1 // ignore-tidy-filelength
7 Within the check phase of type check, we check each item one at a time
8 (bodies of function expressions are checked as part of the containing
9 function). Inference is used to supply types wherever they are unknown.
11 By far the most complex case is checking the body of a function. This
12 can be broken down into several distinct phases:
14 - gather: creates type variables to represent the type of each local
15 variable and pattern binding.
17 - main: the main pass does the lion's share of the work: it
18 determines the types of all expressions, resolves
19 methods, checks for most invalid conditions, and so forth. In
20 some cases, where a type is unknown, it may create a type or region
21 variable and use that as the type of an expression.
23 In the process of checking, various constraints will be placed on
24 these type variables through the subtyping relationships requested
25 through the `demand` module. The `infer` module is in charge
26 of resolving those constraints.
28 - regionck: after main is complete, the regionck pass goes over all
29 types looking for regions and making sure that they did not escape
30 into places they are not in scope. This may also influence the
31 final assignments of the various region variables if there is some
34 - vtable: find and records the impls to use for each trait bound that
35 appears on a type parameter.
37 - writeback: writes the final types within a function body, replacing
38 type variables with their final inferred types. These final types
39 are written into the `tcx.node_types` table, which should *never* contain
40 any reference to a type variable.
44 While type checking a function, the intermediate types for the
45 expressions, blocks, and so forth contained within the function are
46 stored in `fcx.node_types` and `fcx.node_substs`. These types
47 may contain unresolved type variables. After type checking is
48 complete, the functions in the writeback module are used to take the
49 types from this table, resolve them, and then write them into their
50 permanent home in the type context `tcx`.
52 This means that during inferencing you should use `fcx.write_ty()`
53 and `fcx.expr_ty()` / `fcx.node_ty()` to write/obtain the types of
54 nodes within the function.
56 The types of top-level items, which never contain unbound type
57 variables, are stored directly into the `tcx` tables.
59 N.B., a type variable is not the same thing as a type parameter. A
60 type variable is rather an "instance" of a type parameter: that is,
61 given a generic function `fn foo<T>(t: T)`: while checking the
62 function `foo`, the type `ty_param(0)` refers to the type `T`, which
63 is treated in abstract. When `foo()` is called, however, `T` will be
64 substituted for a fresh type variable `N`. This variable will
65 eventually be resolved to some concrete type (which might itself be
85 mod generator_interior;
89 use crate::astconv::{AstConv, PathSeg};
90 use errors::{Applicability, DiagnosticBuilder, DiagnosticId};
91 use rustc::hir::{self, ExprKind, GenericArg, ItemKind, Node, PatKind, QPath};
92 use rustc::hir::def::{CtorOf, Res, DefKind};
93 use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
94 use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
95 use rustc::hir::itemlikevisit::ItemLikeVisitor;
96 use crate::middle::lang_items;
97 use crate::namespace::Namespace;
98 use rustc::infer::{self, InferCtxt, InferOk, InferResult};
99 use rustc::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
100 use rustc_data_structures::indexed_vec::Idx;
101 use rustc_target::spec::abi::Abi;
102 use rustc::infer::opaque_types::OpaqueTypeDecl;
103 use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
104 use rustc::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
105 use rustc::middle::region;
106 use rustc::mir::interpret::{ConstValue, GlobalId};
107 use rustc::traits::{self, ObligationCause, ObligationCauseCode, TraitEngine};
109 self, AdtKind, CanonicalUserType, Ty, TyCtxt, Const, GenericParamDefKind,
110 ToPolyTraitRef, ToPredicate, RegionKind, UserType
112 use rustc::ty::adjustment::{
113 Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, PointerCast
115 use rustc::ty::fold::TypeFoldable;
116 use rustc::ty::query::Providers;
117 use rustc::ty::subst::{UnpackedKind, Subst, InternalSubsts, SubstsRef, UserSelfTy, UserSubsts};
118 use rustc::ty::util::{Representability, IntTypeExt, Discr};
119 use rustc::ty::layout::VariantIdx;
120 use syntax_pos::{self, BytePos, Span, MultiSpan};
121 use syntax_pos::hygiene::CompilerDesugaringKind;
124 use syntax::feature_gate::{GateIssue, emit_feature_err};
126 use syntax::source_map::{DUMMY_SP, original_sp};
127 use syntax::symbol::{kw, sym};
129 use std::cell::{Cell, RefCell, Ref, RefMut};
130 use std::collections::hash_map::Entry;
133 use std::mem::replace;
134 use std::ops::{self, Deref};
137 use crate::require_c_abi_if_c_variadic;
138 use crate::session::Session;
139 use crate::session::config::EntryFnType;
140 use crate::TypeAndSubsts;
142 use crate::util::captures::Captures;
143 use crate::util::common::{ErrorReported, indenter};
144 use crate::util::nodemap::{DefIdMap, DefIdSet, FxHashSet, HirIdMap};
146 pub use self::Expectation::*;
147 use self::autoderef::Autoderef;
148 use self::callee::DeferredCallResolution;
149 use self::coercion::{CoerceMany, DynamicCoerceMany};
150 pub use self::compare_method::{compare_impl_method, compare_const_impl};
151 use self::method::{MethodCallee, SelfSource};
152 use self::TupleArgumentsFlag::*;
154 /// The type of a local binding, including the revealed type for anon types.
155 #[derive(Copy, Clone)]
156 pub struct LocalTy<'tcx> {
158 revealed_ty: Ty<'tcx>
161 /// A wrapper for `InferCtxt`'s `in_progress_tables` field.
162 #[derive(Copy, Clone)]
163 struct MaybeInProgressTables<'a, 'tcx: 'a> {
164 maybe_tables: Option<&'a RefCell<ty::TypeckTables<'tcx>>>,
167 impl<'a, 'tcx> MaybeInProgressTables<'a, 'tcx> {
168 fn borrow(self) -> Ref<'a, ty::TypeckTables<'tcx>> {
169 match self.maybe_tables {
170 Some(tables) => tables.borrow(),
172 bug!("MaybeInProgressTables: inh/fcx.tables.borrow() with no tables")
177 fn borrow_mut(self) -> RefMut<'a, ty::TypeckTables<'tcx>> {
178 match self.maybe_tables {
179 Some(tables) => tables.borrow_mut(),
181 bug!("MaybeInProgressTables: inh/fcx.tables.borrow_mut() with no tables")
187 /// Closures defined within the function. For example:
190 /// bar(move|| { ... })
193 /// Here, the function `foo()` and the closure passed to
194 /// `bar()` will each have their own `FnCtxt`, but they will
195 /// share the inherited fields.
196 pub struct Inherited<'a, 'tcx: 'a> {
197 infcx: InferCtxt<'a, 'tcx>,
199 tables: MaybeInProgressTables<'a, 'tcx>,
201 locals: RefCell<HirIdMap<LocalTy<'tcx>>>,
203 fulfillment_cx: RefCell<Box<dyn TraitEngine<'tcx>>>,
205 // Some additional `Sized` obligations badly affect type inference.
206 // These obligations are added in a later stage of typeck.
207 deferred_sized_obligations: RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
209 // When we process a call like `c()` where `c` is a closure type,
210 // we may not have decided yet whether `c` is a `Fn`, `FnMut`, or
211 // `FnOnce` closure. In that case, we defer full resolution of the
212 // call until upvar inference can kick in and make the
213 // decision. We keep these deferred resolutions grouped by the
214 // def-id of the closure, so that once we decide, we can easily go
215 // back and process them.
216 deferred_call_resolutions: RefCell<DefIdMap<Vec<DeferredCallResolution<'tcx>>>>,
218 deferred_cast_checks: RefCell<Vec<cast::CastCheck<'tcx>>>,
220 deferred_generator_interiors: RefCell<Vec<(hir::BodyId, Ty<'tcx>)>>,
222 // Opaque types found in explicit return types and their
223 // associated fresh inference variable. Writeback resolves these
224 // variables to get the concrete type, which can be used to
225 // 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
226 opaque_types: RefCell<DefIdMap<OpaqueTypeDecl<'tcx>>>,
228 /// Each type parameter has an implicit region bound that
229 /// indicates it must outlive at least the function body (the user
230 /// may specify stronger requirements). This field indicates the
231 /// region of the callee. If it is `None`, then the parameter
232 /// environment is for an item or something where the "callee" is
234 implicit_region_bound: Option<ty::Region<'tcx>>,
236 body_id: Option<hir::BodyId>,
239 impl<'a, 'tcx> Deref for Inherited<'a, 'tcx> {
240 type Target = InferCtxt<'a, 'tcx>;
241 fn deref(&self) -> &Self::Target {
246 /// When type-checking an expression, we propagate downward
247 /// whatever type hint we are able in the form of an `Expectation`.
248 #[derive(Copy, Clone, Debug)]
249 pub enum Expectation<'tcx> {
250 /// We know nothing about what type this expression should have.
253 /// This expression should have the type given (or some subtype).
254 ExpectHasType(Ty<'tcx>),
256 /// This expression will be cast to the `Ty`.
257 ExpectCastableToType(Ty<'tcx>),
259 /// This rvalue expression will be wrapped in `&` or `Box` and coerced
260 /// to `&Ty` or `Box<Ty>`, respectively. `Ty` is `[A]` or `Trait`.
261 ExpectRvalueLikeUnsized(Ty<'tcx>),
264 impl<'a, 'tcx> Expectation<'tcx> {
265 // Disregard "castable to" expectations because they
266 // can lead us astray. Consider for example `if cond
267 // {22} else {c} as u8` -- if we propagate the
268 // "castable to u8" constraint to 22, it will pick the
269 // type 22u8, which is overly constrained (c might not
270 // be a u8). In effect, the problem is that the
271 // "castable to" expectation is not the tightest thing
272 // we can say, so we want to drop it in this case.
273 // The tightest thing we can say is "must unify with
274 // else branch". Note that in the case of a "has type"
275 // constraint, this limitation does not hold.
277 // If the expected type is just a type variable, then don't use
278 // an expected type. Otherwise, we might write parts of the type
279 // when checking the 'then' block which are incompatible with the
281 fn adjust_for_branches(&self, fcx: &FnCtxt<'a, 'tcx>) -> Expectation<'tcx> {
283 ExpectHasType(ety) => {
284 let ety = fcx.shallow_resolve(ety);
285 if !ety.is_ty_var() {
291 ExpectRvalueLikeUnsized(ety) => {
292 ExpectRvalueLikeUnsized(ety)
298 /// Provides an expectation for an rvalue expression given an *optional*
299 /// hint, which is not required for type safety (the resulting type might
300 /// be checked higher up, as is the case with `&expr` and `box expr`), but
301 /// is useful in determining the concrete type.
303 /// The primary use case is where the expected type is a fat pointer,
304 /// like `&[isize]`. For example, consider the following statement:
306 /// let x: &[isize] = &[1, 2, 3];
308 /// In this case, the expected type for the `&[1, 2, 3]` expression is
309 /// `&[isize]`. If however we were to say that `[1, 2, 3]` has the
310 /// expectation `ExpectHasType([isize])`, that would be too strong --
311 /// `[1, 2, 3]` does not have the type `[isize]` but rather `[isize; 3]`.
312 /// It is only the `&[1, 2, 3]` expression as a whole that can be coerced
313 /// to the type `&[isize]`. Therefore, we propagate this more limited hint,
314 /// which still is useful, because it informs integer literals and the like.
315 /// See the test case `test/run-pass/coerce-expect-unsized.rs` and #20169
316 /// for examples of where this comes up,.
317 fn rvalue_hint(fcx: &FnCtxt<'a, 'tcx>, ty: Ty<'tcx>) -> Expectation<'tcx> {
318 match fcx.tcx.struct_tail(ty).sty {
319 ty::Slice(_) | ty::Str | ty::Dynamic(..) => {
320 ExpectRvalueLikeUnsized(ty)
322 _ => ExpectHasType(ty)
326 // Resolves `expected` by a single level if it is a variable. If
327 // there is no expected type or resolution is not possible (e.g.,
328 // no constraints yet present), just returns `None`.
329 fn resolve(self, fcx: &FnCtxt<'a, 'tcx>) -> Expectation<'tcx> {
331 NoExpectation => NoExpectation,
332 ExpectCastableToType(t) => {
333 ExpectCastableToType(fcx.resolve_vars_if_possible(&t))
335 ExpectHasType(t) => {
336 ExpectHasType(fcx.resolve_vars_if_possible(&t))
338 ExpectRvalueLikeUnsized(t) => {
339 ExpectRvalueLikeUnsized(fcx.resolve_vars_if_possible(&t))
344 fn to_option(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
345 match self.resolve(fcx) {
346 NoExpectation => None,
347 ExpectCastableToType(ty) |
349 ExpectRvalueLikeUnsized(ty) => Some(ty),
353 /// It sometimes happens that we want to turn an expectation into
354 /// a **hard constraint** (i.e., something that must be satisfied
355 /// for the program to type-check). `only_has_type` will return
356 /// such a constraint, if it exists.
357 fn only_has_type(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
358 match self.resolve(fcx) {
359 ExpectHasType(ty) => Some(ty),
360 NoExpectation | ExpectCastableToType(_) | ExpectRvalueLikeUnsized(_) => None,
364 /// Like `only_has_type`, but instead of returning `None` if no
365 /// hard constraint exists, creates a fresh type variable.
366 fn coercion_target_type(self, fcx: &FnCtxt<'a, 'tcx>, span: Span) -> Ty<'tcx> {
367 self.only_has_type(fcx)
369 fcx.next_ty_var(TypeVariableOrigin {
370 kind: TypeVariableOriginKind::MiscVariable,
377 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
384 fn maybe_mut_place(m: hir::Mutability) -> Self {
386 hir::MutMutable => Needs::MutPlace,
387 hir::MutImmutable => Needs::None,
392 #[derive(Copy, Clone)]
393 pub struct UnsafetyState {
395 pub unsafety: hir::Unsafety,
396 pub unsafe_push_count: u32,
401 pub fn function(unsafety: hir::Unsafety, def: hir::HirId) -> UnsafetyState {
402 UnsafetyState { def: def, unsafety: unsafety, unsafe_push_count: 0, from_fn: true }
405 pub fn recurse(&mut self, blk: &hir::Block) -> UnsafetyState {
406 match self.unsafety {
407 // If this unsafe, then if the outer function was already marked as
408 // unsafe we shouldn't attribute the unsafe'ness to the block. This
409 // way the block can be warned about instead of ignoring this
410 // extraneous block (functions are never warned about).
411 hir::Unsafety::Unsafe if self.from_fn => *self,
414 let (unsafety, def, count) = match blk.rules {
415 hir::PushUnsafeBlock(..) =>
416 (unsafety, blk.hir_id, self.unsafe_push_count.checked_add(1).unwrap()),
417 hir::PopUnsafeBlock(..) =>
418 (unsafety, blk.hir_id, self.unsafe_push_count.checked_sub(1).unwrap()),
419 hir::UnsafeBlock(..) =>
420 (hir::Unsafety::Unsafe, blk.hir_id, self.unsafe_push_count),
422 (unsafety, self.def, self.unsafe_push_count),
426 unsafe_push_count: count,
433 #[derive(Debug, Copy, Clone)]
439 /// Tracks whether executing a node may exit normally (versus
440 /// return/break/panic, which "diverge", leaving dead code in their
441 /// wake). Tracked semi-automatically (through type variables marked
442 /// as diverging), with some manual adjustments for control-flow
443 /// primitives (approximating a CFG).
444 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
446 /// Potentially unknown, some cases converge,
447 /// others require a CFG to determine them.
450 /// Definitely known to diverge and therefore
451 /// not reach the next sibling or its parent.
454 /// Same as `Always` but with a reachability
455 /// warning already emitted.
459 // Convenience impls for combinig `Diverges`.
