &field.ty(self.tcx(), substs))
1716 fn check_casts(&self) {
1717 let mut deferred_cast_checks = self.inh.deferred_cast_checks.borrow_mut();
1718 for cast in deferred_cast_checks.drain(..) {
1723 /// Apply "fallbacks" to some types
1724 /// ! gets replaced with (), unconstrained ints with i32, and unconstrained floats with f64.
1725 fn default_type_parameters(&self) {
1726 use middle::ty::error::UnconstrainedNumeric::Neither;
1727 use middle::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
1728 for ty in &self.infcx().unsolved_variables() {
1729 let resolved = self.infcx().resolve_type_vars_if_possible(ty);
1730 if self.infcx().type_var_diverges(resolved) {
1731 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1733 match self.infcx().type_is_unconstrained_numeric(resolved) {
1734 UnconstrainedInt => {
1735 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.i32)
1737 UnconstrainedFloat => {
1738 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.f64)
1746 fn select_all_obligations_and_apply_defaults(&self) {
1747 if self.tcx().sess.features.borrow().default_type_parameter_fallback {
1748 self.new_select_all_obligations_and_apply_defaults();
1750 self.old_select_all_obligations_and_apply_defaults();
1754 // Implements old type inference fallback algorithm
1755 fn old_select_all_obligations_and_apply_defaults(&self) {
1756 self.select_obligations_where_possible();
1757 self.default_type_parameters();
1758 self.select_obligations_where_possible();
1761 fn new_select_all_obligations_and_apply_defaults(&self) {
1762 use middle::ty::error::UnconstrainedNumeric::Neither;
1763 use middle::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
1765 // For the time being this errs on the side of being memory wasteful but provides better
1767 // let type_variables = self.infcx().type_variables.clone();
1769 // There is a possibility that this algorithm will have to run an arbitrary number of times
1770 // to terminate so we bound it by the compiler's recursion limit.
1771 for _ in 0..self.tcx().sess.recursion_limit.get() {
1772 // First we try to solve all obligations, it is possible that the last iteration
1773 // has made it possible to make more progress.
1774 self.select_obligations_where_possible();
1776 let mut conflicts = Vec::new();
1778 // Collect all unsolved type, integral and floating point variables.
1779 let unsolved_variables = self.inh.infcx.unsolved_variables();
1781 // We must collect the defaults *before* we do any unification. Because we have
1782 // directly attached defaults to the type variables any unification that occurs
1783 // will erase defaults causing conflicting defaults to be completely ignored.
1784 let default_map: FnvHashMap<_, _> =
1787 .filter_map(|t| self.infcx().default(t).map(|d| (t, d)))
1790 let mut unbound_tyvars = HashSet::new();
1792 debug!("select_all_obligations_and_apply_defaults: defaults={:?}", default_map);
1794 // We loop over the unsolved variables, resolving them and if they are
1795 // and unconstrainted numeric type we add them to the set of unbound
1796 // variables. We do this so we only apply literal fallback to type
1797 // variables without defaults.
1798 for ty in &unsolved_variables {
1799 let resolved = self.infcx().resolve_type_vars_if_possible(ty);
1800 if self.infcx().type_var_diverges(resolved) {
1801 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1803 match self.infcx().type_is_unconstrained_numeric(resolved) {
1804 UnconstrainedInt | UnconstrainedFloat => {
1805 unbound_tyvars.insert(resolved);
1812 // We now remove any numeric types that also have defaults, and instead insert
1813 // the type variable with a defined fallback.
1814 for ty in &unsolved_variables {
1815 if let Some(_default) = default_map.get(ty) {
1816 let resolved = self.infcx().resolve_type_vars_if_possible(ty);
1818 debug!("select_all_obligations_and_apply_defaults: ty: {:?} with default: {:?}",
1821 match resolved.sty {
1822 ty::TyInfer(ty::TyVar(_)) => {
1823 unbound_tyvars.insert(ty);
1826 ty::TyInfer(ty::IntVar(_)) | ty::TyInfer(ty::FloatVar(_)) => {
1827 unbound_tyvars.insert(ty);
1828 if unbound_tyvars.contains(resolved) {
1829 unbound_tyvars.remove(resolved);
1838 // If there are no more fallbacks to apply at this point we have applied all possible
1839 // defaults and type inference will proceed as normal.
1840 if unbound_tyvars.is_empty() {
1844 // Finally we go through each of the unbound type variables and unify them with
1845 // the proper fallback, reporting a conflicting default error if any of the
1846 // unifications fail. We know it must be a conflicting default because the
1847 // variable would only be in `unbound_tyvars` and have a concrete value if
1848 // it had been solved by previously applying a default.
1850 // We wrap this in a transaction for error reporting, if we detect a conflict
1851 // we will rollback the inference context to its prior state so we can probe
1852 // for conflicts and correctly report them.
1855 let _ = self.infcx().commit_if_ok(|_: &infer::CombinedSnapshot| {
1856 for ty in &unbound_tyvars {
1857 if self.infcx().type_var_diverges(ty) {
1858 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1860 match self.infcx().type_is_unconstrained_numeric(ty) {
1861 UnconstrainedInt => {
1862 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.i32)
1864 UnconstrainedFloat => {
1865 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.f64)
1868 if let Some(default) = default_map.get(ty) {
1869 let default = default.clone();
1870 match infer::mk_eqty(self.infcx(), false,
1871 TypeOrigin::Misc(default.origin_span),
1875 conflicts.push((*ty, default));
1884 // If there are conflicts we rollback, otherwise commit
1885 if conflicts.len() > 0 {
1892 if conflicts.len() > 0 {
1893 // Loop through each conflicting default, figuring out the default that caused
1894 // a unification failure and then report an error for each.
1895 for (conflict, default) in conflicts {
1896 let conflicting_default =
1897 self.find_conflicting_default(&unbound_tyvars, &default_map, conflict)
1898 .unwrap_or(type_variable::Default {
1899 ty: self.infcx().next_ty_var(),
1900 origin_span: codemap::DUMMY_SP,
1901 def_id: self.tcx().map.local_def_id(0) // what do I put here?
1904 // This is to ensure that we elimnate any non-determinism from the error
1905 // reporting by fixing an order, it doesn't matter what order we choose
1906 // just that it is consistent.
1907 let (first_default, second_default) =
1908 if default.def_id < conflicting_default.def_id {
1909 (default, conflicting_default)
1911 (conflicting_default, default)
1915 self.infcx().report_conflicting_default_types(
1916 first_default.origin_span,
1923 self.select_obligations_where_possible();
1926 // For use in error handling related to default type parameter fallback. We explicitly
1927 // apply the default that caused conflict first to a local version of the type variable
1928 // table then apply defaults until we find a conflict. That default must be the one
1929 // that caused conflict earlier.
1930 fn find_conflicting_default(&self,
1931 unbound_vars: &HashSet<Ty<'tcx>>,
1932 default_map: &FnvHashMap<&Ty<'tcx>, type_variable::Default<'tcx>>,
1934 -> Option<type_variable::Default<'tcx>> {
1935 use middle::ty::error::UnconstrainedNumeric::Neither;
1936 use middle::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
1938 // Ensure that we apply the conflicting default first
1939 let mut unbound_tyvars = Vec::with_capacity(unbound_vars.len() + 1);
1940 unbound_tyvars.push(conflict);
1941 unbound_tyvars.extend(unbound_vars.iter());
1943 let mut result = None;
1944 // We run the same code as above applying defaults in order, this time when
1945 // we find the conflict we just return it for error reporting above.
1947 // We also run this inside snapshot that never commits so we can do error
1948 // reporting for more then one conflict.
1949 for ty in &unbound_tyvars {
1950 if self.infcx().type_var_diverges(ty) {
1951 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().mk_nil());
1953 match self.infcx().type_is_unconstrained_numeric(ty) {
1954 UnconstrainedInt => {
1955 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.i32)
1957 UnconstrainedFloat => {
1958 demand::eqtype(self, codemap::DUMMY_SP, *ty, self.tcx().types.f64)
1961 if let Some(default) = default_map.get(ty) {
1962 let default = default.clone();
1963 match infer::mk_eqty(self.infcx(), false,
1964 TypeOrigin::Misc(default.origin_span),
1968 result = Some(default);
1980 fn select_all_obligations_or_error(&self) {
1981 debug!("select_all_obligations_or_error");
1983 // upvar inference should have ensured that all deferred call
1984 // resolutions are handled by now.
1985 assert!(self.inh.deferred_call_resolutions.borrow().is_empty());
1987 self.select_all_obligations_and_apply_defaults();
1989 let mut fulfillment_cx = self.inh.fulfillment_cx.borrow_mut();
1990 match fulfillment_cx.select_all_or_error(self.infcx()) {
1992 Err(errors) => { report_fulfillment_errors(self.infcx(), &errors); }
1996 /// Select as many obligations as we can at present.
1997 fn select_obligations_where_possible(&self) {
1999 self.inh.fulfillment_cx
2001 .select_where_possible(self.infcx())
2004 Err(errors) => { report_fulfillment_errors(self.infcx(), &errors); }
2008 fn private_item_is_visible(&self, def_id: DefId) -> bool {
2009 match self.tcx().map.as_local_node_id(def_id) {
2010 Some(node_id) => self.tcx().map.private_item_is_visible_from(node_id, self.body_id),
2011 None => false, // Private items from other crates are never visible
2016 impl<'a, 'tcx> RegionScope for FnCtxt<'a, 'tcx> {
2017 fn object_lifetime_default(&self, span: Span) -> Option<ty::Region> {
2018 Some(self.base_object_lifetime_default(span))
2021 fn base_object_lifetime_default(&self, span: Span) -> ty::Region {
2022 // RFC #599 specifies that object lifetime defaults take
2023 // precedence over other defaults. But within a fn body we
2024 // don't have a *default* region, rather we use inference to
2025 // find the *correct* region, which is strictly more general
2026 // (and anyway, within a fn body the right region may not even
2027 // be something the user can write explicitly, since it might
2028 // be some expression).
2029 self.infcx().next_region_var(infer::MiscVariable(span))
2032 fn anon_regions(&self, span: Span, count: usize)
2033 -> Result<Vec<ty::Region>, Option<Vec<ElisionFailureInfo>>> {
2034 Ok((0..count).map(|_| {
2035 self.infcx().next_region_var(infer::MiscVariable(span))
2040 /// Whether `autoderef` requires types to resolve.
2041 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
2042 pub enum UnresolvedTypeAction {
2043 /// Produce an error and return `TyError` whenever a type cannot
2044 /// be resolved (i.e. it is `TyInfer`).
2046 /// Go on without emitting any errors, and return the unresolved
2047 /// type. Useful for probing, e.g. in coercions.
2051 /// Executes an autoderef loop for the type `t`. At each step, invokes `should_stop` to decide
2052 /// whether to terminate the loop. Returns the final type and number of derefs that it performed.
2054 /// Note: this method does not modify the adjustments table. The caller is responsible for
2055 /// inserting an AutoAdjustment record into the `fcx` using one of the suitable methods.
2056 pub fn autoderef<'a, 'b, 'tcx, E, I, T, F>(fcx: &FnCtxt<'a, 'tcx>,
2060 unresolved_type_action: UnresolvedTypeAction,
2061 mut lvalue_pref: LvaluePreference,
2063 -> (Ty<'tcx>, usize, Option<T>)
2064 // FIXME(eddyb) use copyable iterators when that becomes ergonomic.
2066 I: IntoIterator<Item=&'b hir::Expr>,
2067 F: FnMut(Ty<'tcx>, usize) -> Option<T>,
2069 debug!("autoderef(base_ty={:?}, lvalue_pref={:?})",
2070 base_ty, lvalue_pref);
2072 let mut t = base_ty;
2073 for autoderefs in 0..fcx.tcx().sess.recursion_limit.get() {
2074 let resolved_t = match unresolved_type_action {
2075 UnresolvedTypeAction::Error => {
2076 structurally_resolved_type(fcx, sp, t)
2078 UnresolvedTypeAction::Ignore => {
2079 // We can continue even when the type cannot be resolved
2080 // (i.e. it is an inference variable) because `Ty::builtin_deref`
2081 // and `try_overloaded_deref` both simply return `None`
2082 // in such a case without producing spurious errors.