461 impl ops::BitAnd for Diverges {
463 fn bitand(self, other: Self) -> Self {
464 cmp::min(self, other)
468 impl ops::BitOr for Diverges {
470 fn bitor(self, other: Self) -> Self {
471 cmp::max(self, other)
475 impl ops::BitAndAssign for Diverges {
476 fn bitand_assign(&mut self, other: Self) {
477 *self = *self & other;
481 impl ops::BitOrAssign for Diverges {
482 fn bitor_assign(&mut self, other: Self) {
483 *self = *self | other;
488 fn always(self) -> bool {
489 self >= Diverges::Always
493 pub struct BreakableCtxt<'tcx> {
496 // this is `null` for loops where break with a value is illegal,
497 // such as `while`, `for`, and `while let`
498 coerce: Option<DynamicCoerceMany<'tcx>>,
501 pub struct EnclosingBreakables<'tcx> {
502 stack: Vec<BreakableCtxt<'tcx>>,
503 by_id: HirIdMap<usize>,
506 impl<'tcx> EnclosingBreakables<'tcx> {
507 fn find_breakable(&mut self, target_id: hir::HirId) -> &mut BreakableCtxt<'tcx> {
508 let ix = *self.by_id.get(&target_id).unwrap_or_else(|| {
509 bug!("could not find enclosing breakable with id {}", target_id);
515 pub struct FnCtxt<'a, 'tcx: 'a> {
518 /// The parameter environment used for proving trait obligations
519 /// in this function. This can change when we descend into
520 /// closures (as they bring new things into scope), hence it is
521 /// not part of `Inherited` (as of the time of this writing,
522 /// closures do not yet change the environment, but they will
524 param_env: ty::ParamEnv<'tcx>,
526 /// Number of errors that had been reported when we started
527 /// checking this function. On exit, if we find that *more* errors
528 /// have been reported, we will skip regionck and other work that
529 /// expects the types within the function to be consistent.
530 err_count_on_creation: usize,
532 ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>,
533 ret_coercion_span: RefCell<Option<Span>>,
535 yield_ty: Option<Ty<'tcx>>,
537 ps: RefCell<UnsafetyState>,
539 /// Whether the last checked node generates a divergence (e.g.,
540 /// `return` will set this to `Always`). In general, when entering
541 /// an expression or other node in the tree, the initial value
542 /// indicates whether prior parts of the containing expression may
543 /// have diverged. It is then typically set to `Maybe` (and the
544 /// old value remembered) for processing the subparts of the
545 /// current expression. As each subpart is processed, they may set
546 /// the flag to `Always`, etc. Finally, at the end, we take the
547 /// result and "union" it with the original value, so that when we
548 /// return the flag indicates if any subpart of the parent
549 /// expression (up to and including this part) has diverged. So,
550 /// if you read it after evaluating a subexpression `X`, the value
551 /// you get indicates whether any subexpression that was
552 /// evaluating up to and including `X` diverged.
554 /// We currently use this flag only for diagnostic purposes:
556 /// - To warn about unreachable code: if, after processing a
557 /// sub-expression but before we have applied the effects of the
558 /// current node, we see that the flag is set to `Always`, we
559 /// can issue a warning. This corresponds to something like
560 /// `foo(return)`; we warn on the `foo()` expression. (We then
561 /// update the flag to `WarnedAlways` to suppress duplicate
562 /// reports.) Similarly, if we traverse to a fresh statement (or
563 /// tail expression) from a `Always` setting, we will issue a
564 /// warning. This corresponds to something like `{return;
565 /// foo();}` or `{return; 22}`, where we would warn on the
568 /// An expression represents dead code if, after checking it,
569 /// the diverges flag is set to something other than `Maybe`.
570 diverges: Cell<Diverges>,
572 /// Whether any child nodes have any type errors.
573 has_errors: Cell<bool>,
575 enclosing_breakables: RefCell<EnclosingBreakables<'tcx>>,
577 inh: &'a Inherited<'a, 'tcx>,
580 impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> {
581 type Target = Inherited<'a, 'tcx>;
582 fn deref(&self) -> &Self::Target {
587 /// Helper type of a temporary returned by `Inherited::build(...)`.
588 /// Necessary because we can't write the following bound:
589 /// `F: for<'b, 'tcx> where 'tcx FnOnce(Inherited<'b, 'tcx>)`.
590 pub struct InheritedBuilder<'tcx> {
591 infcx: infer::InferCtxtBuilder<'tcx>,
595 impl Inherited<'_, 'tcx> {
596 pub fn build(tcx: TyCtxt<'tcx>, def_id: DefId) -> InheritedBuilder<'tcx> {
597 let hir_id_root = if def_id.is_local() {
598 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
599 DefId::local(hir_id.owner)
605 infcx: tcx.infer_ctxt().with_fresh_in_progress_tables(hir_id_root),
611 impl<'tcx> InheritedBuilder<'tcx> {
612 fn enter<F, R>(&mut self, f: F) -> R
614 F: for<'a> FnOnce(Inherited<'a, 'tcx>) -> R,
616 let def_id = self.def_id;
617 self.infcx.enter(|infcx| f(Inherited::new(infcx, def_id)))
621 impl Inherited<'a, 'tcx> {
622 fn new(infcx: InferCtxt<'a, 'tcx>, def_id: DefId) -> Self {
624 let item_id = tcx.hir().as_local_hir_id(def_id);
625 let body_id = item_id.and_then(|id| tcx.hir().maybe_body_owned_by(id));
626 let implicit_region_bound = body_id.map(|body_id| {
627 let body = tcx.hir().body(body_id);
628 tcx.mk_region(ty::ReScope(region::Scope {
629 id: body.value.hir_id.local_id,
630 data: region::ScopeData::CallSite
635 tables: MaybeInProgressTables {
636 maybe_tables: infcx.in_progress_tables,
639 fulfillment_cx: RefCell::new(TraitEngine::new(tcx)),
640 locals: RefCell::new(Default::default()),
641 deferred_sized_obligations: RefCell::new(Vec::new()),
642 deferred_call_resolutions: RefCell::new(Default::default()),
643 deferred_cast_checks: RefCell::new(Vec::new()),
644 deferred_generator_interiors: RefCell::new(Vec::new()),
645 opaque_types: RefCell::new(Default::default()),
646 implicit_region_bound,
651 fn register_predicate(&self, obligation: traits::PredicateObligation<'tcx>) {
652 debug!("register_predicate({:?})", obligation);
653 if obligation.has_escaping_bound_vars() {
654 span_bug!(obligation.cause.span, "escaping bound vars in predicate {:?}",
659 .register_predicate_obligation(self, obligation);
662 fn register_predicates<I>(&self, obligations: I)
663 where I: IntoIterator<Item = traits::PredicateObligation<'tcx>>
665 for obligation in obligations {
666 self.register_predicate(obligation);
670 fn register_infer_ok_obligations<T>(&self, infer_ok: InferOk<'tcx, T>) -> T {
671 self.register_predicates(infer_ok.obligations);
675 fn normalize_associated_types_in<T>(&self,
678 param_env: ty::ParamEnv<'tcx>,
680 where T : TypeFoldable<'tcx>
682 let ok = self.partially_normalize_associated_types_in(span, body_id, param_env, value);
683 self.register_infer_ok_obligations(ok)
687 struct CheckItemTypesVisitor<'tcx> {
691 impl ItemLikeVisitor<'tcx> for CheckItemTypesVisitor<'tcx> {
692 fn visit_item(&mut self, i: &'tcx hir::Item) {
693 check_item_type(self.tcx, i);
695 fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem) { }
696 fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem) { }
699 pub fn check_wf_new<'tcx>(tcx: TyCtxt<'tcx>) -> Result<(), ErrorReported> {
700 tcx.sess.track_errors(|| {
701 let mut visit = wfcheck::CheckTypeWellFormedVisitor::new(tcx);
702 tcx.hir().krate().par_visit_all_item_likes(&mut visit);
706 fn check_mod_item_types<'tcx>(tcx: TyCtxt<'tcx>, module_def_id: DefId) {
707 tcx.hir().visit_item_likes_in_module(module_def_id, &mut CheckItemTypesVisitor { tcx });
710 fn typeck_item_bodies<'tcx>(tcx: TyCtxt<'tcx>, crate_num: CrateNum) {
711 debug_assert!(crate_num == LOCAL_CRATE);
712 tcx.par_body_owners(|body_owner_def_id| {
713 tcx.ensure().typeck_tables_of(body_owner_def_id);
717 fn check_item_well_formed<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) {
718 wfcheck::check_item_well_formed(tcx, def_id);
721 fn check_trait_item_well_formed<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) {
722 wfcheck::check_trait_item(tcx, def_id);
725 fn check_impl_item_well_formed<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) {
726 wfcheck::check_impl_item(tcx, def_id);
729 pub fn provide(providers: &mut Providers<'_>) {
730 method::provide(providers);
731 *providers = Providers {
737 check_item_well_formed,
738 check_trait_item_well_formed,
739 check_impl_item_well_formed,
740 check_mod_item_types,
745 fn adt_destructor<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Option<ty::Destructor> {
746 tcx.calculate_dtor(def_id, &mut dropck::check_drop_impl)
749 /// If this `DefId` is a "primary tables entry", returns `Some((body_id, decl))`
750 /// with information about it's body-id and fn-decl (if any). Otherwise,
753 /// If this function returns "some", then `typeck_tables(def_id)` will
754 /// succeed; if it returns `None`, then `typeck_tables(def_id)` may or
755 /// may not succeed. In some cases where this function returns `None`
756 /// (notably closures), `typeck_tables(def_id)` would wind up
757 /// redirecting to the owning function.
758 fn primary_body_of<'tcx>(
761 ) -> Option<(hir::BodyId, Option<&'tcx hir::FnDecl>)> {
762 match tcx.hir().get_by_hir_id(id) {
763 Node::Item(item) => {
765 hir::ItemKind::Const(_, body) |
766 hir::ItemKind::Static(_, _, body) =>
768 hir::ItemKind::Fn(ref decl, .., body) =>
769 Some((body, Some(decl))),
774 Node::TraitItem(item) => {
776 hir::TraitItemKind::Const(_, Some(body)) =>
778 hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Provided(body)) =>
779 Some((body, Some(&sig.decl))),
784 Node::ImplItem(item) => {
786 hir::ImplItemKind::Const(_, body) =>
788 hir::ImplItemKind::Method(ref sig, body) =>
789 Some((body, Some(&sig.decl))),
794 Node::AnonConst(constant) => Some((constant.body, None)),
799 fn has_typeck_tables<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
800 // Closures' tables come from their outermost function,
801 // as they are part of the same "inference environment".
802 let outer_def_id = tcx.closure_base_def_id(def_id);
803 if outer_def_id != def_id {
804 return tcx.has_typeck_tables(outer_def_id);
807 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
808 primary_body_of(tcx, id).is_some()
811 fn used_trait_imports<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx DefIdSet {
812 &*tcx.typeck_tables_of(def_id).used_trait_imports
815 fn typeck_tables_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx ty::TypeckTables<'tcx> {
816 // Closures' tables come from their outermost function,
817 // as they are part of the same "inference environment".
818 let outer_def_id = tcx.closure_base_def_id(def_id);
819 if outer_def_id != def_id {
820 return tcx.typeck_tables_of(outer_def_id);
823 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
824 let span = tcx.hir().span(id);
826 // Figure out what primary body this item has.
827 let (body_id, fn_decl) = primary_body_of(tcx, id).unwrap_or_else(|| {
828 span_bug!(span, "can't type-check body of {:?}", def_id);
830 let body = tcx.hir().body(body_id);
832 let tables = Inherited::build(tcx, def_id).enter(|inh| {
833 let param_env = tcx.param_env(def_id);
834 let fcx = if let Some(decl) = fn_decl {
835 let fn_sig = tcx.fn_sig(def_id);
837 check_abi(tcx, span, fn_sig.abi());
839 // Compute the fty from point of view of inside the fn.
841 tcx.liberate_late_bound_regions(def_id, &fn_sig);
843 inh.normalize_associated_types_in(body.value.span,
848 let fcx = check_fn(&inh, param_env, fn_sig, decl, id, body, None).0;
851 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
852 let expected_type = tcx.type_of(def_id);
853 let expected_type = fcx.normalize_associated_types_in(body.value.span, &expected_type);
854 fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);
856 let revealed_ty = if tcx.features().impl_trait_in_bindings {
857 fcx.instantiate_opaque_types_from_value(
865 // Gather locals in statics (because of block expressions).
866 GatherLocalsVisitor { fcx: &fcx, parent_id: id, }.visit_body(body);
868 fcx.check_expr_coercable_to_type(&body.value, revealed_ty);
870 fcx.write_ty(id, revealed_ty);
875 // All type checking constraints were added, try to fallback unsolved variables.
876 fcx.select_obligations_where_possible(false);
877 let mut fallback_has_occurred = false;
878 for ty in &fcx.unsolved_variables() {
879 fallback_has_occurred |= fcx.fallback_if_possible(ty);
881 fcx.select_obligations_where_possible(fallback_has_occurred);
883 // Even though coercion casts provide type hints, we check casts after fallback for
884 // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
887 // Closure and generator analysis may run after fallback
888 // because they don't constrain other type variables.
889 fcx.closure_analyze(body);
890 assert!(fcx.deferred_call_resolutions.borrow().is_empty());
891 fcx.resolve_generator_interiors(def_id);
893 for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
894 let ty = fcx.normalize_ty(span, ty);
895 fcx.require_type_is_sized(ty, span, code);
897 fcx.select_all_obligations_or_error();
899 if fn_decl.is_some() {
900 fcx.regionck_fn(id, body);
902 fcx.regionck_expr(body);
905 fcx.resolve_type_vars_in_body(body)
908 // Consistency check our TypeckTables instance can hold all ItemLocalIds
909 // it will need to hold.
910 assert_eq!(tables.local_id_root, Some(DefId::local(id.owner)));
915 fn check_abi<'tcx>(tcx: TyCtxt<'tcx>, span: Span, abi: Abi) {
916 if !tcx.sess.target.target.is_abi_supported(abi) {
917 struct_span_err!(tcx.sess, span, E0570,
918 "The ABI `{}` is not supported for the current target", abi).emit()
922 struct GatherLocalsVisitor<'a, 'tcx: 'a> {
923 fcx: &'a FnCtxt<'a, 'tcx>,
924 parent_id: hir::HirId,
927 impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> {
928 fn assign(&mut self, span: Span, nid: hir::HirId, ty_opt: Option<LocalTy<'tcx>>) -> Ty<'tcx> {
931 // infer the variable's type
932 let var_ty = self.fcx.next_ty_var(TypeVariableOrigin {
933 kind: TypeVariableOriginKind::TypeInference,
936 self.fcx.locals.borrow_mut().insert(nid, LocalTy {
943 // take type that the user specified
944 self.fcx.locals.borrow_mut().insert(nid, typ);
951 impl<'a, 'tcx> Visitor<'tcx> for GatherLocalsVisitor<'a, 'tcx> {
952 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
953 NestedVisitorMap::None
956 // Add explicitly-declared locals.
957 fn visit_local(&mut self, local: &'tcx hir::Local) {
958 let local_ty = match local.ty {
960 let o_ty = self.fcx.to_ty(&ty);
962 let revealed_ty = if self.fcx.tcx.features().impl_trait_in_bindings {
963 self.fcx.instantiate_opaque_types_from_value(
971 let c_ty = self.fcx.inh.infcx.canonicalize_user_type_annotation(
972 &UserType::Ty(revealed_ty)
974 debug!("visit_local: ty.hir_id={:?} o_ty={:?} revealed_ty={:?} c_ty={:?}",
975 ty.hir_id, o_ty, revealed_ty, c_ty);
976 self.fcx.tables.borrow_mut().user_provided_types_mut().insert(ty.hir_id, c_ty);
978 Some(LocalTy { decl_ty: o_ty, revealed_ty })
982 self.assign(local.span, local.hir_id, local_ty);
984 debug!("Local variable {:?} is assigned type {}",
986 self.fcx.ty_to_string(
987 self.fcx.locals.borrow().get(&local.hir_id).unwrap().clone().decl_ty));
988 intravisit::walk_local(self, local);
991 // Add pattern bindings.
992 fn visit_pat(&mut self, p: &'tcx hir::Pat) {
993 if let PatKind::Binding(_, _, ident, _) = p.node {
994 let var_ty = self.assign(p.span, p.hir_id, None);
996 let node_id = self.fcx.tcx.hir().hir_to_node_id(p.hir_id);
997 if !self.fcx.tcx.features().unsized_locals {
998 self.fcx.require_type_is_sized(var_ty, p.span,
999 traits::VariableType(node_id));
1002 debug!("Pattern binding {} is assigned to {} with type {:?}",
1004 self.fcx.ty_to_string(
1005 self.fcx.locals.borrow().get(&p.hir_id).unwrap().clone().decl_ty),
1008 intravisit::walk_pat(self, p);
1011 // Don't descend into the bodies of nested closures
1014 _: intravisit::FnKind<'tcx>,
1015 _: &'tcx hir::FnDecl,
1022 /// When `check_fn` is invoked on a generator (i.e., a body that
1023 /// includes yield), it returns back some information about the yield
1025 struct GeneratorTypes<'tcx> {
1026 /// Type of value that is yielded.
1029 /// Types that are captured (see `GeneratorInterior` for more).
1032 /// Indicates if the generator is movable or static (immovable).
1033 movability: hir::GeneratorMovability,
1036 /// Helper used for fns and closures. Does the grungy work of checking a function
1037 /// body and returns the function context used for that purpose, since in the case of a fn item
1038 /// there is still a bit more to do.
1041 /// * inherited: other fields inherited from the enclosing fn (if any)
1042 fn check_fn<'a, 'tcx>(
1043 inherited: &'a Inherited<'a, 'tcx>,
1044 param_env: ty::ParamEnv<'tcx>,
1045 fn_sig: ty::FnSig<'tcx>,
1046 decl: &'tcx hir::FnDecl,
1048 body: &'tcx hir::Body,
1049 can_be_generator: Option<hir::GeneratorMovability>,
1050 ) -> (FnCtxt<'a, 'tcx>, Option<GeneratorTypes<'tcx>>) {
1051 let mut fn_sig = fn_sig.clone();
1053 debug!("check_fn(sig={:?}, fn_id={}, param_env={:?})", fn_sig, fn_id, param_env);
1055 // Create the function context. This is either derived from scratch or,
1056 // in the case of closures, based on the outer context.
1057 let mut fcx = FnCtxt::new(inherited, param_env, body.value.hir_id);
1058 *fcx.ps.borrow_mut() = UnsafetyState::function(fn_sig.unsafety, fn_id);
1060 let declared_ret_ty = fn_sig.output();
1061 fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType);
1062 let revealed_ret_ty = fcx.instantiate_opaque_types_from_value(fn_id, &declared_ret_ty);
1063 fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(revealed_ret_ty)));
1064 fn_sig = fcx.tcx.mk_fn_sig(
1065 fn_sig.inputs().iter().cloned(),
1072 let span = body.value.span;
1074 if body.is_generator && can_be_generator.is_some() {
1075 let yield_ty = fcx.next_ty_var(TypeVariableOrigin {
1076 kind: TypeVariableOriginKind::TypeInference,
1079 fcx.require_type_is_sized(yield_ty, span, traits::SizedYieldType);
1080 fcx.yield_ty = Some(yield_ty);
1083 let outer_def_id = fcx.tcx.closure_base_def_id(fcx.tcx.hir().local_def_id_from_hir_id(fn_id));
1084 let outer_hir_id = fcx.tcx.hir().as_local_hir_id(outer_def_id).unwrap();
1085 GatherLocalsVisitor { fcx: &fcx, parent_id: outer_hir_id, }.visit_body(body);
1087 // Add formal parameters.
1088 for (arg_ty, arg) in fn_sig.inputs().iter().zip(&body.arguments) {
1089 // Check the pattern.
1090 let binding_mode = ty::BindingMode::BindByValue(hir::Mutability::MutImmutable);
1091 fcx.check_pat_walk(&arg.pat, arg_ty, binding_mode, None);
1093 // Check that argument is Sized.
1094 // The check for a non-trivial pattern is a hack to avoid duplicate warnings
1095 // for simple cases like `fn foo(x: Trait)`,
1096 // where we would error once on the parameter as a whole, and once on the binding `x`.
1097 if arg.pat.simple_ident().is_none() && !fcx.tcx.features().unsized_locals {
1098 fcx.require_type_is_sized(arg_ty, decl.output.span(), traits::SizedArgumentType);
1101 fcx.write_ty(arg.hir_id, arg_ty);
1104 inherited.tables.borrow_mut().liberated_fn_sigs_mut().insert(fn_id, fn_sig);
1106 fcx.check_return_expr(&body.value);
1108 // We insert the deferred_generator_interiors entry after visiting the body.
1109 // This ensures that all nested generators appear before the entry of this generator.
1110 // resolve_generator_interiors relies on this property.
1111 let gen_ty = if can_be_generator.is_some() && body.is_generator {
1112 let interior = fcx.next_ty_var(TypeVariableOrigin {
1113 kind: TypeVariableOriginKind::MiscVariable,
1116 fcx.deferred_generator_interiors.borrow_mut().push((body.id(), interior));
1117 Some(GeneratorTypes {
1118 yield_ty: fcx.yield_ty.unwrap(),
1120 movability: can_be_generator.unwrap(),
1126 // Finalize the return check by taking the LUB of the return types
1127 // we saw and assigning it to the expected return type. This isn't
1128 // really expected to fail, since the coercions would have failed
1129 // earlier when trying to find a LUB.
1131 // However, the behavior around `!` is sort of complex. In the
1132 // event that the `actual_return_ty` comes back as `!`, that
1133 // indicates that the fn either does not return or "returns" only
1134 // values of type `!`. In this case, if there is an expected
1135 // return type that is *not* `!`, that should be ok. But if the
1136 // return type is being inferred, we want to "fallback" to `!`:
1138 // let x = move || panic!();
1140 // To allow for that, I am creating a type variable with diverging
1141 // fallback. This was deemed ever so slightly better than unifying
1142 // the return value with `!` because it allows for the caller to
1143 // make more assumptions about the return type (e.g., they could do
1145 // let y: Option<u32> = Some(x());
1147 // which would then cause this return type to become `u32`, not
1149 let coercion = fcx.ret_coercion.take().unwrap().into_inner();
1150 let mut actual_return_ty = coercion.complete(&fcx);
1151 if actual_return_ty.is_never() {
1152 actual_return_ty = fcx.next_diverging_ty_var(
1153 TypeVariableOrigin {
1154 kind: TypeVariableOriginKind::DivergingFn,
1159 fcx.demand_suptype(span, revealed_ret_ty, actual_return_ty);
1161 // Check that the main return type implements the termination trait.
1162 if let Some(term_id) = fcx.tcx.lang_items().termination() {
1163 if let Some((def_id, EntryFnType::Main)) = fcx.tcx.entry_fn(LOCAL_CRATE) {
1164 let main_id = fcx.tcx.hir().as_local_hir_id(def_id).unwrap();
1165 if main_id == fn_id {
1166 let substs = fcx.tcx.mk_substs_trait(declared_ret_ty, &[]);
1167 let trait_ref = ty::TraitRef::new(term_id, substs);
1168 let return_ty_span = decl.output.span();
1169 let cause = traits::ObligationCause::new(
1170 return_ty_span, fn_id, ObligationCauseCode::MainFunctionType);
1172 inherited.register_predicate(
1173 traits::Obligation::new(
1174 cause, param_env, trait_ref.to_predicate()));
1179 // Check that a function marked as `#[panic_handler]` has signature `fn(&PanicInfo) -> !`
1180 if let Some(panic_impl_did) = fcx.tcx.lang_items().panic_impl() {
1181 if panic_impl_did == fcx.tcx.hir().local_def_id_from_hir_id(fn_id) {
1182 if let Some(panic_info_did) = fcx.tcx.lang_items().panic_info() {
1183 // at this point we don't care if there are duplicate handlers or if the handler has
1184 // the wrong signature as this value we'll be used when writing metadata and that
1185 // only happens if compilation succeeded
1186 fcx.tcx.sess.has_panic_handler.try_set_same(true);
1188 if declared_ret_ty.sty != ty::Never {
1189 fcx.tcx.sess.span_err(
1191 "return type should be `!`",
1195 let inputs = fn_sig.inputs();
1196 let span = fcx.tcx.hir().span(fn_id);
1197 if inputs.len() == 1 {
1198 let arg_is_panic_info = match inputs[0].sty {
1199 ty::Ref(region, ty, mutbl) => match ty.sty {
1200 ty::Adt(ref adt, _) => {
1201 adt.did == panic_info_did &&
1202 mutbl == hir::Mutability::MutImmutable &&
1203 *region != RegionKind::ReStatic
1210 if !arg_is_panic_info {
1211 fcx.tcx.sess.span_err(
1212 decl.inputs[0].span,
1213 "argument should be `&PanicInfo`",
1217 if let Node::Item(item) = fcx.tcx.hir().get_by_hir_id(fn_id) {
1218 if let ItemKind::Fn(_, _, ref generics, _) = item.node {
1219 if !generics.params.is_empty() {
1220 fcx.tcx.sess.span_err(
1222 "should have no type parameters",
1228 let span = fcx.tcx.sess.source_map().def_span(span);
1229 fcx.tcx.sess.span_err(span, "function should have one argument");
1232 fcx.tcx.sess.err("language item required, but not found: `panic_info`");
1237 // Check that a function marked as `#[alloc_error_handler]` has signature `fn(Layout) -> !`
1238 if let Some(alloc_error_handler_did) = fcx.tcx.lang_items().oom() {
1239 if alloc_error_handler_did == fcx.tcx.hir().local_def_id_from_hir_id(fn_id) {
1240 if let Some(alloc_layout_did) = fcx.tcx.lang_items().alloc_layout() {
1241 if declared_ret_ty.sty != ty::Never {
1242 fcx.tcx.sess.span_err(
1244 "return type should be `!`",
1248 let inputs = fn_sig.inputs();
1249 let span = fcx.tcx.hir().span(fn_id);
1250 if inputs.len() == 1 {
1251 let arg_is_alloc_layout = match inputs[0].sty {
1252 ty::Adt(ref adt, _) => {
1253 adt.did == alloc_layout_did
1258 if !arg_is_alloc_layout {
1259 fcx.tcx.sess.span_err(
1260 decl.inputs[0].span,
1261 "argument should be `Layout`",
1265 if let Node::Item(item) = fcx.tcx.hir().get_by_hir_id(fn_id) {
1266 if let ItemKind::Fn(_, _, ref generics, _) = item.node {
1267 if !generics.params.is_empty() {
1268 fcx.tcx.sess.span_err(
1270 "`#[alloc_error_handler]` function should have no type \
1277 let span = fcx.tcx.sess.source_map().def_span(span);
1278 fcx.tcx.sess.span_err(span, "function should have one argument");
1281 fcx.tcx.sess.err("language item required, but not found: `alloc_layout`");
1289 fn check_struct<'tcx>(tcx: TyCtxt<'tcx>, id: hir::HirId, span: Span) {
1290 let def_id = tcx.hir().local_def_id_from_hir_id(id);
1291 let def = tcx.adt_def(def_id);
1292 def.destructor(tcx); // force the destructor to be evaluated
1293 check_representable(tcx, span, def_id);
1295 if def.repr.simd() {
1296 check_simd(tcx, span, def_id);
1299 check_transparent(tcx, span, def_id);
1300 check_packed(tcx, span, def_id);
1303 fn check_union<'tcx>(tcx: TyCtxt<'tcx>, id: hir::HirId, span: Span) {
1304 let def_id = tcx.hir().local_def_id_from_hir_id(id);
1305 let def = tcx.adt_def(def_id);
1306 def.destructor(tcx); // force the destructor to be evaluated
1307 check_representable(tcx, span, def_id);
1308 check_transparent(tcx, span, def_id);
1309 check_packed(tcx, span, def_id);
1312 fn check_opaque<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, substs: SubstsRef<'tcx>, span: Span) {
1313 if let Err(partially_expanded_type) = tcx.try_expand_impl_trait_type(def_id, substs) {
1314 let mut err = struct_span_err!(
1315 tcx.sess, span, E0720,
1316 "opaque type expands to a recursive type",
1318 err.span_label(span, "expands to self-referential type");
1319 if let ty::Opaque(..) = partially_expanded_type.sty {
1320 err.note("type resolves to itself");
1322 err.note(&format!("expanded type is `{}`", partially_expanded_type));
1328 pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item) {
1330 "check_item_type(it.hir_id={}, it.name={})",
1332 tcx.def_path_str(tcx.hir().local_def_id_from_hir_id(it.hir_id))
1334 let _indenter = indenter();
1336 // Consts can play a role in type-checking, so they are included here.
1337 hir::ItemKind::Static(..) => {
1338 let def_id = tcx.hir().local_def_id_from_hir_id(it.hir_id);
1339 tcx.typeck_tables_of(def_id);
1340 maybe_check_static_with_link_section(tcx, def_id, it.span);
1342 hir::ItemKind::Const(..) => {
1343 tcx.typeck_tables_of(tcx.hir().local_def_id_from_hir_id(it.hir_id));
1345 hir::ItemKind::Enum(ref enum_definition, _) => {
1346 check_enum(tcx, it.span, &enum_definition.variants, it.hir_id);
1348 hir::ItemKind::Fn(..) => {} // entirely within check_item_body
1349 hir::ItemKind::Impl(.., ref impl_item_refs) => {
1350 debug!("ItemKind::Impl {} with id {}", it.ident, it.hir_id);
1351 let impl_def_id = tcx.hir().local_def_id_from_hir_id(it.hir_id);
1352 if let Some(impl_trait_ref) = tcx.impl_trait_ref(impl_def_id) {
1353 check_impl_items_against_trait(
1360 let trait_def_id = impl_trait_ref.def_id;
1361 check_on_unimplemented(tcx, trait_def_id, it);
1364 hir::ItemKind::Trait(..) => {
1365 let def_id = tcx.hir().local_def_id_from_hir_id(it.hir_id);
1366 check_on_unimplemented(tcx, def_id, it);
1368 hir::ItemKind::Struct(..) => {
1369 check_struct(tcx, it.hir_id, it.span);
1371 hir::ItemKind::Union(..) => {
1372 check_union(tcx, it.hir_id, it.span);
1374 hir::ItemKind::Existential(..) => {
1375 let def_id = tcx.hir().local_def_id_from_hir_id(it.hir_id);
1377 let substs = InternalSubsts::identity_for_item(tcx, def_id);
1378 check_opaque(tcx, def_id, substs, it.span);
1380 hir::ItemKind::Ty(..) => {
1381 let def_id = tcx.hir().local_def_id_from_hir_id(it.hir_id);
1382 let pty_ty = tcx.type_of(def_id);
1383 let generics = tcx.generics_of(def_id);
1384 check_bounds_are_used(tcx, &generics, pty_ty);
1386 hir::ItemKind::ForeignMod(ref m) => {
1387 check_abi(tcx, it.span, m.abi);
1389 if m.abi == Abi::RustIntrinsic {
1390 for item in &m.items {
1391 intrinsic::check_intrinsic_type(tcx, item);
1393 } else if m.abi == Abi::PlatformIntrinsic {
1394 for item in &m.items {
1395 intrinsic::check_platform_intrinsic_type(tcx, item);
1398 for item in &m.items {
1399 let generics = tcx.generics_of(tcx.hir().local_def_id_from_hir_id(item.hir_id));
1400 if generics.params.len() - generics.own_counts().lifetimes != 0 {
1401 let mut err = struct_span_err!(
1405 "foreign items may not have type parameters"
1407 err.span_label(item.span, "can't have type parameters");
1408 // FIXME: once we start storing spans for type arguments, turn this into a
1411 "use specialization instead of type parameters by replacing them \
1412 with concrete types like `u32`",
1417 if let hir::ForeignItemKind::Fn(ref fn_decl, _, _) = item.node {
1418 require_c_abi_if_c_variadic(tcx, fn_decl, m.abi, item.span);
1423 _ => { /* nothing to do */ }
1427 fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: DefId, span: Span) {
1428 // Only restricted on wasm32 target for now
1429 if !tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
1433 // If `#[link_section]` is missing, then nothing to verify
1434 let attrs = tcx.codegen_fn_attrs(id);
1435 if attrs.link_section.is_none() {
1439 // For the wasm32 target statics with #[link_section] are placed into custom
1440 // sections of the final output file, but this isn't link custom sections of
1441 // other executable formats. Namely we can only embed a list of bytes,
1442 // nothing with pointers to anything else or relocations. If any relocation
1443 // show up, reject them here.