2083 fcx.resolve_type_vars_if_possible(t)
2086 if resolved_t.references_error() {
2087 return (resolved_t, autoderefs, None);
2090 match should_stop(resolved_t, autoderefs) {
2091 Some(x) => return (resolved_t, autoderefs, Some(x)),
2095 // Otherwise, deref if type is derefable:
2097 // Super subtle: it might seem as though we should
2098 // pass `opt_expr` to `try_overloaded_deref`, so that
2099 // the (implicit) autoref of using an overloaded deref
2100 // would get added to the adjustment table. However we
2101 // do not do that, because it's kind of a
2102 // "meta-adjustment" -- instead, we just leave it
2103 // unrecorded and know that there "will be" an
2104 // autoref. regionck and other bits of the code base,
2105 // when they encounter an overloaded autoderef, have
2106 // to do some reconstructive surgery. This is a pretty
2107 // complex mess that is begging for a proper MIR.
2108 let mt = if let Some(mt) = resolved_t.builtin_deref(false, lvalue_pref) {
2110 } else if let Some(method) = try_overloaded_deref(fcx, sp, None,
2111 resolved_t, lvalue_pref) {
2112 for expr in maybe_exprs() {
2113 let method_call = MethodCall::autoderef(expr.id, autoderefs as u32);
2114 fcx.inh.tables.borrow_mut().method_map.insert(method_call, method);
2116 make_overloaded_lvalue_return_type(fcx.tcx(), method)
2118 return (resolved_t, autoderefs, None);
2122 if mt.mutbl == hir::MutImmutable {
2123 lvalue_pref = NoPreference;
2127 // We've reached the recursion limit, error gracefully.
2128 span_err!(fcx.tcx().sess, sp, E0055,
2129 "reached the recursion limit while auto-dereferencing {:?}",
2131 (fcx.tcx().types.err, 0, None)
2134 fn try_overloaded_deref<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2136 base_expr: Option<&hir::Expr>,
2138 lvalue_pref: LvaluePreference)
2139 -> Option<MethodCallee<'tcx>>
2141 // Try DerefMut first, if preferred.
2142 let method = match (lvalue_pref, fcx.tcx().lang_items.deref_mut_trait()) {
2143 (PreferMutLvalue, Some(trait_did)) => {
2144 method::lookup_in_trait(fcx, span, base_expr,
2145 token::intern("deref_mut"), trait_did,
2151 // Otherwise, fall back to Deref.
2152 let method = match (method, fcx.tcx().lang_items.deref_trait()) {
2153 (None, Some(trait_did)) => {
2154 method::lookup_in_trait(fcx, span, base_expr,
2155 token::intern("deref"), trait_did,
2158 (method, _) => method
2164 /// For the overloaded lvalue expressions (`*x`, `x[3]`), the trait returns a type of `&T`, but the
2165 /// actual type we assign to the *expression* is `T`. So this function just peels off the return
2166 /// type by one layer to yield `T`.
2167 fn make_overloaded_lvalue_return_type<'tcx>(tcx: &ty::ctxt<'tcx>,
2168 method: MethodCallee<'tcx>)
2169 -> ty::TypeAndMut<'tcx>
2171 // extract method return type, which will be &T;
2172 // all LB regions should have been instantiated during method lookup
2173 let ret_ty = method.ty.fn_ret();
2174 let ret_ty = tcx.no_late_bound_regions(&ret_ty).unwrap().unwrap();
2176 // method returns &T, but the type as visible to user is T, so deref
2177 ret_ty.builtin_deref(true, NoPreference).unwrap()
2180 fn lookup_indexing<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2182 base_expr: &'tcx hir::Expr,
2185 lvalue_pref: LvaluePreference)
2186 -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)>
2188 // FIXME(#18741) -- this is almost but not quite the same as the
2189 // autoderef that normal method probing does. They could likely be
2192 let (ty, autoderefs, final_mt) = autoderef(fcx,
2196 UnresolvedTypeAction::Error,
2199 try_index_step(fcx, MethodCall::expr(expr.id), expr, base_expr,
2200 adj_ty, idx, false, lvalue_pref, idx_ty)
2203 if final_mt.is_some() {
2207 // After we have fully autoderef'd, if the resulting type is [T; n], then
2208 // do a final unsized coercion to yield [T].
2209 if let ty::TyArray(element_ty, _) = ty.sty {
2210 let adjusted_ty = fcx.tcx().mk_slice(element_ty);
2211 try_index_step(fcx, MethodCall::expr(expr.id), expr, base_expr,
2212 adjusted_ty, autoderefs, true, lvalue_pref, idx_ty)
2218 /// To type-check `base_expr[index_expr]`, we progressively autoderef (and otherwise adjust)
2219 /// `base_expr`, looking for a type which either supports builtin indexing or overloaded indexing.
2220 /// This loop implements one step in that search; the autoderef loop is implemented by
2221 /// `lookup_indexing`.
2222 fn try_index_step<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2223 method_call: MethodCall,
2225 base_expr: &'tcx hir::Expr,
2226 adjusted_ty: Ty<'tcx>,
2229 lvalue_pref: LvaluePreference,
2231 -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)>
2233 let tcx = fcx.tcx();
2234 debug!("try_index_step(expr={:?}, base_expr.id={:?}, adjusted_ty={:?}, \
2235 autoderefs={}, unsize={}, index_ty={:?})",
2243 let input_ty = fcx.infcx().next_ty_var();
2245 // First, try built-in indexing.
2246 match (adjusted_ty.builtin_index(), &index_ty.sty) {
2247 (Some(ty), &ty::TyUint(ast::UintTy::Us)) | (Some(ty), &ty::TyInfer(ty::IntVar(_))) => {
2248 debug!("try_index_step: success, using built-in indexing");
2249 // If we had `[T; N]`, we should've caught it before unsizing to `[T]`.
2251 fcx.write_autoderef_adjustment(base_expr.id, autoderefs);
2252 return Some((tcx.types.usize, ty));
2257 // Try `IndexMut` first, if preferred.
2258 let method = match (lvalue_pref, tcx.lang_items.index_mut_trait()) {
2259 (PreferMutLvalue, Some(trait_did)) => {
2260 method::lookup_in_trait_adjusted(fcx,
2263 token::intern("index_mut"),
2268 Some(vec![input_ty]))
2273 // Otherwise, fall back to `Index`.
2274 let method = match (method, tcx.lang_items.index_trait()) {
2275 (None, Some(trait_did)) => {
2276 method::lookup_in_trait_adjusted(fcx,
2279 token::intern("index"),
2284 Some(vec![input_ty]))
2286 (method, _) => method,
2289 // If some lookup succeeds, write callee into table and extract index/element
2290 // type from the method signature.
2291 // If some lookup succeeded, install method in table
2292 method.map(|method| {
2293 debug!("try_index_step: success, using overloaded indexing");
2294 fcx.inh.tables.borrow_mut().method_map.insert(method_call, method);
2295 (input_ty, make_overloaded_lvalue_return_type(fcx.tcx(), method).ty)
2299 fn check_method_argument_types<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2301 method_fn_ty: Ty<'tcx>,
2302 callee_expr: &'tcx hir::Expr,
2303 args_no_rcvr: &'tcx [P<hir::Expr>],
2304 tuple_arguments: TupleArgumentsFlag,
2305 expected: Expectation<'tcx>)
2306 -> ty::FnOutput<'tcx> {
2307 if method_fn_ty.references_error() {
2308 let err_inputs = err_args(fcx.tcx(), args_no_rcvr.len());
2310 let err_inputs = match tuple_arguments {
2311 DontTupleArguments => err_inputs,
2312 TupleArguments => vec![fcx.tcx().mk_tup(err_inputs)],
2315 check_argument_types(fcx,
2322 ty::FnConverging(fcx.tcx().types.err)
2324 match method_fn_ty.sty {
2325 ty::TyFnDef(_, _, ref fty) => {
2326 // HACK(eddyb) ignore self in the definition (see above).
2327 let expected_arg_tys = expected_types_for_fn_args(fcx,
2331 &fty.sig.0.inputs[1..]);
2332 check_argument_types(fcx,
2334 &fty.sig.0.inputs[1..],
2335 &expected_arg_tys[..],
2342 fcx.tcx().sess.span_bug(callee_expr.span,
2343 "method without bare fn type");
2349 /// Generic function that factors out common logic from function calls, method calls and overloaded
2351 fn check_argument_types<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2353 fn_inputs: &[Ty<'tcx>],
2354 expected_arg_tys: &[Ty<'tcx>],
2355 args: &'tcx [P<hir::Expr>],
2357 tuple_arguments: TupleArgumentsFlag) {
2358 let tcx = fcx.ccx.tcx;
2360 // Grab the argument types, supplying fresh type variables
2361 // if the wrong number of arguments were supplied
2362 let supplied_arg_count = if tuple_arguments == DontTupleArguments {
2368 // All the input types from the fn signature must outlive the call
2369 // so as to validate implied bounds.
2370 for &fn_input_ty in fn_inputs {
2371 fcx.register_wf_obligation(fn_input_ty, sp, traits::MiscObligation);
2374 let mut expected_arg_tys = expected_arg_tys;
2375 let expected_arg_count = fn_inputs.len();
2376 let formal_tys = if tuple_arguments == TupleArguments {
2377 let tuple_type = structurally_resolved_type(fcx, sp, fn_inputs[0]);
2378 match tuple_type.sty {
2379 ty::TyTuple(ref arg_types) => {
2380 if arg_types.len() != args.len() {
2381 span_err!(tcx.sess, sp, E0057,
2382 "this function takes {} parameter{} but {} parameter{} supplied",
2384 if arg_types.len() == 1 {""} else {"s"},
2386 if args.len() == 1 {" was"} else {"s were"});
2387 expected_arg_tys = &[];
2388 err_args(fcx.tcx(), args.len())
2390 expected_arg_tys = match expected_arg_tys.get(0) {
2391 Some(&ty) => match ty.sty {
2392 ty::TyTuple(ref tys) => &tys,
2397 (*arg_types).clone()
2401 span_err!(tcx.sess, sp, E0059,
2402 "cannot use call notation; the first type parameter \
2403 for the function trait is neither a tuple nor unit");
2404 expected_arg_tys = &[];
2405 err_args(fcx.tcx(), args.len())
2408 } else if expected_arg_count == supplied_arg_count {
2410 } else if variadic {
2411 if supplied_arg_count >= expected_arg_count {
2414 span_err!(tcx.sess, sp, E0060,
2415 "this function takes at least {} parameter{} \
2416 but {} parameter{} supplied",
2418 if expected_arg_count == 1 {""} else {"s"},
2420 if supplied_arg_count == 1 {" was"} else {"s were"});
2421 expected_arg_tys = &[];
2422 err_args(fcx.tcx(), supplied_arg_count)
2425 span_err!(tcx.sess, sp, E0061,
2426 "this function takes {} parameter{} but {} parameter{} supplied",
2428 if expected_arg_count == 1 {""} else {"s"},
2430 if supplied_arg_count == 1 {" was"} else {"s were"});
2431 expected_arg_tys = &[];
2432 err_args(fcx.tcx(), supplied_arg_count)
2435 debug!("check_argument_types: formal_tys={:?}",
2436 formal_tys.iter().map(|t| fcx.infcx().ty_to_string(*t)).collect::<Vec<String>>());
2438 // Check the arguments.
2439 // We do this in a pretty awful way: first we typecheck any arguments
2440 // that are not anonymous functions, then we typecheck the anonymous
2441 // functions. This is so that we have more information about the types
2442 // of arguments when we typecheck the functions. This isn't really the
2443 // right way to do this.
2444 let xs = [false, true];
2445 let mut any_diverges = false; // has any of the arguments diverged?
2446 let mut warned = false; // have we already warned about unreachable code?
2447 for check_blocks in &xs {
2448 let check_blocks = *check_blocks;
2449 debug!("check_blocks={}", check_blocks);
2451 // More awful hacks: before we check argument types, try to do
2452 // an "opportunistic" vtable resolution of any trait bounds on
2453 // the call. This helps coercions.
2455 fcx.select_obligations_where_possible();
2458 // For variadic functions, we don't have a declared type for all of
2459 // the arguments hence we only do our usual type checking with
2460 // the arguments who's types we do know.
2461 let t = if variadic {
2463 } else if tuple_arguments == TupleArguments {
2468 for (i, arg) in args.iter().take(t).enumerate() {
2469 if any_diverges && !warned {
2473 .add_lint(lint::builtin::UNREACHABLE_CODE,
2476 "unreachable expression".to_string());
2479 let is_block = match arg.node {
2480 hir::ExprClosure(..) => true,
2484 if is_block == check_blocks {
2485 debug!("checking the argument");
2486 let formal_ty = formal_tys[i];
2488 // The special-cased logic below has three functions:
2489 // 1. Provide as good of an expected type as possible.