1444 let instance = ty::Instance::mono(tcx, id);
1445 let cid = GlobalId {
1449 let param_env = ty::ParamEnv::reveal_all();
1450 if let Ok(static_) = tcx.const_eval(param_env.and(cid)) {
1451 let alloc = if let ConstValue::ByRef(_, allocation) = static_.val {
1454 bug!("Matching on non-ByRef static")
1456 if alloc.relocations.len() != 0 {
1457 let msg = "statics with a custom `#[link_section]` must be a \
1458 simple list of bytes on the wasm target with no \
1459 extra levels of indirection such as references";
1460 tcx.sess.span_err(span, msg);
1465 fn check_on_unimplemented<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId, item: &hir::Item) {
1466 let item_def_id = tcx.hir().local_def_id_from_hir_id(item.hir_id);
1467 // an error would be reported if this fails.
1468 let _ = traits::OnUnimplementedDirective::of_item(tcx, trait_def_id, item_def_id);
1471 fn report_forbidden_specialization<'tcx>(
1473 impl_item: &hir::ImplItem,
1476 let mut err = struct_span_err!(
1477 tcx.sess, impl_item.span, E0520,
1478 "`{}` specializes an item from a parent `impl`, but \
1479 that item is not marked `default`",
1481 err.span_label(impl_item.span, format!("cannot specialize default item `{}`",
1484 match tcx.span_of_impl(parent_impl) {
1486 err.span_label(span, "parent `impl` is here");
1487 err.note(&format!("to specialize, `{}` in the parent `impl` must be marked `default`",
1491 err.note(&format!("parent implementation is in crate `{}`", cname));
1498 fn check_specialization_validity<'tcx>(
1500 trait_def: &ty::TraitDef,
1501 trait_item: &ty::AssocItem,
1503 impl_item: &hir::ImplItem,
1505 let ancestors = trait_def.ancestors(tcx, impl_id);
1507 let kind = match impl_item.node {
1508 hir::ImplItemKind::Const(..) => ty::AssocKind::Const,
1509 hir::ImplItemKind::Method(..) => ty::AssocKind::Method,
1510 hir::ImplItemKind::Existential(..) => ty::AssocKind::Existential,
1511 hir::ImplItemKind::Type(_) => ty::AssocKind::Type
1514 let parent = ancestors.defs(tcx, trait_item.ident, kind, trait_def.def_id).nth(1)
1515 .map(|node_item| node_item.map(|parent| parent.defaultness));
1517 if let Some(parent) = parent {
1518 if tcx.impl_item_is_final(&parent) {
1519 report_forbidden_specialization(tcx, impl_item, parent.node.def_id());
1525 fn check_impl_items_against_trait<'tcx>(
1529 impl_trait_ref: ty::TraitRef<'tcx>,
1530 impl_item_refs: &[hir::ImplItemRef],
1532 let impl_span = tcx.sess.source_map().def_span(impl_span);
1534 // If the trait reference itself is erroneous (so the compilation is going
1535 // to fail), skip checking the items here -- the `impl_item` table in `tcx`
1536 // isn't populated for such impls.
1537 if impl_trait_ref.references_error() { return; }
1539 // Locate trait definition and items
1540 let trait_def = tcx.trait_def(impl_trait_ref.def_id);
1541 let mut overridden_associated_type = None;
1543 let impl_items = || impl_item_refs.iter().map(|iiref| tcx.hir().impl_item(iiref.id));
1545 // Check existing impl methods to see if they are both present in trait
1546 // and compatible with trait signature
1547 for impl_item in impl_items() {
1548 let ty_impl_item = tcx.associated_item(
1549 tcx.hir().local_def_id_from_hir_id(impl_item.hir_id));
1550 let ty_trait_item = tcx.associated_items(impl_trait_ref.def_id)
1551 .find(|ac| Namespace::from(&impl_item.node) == Namespace::from(ac.kind) &&
1552 tcx.hygienic_eq(ty_impl_item.ident, ac.ident, impl_trait_ref.def_id))
1554 // Not compatible, but needed for the error message
1555 tcx.associated_items(impl_trait_ref.def_id)
1556 .find(|ac| tcx.hygienic_eq(ty_impl_item.ident, ac.ident, impl_trait_ref.def_id))
1559 // Check that impl definition matches trait definition
1560 if let Some(ty_trait_item) = ty_trait_item {
1561 match impl_item.node {
1562 hir::ImplItemKind::Const(..) => {
1563 // Find associated const definition.
1564 if ty_trait_item.kind == ty::AssocKind::Const {
1565 compare_const_impl(tcx,
1571 let mut err = struct_span_err!(tcx.sess, impl_item.span, E0323,
1572 "item `{}` is an associated const, \
1573 which doesn't match its trait `{}`",
1576 err.span_label(impl_item.span, "does not match trait");
1577 // We can only get the spans from local trait definition
1578 // Same for E0324 and E0325
1579 if let Some(trait_span) = tcx.hir().span_if_local(ty_trait_item.def_id) {
1580 err.span_label(trait_span, "item in trait");
1585 hir::ImplItemKind::Method(..) => {
1586 let trait_span = tcx.hir().span_if_local(ty_trait_item.def_id);
1587 if ty_trait_item.kind == ty::AssocKind::Method {
1588 compare_impl_method(tcx,
1595 let mut err = struct_span_err!(tcx.sess, impl_item.span, E0324,
1596 "item `{}` is an associated method, \
1597 which doesn't match its trait `{}`",
1600 err.span_label(impl_item.span, "does not match trait");
1601 if let Some(trait_span) = tcx.hir().span_if_local(ty_trait_item.def_id) {
1602 err.span_label(trait_span, "item in trait");
1607 hir::ImplItemKind::Existential(..) |
1608 hir::ImplItemKind::Type(_) => {
1609 if ty_trait_item.kind == ty::AssocKind::Type {
1610 if ty_trait_item.defaultness.has_value() {
1611 overridden_associated_type = Some(impl_item);
1614 let mut err = struct_span_err!(tcx.sess, impl_item.span, E0325,
1615 "item `{}` is an associated type, \
1616 which doesn't match its trait `{}`",
1619 err.span_label(impl_item.span, "does not match trait");
1620 if let Some(trait_span) = tcx.hir().span_if_local(ty_trait_item.def_id) {
1621 err.span_label(trait_span, "item in trait");
1628 check_specialization_validity(tcx, trait_def, &ty_trait_item, impl_id, impl_item);
1632 // Check for missing items from trait
1633 let mut missing_items = Vec::new();
1634 let mut invalidated_items = Vec::new();
1635 let associated_type_overridden = overridden_associated_type.is_some();
1636 for trait_item in tcx.associated_items(impl_trait_ref.def_id) {
1637 let is_implemented = trait_def.ancestors(tcx, impl_id)
1638 .defs(tcx, trait_item.ident, trait_item.kind, impl_trait_ref.def_id)
1640 .map(|node_item| !node_item.node.is_from_trait())
1643 if !is_implemented && !tcx.impl_is_default(impl_id) {
1644 if !trait_item.defaultness.has_value() {
1645 missing_items.push(trait_item);
1646 } else if associated_type_overridden {
1647 invalidated_items.push(trait_item.ident);
1652 if !missing_items.is_empty() {
1653 let mut err = struct_span_err!(tcx.sess, impl_span, E0046,
1654 "not all trait items implemented, missing: `{}`",
1655 missing_items.iter()
1656 .map(|trait_item| trait_item.ident.to_string())
1657 .collect::<Vec<_>>().join("`, `"));
1658 err.span_label(impl_span, format!("missing `{}` in implementation",
1659 missing_items.iter()
1660 .map(|trait_item| trait_item.ident.to_string())
1661 .collect::<Vec<_>>().join("`, `")));
1662 for trait_item in missing_items {
1663 if let Some(span) = tcx.hir().span_if_local(trait_item.def_id) {
1664 err.span_label(span, format!("`{}` from trait", trait_item.ident));
1666 err.note_trait_signature(trait_item.ident.to_string(),
1667 trait_item.signature(tcx));
1673 if !invalidated_items.is_empty() {
1674 let invalidator = overridden_associated_type.unwrap();
1675 span_err!(tcx.sess, invalidator.span, E0399,
1676 "the following trait items need to be reimplemented \
1677 as `{}` was overridden: `{}`",
1679 invalidated_items.iter()
1680 .map(|name| name.to_string())
1681 .collect::<Vec<_>>().join("`, `"))
1685 /// Checks whether a type can be represented in memory. In particular, it
1686 /// identifies types that contain themselves without indirection through a
1687 /// pointer, which would mean their size is unbounded.
1688 fn check_representable<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, item_def_id: DefId) -> bool {
1689 let rty = tcx.type_of(item_def_id);
1691 // Check that it is possible to represent this type. This call identifies
1692 // (1) types that contain themselves and (2) types that contain a different
1693 // recursive type. It is only necessary to throw an error on those that
1694 // contain themselves. For case 2, there must be an inner type that will be
1695 // caught by case 1.
1696 match rty.is_representable(tcx, sp) {
1697 Representability::SelfRecursive(spans) => {
1698 let mut err = tcx.recursive_type_with_infinite_size_error(item_def_id);
1700 err.span_label(span, "recursive without indirection");
1705 Representability::Representable | Representability::ContainsRecursive => (),
1710 pub fn check_simd<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, def_id: DefId) {
1711 let t = tcx.type_of(def_id);
1712 if let ty::Adt(def, substs) = t.sty {
1713 if def.is_struct() {
1714 let fields = &def.non_enum_variant().fields;
1715 if fields.is_empty() {
1716 span_err!(tcx.sess, sp, E0075, "SIMD vector cannot be empty");
1719 let e = fields[0].ty(tcx, substs);
1720 if !fields.iter().all(|f| f.ty(tcx, substs) == e) {
1721 struct_span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous")
1722 .span_label(sp, "SIMD elements must have the same type")
1727 ty::Param(_) => { /* struct<T>(T, T, T, T) is ok */ }
1728 _ if e.is_machine() => { /* struct(u8, u8, u8, u8) is ok */ }
1730 span_err!(tcx.sess, sp, E0077,
1731 "SIMD vector element type should be machine type");
1739 fn check_packed<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, def_id: DefId) {
1740 let repr = tcx.adt_def(def_id).repr;
1742 for attr in tcx.get_attrs(def_id).iter() {
1743 for r in attr::find_repr_attrs(&tcx.sess.parse_sess, attr) {
1744 if let attr::ReprPacked(pack) = r {
1745 if pack != repr.pack {
1746 struct_span_err!(tcx.sess, sp, E0634,
1747 "type has conflicting packed representation hints").emit();
1753 struct_span_err!(tcx.sess, sp, E0587,
1754 "type has conflicting packed and align representation hints").emit();
1756 else if check_packed_inner(tcx, def_id, &mut Vec::new()) {
1757 struct_span_err!(tcx.sess, sp, E0588,
1758 "packed type cannot transitively contain a `[repr(align)]` type").emit();
1763 fn check_packed_inner<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, stack: &mut Vec<DefId>) -> bool {
1764 let t = tcx.type_of(def_id);
1765 if stack.contains(&def_id) {
1766 debug!("check_packed_inner: {:?} is recursive", t);
1769 if let ty::Adt(def, substs) = t.sty {
1770 if def.is_struct() || def.is_union() {
1771 if tcx.adt_def(def.did).repr.align > 0 {
1774 // push struct def_id before checking fields
1776 for field in &def.non_enum_variant().fields {
1777 let f = field.ty(tcx, substs);
1778 if let ty::Adt(def, _) = f.sty {
1779 if check_packed_inner(tcx, def.did, stack) {
1784 // only need to pop if not early out
1791 fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, def_id: DefId) {
1792 let adt = tcx.adt_def(def_id);
1793 if !adt.repr.transparent() {
1798 if !tcx.features().transparent_enums {
1799 emit_feature_err(&tcx.sess.parse_sess,
1800 sym::transparent_enums,
1802 GateIssue::Language,
1803 "transparent enums are unstable");
1805 if adt.variants.len() != 1 {
1806 let variant_spans: Vec<_> = adt.variants.iter().map(|variant| {
1807 tcx.hir().span_if_local(variant.def_id).unwrap()
1809 let mut err = struct_span_err!(tcx.sess, sp, E0731,
1810 "transparent enum needs exactly one variant, but has {}",
1811 adt.variants.len());
1812 if !variant_spans.is_empty() {
1813 err.span_note(variant_spans, &format!("the following variants exist on `{}`",
1814 tcx.def_path_str(def_id)));
1817 if adt.variants.is_empty() {
1818 // Don't bother checking the fields. No variants (and thus no fields) exist.
1824 if adt.is_union() && !tcx.features().transparent_unions {
1825 emit_feature_err(&tcx.sess.parse_sess,
1826 sym::transparent_unions,
1828 GateIssue::Language,
1829 "transparent unions are unstable");
1832 // For each field, figure out if it's known to be a ZST and align(1)
1833 let field_infos = adt.all_fields().map(|field| {
1834 let ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, field.did));
1835 let param_env = tcx.param_env(field.did);
1836 let layout = tcx.layout_of(param_env.and(ty));
1837 // We are currently checking the type this field came from, so it must be local
1838 let span = tcx.hir().span_if_local(field.did).unwrap();
1839 let zst = layout.map(|layout| layout.is_zst()).unwrap_or(false);
1840 let align1 = layout.map(|layout| layout.align.abi.bytes() == 1).unwrap_or(false);
1844 let non_zst_fields = field_infos.clone().filter(|(_span, zst, _align1)| !*zst);
1845 let non_zst_count = non_zst_fields.clone().count();
1846 if non_zst_count != 1 {
1847 let field_spans: Vec<_> = non_zst_fields.map(|(span, _zst, _align1)| span).collect();
1849 let mut err = struct_span_err!(tcx.sess, sp, E0690,
1850 "{}transparent {} needs exactly one non-zero-sized field, but has {}",
1851 if adt.is_enum() { "the variant of a " } else { "" },
1854 if !field_spans.is_empty() {
1855 err.span_note(field_spans,
1856 &format!("the following non-zero-sized fields exist on `{}`:",
1857 tcx.def_path_str(def_id)));
1861 for (span, zst, align1) in field_infos {
1863 span_err!(tcx.sess, span, E0691,
1864 "zero-sized field in transparent {} has alignment larger than 1",
1870 #[allow(trivial_numeric_casts)]
1871 pub fn check_enum<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, vs: &'tcx [hir::Variant], id: hir::HirId) {
1872 let def_id = tcx.hir().local_def_id_from_hir_id(id);
1873 let def = tcx.adt_def(def_id);
1874 def.destructor(tcx); // force the destructor to be evaluated
1877 let attributes = tcx.get_attrs(def_id);
1878 if let Some(attr) = attr::find_by_name(&attributes, sym::repr) {
1880 tcx.sess, attr.span, E0084,
1881 "unsupported representation for zero-variant enum")
1882 .span_label(sp, "zero-variant enum")
1887 let repr_type_ty = def.repr.discr_type().to_ty(tcx);
1888 if repr_type_ty == tcx.types.i128 || repr_type_ty == tcx.types.u128 {
1889 if !tcx.features().repr128 {
1890 emit_feature_err(&tcx.sess.parse_sess,
1893 GateIssue::Language,
1894 "repr with 128-bit type is unstable");
1899 if let Some(ref e) = v.node.disr_expr {
1900 tcx.typeck_tables_of(tcx.hir().local_def_id_from_hir_id(e.hir_id));
1904 let mut disr_vals: Vec<Discr<'tcx>> = Vec::with_capacity(vs.len());
1905 for ((_, discr), v) in def.discriminants(tcx).zip(vs) {
1906 // Check for duplicate discriminant values
1907 if let Some(i) = disr_vals.iter().position(|&x| x.val == discr.val) {
1908 let variant_did = def.variants[VariantIdx::new(i)].def_id;
1909 let variant_i_hir_id = tcx.hir().as_local_hir_id(variant_did).unwrap();
1910 let variant_i = tcx.hir().expect_variant(variant_i_hir_id);
1911 let i_span = match variant_i.node.disr_expr {
1912 Some(ref expr) => tcx.hir().span(expr.hir_id),
1913 None => tcx.hir().span(variant_i_hir_id)
1915 let span = match v.node.disr_expr {
1916 Some(ref expr) => tcx.hir().span(expr.hir_id),
1919 struct_span_err!(tcx.sess, span, E0081,
1920 "discriminant value `{}` already exists", disr_vals[i])
1921 .span_label(i_span, format!("first use of `{}`", disr_vals[i]))
1922 .span_label(span , format!("enum already has `{}`", disr_vals[i]))
1925 disr_vals.push(discr);
1928 check_representable(tcx, sp, def_id);
1929 check_transparent(tcx, sp, def_id);
1932 fn report_unexpected_variant_res<'tcx>(tcx: TyCtxt<'tcx>, res: Res, span: Span, qpath: &QPath) {
1933 span_err!(tcx.sess, span, E0533,
1934 "expected unit struct/variant or constant, found {} `{}`",
1936 hir::print::to_string(tcx.hir(), |s| s.print_qpath(qpath, false)));
1939 impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
1940 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
1944 fn get_type_parameter_bounds(&self, _: Span, def_id: DefId)
1945 -> &'tcx ty::GenericPredicates<'tcx>
1948 let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
1949 let item_id = tcx.hir().ty_param_owner(hir_id);
1950 let item_def_id = tcx.hir().local_def_id_from_hir_id(item_id);
1951 let generics = tcx.generics_of(item_def_id);
1952 let index = generics.param_def_id_to_index[&def_id];
1953 tcx.arena.alloc(ty::GenericPredicates {
1955 predicates: self.param_env.caller_bounds.iter().filter_map(|&predicate| {
1957 ty::Predicate::Trait(ref data)
1958 if data.skip_binder().self_ty().is_param(index) => {
1959 // HACK(eddyb) should get the original `Span`.
1960 let span = tcx.def_span(def_id);
1961 Some((predicate, span))
1971 def: Option<&ty::GenericParamDef>,
1973 ) -> Option<ty::Region<'tcx>> {
1975 Some(def) => infer::EarlyBoundRegion(span, def.name),
1976 None => infer::MiscVariable(span)
1978 Some(self.next_region_var(v))
1981 fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
1982 if let Some(param) = param {
1983 if let UnpackedKind::Type(ty) = self.var_for_def(span, param).unpack() {
1988 self.next_ty_var(TypeVariableOrigin {
1989 kind: TypeVariableOriginKind::TypeInference,
1998 param: Option<&ty::GenericParamDef>,
2000 ) -> &'tcx Const<'tcx> {
2001 if let Some(param) = param {
2002 if let UnpackedKind::Const(ct) = self.var_for_def(span, param).unpack() {
2007 self.next_const_var(ty, ConstVariableOrigin {
2008 kind: ConstVariableOriginKind::ConstInference,
2014 fn projected_ty_from_poly_trait_ref(&self,
2017 poly_trait_ref: ty::PolyTraitRef<'tcx>)
2020 let (trait_ref, _) = self.replace_bound_vars_with_fresh_vars(
2022 infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id),
2026 self.tcx().mk_projection(item_def_id, trait_ref.substs)
2029 fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
2030 if ty.has_escaping_bound_vars() {
2031 ty // FIXME: normalization and escaping regions
2033 self.normalize_associated_types_in(span, &ty)
2037 fn set_tainted_by_errors(&self) {
2038 self.infcx.set_tainted_by_errors()
2041 fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) {
2042 self.write_ty(hir_id, ty)
2046 /// Controls whether the arguments are tupled. This is used for the call
2049 /// Tupling means that all call-side arguments are packed into a tuple and
2050 /// passed as a single parameter. For example, if tupling is enabled, this
2053 /// fn f(x: (isize, isize))
2055 /// Can be called as:
2062 #[derive(Clone, Eq, PartialEq)]
2063 enum TupleArgumentsFlag {
2068 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
2070 inh: &'a Inherited<'a, 'tcx>,
2071 param_env: ty::ParamEnv<'tcx>,
2072 body_id: hir::HirId,
2073 ) -> FnCtxt<'a, 'tcx> {
2077 err_count_on_creation: inh.tcx.sess.err_count(),
2079 ret_coercion_span: RefCell::new(None),
2081 ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal,
2082 hir::CRATE_HIR_ID)),
2083 diverges: Cell::new(Diverges::Maybe),
2084 has_errors: Cell::new(false),
2085 enclosing_breakables: RefCell::new(EnclosingBreakables {
2087 by_id: Default::default(),
2093 pub fn sess(&self) -> &Session {
2097 pub fn err_count_since_creation(&self) -> usize {
2098 self.tcx.sess.err_count() - self.err_count_on_creation
2101 /// Produces warning on the given node, if the current point in the
2102 /// function is unreachable, and there hasn't been another warning.
2103 fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) {
2104 if self.diverges.get() == Diverges::Always &&
2105 // If span arose from a desugaring of `if` then it is the condition itself,
2106 // which diverges, that we are about to lint on. This gives suboptimal diagnostics
2107 // and so we stop here and allow the block of the `if`-expression to be linted instead.
2108 !span.is_compiler_desugaring(CompilerDesugaringKind::IfTemporary) {
2109 self.diverges.set(Diverges::WarnedAlways);
2111 debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);
2113 let msg = format!("unreachable {}", kind);
2114 self.tcx().lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, &msg);
2120 code: ObligationCauseCode<'tcx>)
2121 -> ObligationCause<'tcx> {
2122 ObligationCause::new(span, self.body_id, code)
2125 pub fn misc(&self, span: Span) -> ObligationCause<'tcx> {
2126 self.cause(span, ObligationCauseCode::MiscObligation)
2129 /// Resolves type variables in `ty` if possible. Unlike the infcx
2130 /// version (resolve_vars_if_possible), this version will
2131 /// also select obligations if it seems useful, in an effort
2132 /// to get more type information.
2133 fn resolve_type_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
2134 debug!("resolve_type_vars_with_obligations(ty={:?})", ty);
2136 // No Infer()? Nothing needs doing.
2137 if !ty.has_infer_types() {
2138 debug!("resolve_type_vars_with_obligations: ty={:?}", ty);
2142 // If `ty` is a type variable, see whether we already know what it is.
2143 ty = self.resolve_vars_if_possible(&ty);
2144 if !ty.has_infer_types() {
2145 debug!("resolve_type_vars_with_obligations: ty={:?}", ty);
2149 // If not, try resolving pending obligations as much as
2150 // possible. This can help substantially when there are
2151 // indirect dependencies that don't seem worth tracking
2153 self.select_obligations_where_possible(false);
2154 ty = self.resolve_vars_if_possible(&ty);
2156 debug!("resolve_type_vars_with_obligations: ty={:?}", ty);
2160 fn record_deferred_call_resolution(
2162 closure_def_id: DefId,
2163 r: DeferredCallResolution<'tcx>,
2165 let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
2166 deferred_call_resolutions.entry(closure_def_id).or_default().push(r);
2169 fn remove_deferred_call_resolutions(
2171 closure_def_id: DefId,
2172 ) -> Vec<DeferredCallResolution<'tcx>> {
2173 let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut();
2174 deferred_call_resolutions.remove(&closure_def_id).unwrap_or(vec![])
2177 pub fn tag(&self) -> String {
2178 format!("{:p}", self)
2181 pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> {
2182 self.locals.borrow().get(&nid).cloned().unwrap_or_else(||
2183 span_bug!(span, "no type for local variable {}",
2184 self.tcx.hir().node_to_string(nid))
2189 pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) {
2190 debug!("write_ty({:?}, {:?}) in fcx {}",
2191 id, self.resolve_vars_if_possible(&ty), self.tag());
2192 self.tables.borrow_mut().node_types_mut().insert(id, ty);
2194 if ty.references_error() {
2195 self.has_errors.set(true);
2196 self.set_tainted_by_errors();
2200 pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) {
2201 self.tables.borrow_mut().field_indices_mut().insert(hir_id, index);
2204 fn write_resolution(&self, hir_id: hir::HirId, r: Result<(DefKind, DefId), ErrorReported>) {
2205 self.tables.borrow_mut().type_dependent_defs_mut().insert(hir_id, r);
2208 pub fn write_method_call(&self,
2210 method: MethodCallee<'tcx>) {
2211 debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method);
2212 self.write_resolution(hir_id, Ok((DefKind::Method, method.def_id)));
2213 self.write_substs(hir_id, method.substs);
2215 // When the method is confirmed, the `method.substs` includes
2216 // parameters from not just the method, but also the impl of
2217 // the method -- in particular, the `Self` type will be fully
2218 // resolved. However, those are not something that the "user
2219 // specified" -- i.e., those types come from the inferred type
2220 // of the receiver, not something the user wrote. So when we
2221 // create the user-substs, we want to replace those earlier
2222 // types with just the types that the user actually wrote --
2223 // that is, those that appear on the *method itself*.
2225 // As an example, if the user wrote something like
2226 // `foo.bar::<u32>(...)` -- the `Self` type here will be the
2227 // type of `foo` (possibly adjusted), but we don't want to
2228 // include that. We want just the `[_, u32]` part.
2229 if !method.substs.is_noop() {
2230 let method_generics = self.tcx.generics_of(method.def_id);
2231 if !method_generics.params.is_empty() {
2232 let user_type_annotation = self.infcx.probe(|_| {
2233 let user_substs = UserSubsts {
2234 substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| {
2235 let i = param.index as usize;
2236 if i < method_generics.parent_count {
2237 self.infcx.var_for_def(DUMMY_SP, param)
2242 user_self_ty: None, // not relevant here
2245 self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf(
2251 debug!("write_method_call: user_type_annotation={:?}", user_type_annotation);
2252 self.write_user_type_annotation(hir_id, user_type_annotation);
2257 pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) {
2258 if !substs.is_noop() {
2259 debug!("write_substs({:?}, {:?}) in fcx {}",
2264 self.tables.borrow_mut().node_substs_mut().insert(node_id, substs);
2268 /// Given the substs that we just converted from the HIR, try to
2269 /// canonicalize them and store them as user-given substitutions
2270 /// (i.e., substitutions that must be respected by the NLL check).
2272 /// This should be invoked **before any unifications have
2273 /// occurred**, so that annotations like `Vec<_>` are preserved
2275 pub fn write_user_type_annotation_from_substs(
2279 substs: SubstsRef<'tcx>,
2280 user_self_ty: Option<UserSelfTy<'tcx>>,
2283 "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \
2284 user_self_ty={:?} in fcx {}",
2285 hir_id, def_id, substs, user_self_ty, self.tag(),
2288 if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) {
2289 let canonicalized = self.infcx.canonicalize_user_type_annotation(
2290 &UserType::TypeOf(def_id, UserSubsts {
2295 debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized);
2296 self.write_user_type_annotation(hir_id, canonicalized);
2300 pub fn write_user_type_annotation(
2303 canonical_user_type_annotation: CanonicalUserType<'tcx>,
2306 "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}",
2307 hir_id, canonical_user_type_annotation, self.tag(),
2310 if !canonical_user_type_annotation.is_identity() {
2311 self.tables.borrow_mut().user_provided_types_mut().insert(
2312 hir_id, canonical_user_type_annotation
2315 debug!("write_user_type_annotation: skipping identity substs");
2319 pub fn apply_adjustments(&self, expr: &hir::Expr, adj: Vec<Adjustment<'tcx>>) {
2320 debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj);
2326 match self.tables.borrow_mut().adjustments_mut().entry(expr.hir_id) {
2327 Entry::Vacant(entry) => { entry.insert(adj); },
2328 Entry::Occupied(mut entry) => {
2329 debug!(" - composing on top of {:?}", entry.get());
2330 match (&entry.get()[..], &adj[..]) {
2331 // Applying any adjustment on top of a NeverToAny
2332 // is a valid NeverToAny adjustment, because it can't
2334 (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return,
2336 Adjustment { kind: Adjust::Deref(_), .. },
2337 Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. },
2339 Adjustment { kind: Adjust::Deref(_), .. },
2340 .. // Any following adjustments are allowed.
2342 // A reborrow has no effect before a dereference.
2344 // FIXME: currently we never try to compose autoderefs
2345 // and ReifyFnPointer/UnsafeFnPointer, but we could.
2347 bug!("while adjusting {:?}, can't compose {:?} and {:?}",
2348 expr, entry.get(), adj)
2350 *entry.get_mut() = adj;
2355 /// Basically whenever we are converting from a type scheme into
2356 /// the fn body space, we always want to normalize associated
2357 /// types as well. This function combines the two.
2358 fn instantiate_type_scheme<T>(&self,
2360 substs: SubstsRef<'tcx>,
2363 where T : TypeFoldable<'tcx>
2365 let value = value.subst(self.tcx, substs);
2366 let result = self.normalize_associated_types_in(span, &value);
2367 debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}",
2374 /// As `instantiate_type_scheme`, but for the bounds found in a
2375 /// generic type scheme.
2376 fn instantiate_bounds(&self, span: Span, def_id: DefId, substs: SubstsRef<'tcx>)
2377 -> ty::InstantiatedPredicates<'tcx> {
2378 let bounds = self.tcx.predicates_of(def_id);
2379 let result = bounds.instantiate(self.tcx, substs);
2380 let result = self.normalize_associated_types_in(span, &result);
2381 debug!("instantiate_bounds(bounds={:?}, substs={:?}) = {:?}",
2388 /// Replaces the opaque types from the given value with type variables,
2389 /// and records the `OpaqueTypeMap` for later use during writeback. See
2390 /// `InferCtxt::instantiate_opaque_types` for more details.
2391 fn instantiate_opaque_types_from_value<T: TypeFoldable<'tcx>>(
2393 parent_id: hir::HirId,
2396 let parent_def_id = self.tcx.hir().local_def_id_from_hir_id(parent_id);
2397 debug!("instantiate_opaque_types_from_value(parent_def_id={:?}, value={:?})",
2401 let (value, opaque_type_map) = self.register_infer_ok_obligations(
2402 self.instantiate_opaque_types(
2410 let mut opaque_types = self.opaque_types.borrow_mut();
2411 for (ty, decl) in opaque_type_map {
2412 let old_value = opaque_types.insert(ty, decl);
2413 assert!(old_value.is_none(), "instantiated twice: {:?}/{:?}", ty, decl);
2419 fn normalize_associated_types_in<T>(&self, span: Span, value: &T) -> T
2420 where T : TypeFoldable<'tcx>
2422 self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value)
2425 fn normalize_associated_types_in_as_infer_ok<T>(&self, span: Span, value: &T)
2427 where T : TypeFoldable<'tcx>
2429 self.inh.partially_normalize_associated_types_in(span,
2435 pub fn require_type_meets(&self,
2438 code: traits::ObligationCauseCode<'tcx>,
2441 self.register_bound(
2444 traits::ObligationCause::new(span, self.body_id, code));
2447 pub fn require_type_is_sized(&self,
2450 code: traits::ObligationCauseCode<'tcx>)
2452 let lang_item = self.tcx.require_lang_item(lang_items::SizedTraitLangItem);
2453 self.require_type_meets(ty, span, code, lang_item);
2456 pub fn require_type_is_sized_deferred(&self,
2459 code: traits::ObligationCauseCode<'tcx>)
2461 self.deferred_sized_obligations.borrow_mut().push((ty, span, code));
2464 pub fn register_bound(&self,
2467 cause: traits::ObligationCause<'tcx>)
2469 self.fulfillment_cx.borrow_mut()
2470 .register_bound(self, self.param_env, ty, def_id, cause);
2473 pub fn to_ty(&self, ast_t: &hir::Ty) -> Ty<'tcx> {
2474 let t = AstConv::ast_ty_to_ty(self, ast_t);
2475 self.register_wf_obligation(t, ast_t.span, traits::MiscObligation);
2479 pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
2480 let ty = self.to_ty(ast_ty);
2481 debug!("to_ty_saving_user_provided_ty: ty={:?}", ty);
2483 if Self::can_contain_user_lifetime_bounds(ty) {
2484 let c_ty = self.infcx.canonicalize_response(&UserType::Ty(ty));
2485 debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty);
2486 self.tables.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty);
2492 /// Returns the `DefId` of the constant parameter that the provided expression is a path to.