2490 let expected = expected_arg_tys.get(i).map(|&ty| {
2491 Expectation::rvalue_hint(fcx.tcx(), ty)
2494 check_expr_with_expectation(fcx, &arg,
2495 expected.unwrap_or(ExpectHasType(formal_ty)));
2496 // 2. Coerce to the most detailed type that could be coerced
2497 // to, which is `expected_ty` if `rvalue_hint` returns an
2498 // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
2499 let coerce_ty = expected.and_then(|e| e.only_has_type(fcx));
2500 demand::coerce(fcx, arg.span, coerce_ty.unwrap_or(formal_ty), &arg);
2502 // 3. Relate the expected type and the formal one,
2503 // if the expected type was used for the coercion.
2504 coerce_ty.map(|ty| demand::suptype(fcx, arg.span, formal_ty, ty));
2507 if let Some(&arg_ty) = fcx.inh.tables.borrow().node_types.get(&arg.id) {
2508 any_diverges = any_diverges || fcx.infcx().type_var_diverges(arg_ty);
2511 if any_diverges && !warned {
2512 let parent = fcx.ccx.tcx.map.get_parent_node(args[0].id);
2516 .add_lint(lint::builtin::UNREACHABLE_CODE,
2519 "unreachable call".to_string());
2525 // We also need to make sure we at least write the ty of the other
2526 // arguments which we skipped above.
2528 for arg in args.iter().skip(expected_arg_count) {
2529 check_expr(fcx, &arg);
2531 // There are a few types which get autopromoted when passed via varargs
2532 // in C but we just error out instead and require explicit casts.
2533 let arg_ty = structurally_resolved_type(fcx, arg.span,
2536 ty::TyFloat(ast::FloatTy::F32) => {
2537 fcx.type_error_message(arg.span,
2539 format!("can't pass an {} to variadic \
2540 function, cast to c_double", t)
2543 ty::TyInt(ast::IntTy::I8) | ty::TyInt(ast::IntTy::I16) | ty::TyBool => {
2544 fcx.type_error_message(arg.span, |t| {
2545 format!("can't pass {} to variadic \
2546 function, cast to c_int",
2550 ty::TyUint(ast::UintTy::U8) | ty::TyUint(ast::UintTy::U16) => {
2551 fcx.type_error_message(arg.span, |t| {
2552 format!("can't pass {} to variadic \
2553 function, cast to c_uint",
2563 // FIXME(#17596) Ty<'tcx> is incorrectly invariant w.r.t 'tcx.
2564 fn err_args<'tcx>(tcx: &TyCtxt<'tcx>, len: usize) -> Vec<Ty<'tcx>> {
2565 (0..len).map(|_| tcx.types.err).collect()
2568 fn write_call<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2569 call_expr: &hir::Expr,
2570 output: ty::FnOutput<'tcx>) {
2571 fcx.write_ty(call_expr.id, match output {
2572 ty::FnConverging(output_ty) => output_ty,
2573 ty::FnDiverging => fcx.infcx().next_diverging_ty_var()
2577 // AST fragment checking
2578 fn check_lit<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2580 expected: Expectation<'tcx>)
2583 let tcx = fcx.ccx.tcx;
2586 ast::LitKind::Str(..) => tcx.mk_static_str(),
2587 ast::LitKind::ByteStr(ref v) => {
2588 tcx.mk_imm_ref(tcx.mk_region(ty::ReStatic),
2589 tcx.mk_array(tcx.types.u8, v.len()))
2591 ast::LitKind::Byte(_) => tcx.types.u8,
2592 ast::LitKind::Char(_) => tcx.types.char,
2593 ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t),
2594 ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t),
2595 ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => {
2596 let opt_ty = expected.to_option(fcx).and_then(|ty| {
2598 ty::TyInt(_) | ty::TyUint(_) => Some(ty),
2599 ty::TyChar => Some(tcx.types.u8),
2600 ty::TyRawPtr(..) => Some(tcx.types.usize),
2601 ty::TyFnDef(..) | ty::TyFnPtr(_) => Some(tcx.types.usize),
2605 opt_ty.unwrap_or_else(
2606 || tcx.mk_int_var(fcx.infcx().next_int_var_id()))
2608 ast::LitKind::Float(_, t) => tcx.mk_mach_float(t),
2609 ast::LitKind::FloatUnsuffixed(_) => {
2610 let opt_ty = expected.to_option(fcx).and_then(|ty| {
2612 ty::TyFloat(_) => Some(ty),
2616 opt_ty.unwrap_or_else(
2617 || tcx.mk_float_var(fcx.infcx().next_float_var_id()))
2619 ast::LitKind::Bool(_) => tcx.types.bool
2623 fn check_expr_eq_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2624 expr: &'tcx hir::Expr,
2625 expected: Ty<'tcx>) {
2626 check_expr_with_hint(fcx, expr, expected);
2627 demand::eqtype(fcx, expr.span, expected, fcx.expr_ty(expr));
2630 pub fn check_expr_has_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2631 expr: &'tcx hir::Expr,
2632 expected: Ty<'tcx>) {
2633 check_expr_with_hint(fcx, expr, expected);
2634 demand::suptype(fcx, expr.span, expected, fcx.expr_ty(expr));
2637 fn check_expr_coercable_to_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2638 expr: &'tcx hir::Expr,
2639 expected: Ty<'tcx>) {
2640 check_expr_with_hint(fcx, expr, expected);
2641 demand::coerce(fcx, expr.span, expected, expr);
2644 fn check_expr_with_hint<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>, expr: &'tcx hir::Expr,
2645 expected: Ty<'tcx>) {
2646 check_expr_with_expectation(fcx, expr, ExpectHasType(expected))
2649 fn check_expr_with_expectation<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2650 expr: &'tcx hir::Expr,
2651 expected: Expectation<'tcx>) {
2652 check_expr_with_expectation_and_lvalue_pref(fcx, expr, expected, NoPreference)
2655 fn check_expr<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, expr: &'tcx hir::Expr) {
2656 check_expr_with_expectation(fcx, expr, NoExpectation)
2659 fn check_expr_with_lvalue_pref<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, expr: &'tcx hir::Expr,
2660 lvalue_pref: LvaluePreference) {
2661 check_expr_with_expectation_and_lvalue_pref(fcx, expr, NoExpectation, lvalue_pref)
2664 // determine the `self` type, using fresh variables for all variables
2665 // declared on the impl declaration e.g., `impl<A,B> for Vec<(A,B)>`
2666 // would return ($0, $1) where $0 and $1 are freshly instantiated type
2668 pub fn impl_self_ty<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2669 span: Span, // (potential) receiver for this impl
2671 -> TypeAndSubsts<'tcx> {
2672 let tcx = fcx.tcx();
2674 let ity = tcx.lookup_item_type(did);
2675 let (tps, rps, raw_ty) =
2676 (ity.generics.types.get_slice(subst::TypeSpace),
2677 ity.generics.regions.get_slice(subst::TypeSpace),
2680 debug!("impl_self_ty: tps={:?} rps={:?} raw_ty={:?}", tps, rps, raw_ty);
2682 let rps = fcx.inh.infcx.region_vars_for_defs(span, rps);
2683 let mut substs = subst::Substs::new(
2684 VecPerParamSpace::empty(),
2685 VecPerParamSpace::new(rps, Vec::new(), Vec::new()));
2686 fcx.inh.infcx.type_vars_for_defs(span, ParamSpace::TypeSpace, &mut substs, tps);
2687 let substd_ty = fcx.instantiate_type_scheme(span, &substs, &raw_ty);
2689 TypeAndSubsts { substs: substs, ty: substd_ty }
2692 /// Controls whether the arguments are tupled. This is used for the call
2695 /// Tupling means that all call-side arguments are packed into a tuple and
2696 /// passed as a single parameter. For example, if tupling is enabled, this
2699 /// fn f(x: (isize, isize))
2701 /// Can be called as:
2708 #[derive(Clone, Eq, PartialEq)]
2709 enum TupleArgumentsFlag {
2714 /// Unifies the return type with the expected type early, for more coercions
2715 /// and forward type information on the argument expressions.
2716 fn expected_types_for_fn_args<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2718 expected_ret: Expectation<'tcx>,
2719 formal_ret: ty::FnOutput<'tcx>,
2720 formal_args: &[Ty<'tcx>])
2722 let expected_args = expected_ret.only_has_type(fcx).and_then(|ret_ty| {
2723 if let ty::FnConverging(formal_ret_ty) = formal_ret {
2724 fcx.infcx().commit_regions_if_ok(|| {
2725 // Attempt to apply a subtyping relationship between the formal
2726 // return type (likely containing type variables if the function
2727 // is polymorphic) and the expected return type.
2728 // No argument expectations are produced if unification fails.
2729 let origin = TypeOrigin::Misc(call_span);
2730 let ures = fcx.infcx().sub_types(false, origin, formal_ret_ty, ret_ty);
2731 // FIXME(#15760) can't use try! here, FromError doesn't default
2732 // to identity so the resulting type is not constrained.
2733 if let Err(e) = ures {
2737 // Record all the argument types, with the substitutions
2738 // produced from the above subtyping unification.
2739 Ok(formal_args.iter().map(|ty| {
2740 fcx.infcx().resolve_type_vars_if_possible(ty)
2746 }).unwrap_or(vec![]);
2747 debug!("expected_types_for_fn_args(formal={:?} -> {:?}, expected={:?} -> {:?})",
2748 formal_args, formal_ret,
2749 expected_args, expected_ret);
2754 /// If an expression has any sub-expressions that result in a type error,
2755 /// inspecting that expression's type with `ty.references_error()` will return
2756 /// true. Likewise, if an expression is known to diverge, inspecting its
2757 /// type with `ty::type_is_bot` will return true (n.b.: since Rust is
2758 /// strict, _|_ can appear in the type of an expression that does not,
2759 /// itself, diverge: for example, fn() -> _|_.)
2760 /// Note that inspecting a type's structure *directly* may expose the fact
2761 /// that there are actually multiple representations for `TyError`, so avoid
2762 /// that when err needs to be handled differently.
2763 fn check_expr_with_expectation_and_lvalue_pref<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2764 expr: &'tcx hir::Expr,
2765 expected: Expectation<'tcx>,
2766 lvalue_pref: LvaluePreference) {
2767 debug!(">> typechecking: expr={:?} expected={:?}",
2770 // Checks a method call.
2771 fn check_method_call<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2772 expr: &'tcx hir::Expr,
2773 method_name: Spanned<ast::Name>,
2774 args: &'tcx [P<hir::Expr>],
2776 expected: Expectation<'tcx>,
2777 lvalue_pref: LvaluePreference) {
2778 let rcvr = &args[0];
2779 check_expr_with_lvalue_pref(fcx, &rcvr, lvalue_pref);
2781 // no need to check for bot/err -- callee does that
2782 let expr_t = structurally_resolved_type(fcx,
2784 fcx.expr_ty(&rcvr));
2786 let tps = tps.iter().map(|ast_ty| fcx.to_ty(&ast_ty)).collect::<Vec<_>>();
2787 let fn_ty = match method::lookup(fcx,
2795 let method_ty = method.ty;
2796 let method_call = MethodCall::expr(expr.id);
2797 fcx.inh.tables.borrow_mut().method_map.insert(method_call, method);
2801 if method_name.node != special_idents::invalid.name {
2802 method::report_error(fcx, method_name.span, expr_t,
2803 method_name.node, Some(rcvr), error);
2805 fcx.write_error(expr.id);
2810 // Call the generic checker.
2811 let ret_ty = check_method_argument_types(fcx,
2819 write_call(fcx, expr, ret_ty);
2822 // A generic function for checking the then and else in an if
2824 fn check_then_else<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
2825 cond_expr: &'tcx hir::Expr,
2826 then_blk: &'tcx hir::Block,
2827 opt_else_expr: Option<&'tcx hir::Expr>,
2830 expected: Expectation<'tcx>) {
2831 check_expr_has_type(fcx, cond_expr, fcx.tcx().types.bool);
2833 let expected = expected.adjust_for_branches(fcx);
2834 check_block_with_expected(fcx, then_blk, expected);
2835 let then_ty = fcx.node_ty(then_blk.id);
2837 let branches_ty = match opt_else_expr {
2838 Some(ref else_expr) => {
2839 check_expr_with_expectation(fcx, &else_expr, expected);
2840 let else_ty = fcx.expr_ty(&else_expr);
2841 infer::common_supertype(fcx.infcx(),
2842 TypeOrigin::IfExpression(sp),
2848 infer::common_supertype(fcx.infcx(),
2849 TypeOrigin::IfExpressionWithNoElse(sp),
2856 let cond_ty = fcx.expr_ty(cond_expr);
2857 let if_ty = if cond_ty.references_error() {
2863 fcx.write_ty(id, if_ty);
2866 // Check field access expressions
2867 fn check_field<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
2868 expr: &'tcx hir::Expr,
2869 lvalue_pref: LvaluePreference,
2870 base: &'tcx hir::Expr,
2871 field: &Spanned<ast::Name>) {
2872 check_expr_with_lvalue_pref(fcx, base, lvalue_pref);
2873 let expr_t = structurally_resolved_type(fcx, expr.span,
2875 // FIXME(eddyb) #12808 Integrate privacy into this auto-deref loop.