2493 pub fn const_param_def_id(&self, hir_c: &hir::AnonConst) -> Option<DefId> {
2494 AstConv::const_param_def_id(self, &self.tcx.hir().body(hir_c.body).value)
2497 pub fn to_const(&self, ast_c: &hir::AnonConst, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> {
2498 AstConv::ast_const_to_const(self, ast_c, ty)
2501 // If the type given by the user has free regions, save it for later, since
2502 // NLL would like to enforce those. Also pass in types that involve
2503 // projections, since those can resolve to `'static` bounds (modulo #54940,
2504 // which hopefully will be fixed by the time you see this comment, dear
2505 // reader, although I have my doubts). Also pass in types with inference
2506 // types, because they may be repeated. Other sorts of things are already
2507 // sufficiently enforced with erased regions. =)
2508 fn can_contain_user_lifetime_bounds<T>(t: T) -> bool
2510 T: TypeFoldable<'tcx>
2512 t.has_free_regions() || t.has_projections() || t.has_infer_types()
2515 pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> {
2516 match self.tables.borrow().node_types().get(id) {
2518 None if self.is_tainted_by_errors() => self.tcx.types.err,
2520 bug!("no type for node {}: {} in fcx {}",
2521 id, self.tcx.hir().node_to_string(id),
2527 /// Registers an obligation for checking later, during regionck, that the type `ty` must
2528 /// outlive the region `r`.
2529 pub fn register_wf_obligation(&self,
2532 code: traits::ObligationCauseCode<'tcx>)
2534 // WF obligations never themselves fail, so no real need to give a detailed cause:
2535 let cause = traits::ObligationCause::new(span, self.body_id, code);
2536 self.register_predicate(traits::Obligation::new(cause,
2538 ty::Predicate::WellFormed(ty)));
2541 /// Registers obligations that all types appearing in `substs` are well-formed.
2542 pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr) {
2543 for ty in substs.types() {
2544 self.register_wf_obligation(ty, expr.span, traits::MiscObligation);
2548 /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each
2549 /// type/region parameter was instantiated (`substs`), creates and registers suitable
2550 /// trait/region obligations.
2552 /// For example, if there is a function:
2555 /// fn foo<'a,T:'a>(...)
2558 /// and a reference:
2564 /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a`
2565 /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally.
2566 pub fn add_obligations_for_parameters(&self,
2567 cause: traits::ObligationCause<'tcx>,
2568 predicates: &ty::InstantiatedPredicates<'tcx>)
2570 assert!(!predicates.has_escaping_bound_vars());
2572 debug!("add_obligations_for_parameters(predicates={:?})",
2575 for obligation in traits::predicates_for_generics(cause, self.param_env, predicates) {
2576 self.register_predicate(obligation);
2580 // FIXME(arielb1): use this instead of field.ty everywhere
2581 // Only for fields! Returns <none> for methods>
2582 // Indifferent to privacy flags
2583 pub fn field_ty(&self,
2585 field: &'tcx ty::FieldDef,
2586 substs: SubstsRef<'tcx>)
2589 self.normalize_associated_types_in(span, &field.ty(self.tcx, substs))
2592 fn check_casts(&self) {
2593 let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
2594 for cast in deferred_cast_checks.drain(..) {
2599 fn resolve_generator_interiors(&self, def_id: DefId) {
2600 let mut generators = self.deferred_generator_interiors.borrow_mut();
2601 for (body_id, interior) in generators.drain(..) {
2602 self.select_obligations_where_possible(false);
2603 generator_interior::resolve_interior(self, def_id, body_id, interior);
2607 // Tries to apply a fallback to `ty` if it is an unsolved variable.
2608 // Non-numerics get replaced with ! or () (depending on whether
2609 // feature(never_type) is enabled, unconstrained ints with i32,
2610 // unconstrained floats with f64.
2611 // Fallback becomes very dubious if we have encountered type-checking errors.
2612 // In that case, fallback to Error.
2613 // The return value indicates whether fallback has occurred.
2614 fn fallback_if_possible(&self, ty: Ty<'tcx>) -> bool {
2615 use rustc::ty::error::UnconstrainedNumeric::Neither;
2616 use rustc::ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat};
2618 assert!(ty.is_ty_infer());
2619 let fallback = match self.type_is_unconstrained_numeric(ty) {
2620 _ if self.is_tainted_by_errors() => self.tcx().types.err,
2621 UnconstrainedInt => self.tcx.types.i32,
2622 UnconstrainedFloat => self.tcx.types.f64,
2623 Neither if self.type_var_diverges(ty) => self.tcx.mk_diverging_default(),
2624 Neither => return false,
2626 debug!("fallback_if_possible: defaulting `{:?}` to `{:?}`", ty, fallback);
2627 self.demand_eqtype(syntax_pos::DUMMY_SP, ty, fallback);
2631 fn select_all_obligations_or_error(&self) {
2632 debug!("select_all_obligations_or_error");
2633 if let Err(errors) = self.fulfillment_cx.borrow_mut().select_all_or_error(&self) {
2634 self.report_fulfillment_errors(&errors, self.inh.body_id, false);
2638 /// Select as many obligations as we can at present.
2639 fn select_obligations_where_possible(&self, fallback_has_occurred: bool) {
2640 if let Err(errors) = self.fulfillment_cx.borrow_mut().select_where_possible(self) {
2641 self.report_fulfillment_errors(&errors, self.inh.body_id, fallback_has_occurred);
2645 /// For the overloaded place expressions (`*x`, `x[3]`), the trait
2646 /// returns a type of `&T`, but the actual type we assign to the
2647 /// *expression* is `T`. So this function just peels off the return
2648 /// type by one layer to yield `T`.
2649 fn make_overloaded_place_return_type(&self,
2650 method: MethodCallee<'tcx>)
2651 -> ty::TypeAndMut<'tcx>
2653 // extract method return type, which will be &T;
2654 let ret_ty = method.sig.output();
2656 // method returns &T, but the type as visible to user is T, so deref
2657 ret_ty.builtin_deref(true).unwrap()
2663 base_expr: &'tcx hir::Expr,
2667 ) -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)> {
2668 // FIXME(#18741) -- this is almost but not quite the same as the
2669 // autoderef that normal method probing does. They could likely be
2672 let mut autoderef = self.autoderef(base_expr.span, base_ty);
2673 let mut result = None;
2674 while result.is_none() && autoderef.next().is_some() {
2675 result = self.try_index_step(expr, base_expr, &autoderef, needs, idx_ty);
2677 autoderef.finalize(self);
2681 /// To type-check `base_expr[index_expr]`, we progressively autoderef
2682 /// (and otherwise adjust) `base_expr`, looking for a type which either
2683 /// supports builtin indexing or overloaded indexing.
2684 /// This loop implements one step in that search; the autoderef loop
2685 /// is implemented by `lookup_indexing`.
2689 base_expr: &hir::Expr,
2690 autoderef: &Autoderef<'a, 'tcx>,
2693 ) -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)> {
2694 let adjusted_ty = autoderef.unambiguous_final_ty(self);
2695 debug!("try_index_step(expr={:?}, base_expr={:?}, adjusted_ty={:?}, \
2702 for &unsize in &[false, true] {
2703 let mut self_ty = adjusted_ty;
2705 // We only unsize arrays here.
2706 if let ty::Array(element_ty, _) = adjusted_ty.sty {
2707 self_ty = self.tcx.mk_slice(element_ty);
2713 // If some lookup succeeds, write callee into table and extract index/element
2714 // type from the method signature.
2715 // If some lookup succeeded, install method in table
2716 let input_ty = self.next_ty_var(TypeVariableOrigin {
2717 kind: TypeVariableOriginKind::AutoDeref,
2718 span: base_expr.span,
2720 let method = self.try_overloaded_place_op(
2721 expr.span, self_ty, &[input_ty], needs, PlaceOp::Index);
2723 let result = method.map(|ok| {
2724 debug!("try_index_step: success, using overloaded indexing");
2725 let method = self.register_infer_ok_obligations(ok);
2727 let mut adjustments = autoderef.adjust_steps(self, needs);
2728 if let ty::Ref(region, _, r_mutbl) = method.sig.inputs()[0].sty {
2729 let mutbl = match r_mutbl {
2730 hir::MutImmutable => AutoBorrowMutability::Immutable,
2731 hir::MutMutable => AutoBorrowMutability::Mutable {
2732 // Indexing can be desugared to a method call,
2733 // so maybe we could use two-phase here.
2734 // See the documentation of AllowTwoPhase for why that's
2735 // not the case today.
2736 allow_two_phase_borrow: AllowTwoPhase::No,
2739 adjustments.push(Adjustment {
2740 kind: Adjust::Borrow(AutoBorrow::Ref(region, mutbl)),
2741 target: self.tcx.mk_ref(region, ty::TypeAndMut {
2748 adjustments.push(Adjustment {
2749 kind: Adjust::Pointer(PointerCast::Unsize),
2750 target: method.sig.inputs()[0]
2753 self.apply_adjustments(base_expr, adjustments);
2755 self.write_method_call(expr.hir_id, method);
2756 (input_ty, self.make_overloaded_place_return_type(method).ty)
2758 if result.is_some() {
2766 fn resolve_place_op(&self, op: PlaceOp, is_mut: bool) -> (Option<DefId>, ast::Ident) {
2767 let (tr, name) = match (op, is_mut) {
2768 (PlaceOp::Deref, false) => (self.tcx.lang_items().deref_trait(), sym::deref),
2769 (PlaceOp::Deref, true) => (self.tcx.lang_items().deref_mut_trait(), sym::deref_mut),
2770 (PlaceOp::Index, false) => (self.tcx.lang_items().index_trait(), sym::index),
2771 (PlaceOp::Index, true) => (self.tcx.lang_items().index_mut_trait(), sym::index_mut),
2773 (tr, ast::Ident::with_empty_ctxt(name))
2776 fn try_overloaded_place_op(&self,
2779 arg_tys: &[Ty<'tcx>],
2782 -> Option<InferOk<'tcx, MethodCallee<'tcx>>>
2784 debug!("try_overloaded_place_op({:?},{:?},{:?},{:?})",
2790 // Try Mut first, if needed.
2791 let (mut_tr, mut_op) = self.resolve_place_op(op, true);
2792 let method = match (needs, mut_tr) {
2793 (Needs::MutPlace, Some(trait_did)) => {
2794 self.lookup_method_in_trait(span, mut_op, trait_did, base_ty, Some(arg_tys))
2799 // Otherwise, fall back to the immutable version.
2800 let (imm_tr, imm_op) = self.resolve_place_op(op, false);
2801 let method = match (method, imm_tr) {
2802 (None, Some(trait_did)) => {
2803 self.lookup_method_in_trait(span, imm_op, trait_did, base_ty, Some(arg_tys))
2805 (method, _) => method,
2811 fn check_method_argument_types(
2815 method: Result<MethodCallee<'tcx>, ()>,
2816 args_no_rcvr: &'tcx [hir::Expr],
2817 tuple_arguments: TupleArgumentsFlag,
2818 expected: Expectation<'tcx>,
2820 let has_error = match method {
2822 method.substs.references_error() || method.sig.references_error()
2827 let err_inputs = self.err_args(args_no_rcvr.len());
2829 let err_inputs = match tuple_arguments {
2830 DontTupleArguments => err_inputs,
2831 TupleArguments => vec![self.tcx.intern_tup(&err_inputs[..])],
2834 self.check_argument_types(sp, expr_sp, &err_inputs[..], &[], args_no_rcvr,
2835 false, tuple_arguments, None);
2836 return self.tcx.types.err;
2839 let method = method.unwrap();
2840 // HACK(eddyb) ignore self in the definition (see above).
2841 let expected_arg_tys = self.expected_inputs_for_expected_output(
2844 method.sig.output(),
2845 &method.sig.inputs()[1..]
2847 self.check_argument_types(sp, expr_sp, &method.sig.inputs()[1..], &expected_arg_tys[..],
2848 args_no_rcvr, method.sig.c_variadic, tuple_arguments,
2849 self.tcx.hir().span_if_local(method.def_id));
2853 fn self_type_matches_expected_vid(
2855 trait_ref: ty::PolyTraitRef<'tcx>,
2856 expected_vid: ty::TyVid,
2858 let self_ty = self.shallow_resolve(trait_ref.self_ty());
2860 "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})",
2861 trait_ref, self_ty, expected_vid
2864 ty::Infer(ty::TyVar(found_vid)) => {
2865 // FIXME: consider using `sub_root_var` here so we
2866 // can see through subtyping.
2867 let found_vid = self.root_var(found_vid);
2868 debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid);
2869 expected_vid == found_vid
2875 fn obligations_for_self_ty<'b>(
2878 ) -> impl Iterator<Item = (ty::PolyTraitRef<'tcx>, traits::PredicateObligation<'tcx>)>
2881 // FIXME: consider using `sub_root_var` here so we
2882 // can see through subtyping.
2883 let ty_var_root = self.root_var(self_ty);
2884 debug!("obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}",
2885 self_ty, ty_var_root,
2886 self.fulfillment_cx.borrow().pending_obligations());
2890 .pending_obligations()
2892 .filter_map(move |obligation| match obligation.predicate {
2893 ty::Predicate::Projection(ref data) =>
2894 Some((data.to_poly_trait_ref(self.tcx), obligation)),
2895 ty::Predicate::Trait(ref data) =>
2896 Some((data.to_poly_trait_ref(), obligation)),
2897 ty::Predicate::Subtype(..) => None,
2898 ty::Predicate::RegionOutlives(..) => None,
2899 ty::Predicate::TypeOutlives(..) => None,
2900 ty::Predicate::WellFormed(..) => None,
2901 ty::Predicate::ObjectSafe(..) => None,
2902 ty::Predicate::ConstEvaluatable(..) => None,
2903 // N.B., this predicate is created by breaking down a
2904 // `ClosureType: FnFoo()` predicate, where
2905 // `ClosureType` represents some `Closure`. It can't
2906 // possibly be referring to the current closure,
2907 // because we haven't produced the `Closure` for
2908 // this closure yet; this is exactly why the other
2909 // code is looking for a self type of a unresolved
2910 // inference variable.
2911 ty::Predicate::ClosureKind(..) => None,
2912 }).filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root))
2915 fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool {
2916 self.obligations_for_self_ty(self_ty).any(|(tr, _)| {
2917 Some(tr.def_id()) == self.tcx.lang_items().sized_trait()
2921 /// Generic function that factors out common logic from function calls,
2922 /// method calls and overloaded operators.
2923 fn check_argument_types(
2927 fn_inputs: &[Ty<'tcx>],
2928 expected_arg_tys: &[Ty<'tcx>],
2929 args: &'tcx [hir::Expr],
2931 tuple_arguments: TupleArgumentsFlag,
2932 def_span: Option<Span>,
2936 // Grab the argument types, supplying fresh type variables
2937 // if the wrong number of arguments were supplied
2938 let supplied_arg_count = if tuple_arguments == DontTupleArguments {
2944 // All the input types from the fn signature must outlive the call
2945 // so as to validate implied bounds.