2876 let (_, autoderefs, field_ty) = autoderef(fcx,
2880 UnresolvedTypeAction::Error,
2884 ty::TyStruct(base_def, substs) => {
2885 debug!("struct named {:?}", base_t);
2886 base_def.struct_variant()
2887 .find_field_named(field.node)
2888 .map(|f| fcx.field_ty(expr.span, f, substs))
2895 fcx.write_ty(expr.id, field_ty);
2896 fcx.write_autoderef_adjustment(base.id, autoderefs);
2902 if field.node == special_idents::invalid.name {
2903 fcx.write_error(expr.id);
2907 if method::exists(fcx, field.span, field.node, expr_t, expr.id) {
2908 fcx.type_error_struct(field.span,
2910 format!("attempted to take value of method `{}` on type \
2911 `{}`", field.node, actual)
2914 .fileline_help(field.span,
2915 "maybe a `()` to call it is missing? \
2916 If not, try an anonymous function")
2919 let mut err = fcx.type_error_struct(
2922 format!("attempted access of field `{}` on \
2923 type `{}`, but no field with that \
2929 if let ty::TyStruct(def, _) = expr_t.sty {
2930 suggest_field_names(&mut err, def.struct_variant(), field, vec![]);
2935 fcx.write_error(expr.id);
2938 // displays hints about the closest matches in field names
2939 fn suggest_field_names<'tcx>(err: &mut DiagnosticBuilder,
2940 variant: ty::VariantDef<'tcx>,
2941 field: &Spanned<ast::Name>,
2942 skip : Vec<InternedString>) {
2943 let name = field.node.as_str();
2944 let names = variant.fields
2946 .filter_map(|ref field| {
2947 // ignore already set fields and private fields from non-local crates
2948 if skip.iter().any(|x| *x == field.name.as_str()) ||
2949 (variant.did.krate != LOCAL_CRATE && field.vis != Visibility::Public) {
2956 // only find fits with at least one matching letter
2957 if let Some(name) = find_best_match_for_name(names, &name, Some(name.len())) {
2958 err.span_help(field.span,
2959 &format!("did you mean `{}`?", name));
2963 // Check tuple index expressions
2964 fn check_tup_field<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
2965 expr: &'tcx hir::Expr,
2966 lvalue_pref: LvaluePreference,
2967 base: &'tcx hir::Expr,
2968 idx: codemap::Spanned<usize>) {
2969 check_expr_with_lvalue_pref(fcx, base, lvalue_pref);
2970 let expr_t = structurally_resolved_type(fcx, expr.span,
2972 let mut tuple_like = false;
2973 // FIXME(eddyb) #12808 Integrate privacy into this auto-deref loop.
2974 let (_, autoderefs, field_ty) = autoderef(fcx,
2978 UnresolvedTypeAction::Error,
2982 ty::TyStruct(base_def, substs) => {
2983 tuple_like = base_def.struct_variant().is_tuple_struct();
2985 debug!("tuple struct named {:?}", base_t);
2986 base_def.struct_variant()
2989 .map(|f| fcx.field_ty(expr.span, f, substs))
2994 ty::TyTuple(ref v) => {
2996 if idx.node < v.len() { Some(v[idx.node]) } else { None }
3003 fcx.write_ty(expr.id, field_ty);
3004 fcx.write_autoderef_adjustment(base.id, autoderefs);
3009 fcx.type_error_message(
3013 format!("attempted out-of-bounds tuple index `{}` on \
3018 format!("attempted tuple index `{}` on type `{}`, but the \
3019 type was not a tuple or tuple struct",
3026 fcx.write_error(expr.id);
3029 fn report_unknown_field<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3031 variant: ty::VariantDef<'tcx>,
3033 skip_fields: &[hir::Field]) {
3034 let mut err = fcx.type_error_struct(
3036 |actual| if let ty::TyEnum(..) = ty.sty {
3037 format!("struct variant `{}::{}` has no field named `{}`",
3038 actual, variant.name.as_str(), field.name.node)
3040 format!("structure `{}` has no field named `{}`",
3041 actual, field.name.node)
3045 // prevent all specified fields from being suggested
3046 let skip_fields = skip_fields.iter().map(|ref x| x.name.node.as_str());
3047 suggest_field_names(&mut err, variant, &field.name, skip_fields.collect());
3051 fn check_expr_struct_fields<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3054 variant: ty::VariantDef<'tcx>,
3055 ast_fields: &'tcx [hir::Field],
3056 check_completeness: bool) {
3057 let tcx = fcx.ccx.tcx;
3058 let substs = match adt_ty.sty {
3059 ty::TyStruct(_, substs) | ty::TyEnum(_, substs) => substs,
3060 _ => tcx.sess.span_bug(span, "non-ADT passed to check_expr_struct_fields")
3063 let mut remaining_fields = FnvHashMap();
3064 for field in &variant.fields {
3065 remaining_fields.insert(field.name, field);
3068 let mut error_happened = false;
3070 // Typecheck each field.
3071 for field in ast_fields {
3072 let expected_field_type;
3074 if let Some(v_field) = remaining_fields.remove(&field.name.node) {
3075 expected_field_type = fcx.field_ty(field.span, v_field, substs);
3077 error_happened = true;
3078 expected_field_type = tcx.types.err;
3079 if let Some(_) = variant.find_field_named(field.name.node) {
3080 span_err!(fcx.tcx().sess, field.name.span, E0062,
3081 "field `{}` specified more than once",
3084 report_unknown_field(fcx, adt_ty, variant, field, ast_fields);
3088 // Make sure to give a type to the field even if there's
3089 // an error, so we can continue typechecking
3090 check_expr_coercable_to_type(fcx, &field.expr, expected_field_type);
3093 // Make sure the programmer specified all the fields.
3094 if check_completeness &&
3096 !remaining_fields.is_empty()
3098 span_err!(tcx.sess, span, E0063,
3099 "missing field{} {} in initializer of `{}`",
3100 if remaining_fields.len() == 1 {""} else {"s"},
3101 remaining_fields.keys()
3102 .map(|n| format!("`{}`", n))
3103 .collect::<Vec<_>>()
3110 fn check_struct_fields_on_error<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
3112 fields: &'tcx [hir::Field],
3113 base_expr: &'tcx Option<P<hir::Expr>>) {
3114 // Make sure to still write the types
3115 // otherwise we might ICE
3116 fcx.write_error(id);
3117 for field in fields {
3118 check_expr(fcx, &field.expr);
3121 Some(ref base) => check_expr(fcx, &base),
3126 fn check_expr_struct<'a, 'tcx>(fcx: &FnCtxt<'a,'tcx>,
3129 fields: &'tcx [hir::Field],
3130 base_expr: &'tcx Option<P<hir::Expr>>)
3132 let tcx = fcx.tcx();
3134 // Find the relevant variant
3135 let def = lookup_full_def(tcx, path.span, expr.id);
3136 if def == Def::Err {
3137 check_struct_fields_on_error(fcx, expr.id, fields, base_expr);
3140 let variant = match fcx.def_struct_variant(def, path.span) {
3141 Some((_, variant)) => variant,
3143 span_err!(fcx.tcx().sess, path.span, E0071,
3144 "`{}` does not name a structure",
3145 pprust::path_to_string(path));
3146 check_struct_fields_on_error(fcx, expr.id, fields, base_expr);
3151 let expr_ty = fcx.instantiate_type(def.def_id(), path);
3152 fcx.write_ty(expr.id, expr_ty);
3154 check_expr_struct_fields(fcx, expr_ty, expr.span, variant, fields,
3155 base_expr.is_none());
3156 if let &Some(ref base_expr) = base_expr {
3157 check_expr_has_type(fcx, base_expr, expr_ty);
3159 ty::TyStruct(adt, substs) => {
3160 fcx.inh.tables.borrow_mut().fru_field_types.insert(
3162 adt.struct_variant().fields.iter().map(|f| {
3163 fcx.normalize_associated_types_in(
3164 expr.span, &f.ty(tcx, substs)
3170 span_err!(tcx.sess, base_expr.span, E0436,
3171 "functional record update syntax requires a struct");
3177 type ExprCheckerWithTy = fn(&FnCtxt, &hir::Expr, Ty);
3179 let tcx = fcx.ccx.tcx;
3182 hir::ExprBox(ref subexpr) => {
3183 let expected_inner = expected.to_option(fcx).map_or(NoExpectation, |ty| {
3185 ty::TyBox(ty) => Expectation::rvalue_hint(tcx, ty),
3189 check_expr_with_expectation(fcx, subexpr, expected_inner);
3190 let referent_ty = fcx.expr_ty(&subexpr);
3191 fcx.write_ty(id, tcx.mk_box(referent_ty));
3194 hir::ExprLit(ref lit) => {
3195 let typ = check_lit(fcx, &lit, expected);
3196 fcx.write_ty(id, typ);
3198 hir::ExprBinary(op, ref lhs, ref rhs) => {
3199 op::check_binop(fcx, expr, op, lhs, rhs);
3201 hir::ExprAssignOp(op, ref lhs, ref rhs) => {
3202 op::check_binop_assign(fcx, expr, op, lhs, rhs);
3204 hir::ExprUnary(unop, ref oprnd) => {
3205 let expected_inner = match unop {
3206 hir::UnNot | hir::UnNeg => {
3213 let lvalue_pref = match unop {
3214 hir::UnDeref => lvalue_pref,
3217 check_expr_with_expectation_and_lvalue_pref(
3218 fcx, &oprnd, expected_inner, lvalue_pref);
3219 let mut oprnd_t = fcx.expr_ty(&oprnd);
3221 if !oprnd_t.references_error() {
3224 oprnd_t = structurally_resolved_type(fcx, expr.span, oprnd_t);
3226 if let Some(mt) = oprnd_t.builtin_deref(true, NoPreference) {
3228 } else if let Some(method) = try_overloaded_deref(
3229 fcx, expr.span, Some(&oprnd), oprnd_t, lvalue_pref) {
3230 oprnd_t = make_overloaded_lvalue_return_type(tcx, method).ty;
3231 fcx.inh.tables.borrow_mut().method_map.insert(MethodCall::expr(expr.id),
3234 fcx.type_error_message(expr.span, |actual| {
3235 format!("type `{}` cannot be \
3236 dereferenced", actual)
3238 oprnd_t = tcx.types.err;
3242 oprnd_t = structurally_resolved_type(fcx, oprnd.span,
3244 if !(oprnd_t.is_integral() || oprnd_t.sty == ty::TyBool) {
3245 oprnd_t = op::check_user_unop(fcx, "!", "not",
3246 tcx.lang_items.not_trait(),
3247 expr, &oprnd, oprnd_t, unop);
3251 oprnd_t = structurally_resolved_type(fcx, oprnd.span,
3253 if !(oprnd_t.is_integral() || oprnd_t.is_fp()) {
3254 oprnd_t = op::check_user_unop(fcx, "-", "neg",
3255 tcx.lang_items.neg_trait(),
3256 expr, &oprnd, oprnd_t, unop);
3261 fcx.write_ty(id, oprnd_t);
3263 hir::ExprAddrOf(mutbl, ref oprnd) => {
3264 let hint = expected.only_has_type(fcx).map_or(NoExpectation, |ty| {
3266 ty::TyRef(_, ref mt) | ty::TyRawPtr(ref mt) => {
3267 if fcx.tcx().expr_is_lval(&oprnd) {
3268 // Lvalues may legitimately have unsized types.
3269 // For example, dereferences of a fat pointer and
3270 // the last field of a struct can be unsized.