2946 for &fn_input_ty in fn_inputs {
2947 self.register_wf_obligation(fn_input_ty, sp, traits::MiscObligation);
2950 let expected_arg_count = fn_inputs.len();
2952 let param_count_error = |expected_count: usize,
2957 let mut err = tcx.sess.struct_span_err_with_code(sp,
2958 &format!("this function takes {}{} but {} {} supplied",
2959 if c_variadic { "at least " } else { "" },
2960 potentially_plural_count(expected_count, "parameter"),
2961 potentially_plural_count(arg_count, "parameter"),
2962 if arg_count == 1 {"was"} else {"were"}),
2963 DiagnosticId::Error(error_code.to_owned()));
2965 if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().def_span(sp)) {
2966 err.span_label(def_s, "defined here");
2969 let sugg_span = tcx.sess.source_map().end_point(expr_sp);
2970 // remove closing `)` from the span
2971 let sugg_span = sugg_span.shrink_to_lo();
2972 err.span_suggestion(
2974 "expected the unit value `()`; create it with empty parentheses",
2976 Applicability::MachineApplicable);
2978 err.span_label(sp, format!("expected {}{}",
2979 if c_variadic { "at least " } else { "" },
2980 potentially_plural_count(expected_count, "parameter")));
2985 let mut expected_arg_tys = expected_arg_tys.to_vec();
2987 let formal_tys = if tuple_arguments == TupleArguments {
2988 let tuple_type = self.structurally_resolved_type(sp, fn_inputs[0]);
2989 match tuple_type.sty {
2990 ty::Tuple(arg_types) if arg_types.len() != args.len() => {
2991 param_count_error(arg_types.len(), args.len(), "E0057", false, false);
2992 expected_arg_tys = vec![];
2993 self.err_args(args.len())
2995 ty::Tuple(arg_types) => {
2996 expected_arg_tys = match expected_arg_tys.get(0) {
2997 Some(&ty) => match ty.sty {
2998 ty::Tuple(ref tys) => tys.iter().map(|k| k.expect_ty()).collect(),
3003 arg_types.iter().map(|k| k.expect_ty()).collect()
3006 span_err!(tcx.sess, sp, E0059,
3007 "cannot use call notation; the first type parameter \
3008 for the function trait is neither a tuple nor unit");
3009 expected_arg_tys = vec![];
3010 self.err_args(args.len())
3013 } else if expected_arg_count == supplied_arg_count {
3015 } else if c_variadic {
3016 if supplied_arg_count >= expected_arg_count {
3019 param_count_error(expected_arg_count, supplied_arg_count, "E0060", true, false);
3020 expected_arg_tys = vec![];
3021 self.err_args(supplied_arg_count)
3024 // is the missing argument of type `()`?
3025 let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 {
3026 self.resolve_vars_if_possible(&expected_arg_tys[0]).is_unit()
3027 } else if fn_inputs.len() == 1 && supplied_arg_count == 0 {
3028 self.resolve_vars_if_possible(&fn_inputs[0]).is_unit()
3032 param_count_error(expected_arg_count, supplied_arg_count, "E0061", false, sugg_unit);
3034 expected_arg_tys = vec![];
3035 self.err_args(supplied_arg_count)
3038 debug!("check_argument_types: formal_tys={:?}",
3039 formal_tys.iter().map(|t| self.ty_to_string(*t)).collect::<Vec<String>>());
3041 // If there is no expectation, expect formal_tys.
3042 let expected_arg_tys = if !expected_arg_tys.is_empty() {
3048 // Check the arguments.
3049 // We do this in a pretty awful way: first we type-check any arguments
3050 // that are not closures, then we type-check the closures. This is so
3051 // that we have more information about the types of arguments when we
3052 // type-check the functions. This isn't really the right way to do this.
3053 for &check_closures in &[false, true] {
3054 debug!("check_closures={}", check_closures);
3056 // More awful hacks: before we check argument types, try to do
3057 // an "opportunistic" vtable resolution of any trait bounds on
3058 // the call. This helps coercions.
3060 self.select_obligations_where_possible(false);
3063 // For C-variadic functions, we don't have a declared type for all of
3064 // the arguments hence we only do our usual type checking with
3065 // the arguments who's types we do know.
3066 let t = if c_variadic {
3068 } else if tuple_arguments == TupleArguments {
3073 for (i, arg) in args.iter().take(t).enumerate() {
3074 // Warn only for the first loop (the "no closures" one).
3075 // Closure arguments themselves can't be diverging, but
3076 // a previous argument can, e.g., `foo(panic!(), || {})`.
3077 if !check_closures {
3078 self.warn_if_unreachable(arg.hir_id, arg.span, "expression");
3081 let is_closure = match arg.node {
3082 ExprKind::Closure(..) => true,
3086 if is_closure != check_closures {
3090 debug!("checking the argument");
3091 let formal_ty = formal_tys[i];
3093 // The special-cased logic below has three functions:
3094 // 1. Provide as good of an expected type as possible.
3095 let expected = Expectation::rvalue_hint(self, expected_arg_tys[i]);
3097 let checked_ty = self.check_expr_with_expectation(&arg, expected);
3099 // 2. Coerce to the most detailed type that could be coerced
3100 // to, which is `expected_ty` if `rvalue_hint` returns an
3101 // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
3102 let coerce_ty = expected.only_has_type(self).unwrap_or(formal_ty);
3103 // We're processing function arguments so we definitely want to use
3104 // two-phase borrows.
3105 self.demand_coerce(&arg, checked_ty, coerce_ty, AllowTwoPhase::Yes);
3107 // 3. Relate the expected type and the formal one,
3108 // if the expected type was used for the coercion.
3109 self.demand_suptype(arg.span, formal_ty, coerce_ty);
3113 // We also need to make sure we at least write the ty of the other
3114 // arguments which we skipped above.
3116 fn variadic_error<'tcx>(s: &Session, span: Span, t: Ty<'tcx>, cast_ty: &str) {
3117 use crate::structured_errors::{VariadicError, StructuredDiagnostic};
3118 VariadicError::new(s, span, t, cast_ty).diagnostic().emit();
3121 for arg in args.iter().skip(expected_arg_count) {
3122 let arg_ty = self.check_expr(&arg);
3124 // There are a few types which get autopromoted when passed via varargs
3125 // in C but we just error out instead and require explicit casts.
3126 let arg_ty = self.structurally_resolved_type(arg.span, arg_ty);
3128 ty::Float(ast::FloatTy::F32) => {
3129 variadic_error(tcx.sess, arg.span, arg_ty, "c_double");
3131 ty::Int(ast::IntTy::I8) | ty::Int(ast::IntTy::I16) | ty::Bool => {
3132 variadic_error(tcx.sess, arg.span, arg_ty, "c_int");
3134 ty::Uint(ast::UintTy::U8) | ty::Uint(ast::UintTy::U16) => {
3135 variadic_error(tcx.sess, arg.span, arg_ty, "c_uint");
3138 let ptr_ty = self.tcx.mk_fn_ptr(arg_ty.fn_sig(self.tcx));
3139 let ptr_ty = self.resolve_vars_if_possible(&ptr_ty);
3140 variadic_error(tcx.sess, arg.span, arg_ty, &ptr_ty.to_string());
3148 fn err_args(&self, len: usize) -> Vec<Ty<'tcx>> {
3149 vec![self.tcx.types.err; len]
3152 // AST fragment checking
3155 expected: Expectation<'tcx>)
3161 ast::LitKind::Str(..) => tcx.mk_static_str(),
3162 ast::LitKind::ByteStr(ref v) => {
3163 tcx.mk_imm_ref(tcx.lifetimes.re_static,
3164 tcx.mk_array(tcx.types.u8, v.len() as u64))
3166 ast::LitKind::Byte(_) => tcx.types.u8,
3167 ast::LitKind::Char(_) => tcx.types.char,
3168 ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t),
3169 ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t),
3170 ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => {
3171 let opt_ty = expected.to_option(self).and_then(|ty| {
3173 ty::Int(_) | ty::Uint(_) => Some(ty),
3174 ty::Char => Some(tcx.types.u8),
3175 ty::RawPtr(..) => Some(tcx.types.usize),
3176 ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize),
3180 opt_ty.unwrap_or_else(|| self.next_int_var())
3182 ast::LitKind::Float(_, t) => tcx.mk_mach_float(t),
3183 ast::LitKind::FloatUnsuffixed(_) => {
3184 let opt_ty = expected.to_option(self).and_then(|ty| {
3186 ty::Float(_) => Some(ty),
3190 opt_ty.unwrap_or_else(|| self.next_float_var())
3192 ast::LitKind::Bool(_) => tcx.types.bool,
3193 ast::LitKind::Err(_) => tcx.types.err,
3197 // Determine the `Self` type, using fresh variables for all variables
3198 // declared on the impl declaration e.g., `impl<A,B> for Vec<(A,B)>`
3199 // would return `($0, $1)` where `$0` and `$1` are freshly instantiated type
3201 pub fn impl_self_ty(&self,
3202 span: Span, // (potential) receiver for this impl
3204 -> TypeAndSubsts<'tcx> {
3205 let ity = self.tcx.type_of(did);
3206 debug!("impl_self_ty: ity={:?}", ity);
3208 let substs = self.fresh_substs_for_item(span, did);
3209 let substd_ty = self.instantiate_type_scheme(span, &substs, &ity);
3211 TypeAndSubsts { substs: substs, ty: substd_ty }
3214 /// Unifies the output type with the expected type early, for more coercions
3215 /// and forward type information on the input expressions.
3216 fn expected_inputs_for_expected_output(&self,
3218 expected_ret: Expectation<'tcx>,
3219 formal_ret: Ty<'tcx>,
3220 formal_args: &[Ty<'tcx>])
3222 let formal_ret = self.resolve_type_vars_with_obligations(formal_ret);
3223 let ret_ty = match expected_ret.only_has_type(self) {
3225 None => return Vec::new()
3227 let expect_args = self.fudge_inference_if_ok(|| {
3228 // Attempt to apply a subtyping relationship between the formal
3229 // return type (likely containing type variables if the function
3230 // is polymorphic) and the expected return type.
3231 // No argument expectations are produced if unification fails.
3232 let origin = self.misc(call_span);
3233 let ures = self.at(&origin, self.param_env).sup(ret_ty, &formal_ret);
3235 // FIXME(#27336) can't use ? here, Try::from_error doesn't default
3236 // to identity so the resulting type is not constrained.
3239 // Process any obligations locally as much as
3240 // we can. We don't care if some things turn
3241 // out unconstrained or ambiguous, as we're
3242 // just trying to get hints here.
3243 self.save_and_restore_in_snapshot_flag(|_| {
3244 let mut fulfill = TraitEngine::new(self.tcx);
3245 for obligation in ok.obligations {
3246 fulfill.register_predicate_obligation(self, obligation);
3248 fulfill.select_where_possible(self)
3249 }).map_err(|_| ())?;
3251 Err(_) => return Err(()),
3254 // Record all the argument types, with the substitutions
3255 // produced from the above subtyping unification.
3256 Ok(formal_args.iter().map(|ty| {
3257 self.resolve_vars_if_possible(ty)
3259 }).unwrap_or_default();
3260 debug!("expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})",
3261 formal_args, formal_ret,
3262 expect_args, expected_ret);
3266 pub fn check_struct_path(&self,
3269 -> Option<(&'tcx ty::VariantDef, Ty<'tcx>)> {
3270 let path_span = match *qpath {
3271 QPath::Resolved(_, ref path) => path.span,
3272 QPath::TypeRelative(ref qself, _) => qself.span
3274 let (def, ty) = self.finish_resolving_struct_path(qpath, path_span, hir_id);
3275 let variant = match def {
3277 self.set_tainted_by_errors();
3280 Res::Def(DefKind::Variant, _) => {
3282 ty::Adt(adt, substs) => {
3283 Some((adt.variant_of_res(def), adt.did, substs))
3285 _ => bug!("unexpected type: {:?}", ty)
3288 Res::Def(DefKind::Struct, _)
3289 | Res::Def(DefKind::Union, _)
3290 | Res::Def(DefKind::TyAlias, _)
3291 | Res::Def(DefKind::AssocTy, _)
3292 | Res::SelfTy(..) => {
3294 ty::Adt(adt, substs) if !adt.is_enum() => {
3295 Some((adt.non_enum_variant(), adt.did, substs))
3300 _ => bug!("unexpected definition: {:?}", def)
3303 if let Some((variant, did, substs)) = variant {
3304 debug!("check_struct_path: did={:?} substs={:?}", did, substs);
3305 self.write_user_type_annotation_from_substs(hir_id, did, substs, None);
3307 // Check bounds on type arguments used in the path.
3308 let bounds = self.instantiate_bounds(path_span, did, substs);
3309 let cause = traits::ObligationCause::new(path_span, self.body_id,
3310 traits::ItemObligation(did));
3311 self.add_obligations_for_parameters(cause, &bounds);
3315 struct_span_err!(self.tcx.sess, path_span, E0071,
3316 "expected struct, variant or union type, found {}",
3317 ty.sort_string(self.tcx))
3318 .span_label(path_span, "not a struct")
3324 // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary.
3325 // The newly resolved definition is written into `type_dependent_defs`.
3326 fn finish_resolving_struct_path(&self,
3333 QPath::Resolved(ref maybe_qself, ref path) => {
3334 let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself));
3335 let ty = AstConv::res_to_ty(self, self_ty, path, true);
3338 QPath::TypeRelative(ref qself, ref segment) => {
3339 let ty = self.to_ty(qself);
3341 let res = if let hir::TyKind::Path(QPath::Resolved(_, ref path)) = qself.node {
3346 let result = AstConv::associated_path_to_ty(
3355 let ty = result.map(|(ty, _, _)| ty).unwrap_or(self.tcx().types.err);
3356 let result = result.map(|(_, kind, def_id)| (kind, def_id));
3358 // Write back the new resolution.
3359 self.write_resolution(hir_id, result);
3361 (result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), ty)
3366 /// Resolves an associated value path into a base type and associated constant, or method
3367 /// resolution. The newly resolved definition is written into `type_dependent_defs`.
3368 pub fn resolve_ty_and_res_ufcs<'b>(&self,
3372 -> (Res, Option<Ty<'tcx>>, &'b [hir::PathSegment])
3374 debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span);
3375 let (ty, qself, item_segment) = match *qpath {
3376 QPath::Resolved(ref opt_qself, ref path) => {
3378 opt_qself.as_ref().map(|qself| self.to_ty(qself)),
3379 &path.segments[..]);
3381 QPath::TypeRelative(ref qself, ref segment) => {
3382 (self.to_ty(qself), qself, segment)
3385 if let Some(&cached_result) = self.tables.borrow().type_dependent_defs().get(hir_id) {
3386 // Return directly on cache hit. This is useful to avoid doubly reporting
3387 // errors with default match binding modes. See #44614.
3388 let def = cached_result.map(|(kind, def_id)| Res::Def(kind, def_id))
3389 .unwrap_or(Res::Err);
3390 return (def, Some(ty), slice::from_ref(&**item_segment));
3392 let item_name = item_segment.ident;
3393 let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| {
3394 let result = match error {
3395 method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
3396 _ => Err(ErrorReported),
3398 if item_name.name != kw::Invalid {
3399 self.report_method_error(
3403 SelfSource::QPath(qself),
3411 // Write back the new resolution.
3412 self.write_resolution(hir_id, result);
3414 result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err),
3416 slice::from_ref(&**item_segment),
3420 pub fn check_decl_initializer(
3422 local: &'tcx hir::Local,
3423 init: &'tcx hir::Expr,
3425 // FIXME(tschottdorf): `contains_explicit_ref_binding()` must be removed
3426 // for #42640 (default match binding modes).
3429 let ref_bindings = local.pat.contains_explicit_ref_binding();
3431 let local_ty = self.local_ty(init.span, local.hir_id).revealed_ty;
3432 if let Some(m) = ref_bindings {
3433 // Somewhat subtle: if we have a `ref` binding in the pattern,
3434 // we want to avoid introducing coercions for the RHS. This is
3435 // both because it helps preserve sanity and, in the case of
3436 // ref mut, for soundness (issue #23116). In particular, in
3437 // the latter case, we need to be clear that the type of the
3438 // referent for the reference that results is *equal to* the
3439 // type of the place it is referencing, and not some
3440 // supertype thereof.