3271 ExpectHasType(mt.ty)
3273 Expectation::rvalue_hint(tcx, mt.ty)
3279 let lvalue_pref = LvaluePreference::from_mutbl(mutbl);
3280 check_expr_with_expectation_and_lvalue_pref(fcx,
3285 let tm = ty::TypeAndMut { ty: fcx.expr_ty(&oprnd), mutbl: mutbl };
3286 let oprnd_t = if tm.ty.references_error() {
3289 // Note: at this point, we cannot say what the best lifetime
3290 // is to use for resulting pointer. We want to use the
3291 // shortest lifetime possible so as to avoid spurious borrowck
3292 // errors. Moreover, the longest lifetime will depend on the
3293 // precise details of the value whose address is being taken
3294 // (and how long it is valid), which we don't know yet until type
3295 // inference is complete.
3297 // Therefore, here we simply generate a region variable. The
3298 // region inferencer will then select the ultimate value.
3299 // Finally, borrowck is charged with guaranteeing that the
3300 // value whose address was taken can actually be made to live
3301 // as long as it needs to live.
3302 let region = fcx.infcx().next_region_var(infer::AddrOfRegion(expr.span));
3303 tcx.mk_ref(tcx.mk_region(region), tm)
3305 fcx.write_ty(id, oprnd_t);
3307 hir::ExprPath(ref maybe_qself, ref path) => {
3308 let opt_self_ty = maybe_qself.as_ref().map(|qself| {
3309 fcx.to_ty(&qself.ty)
3312 let path_res = if let Some(&d) = tcx.def_map.borrow().get(&id) {
3314 } else if let Some(hir::QSelf { position: 0, .. }) = *maybe_qself {
3315 // Create some fake resolution that can't possibly be a type.
3316 def::PathResolution {
3317 base_def: Def::Mod(tcx.map.local_def_id(ast::CRATE_NODE_ID)),
3318 depth: path.segments.len()
3321 tcx.sess.span_bug(expr.span,
3322 &format!("unbound path {:?}", expr))
3325 if let Some((opt_ty, segments, def)) =
3326 resolve_ty_and_def_ufcs(fcx, path_res, opt_self_ty, path,
3327 expr.span, expr.id) {
3328 if def != Def::Err {
3329 let (scheme, predicates) = type_scheme_and_predicates_for_def(fcx,
3332 instantiate_path(fcx,
3341 fcx.write_ty(id, fcx.tcx().types.err);
3345 // We always require that the type provided as the value for
3346 // a type parameter outlives the moment of instantiation.
3347 fcx.opt_node_ty_substs(expr.id, |item_substs| {
3348 fcx.add_wf_bounds(&item_substs.substs, expr);
3351 hir::ExprInlineAsm(ref ia) => {
3352 for &(_, ref input) in &ia.inputs {
3353 check_expr(fcx, &input);
3355 for out in &ia.outputs {
3356 check_expr(fcx, &out.expr);
3360 hir::ExprBreak(_) => { fcx.write_ty(id, fcx.infcx().next_diverging_ty_var()); }
3361 hir::ExprAgain(_) => { fcx.write_ty(id, fcx.infcx().next_diverging_ty_var()); }
3362 hir::ExprRet(ref expr_opt) => {
3364 ty::FnConverging(result_type) => {
3367 if let Err(_) = fcx.mk_eqty(false, TypeOrigin::Misc(expr.span),
3368 result_type, fcx.tcx().mk_nil()) {
3369 span_err!(tcx.sess, expr.span, E0069,
3370 "`return;` in a function whose return type is \
3374 check_expr_coercable_to_type(fcx, &e, result_type);
3378 ty::FnDiverging => {
3379 if let Some(ref e) = *expr_opt {
3380 check_expr(fcx, &e);
3382 span_err!(tcx.sess, expr.span, E0166,
3383 "`return` in a function declared as diverging");
3386 fcx.write_ty(id, fcx.infcx().next_diverging_ty_var());
3388 hir::ExprAssign(ref lhs, ref rhs) => {
3389 check_expr_with_lvalue_pref(fcx, &lhs, PreferMutLvalue);
3391 let tcx = fcx.tcx();
3392 if !tcx.expr_is_lval(&lhs) {
3393 span_err!(tcx.sess, expr.span, E0070,
3394 "invalid left-hand side expression");
3397 let lhs_ty = fcx.expr_ty(&lhs);
3398 check_expr_coercable_to_type(fcx, &rhs, lhs_ty);
3399 let rhs_ty = fcx.expr_ty(&rhs);
3401 fcx.require_expr_have_sized_type(&lhs, traits::AssignmentLhsSized);
3403 if lhs_ty.references_error() || rhs_ty.references_error() {
3404 fcx.write_error(id);
3409 hir::ExprIf(ref cond, ref then_blk, ref opt_else_expr) => {
3410 check_then_else(fcx, &cond, &then_blk, opt_else_expr.as_ref().map(|e| &**e),
3411 id, expr.span, expected);
3413 hir::ExprWhile(ref cond, ref body, _) => {
3414 check_expr_has_type(fcx, &cond, tcx.types.bool);
3415 check_block_no_value(fcx, &body);
3416 let cond_ty = fcx.expr_ty(&cond);
3417 let body_ty = fcx.node_ty(body.id);
3418 if cond_ty.references_error() || body_ty.references_error() {
3419 fcx.write_error(id);
3425 hir::ExprLoop(ref body, _) => {
3426 check_block_no_value(fcx, &body);
3427 if !may_break(tcx, expr.id, &body) {
3428 fcx.write_ty(id, fcx.infcx().next_diverging_ty_var());
3433 hir::ExprMatch(ref discrim, ref arms, match_src) => {
3434 _match::check_match(fcx, expr, &discrim, arms, expected, match_src);
3436 hir::ExprClosure(capture, ref decl, ref body) => {
3437 closure::check_expr_closure(fcx, expr, capture, &decl, &body, expected);
3439 hir::ExprBlock(ref b) => {
3440 check_block_with_expected(fcx, &b, expected);
3441 fcx.write_ty(id, fcx.node_ty(b.id));
3443 hir::ExprCall(ref callee, ref args) => {
3444 callee::check_call(fcx, expr, &callee, &args[..], expected);
3446 // we must check that return type of called functions is WF:
3447 let ret_ty = fcx.expr_ty(expr);
3448 fcx.register_wf_obligation(ret_ty, expr.span, traits::MiscObligation);
3450 hir::ExprMethodCall(name, ref tps, ref args) => {
3451 check_method_call(fcx, expr, name, &args[..], &tps[..], expected, lvalue_pref);
3452 let arg_tys = args.iter().map(|a| fcx.expr_ty(&a));
3453 let args_err = arg_tys.fold(false, |rest_err, a| rest_err || a.references_error());
3455 fcx.write_error(id);
3458 hir::ExprCast(ref e, ref t) => {
3459 if let hir::TyFixedLengthVec(_, ref count_expr) = t.node {
3460 check_expr_with_hint(fcx, &count_expr, tcx.types.usize);
3463 // Find the type of `e`. Supply hints based on the type we are casting to,
3465 let t_cast = fcx.to_ty(t);
3466 let t_cast = structurally_resolved_type(fcx, expr.span, t_cast);
3467 check_expr_with_expectation(fcx, e, ExpectCastableToType(t_cast));
3468 let t_expr = fcx.expr_ty(e);
3469 let t_cast = fcx.infcx().resolve_type_vars_if_possible(&t_cast);
3471 // Eagerly check for some obvious errors.
3472 if t_expr.references_error() || t_cast.references_error() {
3473 fcx.write_error(id);
3474 } else if !fcx.type_is_known_to_be_sized(t_cast, expr.span) {
3475 report_cast_to_unsized_type(fcx, expr.span, t.span, e.span, t_cast, t_expr, id);
3477 // Write a type for the whole expression, assuming everything is going
3479 fcx.write_ty(id, t_cast);
3481 // Defer other checks until we're done type checking.
3482 let mut deferred_cast_checks = fcx.inh.deferred_cast_checks.borrow_mut();
3483 let cast_check = cast::CastCheck::new(e, t_expr, t_cast, expr.span);
3484 deferred_cast_checks.push(cast_check);
3487 hir::ExprType(ref e, ref t) => {
3488 let typ = fcx.to_ty(&t);
3489 check_expr_eq_type(fcx, &e, typ);
3490 fcx.write_ty(id, typ);
3492 hir::ExprVec(ref args) => {
3493 let uty = expected.to_option(fcx).and_then(|uty| {
3495 ty::TyArray(ty, _) | ty::TySlice(ty) => Some(ty),
3500 let typ = match uty {
3503 check_expr_coercable_to_type(fcx, &e, uty);
3508 let t: Ty = fcx.infcx().next_ty_var();
3510 check_expr_has_type(fcx, &e, t);
3515 let typ = tcx.mk_array(typ, args.len());
3516 fcx.write_ty(id, typ);
3518 hir::ExprRepeat(ref element, ref count_expr) => {
3519 check_expr_has_type(fcx, &count_expr, tcx.types.usize);
3520 let count = fcx.tcx().eval_repeat_count(&count_expr);
3522 let uty = match expected {
3523 ExpectHasType(uty) => {
3525 ty::TyArray(ty, _) | ty::TySlice(ty) => Some(ty),
3532 let (element_ty, t) = match uty {
3534 check_expr_coercable_to_type(fcx, &element, uty);
3538 let t: Ty = fcx.infcx().next_ty_var();
3539 check_expr_has_type(fcx, &element, t);
3540 (fcx.expr_ty(&element), t)
3545 // For [foo, ..n] where n > 1, `foo` must have
3547 fcx.require_type_meets(
3554 if element_ty.references_error() {
3555 fcx.write_error(id);
3557 let t = tcx.mk_array(t, count);
3558 fcx.write_ty(id, t);
3561 hir::ExprTup(ref elts) => {
3562 let flds = expected.only_has_type(fcx).and_then(|ty| {
3564 ty::TyTuple(ref flds) => Some(&flds[..]),
3568 let mut err_field = false;
3570 let elt_ts = elts.iter().enumerate().map(|(i, e)| {
3571 let t = match flds {
3572 Some(ref fs) if i < fs.len() => {
3574 check_expr_coercable_to_type(fcx, &e, ety);
3578 check_expr_with_expectation(fcx, &e, NoExpectation);
3582 err_field = err_field || t.references_error();
3586 fcx.write_error(id);
3588 let typ = tcx.mk_tup(elt_ts);
3589 fcx.write_ty(id, typ);
3592 hir::ExprStruct(ref path, ref fields, ref base_expr) => {
3593 check_expr_struct(fcx, expr, path, fields, base_expr);
3595 fcx.require_expr_have_sized_type(expr, traits::StructInitializerSized);
3597 hir::ExprField(ref base, ref field) => {
3598 check_field(fcx, expr, lvalue_pref, &base, field);
3600 hir::ExprTupField(ref base, idx) => {
3601 check_tup_field(fcx, expr, lvalue_pref, &base, idx);
3603 hir::ExprIndex(ref base, ref idx) => {
3604 check_expr_with_lvalue_pref(fcx, &base, lvalue_pref);
3605 check_expr(fcx, &idx);
3607 let base_t = fcx.expr_ty(&base);
3608 let idx_t = fcx.expr_ty(&idx);
3610 if base_t.references_error() {
3611 fcx.write_ty(id, base_t);
3612 } else if idx_t.references_error() {
3613 fcx.write_ty(id, idx_t);
3615 let base_t = structurally_resolved_type(fcx, expr.span, base_t);
3616 match lookup_indexing(fcx, expr, base, base_t, idx_t, lvalue_pref) {
3617 Some((index_ty, element_ty)) => {
3618 let idx_expr_ty = fcx.expr_ty(idx);
3619 demand::eqtype(fcx, expr.span, index_ty, idx_expr_ty);
3620 fcx.write_ty(id, element_ty);
3623 check_expr_has_type(fcx, &idx, fcx.tcx().types.err);
3624 fcx.type_error_message(
3627 format!("cannot index a value of type `{}`",
3632 fcx.write_ty(id, fcx.tcx().types.err);
3639 debug!("type of expr({}) {} is...", expr.id,
3640 pprust::expr_to_string(expr));
3641 debug!("... {:?}, expected is {:?}",
3646 pub fn resolve_ty_and_def_ufcs<'a, 'b, 'tcx>(fcx: &FnCtxt<'b, 'tcx>,
3647 path_res: def::PathResolution,
3648 opt_self_ty: Option<Ty<'tcx>>,
3649 path: &'a hir::Path,
3651 node_id: ast::NodeId)
3652 -> Option<(Option<Ty<'tcx>>,
3653 &'a [hir::PathSegment],
3657 // If fully resolved already, we don't have to do anything.
3658 if path_res.depth == 0 {
3659 Some((opt_self_ty, &path.segments, path_res.base_def))
3661 let mut def = path_res.base_def;
3662 let ty_segments = path.segments.split_last().unwrap().1;
3663 let base_ty_end = path.segments.len() - path_res.depth;
3664 let ty = astconv::finish_resolving_def_to_ty(fcx, fcx, span,
3665 PathParamMode::Optional,
3668 &ty_segments[..base_ty_end],
3669 &ty_segments[base_ty_end..]);
3670 let item_segment = path.segments.last().unwrap();
3671 let item_name = item_segment.identifier.name;
3672 match method::resolve_ufcs(fcx, span, item_name, ty, node_id) {
3674 // Write back the new resolution.
3675 fcx.ccx.tcx.def_map.borrow_mut()
3676 .insert(node_id, def::PathResolution {
3680 Some((Some(ty), slice::ref_slice(item_segment), def))
3683 if item_name != special_idents::invalid.name {
3684 method::report_error(fcx, span, ty, item_name, None, error);
3686 fcx.write_error(node_id);
3693 impl<'tcx> Expectation<'tcx> {
3694 /// Provide an expectation for an rvalue expression given an *optional*
3695 /// hint, which is not required for type safety (the resulting type might
3696 /// be checked higher up, as is the case with `&expr` and `box expr`), but
3697 /// is useful in determining the concrete type.
3699 /// The primary use case is where the expected type is a fat pointer,
3700 /// like `&[isize]`. For example, consider the following statement:
3702 /// let x: &[isize] = &[1, 2, 3];
3704 /// In this case, the expected type for the `&[1, 2, 3]` expression is
3705 /// `&[isize]`. If however we were to say that `[1, 2, 3]` has the
3706 /// expectation `ExpectHasType([isize])`, that would be too strong --
3707 /// `[1, 2, 3]` does not have the type `[isize]` but rather `[isize; 3]`.
3708 /// It is only the `&[1, 2, 3]` expression as a whole that can be coerced
3709 /// to the type `&[isize]`. Therefore, we propagate this more limited hint,
3710 /// which still is useful, because it informs integer literals and the like.
3711 /// See the test case `test/run-pass/coerce-expect-unsized.rs` and #20169
3712 /// for examples of where this comes up,.
3713 fn rvalue_hint(tcx: &TyCtxt<'tcx>, ty: Ty<'tcx>) -> Expectation<'tcx> {
3714 match tcx.struct_tail(ty).sty {
3715 ty::TySlice(_) | ty::TyStr | ty::TyTrait(..) => {
3716 ExpectRvalueLikeUnsized(ty)
3718 _ => ExpectHasType(ty)
3722 // Resolves `expected` by a single level if it is a variable. If
3723 // there is no expected type or resolution is not possible (e.g.,
3724 // no constraints yet present), just returns `None`.
3725 fn resolve<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Expectation<'tcx> {
3730 ExpectCastableToType(t) => {
3731 ExpectCastableToType(
3732 fcx.infcx().resolve_type_vars_if_possible(&t))
3734 ExpectHasType(t) => {
3736 fcx.infcx().resolve_type_vars_if_possible(&t))
3738 ExpectRvalueLikeUnsized(t) => {
3739 ExpectRvalueLikeUnsized(
3740 fcx.infcx().resolve_type_vars_if_possible(&t))
3745 fn to_option<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
3746 match self.resolve(fcx) {
3747 NoExpectation => None,
3748 ExpectCastableToType(ty) |
3750 ExpectRvalueLikeUnsized(ty) => Some(ty),
3754 fn only_has_type<'a>(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
3755 match self.resolve(fcx) {
3756 ExpectHasType(ty) => Some(ty),
3762 pub fn check_decl_initializer<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
3763 local: &'tcx hir::Local,
3764 init: &'tcx hir::Expr)
3766 let ref_bindings = fcx.tcx().pat_contains_ref_binding(&local.pat);
3768 let local_ty = fcx.local_ty(init.span, local.id);
3769 if let Some(m) = ref_bindings {
3770 // Somewhat subtle: if we have a `ref` binding in the pattern,
3771 // we want to avoid introducing coercions for the RHS. This is
3772 // both because it helps preserve sanity and, in the case of
3773 // ref mut, for soundness (issue #23116). In particular, in
3774 // the latter case, we need to be clear that the type of the
3775 // referent for the reference that results is *equal to* the
3776 // type of the lvalue it is referencing, and not some
3777 // supertype thereof.
3778 check_expr_with_lvalue_pref(fcx, init, LvaluePreference::from_mutbl(m));
3779 let init_ty = fcx.expr_ty(init);
3780 demand::eqtype(fcx, init.span, init_ty, local_ty);
3782 check_expr_coercable_to_type(fcx, init, local_ty)
3786 pub fn check_decl_local<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, local: &'tcx hir::Local) {
3787 let tcx = fcx.ccx.tcx;
3789 let t = fcx.local_ty(local.span, local.id);
3790 fcx.write_ty(local.id, t);
3792 if let Some(ref init) = local.init {
3793 check_decl_initializer(fcx, local, &init);
3794 let init_ty = fcx.expr_ty(&init);
3795 if init_ty.references_error() {
3796 fcx.write_ty(local.id, init_ty);
3800 let pcx = pat_ctxt {
3802 map: pat_id_map(&tcx.def_map, &local.pat),
3804 _match::check_pat(&pcx, &local.pat, t);
3805 let pat_ty = fcx.node_ty(local.pat.id);
3806 if pat_ty.references_error() {
3807 fcx.write_ty(local.id, pat_ty);
3811 pub fn check_stmt<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, stmt: &'tcx hir::Stmt) {
3813 let mut saw_bot = false;
3814 let mut saw_err = false;
3816 hir::StmtDecl(ref decl, id) => {
3819 hir::DeclLocal(ref l) => {
3820 check_decl_local(fcx, &l);
3821 let l_t = fcx.node_ty(l.id);
3822 saw_bot = saw_bot || fcx.infcx().type_var_diverges(l_t);
3823 saw_err = saw_err || l_t.references_error();
3825 hir::DeclItem(_) => {/* ignore for now */ }
3828 hir::StmtExpr(ref expr, id) => {
3830 // Check with expected type of ()
3831 check_expr_has_type(fcx, &expr, fcx.tcx().mk_nil());
3832 let expr_ty = fcx.expr_ty(&expr);
3833 saw_bot = saw_bot || fcx.infcx().type_var_diverges(expr_ty);
3834 saw_err = saw_err || expr_ty.references_error();
3836 hir::StmtSemi(ref expr, id) => {
3838 check_expr(fcx, &expr);
3839 let expr_ty = fcx.expr_ty(&expr);
3840 saw_bot |= fcx.infcx().type_var_diverges(expr_ty);
3841 saw_err |= expr_ty.references_error();
3845 fcx.write_ty(node_id, fcx.infcx().next_diverging_ty_var());
3848 fcx.write_error(node_id);
3851 fcx.write_nil(node_id)
3855 pub fn check_block_no_value<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>, blk: &'tcx hir::Block) {
3856 check_block_with_expected(fcx, blk, ExpectHasType(fcx.tcx().mk_nil()));
3857 let blkty = fcx.node_ty(blk.id);
3858 if blkty.references_error() {
3859 fcx.write_error(blk.id);
3861 let nilty = fcx.tcx().mk_nil();
3862 demand::suptype(fcx, blk.span, nilty, blkty);
3866 fn check_block_with_expected<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3867 blk: &'tcx hir::Block,
3868 expected: Expectation<'tcx>) {
3870 let mut fcx_ps = fcx.ps.borrow_mut();
3871 let unsafety_state = fcx_ps.recurse(blk);
3872 replace(&mut *fcx_ps, unsafety_state)
3875 let mut warned = false;
3876 let mut any_diverges = false;
3877 let mut any_err = false;
3878 for s in &blk.stmts {
3880 let s_id = ::rustc_front::util::stmt_id(s);
3881 let s_ty = fcx.node_ty(s_id);
3882 if any_diverges && !warned && match s.node {
3883 hir::StmtDecl(ref decl, _) => {
3885 hir::DeclLocal(_) => true,
3889 hir::StmtExpr(_, _) | hir::StmtSemi(_, _) => true,
3894 .add_lint(lint::builtin::UNREACHABLE_CODE,
3897 "unreachable statement".to_string());
3900 any_diverges = any_diverges || fcx.infcx().type_var_diverges(s_ty);
3901 any_err = any_err || s_ty.references_error();
3904 None => if any_err {
3905 fcx.write_error(blk.id);
3906 } else if any_diverges {
3907 fcx.write_ty(blk.id, fcx.infcx().next_diverging_ty_var());
3909 fcx.write_nil(blk.id);
3912 if any_diverges && !warned {
3916 .add_lint(lint::builtin::UNREACHABLE_CODE,
3919 "unreachable expression".to_string());
3921 let ety = match expected {
3922 ExpectHasType(ety) => {
3923 check_expr_coercable_to_type(fcx, &e, ety);
3927 check_expr_with_expectation(fcx, &e, expected);
3933 fcx.write_error(blk.id);
3934 } else if any_diverges {
3935 fcx.write_ty(blk.id, fcx.infcx().next_diverging_ty_var());
3937 fcx.write_ty(blk.id, ety);
3942 *fcx.ps.borrow_mut() = prev;
3945 /// Checks a constant appearing in a type. At the moment this is just the
3946 /// length expression in a fixed-length vector, but someday it might be
3947 /// extended to type-level numeric literals.
3948 fn check_const_in_type<'a,'tcx>(ccx: &'a CrateCtxt<'a,'tcx>,
3949 expr: &'tcx hir::Expr,
3950 expected_type: Ty<'tcx>) {
3951 let tables = RefCell::new(ty::Tables::empty());
3952 let inh = static_inherited_fields(ccx, &tables);
3953 let fcx = blank_fn_ctxt(ccx, &inh, ty::FnConverging(expected_type), expr.id);
3954 check_const_with_ty(&fcx, expr.span, expr, expected_type);
3957 fn check_const<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
3961 let tables = RefCell::new(ty::Tables::empty());
3962 let inh = static_inherited_fields(ccx, &tables);
3963 let rty = ccx.tcx.node_id_to_type(id);
3964 let fcx = blank_fn_ctxt(ccx, &inh, ty::FnConverging(rty), e.id);
3965 let declty = fcx.ccx.tcx.lookup_item_type(ccx.tcx.map.local_def_id(id)).ty;
3966 check_const_with_ty(&fcx, sp, e, declty);
3969 fn check_const_with_ty<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
3973 // Gather locals in statics (because of block expressions).
3974 // This is technically unnecessary because locals in static items are forbidden,
3975 // but prevents type checking from blowing up before const checking can properly
3977 GatherLocalsVisitor { fcx: fcx }.visit_expr(e);
3979 check_expr_with_hint(fcx, e, declty);
3980 demand::coerce(fcx, e.span, declty, e);
3982 fcx.select_all_obligations_and_apply_defaults();
3983 upvar::closure_analyze_const(&fcx, e);
3984 fcx.select_obligations_where_possible();
3986 fcx.select_all_obligations_or_error();
3988 regionck::regionck_expr(fcx, e);
3989 writeback::resolve_type_vars_in_expr(fcx, e);
3992 /// Checks whether a type can be represented in memory. In particular, it
3993 /// identifies types that contain themselves without indirection through a
3994 /// pointer, which would mean their size is unbounded.
3995 pub fn check_representable(tcx: &TyCtxt,
3997 item_id: ast::NodeId,
3998 _designation: &str) -> bool {
3999 let rty = tcx.node_id_to_type(item_id);
4001 // Check that it is possible to represent this type. This call identifies
4002 // (1) types that contain themselves and (2) types that contain a different
4003 // recursive type. It is only necessary to throw an error on those that
4004 // contain themselves. For case 2, there must be an inner type that will be
4005 // caught by case 1.
4006 match rty.is_representable(tcx, sp) {
4007 Representability::SelfRecursive => {
4008 let item_def_id = tcx.map.local_def_id(item_id);
4009 traits::recursive_type_with_infinite_size_error(tcx, item_def_id).emit();
4012 Representability::Representable | Representability::ContainsRecursive => (),
4017 pub fn check_simd(tcx: &TyCtxt, sp: Span, id: ast::NodeId) {
4018 let t = tcx.node_id_to_type(id);
4020 ty::TyStruct(def, substs) => {
4021 let fields = &def.struct_variant().fields;
4022 if fields.is_empty() {
4023 span_err!(tcx.sess, sp, E0075, "SIMD vector cannot be empty");
4026 let e = fields[0].ty(tcx, substs);
4027 if !fields.iter().all(|f| f.ty(tcx, substs) == e) {
4028 span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous");
4032 ty::TyParam(_) => { /* struct<T>(T, T, T, T) is ok */ }
4033 _ if e.is_machine() => { /* struct(u8, u8, u8, u8) is ok */ }
4035 span_err!(tcx.sess, sp, E0077,
4036 "SIMD vector element type should be machine type");
4045 pub fn check_enum_variants<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
4047 vs: &'tcx [hir::Variant],
4049 // disr_in_range should be removed once we have forced type hints for consts
4050 fn disr_in_range(ccx: &CrateCtxt,
4052 disr: ty::Disr) -> bool {
4053 fn uint_in_range(ccx: &CrateCtxt, ty: ast::UintTy, disr: ty::Disr) -> bool {
4055 ast::UintTy::U8 => disr as u8 as Disr == disr,
4056 ast::UintTy::U16 => disr as u16 as Disr == disr,
4057 ast::UintTy::U32 => disr as u32 as Disr == disr,
4058 ast::UintTy::U64 => disr as u64 as Disr == disr,
4059 ast::UintTy::Us => uint_in_range(ccx, ccx.tcx.sess.target.uint_type, disr)
4062 fn int_in_range(ccx: &CrateCtxt, ty: ast::IntTy, disr: ty::Disr) -> bool {
4064 ast::IntTy::I8 => disr as i8 as Disr == disr,
4065 ast::IntTy::I16 => disr as i16 as Disr == disr,
4066 ast::IntTy::I32 => disr as i32 as Disr == disr,
4067 ast::IntTy::I64 => disr as i64 as Disr == disr,
4068 ast::IntTy::Is => int_in_range(ccx, ccx.tcx.sess.target.int_type, disr)
4072 attr::UnsignedInt(ty) => uint_in_range(ccx, ty, disr),
4073 attr::SignedInt(ty) => int_in_range(ccx, ty, disr)
4077 fn do_check<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
4078 vs: &'tcx [hir::Variant],
4080 hint: attr::ReprAttr) {
4081 #![allow(trivial_numeric_casts)]
4083 let rty = ccx.tcx.node_id_to_type(id);
4084 let mut disr_vals: Vec<ty::Disr> = Vec::new();
4086 let tables = RefCell::new(ty::Tables::empty());
4087 let inh = static_inherited_fields(ccx, &tables);
4088 let fcx = blank_fn_ctxt(ccx, &inh, ty::FnConverging(rty), id);
4090 let (_, repr_type_ty) = ccx.tcx.enum_repr_type(Some(&hint));
4092 if let Some(ref e) = v.node.disr_expr {
4093 check_const_with_ty(&fcx, e.span, e, repr_type_ty);
4097 let def_id = ccx.tcx.map.local_def_id(id);
4099 let variants = &ccx.tcx.lookup_adt_def(def_id).variants;
4100 for (v, variant) in vs.iter().zip(variants.iter()) {
4101 let current_disr_val = variant.disr_val;
4103 // Check for duplicate discriminant values
4104 match disr_vals.iter().position(|&x| x == current_disr_val) {
4106 let mut err = struct_span_err!(ccx.tcx.sess, v.span, E0081,
4107 "discriminant value `{}` already exists", disr_vals[i]);
4108 let variant_i_node_id = ccx.tcx.map.as_local_node_id(variants[i].did).unwrap();
4109 span_note!(&mut err, ccx.tcx.map.span(variant_i_node_id),
4110 "conflicting discriminant here");
4115 // Check for unrepresentable discriminant values
4117 attr::ReprAny | attr::ReprExtern => {
4118 disr_vals.push(current_disr_val);
4120 attr::ReprInt(sp, ity) => {
4121 if !disr_in_range(ccx, ity, current_disr_val) {
4122 let mut err = struct_span_err!(ccx.tcx.sess, v.span, E0082,
4123 "discriminant value outside specified type");
4124 span_note!(&mut err, sp,
4125 "discriminant type specified here");
4129 // Error reported elsewhere.
4130 attr::ReprSimd | attr::ReprPacked => {}
4135 let def_id = ccx.tcx.map.local_def_id(id);
4136 let hint = *ccx.tcx.lookup_repr_hints(def_id).get(0).unwrap_or(&attr::ReprAny);
4138 if hint != attr::ReprAny && vs.is_empty() {
4139 span_err!(ccx.tcx.sess, sp, E0084,
4140 "unsupported representation for zero-variant enum");
4143 do_check(ccx, vs, id, hint);
4145 check_representable(ccx.tcx, sp, id, "enum");
4148 // Returns the type parameter count and the type for the given definition.
4149 fn type_scheme_and_predicates_for_def<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4152 -> (TypeScheme<'tcx>, GenericPredicates<'tcx>) {
4154 Def::Local(_, nid) | Def::Upvar(_, nid, _, _) => {
4155 let typ = fcx.local_ty(sp, nid);
4156 (ty::TypeScheme { generics: ty::Generics::empty(), ty: typ },
4157 ty::GenericPredicates::empty())
4159 Def::Fn(id) | Def::Method(id) |
4160 Def::Static(id, _) | Def::Variant(_, id) |
4161 Def::Struct(id) | Def::Const(id) | Def::AssociatedConst(id) => {
4162 (fcx.tcx().lookup_item_type(id), fcx.tcx().lookup_predicates(id))
4167 Def::AssociatedTy(..) |
4171 Def::ForeignMod(..) |
4175 fcx.ccx.tcx.sess.span_bug(sp, &format!("expected value, found {:?}", defn));
4180 // Instantiates the given path, which must refer to an item with the given
4181 // number of type parameters and type.
4182 pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4183 segments: &[hir::PathSegment],
4184 type_scheme: TypeScheme<'tcx>,
4185 type_predicates: &ty::GenericPredicates<'tcx>,
4186 opt_self_ty: Option<Ty<'tcx>>,
4189 node_id: ast::NodeId) {
4190 debug!("instantiate_path(path={:?}, def={:?}, node_id={}, type_scheme={:?})",
4196 // We need to extract the type parameters supplied by the user in
4197 // the path `path`. Due to the current setup, this is a bit of a
4198 // tricky-process; the problem is that resolve only tells us the
4199 // end-point of the path resolution, and not the intermediate steps.
4200 // Luckily, we can (at least for now) deduce the intermediate steps
4201 // just from the end-point.
4203 // There are basically four cases to consider:
4205 // 1. Reference to a *type*, such as a struct or enum:
4207 // mod a { struct Foo<T> { ... } }
4209 // Because we don't allow types to be declared within one
4210 // another, a path that leads to a type will always look like
4211 // `a::b::Foo<T>` where `a` and `b` are modules. This implies
4212 // that only the final segment can have type parameters, and
4213 // they are located in the TypeSpace.
4215 // *Note:* Generally speaking, references to types don't
4216 // actually pass through this function, but rather the
4217 // `ast_ty_to_ty` function in `astconv`. However, in the case
4218 // of struct patterns (and maybe literals) we do invoke
4219 // `instantiate_path` to get the general type of an instance of
4220 // a struct. (In these cases, there are actually no type
4221 // parameters permitted at present, but perhaps we will allow
4222 // them in the future.)
4224 // 1b. Reference to an enum variant or tuple-like struct:
4226 // struct foo<T>(...)
4227 // enum E<T> { foo(...) }
4229 // In these cases, the parameters are declared in the type
4232 // 2. Reference to a *fn item*:
4236 // In this case, the path will again always have the form
4237 // `a::b::foo::<T>` where only the final segment should have
4238 // type parameters. However, in this case, those parameters are
4239 // declared on a value, and hence are in the `FnSpace`.
4241 // 3. Reference to a *method*:
4243 // impl<A> SomeStruct<A> {
4247 // Here we can have a path like
4248 // `a::b::SomeStruct::<A>::foo::<B>`, in which case parameters
4249 // may appear in two places. The penultimate segment,
4250 // `SomeStruct::<A>`, contains parameters in TypeSpace, and the
4251 // final segment, `foo::<B>` contains parameters in fn space.
4253 // 4. Reference to an *associated const*:
4255 // impl<A> AnotherStruct<A> {
4256 // const FOO: B = BAR;
4259 // The path in this case will look like
4260 // `a::b::AnotherStruct::<A>::FOO`, so the penultimate segment
4261 // only will have parameters in TypeSpace.
4263 // The first step then is to categorize the segments appropriately.
4265 assert!(!segments.is_empty());
4267 let mut ufcs_associated = None;
4268 let mut segment_spaces: Vec<_>;
4270 // Case 1 and 1b. Reference to a *type* or *enum variant*.
4276 Def::AssociatedTy(..) |
4279 Def::TyParam(..) => {
4280 // Everything but the final segment should have no
4281 // parameters at all.
4282 segment_spaces = vec![None; segments.len() - 1];
4283 segment_spaces.push(Some(subst::TypeSpace));
4286 // Case 2. Reference to a top-level value.
4289 Def::Static(..) => {
4290 segment_spaces = vec![None; segments.len() - 1];
4291 segment_spaces.push(Some(subst::FnSpace));
4294 // Case 3. Reference to a method.
4295 Def::Method(def_id) => {
4296 let container = fcx.tcx().impl_or_trait_item(def_id).container();
4298 ty::TraitContainer(trait_did) => {
4299 callee::check_legal_trait_for_method_call(fcx.ccx, span, trait_did)
4301 ty::ImplContainer(_) => {}
4304 if segments.len() >= 2 {
4305 segment_spaces = vec![None; segments.len() - 2];
4306 segment_spaces.push(Some(subst::TypeSpace));
4307 segment_spaces.push(Some(subst::FnSpace));
4309 // `<T>::method` will end up here, and so can `T::method`.
4310 let self_ty = opt_self_ty.expect("UFCS sugared method missing Self");
4311 segment_spaces = vec![Some(subst::FnSpace)];
4312 ufcs_associated = Some((container, self_ty));
4316 Def::AssociatedConst(def_id) => {
4317 let container = fcx.tcx().impl_or_trait_item(def_id).container();
4319 ty::TraitContainer(trait_did) => {
4320 callee::check_legal_trait_for_method_call(fcx.ccx, span, trait_did)
4322 ty::ImplContainer(_) => {}
4325 if segments.len() >= 2 {
4326 segment_spaces = vec![None; segments.len() - 2];
4327 segment_spaces.push(Some(subst::TypeSpace));
4328 segment_spaces.push(None);
4330 // `<T>::CONST` will end up here, and so can `T::CONST`.
4331 let self_ty = opt_self_ty.expect("UFCS sugared const missing Self");
4332 segment_spaces = vec![None];
4333 ufcs_associated = Some((container, self_ty));
4337 // Other cases. Various nonsense that really shouldn't show up
4338 // here. If they do, an error will have been reported
4339 // elsewhere. (I hope)
4341 Def::ForeignMod(..) |
4346 segment_spaces = vec![None; segments.len()];
4349 assert_eq!(segment_spaces.len(), segments.len());
4351 // In `<T as Trait<A, B>>::method`, `A` and `B` are mandatory, but
4352 // `opt_self_ty` can also be Some for `Foo::method`, where Foo's
4353 // type parameters are not mandatory.
4354 let require_type_space = opt_self_ty.is_some() && ufcs_associated.is_none();
4356 debug!("segment_spaces={:?}", segment_spaces);
4358 // Next, examine the definition, and determine how many type
4359 // parameters we expect from each space.
4360 let type_defs = &type_scheme.generics.types;
4361 let region_defs = &type_scheme.generics.regions;
4363 // Now that we have categorized what space the parameters for each
4364 // segment belong to, let's sort out the parameters that the user
4365 // provided (if any) into their appropriate spaces. We'll also report
4366 // errors if type parameters are provided in an inappropriate place.
4367 let mut substs = Substs::empty();
4368 for (opt_space, segment) in segment_spaces.iter().zip(segments) {
4371 prohibit_type_params(fcx.tcx(), slice::ref_slice(segment));
4375 push_explicit_parameters_from_segment_to_substs(fcx,
4385 if let Some(self_ty) = opt_self_ty {
4386 if type_defs.len(subst::SelfSpace) == 1 {
4387 substs.types.push(subst::SelfSpace, self_ty);
4391 // Now we have to compare the types that the user *actually*
4392 // provided against the types that were *expected*. If the user
4393 // did not provide any types, then we want to substitute inference
4394 // variables. If the user provided some types, we may still need
4395 // to add defaults. If the user provided *too many* types, that's
4397 for &space in &[subst::SelfSpace, subst::TypeSpace, subst::FnSpace] {
4398 adjust_type_parameters(fcx, span, space, type_defs,
4399 require_type_space, &mut substs);
4400 assert_eq!(substs.types.len(space), type_defs.len(space));
4402 adjust_region_parameters(fcx, span, space, region_defs, &mut substs);
4403 assert_eq!(substs.regions().len(space), region_defs.len(space));
4406 // The things we are substituting into the type should not contain
4407 // escaping late-bound regions, and nor should the base type scheme.
4408 assert!(!substs.has_regions_escaping_depth(0));
4409 assert!(!type_scheme.has_escaping_regions());
4411 // Add all the obligations that are required, substituting and
4412 // normalized appropriately.
4413 let bounds = fcx.instantiate_bounds(span, &substs, &type_predicates);
4414 fcx.add_obligations_for_parameters(
4415 traits::ObligationCause::new(span, fcx.body_id, traits::ItemObligation(def.def_id())),
4418 // Substitute the values for the type parameters into the type of
4419 // the referenced item.
4420 let ty_substituted = fcx.instantiate_type_scheme(span, &substs, &type_scheme.ty);
4423 if let Some((ty::ImplContainer(impl_def_id), self_ty)) = ufcs_associated {
4424 // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
4425 // is inherent, there is no `Self` parameter, instead, the impl needs
4426 // type parameters, which we can infer by unifying the provided `Self`
4427 // with the substituted impl type.
4428 let impl_scheme = fcx.tcx().lookup_item_type(impl_def_id);
4429 assert_eq!(substs.types.len(subst::TypeSpace),
4430 impl_scheme.generics.types.len(subst::TypeSpace));
4431 assert_eq!(substs.regions().len(subst::TypeSpace),
4432 impl_scheme.generics.regions.len(subst::TypeSpace));
4434 let impl_ty = fcx.instantiate_type_scheme(span, &substs, &impl_scheme.ty);
4435 if fcx.mk_subty(false, TypeOrigin::Misc(span), self_ty, impl_ty).is_err() {
4436 fcx.tcx().sess.span_bug(span,
4438 "instantiate_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
4444 debug!("instantiate_path: type of {:?} is {:?}",
4447 fcx.write_ty(node_id, ty_substituted);
4448 fcx.write_substs(node_id, ty::ItemSubsts { substs: substs });
4451 /// Finds the parameters that the user provided and adds them to `substs`. If too many
4452 /// parameters are provided, then reports an error and clears the output vector.
4454 /// We clear the output vector because that will cause the `adjust_XXX_parameters()` later to
4455 /// use inference variables. This seems less likely to lead to derived errors.
4457 /// Note that we *do not* check for *too few* parameters here. Due to the presence of defaults
4458 /// etc that is more complicated. I wanted however to do the reporting of *too many* parameters
4459 /// here because we can easily use the precise span of the N+1'th parameter.
4460 fn push_explicit_parameters_from_segment_to_substs<'a, 'tcx>(
4461 fcx: &FnCtxt<'a, 'tcx>,
4462 space: subst::ParamSpace,
4464 type_defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4465 region_defs: &VecPerParamSpace<ty::RegionParameterDef>,
4466 segment: &hir::PathSegment,
4467 substs: &mut Substs<'tcx>)
4469 match segment.parameters {
4470 hir::AngleBracketedParameters(ref data) => {
4471 push_explicit_angle_bracketed_parameters_from_segment_to_substs(
4472 fcx, space, type_defs, region_defs, data, substs);
4475 hir::ParenthesizedParameters(ref data) => {
4476 span_err!(fcx.tcx().sess, span, E0238,
4477 "parenthesized parameters may only be used with a trait");
4478 push_explicit_parenthesized_parameters_from_segment_to_substs(
4479 fcx, space, span, type_defs, data, substs);
4484 fn push_explicit_angle_bracketed_parameters_from_segment_to_substs<'a, 'tcx>(
4485 fcx: &FnCtxt<'a, 'tcx>,
4486 space: subst::ParamSpace,
4487 type_defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4488 region_defs: &VecPerParamSpace<ty::RegionParameterDef>,
4489 data: &hir::AngleBracketedParameterData,
4490 substs: &mut Substs<'tcx>)
4493 let type_count = type_defs.len(space);
4494 assert_eq!(substs.types.len(space), 0);
4495 for (i, typ) in data.types.iter().enumerate() {
4496 let t = fcx.to_ty(&typ);
4498 substs.types.push(space, t);
4499 } else if i == type_count {
4500 span_err!(fcx.tcx().sess, typ.span, E0087,
4501 "too many type parameters provided: \
4502 expected at most {} parameter{}, \
4503 found {} parameter{}",
4505 if type_count == 1 {""} else {"s"},
4507 if data.types.len() == 1 {""} else {"s"});
4508 substs.types.truncate(space, 0);
4514 if !data.bindings.is_empty() {
4515 span_err!(fcx.tcx().sess, data.bindings[0].span, E0182,
4516 "unexpected binding of associated item in expression path \
4517 (only allowed in type paths)");
4521 let region_count = region_defs.len(space);
4522 assert_eq!(substs.regions().len(space), 0);
4523 for (i, lifetime) in data.lifetimes.iter().enumerate() {
4524 let r = ast_region_to_region(fcx.tcx(), lifetime);
4525 if i < region_count {
4526 substs.mut_regions().push(space, r);
4527 } else if i == region_count {
4528 span_err!(fcx.tcx().sess, lifetime.span, E0088,
4529 "too many lifetime parameters provided: \
4530 expected {} parameter{}, found {} parameter{}",
4532 if region_count == 1 {""} else {"s"},
4533 data.lifetimes.len(),
4534 if data.lifetimes.len() == 1 {""} else {"s"});
4535 substs.mut_regions().truncate(space, 0);
4543 /// `push_explicit_angle_bracketed_parameters_from_segment_to_substs`,
4544 /// but intended for `Foo(A,B) -> C` form. This expands to
4545 /// roughly the same thing as `Foo<(A,B),C>`. One important
4546 /// difference has to do with the treatment of anonymous
4547 /// regions, which are translated into bound regions (NYI).
4548 fn push_explicit_parenthesized_parameters_from_segment_to_substs<'a, 'tcx>(
4549 fcx: &FnCtxt<'a, 'tcx>,
4550 space: subst::ParamSpace,
4552 type_defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4553 data: &hir::ParenthesizedParameterData,
4554 substs: &mut Substs<'tcx>)
4556 let type_count = type_defs.len(space);
4558 span_err!(fcx.tcx().sess, span, E0167,
4559 "parenthesized form always supplies 2 type parameters, \
4560 but only {} parameter(s) were expected",
4564 let input_tys: Vec<Ty> =
4565 data.inputs.iter().map(|ty| fcx.to_ty(&ty)).collect();
4567 let tuple_ty = fcx.tcx().mk_tup(input_tys);
4569 if type_count >= 1 {
4570 substs.types.push(space, tuple_ty);
4573 let output_ty: Option<Ty> =
4574 data.output.as_ref().map(|ty| fcx.to_ty(&ty));
4577 output_ty.unwrap_or(fcx.tcx().mk_nil());
4579 if type_count >= 2 {
4580 substs.types.push(space, output_ty);
4584 fn adjust_type_parameters<'a, 'tcx>(
4585 fcx: &FnCtxt<'a, 'tcx>,
4588 defs: &VecPerParamSpace<ty::TypeParameterDef<'tcx>>,
4589 require_type_space: bool,
4590 substs: &mut Substs<'tcx>)
4592 let provided_len = substs.types.len(space);
4593 let desired = defs.get_slice(space);
4594 let required_len = desired.iter()
4595 .take_while(|d| d.default.is_none())
4598 debug!("adjust_type_parameters(space={:?}, \
4607 // Enforced by `push_explicit_parameters_from_segment_to_substs()`.
4608 assert!(provided_len <= desired.len());
4610 // Nothing specified at all: supply inference variables for
4612 if provided_len == 0 && !(require_type_space && space == subst::TypeSpace) {
4613 substs.types.replace(space, Vec::new());
4614 fcx.infcx().type_vars_for_defs(span, space, substs, &desired[..]);
4618 // Too few parameters specified: report an error and use Err
4620 if provided_len < required_len {
4622 if desired.len() != required_len { "at least " } else { "" };
4623 span_err!(fcx.tcx().sess, span, E0089,
4624 "too few type parameters provided: expected {}{} parameter{}, \
4625 found {} parameter{}",
4626 qualifier, required_len,
4627 if required_len == 1 {""} else {"s"},
4629 if provided_len == 1 {""} else {"s"});
4630 substs.types.replace(space, vec![fcx.tcx().types.err; desired.len()]);
4634 // Otherwise, add in any optional parameters that the user
4635 // omitted. The case of *too many* parameters is handled
4637 // push_explicit_parameters_from_segment_to_substs(). Note
4638 // that the *default* type are expressed in terms of all prior
4639 // parameters, so we have to substitute as we go with the
4640 // partial substitution that we have built up.
4641 for i in provided_len..desired.len() {
4642 let default = desired[i].default.unwrap();
4643 let default = default.subst_spanned(fcx.tcx(), substs, Some(span));
4644 substs.types.push(space, default);
4646 assert_eq!(substs.types.len(space), desired.len());
4648 debug!("Final substs: {:?}", substs);
4651 fn adjust_region_parameters(
4655 defs: &VecPerParamSpace<ty::RegionParameterDef>,
4656 substs: &mut Substs)
4658 let provided_len = substs.mut_regions().len(space);
4659 let desired = defs.get_slice(space);
4661 // Enforced by `push_explicit_parameters_from_segment_to_substs()`.
4662 assert!(provided_len <= desired.len());
4664 // If nothing was provided, just use inference variables.
4665 if provided_len == 0 {
4666 substs.mut_regions().replace(
4668 fcx.infcx().region_vars_for_defs(span, desired));
4672 // If just the right number were provided, everybody is happy.
4673 if provided_len == desired.len() {
4677 // Otherwise, too few were provided. Report an error and then
4678 // use inference variables.
4679 span_err!(fcx.tcx().sess, span, E0090,
4680 "too few lifetime parameters provided: expected {} parameter{}, \
4681 found {} parameter{}",
4683 if desired.len() == 1 {""} else {"s"},
4685 if provided_len == 1 {""} else {"s"});
4687 substs.mut_regions().replace(
4689 fcx.infcx().region_vars_for_defs(span, desired));
4693 fn structurally_resolve_type_or_else<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
4697 where F: Fn() -> Ty<'tcx>
4699 let mut ty = fcx.resolve_type_vars_if_possible(ty);
4702 let alternative = f();
4705 if alternative.is_ty_var() || alternative.references_error() {
4706 fcx.type_error_message(sp, |_actual| {
4707 "the type of this value must be known in this context".to_string()
4709 demand::suptype(fcx, sp, fcx.tcx().types.err, ty);
4710 ty = fcx.tcx().types.err;
4712 demand::suptype(fcx, sp, alternative, ty);
4720 // Resolves `typ` by a single level if `typ` is a type variable. If no
4721 // resolution is possible, then an error is reported.
4722 pub fn structurally_resolved_type<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
4727 structurally_resolve_type_or_else(fcx, sp, ty, || {
4732 // Returns true if b contains a break that can exit from b
4733 pub fn may_break(cx: &TyCtxt, id: ast::NodeId, b: &hir::Block) -> bool {
4734 // First: is there an unlabeled break immediately
4736 (loop_query(&b, |e| {
4738 hir::ExprBreak(None) => true,
4742 // Second: is there a labeled break with label
4743 // <id> nested anywhere inside the loop?
4744 (block_query(b, |e| {
4745 if let hir::ExprBreak(Some(_)) = e.node {
4746 lookup_full_def(cx, e.span, e.id) == Def::Label(id)
4753 pub fn check_bounds_are_used<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
4754 tps: &[hir::TyParam],
4756 debug!("check_bounds_are_used(n_tps={}, ty={:?})",
4759 // make a vector of booleans initially false, set to true when used
4760 if tps.is_empty() { return; }
4761 let mut tps_used = vec![false; tps.len()];
4763 for leaf_ty in ty.walk() {
4764 if let ty::TyParam(ParamTy {idx, ..}) = leaf_ty.sty {
4765 debug!("Found use of ty param num {}", idx);
4766 tps_used[idx as usize] = true;
4770 for (i, b) in tps_used.iter().enumerate() {
4772 span_err!(ccx.tcx.sess, tps[i].span, E0091,
4773 "type parameter `{}` is unused",