3441 let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m));
3442 self.demand_eqtype(init.span, local_ty, init_ty);
3445 self.check_expr_coercable_to_type(init, local_ty)
3449 pub fn check_decl_local(&self, local: &'tcx hir::Local) {
3450 let t = self.local_ty(local.span, local.hir_id).decl_ty;
3451 self.write_ty(local.hir_id, t);
3453 if let Some(ref init) = local.init {
3454 let init_ty = self.check_decl_initializer(local, &init);
3455 if init_ty.references_error() {
3456 self.write_ty(local.hir_id, init_ty);
3460 self.check_pat_walk(
3463 ty::BindingMode::BindByValue(hir::Mutability::MutImmutable),
3466 let pat_ty = self.node_ty(local.pat.hir_id);
3467 if pat_ty.references_error() {
3468 self.write_ty(local.hir_id, pat_ty);
3472 pub fn check_stmt(&self, stmt: &'tcx hir::Stmt) {
3473 // Don't do all the complex logic below for `DeclItem`.
3475 hir::StmtKind::Item(..) => return,
3476 hir::StmtKind::Local(..) | hir::StmtKind::Expr(..) | hir::StmtKind::Semi(..) => {}
3479 self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement");
3481 // Hide the outer diverging and `has_errors` flags.
3482 let old_diverges = self.diverges.get();
3483 let old_has_errors = self.has_errors.get();
3484 self.diverges.set(Diverges::Maybe);
3485 self.has_errors.set(false);
3488 hir::StmtKind::Local(ref l) => {
3489 self.check_decl_local(&l);
3492 hir::StmtKind::Item(_) => {}
3493 hir::StmtKind::Expr(ref expr) => {
3494 // Check with expected type of `()`.
3495 self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit());
3497 hir::StmtKind::Semi(ref expr) => {
3498 self.check_expr(&expr);
3502 // Combine the diverging and `has_error` flags.
3503 self.diverges.set(self.diverges.get() | old_diverges);
3504 self.has_errors.set(self.has_errors.get() | old_has_errors);
3507 pub fn check_block_no_value(&self, blk: &'tcx hir::Block) {
3508 let unit = self.tcx.mk_unit();
3509 let ty = self.check_block_with_expected(blk, ExpectHasType(unit));
3511 // if the block produces a `!` value, that can always be
3512 // (effectively) coerced to unit.
3514 self.demand_suptype(blk.span, unit, ty);
3518 fn check_block_with_expected(
3520 blk: &'tcx hir::Block,
3521 expected: Expectation<'tcx>,
3524 let mut fcx_ps = self.ps.borrow_mut();
3525 let unsafety_state = fcx_ps.recurse(blk);
3526 replace(&mut *fcx_ps, unsafety_state)
3529 // In some cases, blocks have just one exit, but other blocks
3530 // can be targeted by multiple breaks. This can happen both
3531 // with labeled blocks as well as when we desugar
3532 // a `try { ... }` expression.
3536 // 'a: { if true { break 'a Err(()); } Ok(()) }
3538 // Here we would wind up with two coercions, one from
3539 // `Err(())` and the other from the tail expression
3540 // `Ok(())`. If the tail expression is omitted, that's a
3541 // "forced unit" -- unless the block diverges, in which
3542 // case we can ignore the tail expression (e.g., `'a: {
3543 // break 'a 22; }` would not force the type of the block
3545 let tail_expr = blk.expr.as_ref();
3546 let coerce_to_ty = expected.coercion_target_type(self, blk.span);
3547 let coerce = if blk.targeted_by_break {
3548 CoerceMany::new(coerce_to_ty)
3550 let tail_expr: &[P<hir::Expr>] = match tail_expr {
3551 Some(e) => slice::from_ref(e),
3554 CoerceMany::with_coercion_sites(coerce_to_ty, tail_expr)
3557 let prev_diverges = self.diverges.get();
3558 let ctxt = BreakableCtxt {
3559 coerce: Some(coerce),
3563 let (ctxt, ()) = self.with_breakable_ctxt(blk.hir_id, ctxt, || {
3564 for s in &blk.stmts {
3568 // check the tail expression **without** holding the
3569 // `enclosing_breakables` lock below.
3570 let tail_expr_ty = tail_expr.map(|t| self.check_expr_with_expectation(t, expected));
3572 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
3573 let ctxt = enclosing_breakables.find_breakable(blk.hir_id);
3574 let coerce = ctxt.coerce.as_mut().unwrap();
3575 if let Some(tail_expr_ty) = tail_expr_ty {
3576 let tail_expr = tail_expr.unwrap();
3577 let cause = self.cause(tail_expr.span,
3578 ObligationCauseCode::BlockTailExpression(blk.hir_id));
3584 // Subtle: if there is no explicit tail expression,
3585 // that is typically equivalent to a tail expression
3586 // of `()` -- except if the block diverges. In that
3587 // case, there is no value supplied from the tail
3588 // expression (assuming there are no other breaks,
3589 // this implies that the type of the block will be
3592 // #41425 -- label the implicit `()` as being the
3593 // "found type" here, rather than the "expected type".
3594 if !self.diverges.get().always() {
3595 // #50009 -- Do not point at the entire fn block span, point at the return type
3596 // span, as it is the cause of the requirement, and
3597 // `consider_hint_about_removing_semicolon` will point at the last expression
3598 // if it were a relevant part of the error. This improves usability in editors
3599 // that highlight errors inline.
3600 let mut sp = blk.span;
3601 let mut fn_span = None;
3602 if let Some((decl, ident)) = self.get_parent_fn_decl(blk.hir_id) {
3603 let ret_sp = decl.output.span();
3604 if let Some(block_sp) = self.parent_item_span(blk.hir_id) {
3605 // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the
3606 // output would otherwise be incorrect and even misleading. Make sure
3607 // the span we're aiming at correspond to a `fn` body.
3608 if block_sp == blk.span {
3610 fn_span = Some(ident.span);
3614 coerce.coerce_forced_unit(self, &self.misc(sp), &mut |err| {
3615 if let Some(expected_ty) = expected.only_has_type(self) {
3616 self.consider_hint_about_removing_semicolon(blk, expected_ty, err);
3618 if let Some(fn_span) = fn_span {
3619 err.span_label(fn_span, "this function's body doesn't return");
3627 // If we can break from the block, then the block's exit is always reachable
3628 // (... as long as the entry is reachable) - regardless of the tail of the block.
3629 self.diverges.set(prev_diverges);
3632 let mut ty = ctxt.coerce.unwrap().complete(self);
3634 if self.has_errors.get() || ty.references_error() {
3635 ty = self.tcx.types.err
3638 self.write_ty(blk.hir_id, ty);
3640 *self.ps.borrow_mut() = prev;
3644 fn parent_item_span(&self, id: hir::HirId) -> Option<Span> {
3645 let node = self.tcx.hir().get_by_hir_id(self.tcx.hir().get_parent_item(id));
3647 Node::Item(&hir::Item {
3648 node: hir::ItemKind::Fn(_, _, _, body_id), ..
3650 Node::ImplItem(&hir::ImplItem {
3651 node: hir::ImplItemKind::Method(_, body_id), ..
3653 let body = self.tcx.hir().body(body_id);
3654 if let ExprKind::Block(block, _) = &body.value.node {
3655 return Some(block.span);
3663 /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise.
3664 fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(hir::FnDecl, ast::Ident)> {
3665 let parent = self.tcx.hir().get_by_hir_id(self.tcx.hir().get_parent_item(blk_id));
3666 self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident))
3669 /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
3670 fn get_node_fn_decl(&self, node: Node<'_>) -> Option<(hir::FnDecl, ast::Ident, bool)> {
3672 Node::Item(&hir::Item {
3673 ident, node: hir::ItemKind::Fn(ref decl, ..), ..
3674 }) => decl.clone().and_then(|decl| {
3675 // This is less than ideal, it will not suggest a return type span on any
3676 // method called `main`, regardless of whether it is actually the entry point,
3677 // but it will still present it as the reason for the expected type.
3678 Some((decl, ident, ident.name != sym::main))
3680 Node::TraitItem(&hir::TraitItem {
3681 ident, node: hir::TraitItemKind::Method(hir::MethodSig {
3684 }) => decl.clone().and_then(|decl| Some((decl, ident, true))),
3685 Node::ImplItem(&hir::ImplItem {
3686 ident, node: hir::ImplItemKind::Method(hir::MethodSig {
3689 }) => decl.clone().and_then(|decl| Some((decl, ident, false))),
3694 /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a
3695 /// suggestion can be made, `None` otherwise.
3696 pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(hir::FnDecl, bool)> {
3697 // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
3698 // `while` before reaching it, as block tail returns are not available in them.
3699 self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| {
3700 let parent = self.tcx.hir().get_by_hir_id(blk_id);
3701 self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
3705 /// On implicit return expressions with mismatched types, provides the following suggestions:
3707 /// - Points out the method's return type as the reason for the expected type.
3708 /// - Possible missing semicolon.
3709 /// - Possible missing return type if the return type is the default, and not `fn main()`.
3710 pub fn suggest_mismatched_types_on_tail(
3712 err: &mut DiagnosticBuilder<'tcx>,
3713 expression: &'tcx hir::Expr,
3719 self.suggest_missing_semicolon(err, expression, expected, cause_span);
3720 let mut pointing_at_return_type = false;
3721 if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) {
3722 pointing_at_return_type = self.suggest_missing_return_type(
3723 err, &fn_decl, expected, found, can_suggest);
3725 self.suggest_ref_or_into(err, expression, expected, found);
3726 pointing_at_return_type
3729 pub fn suggest_ref_or_into(
3731 err: &mut DiagnosticBuilder<'tcx>,
3736 if let Some((sp, msg, suggestion)) = self.check_ref(expr, found, expected) {
3737 err.span_suggestion(
3741 Applicability::MachineApplicable,
3743 } else if !self.check_for_cast(err, expr, found, expected) {
3744 let is_struct_pat_shorthand_field = self.is_hir_id_from_struct_pattern_shorthand_field(
3748 let methods = self.get_conversion_methods(expr.span, expected, found);
3749 if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) {
3750 let mut suggestions = iter::repeat(&expr_text).zip(methods.iter())
3751 .filter_map(|(receiver, method)| {
3752 let method_call = format!(".{}()", method.ident);
3753 if receiver.ends_with(&method_call) {
3754 None // do not suggest code that is already there (#53348)
3756 let method_call_list = [".to_vec()", ".to_string()"];
3757 let sugg = if receiver.ends_with(".clone()")
3758 && method_call_list.contains(&method_call.as_str()) {
3759 let max_len = receiver.rfind(".").unwrap();
3760 format!("{}{}", &receiver[..max_len], method_call)
3762 format!("{}{}", receiver, method_call)
3764 Some(if is_struct_pat_shorthand_field {
3765 format!("{}: {}", receiver, sugg)
3771 if suggestions.peek().is_some() {
3772 err.span_suggestions(
3774 "try using a conversion method",
3776 Applicability::MaybeIncorrect,
3783 /// A common error is to forget to add a semicolon at the end of a block, e.g.,
3787 /// bar_that_returns_u32()
3791 /// This routine checks if the return expression in a block would make sense on its own as a
3792 /// statement and the return type has been left as default or has been specified as `()`. If so,
3793 /// it suggests adding a semicolon.
3794 fn suggest_missing_semicolon(
3796 err: &mut DiagnosticBuilder<'tcx>,
3797 expression: &'tcx hir::Expr,
3801 if expected.is_unit() {
3802 // `BlockTailExpression` only relevant if the tail expr would be
3803 // useful on its own.
3804 match expression.node {
3805 ExprKind::Call(..) |
3806 ExprKind::MethodCall(..) |
3807 ExprKind::While(..) |
3808 ExprKind::Loop(..) |
3809 ExprKind::Match(..) |
3810 ExprKind::Block(..) => {
3811 let sp = self.tcx.sess.source_map().next_point(cause_span);
3812 err.span_suggestion(
3814 "try adding a semicolon",
3816 Applicability::MachineApplicable);
3823 /// A possible error is to forget to add a return type that is needed:
3827 /// bar_that_returns_u32()
3831 /// This routine checks if the return type is left as default, the method is not part of an
3832 /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return
3834 fn suggest_missing_return_type(
3836 err: &mut DiagnosticBuilder<'tcx>,
3837 fn_decl: &hir::FnDecl,
3842 // Only suggest changing the return type for methods that
3843 // haven't set a return type at all (and aren't `fn main()` or an impl).
3844 match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) {
3845 (&hir::FunctionRetTy::DefaultReturn(span), true, true, true) => {
3846 err.span_suggestion(
3848 "try adding a return type",
3849 format!("-> {} ", self.resolve_type_vars_with_obligations(found)),
3850 Applicability::MachineApplicable);
3853 (&hir::FunctionRetTy::DefaultReturn(span), false, true, true) => {
3854 err.span_label(span, "possibly return type missing here?");
3857 (&hir::FunctionRetTy::DefaultReturn(span), _, false, true) => {
3858 // `fn main()` must return `()`, do not suggest changing return type
3859 err.span_label(span, "expected `()` because of default return type");
3862 // expectation was caused by something else, not the default return
3863 (&hir::FunctionRetTy::DefaultReturn(_), _, _, false) => false,
3864 (&hir::FunctionRetTy::Return(ref ty), _, _, _) => {
3865 // Only point to return type if the expected type is the return type, as if they
3866 // are not, the expectation must have been caused by something else.
3867 debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.node);
3869 let ty = AstConv::ast_ty_to_ty(self, ty);
3870 debug!("suggest_missing_return_type: return type {:?}", ty);
3871 debug!("suggest_missing_return_type: expected type {:?}", ty);
3872 if ty.sty == expected.sty {
3873 err.span_label(sp, format!("expected `{}` because of return type",
3882 /// A common error is to add an extra semicolon:
3885 /// fn foo() -> usize {
3890 /// This routine checks if the final statement in a block is an
3891 /// expression with an explicit semicolon whose type is compatible
3892 /// with `expected_ty`. If so, it suggests removing the semicolon.
3893 fn consider_hint_about_removing_semicolon(
3895 blk: &'tcx hir::Block,
3896 expected_ty: Ty<'tcx>,
3897 err: &mut DiagnosticBuilder<'_>,
3899 if let Some(span_semi) = self.could_remove_semicolon(blk, expected_ty) {
3900 err.span_suggestion(
3902 "consider removing this semicolon",
3904 Applicability::MachineApplicable,
3909 fn could_remove_semicolon(&self, blk: &'tcx hir::Block, expected_ty: Ty<'tcx>) -> Option<Span> {
3910 // Be helpful when the user wrote `{... expr;}` and
3911 // taking the `;` off is enough to fix the error.
3912 let last_stmt = blk.stmts.last()?;
3913 let last_expr = match last_stmt.node {
3914 hir::StmtKind::Semi(ref e) => e,
3917 let last_expr_ty = self.node_ty(last_expr.hir_id);
3918 if self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err() {
3921 let original_span = original_sp(last_stmt.span, blk.span);
3922 Some(original_span.with_lo(original_span.hi() - BytePos(1)))
3925 // Rewrite `SelfCtor` to `Ctor`
3926 pub fn rewrite_self_ctor(
3930 ) -> Result<Res, ErrorReported> {
3932 if let Res::SelfCtor(impl_def_id) = res {
3933 let ty = self.impl_self_ty(span, impl_def_id).ty;
3934 let adt_def = ty.ty_adt_def();
3937 Some(adt_def) if adt_def.has_ctor() => {
3938 let variant = adt_def.non_enum_variant();
3939 let ctor_def_id = variant.ctor_def_id.unwrap();
3940 Ok(Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id))
3943 let mut err = tcx.sess.struct_span_err(span,
3944 "the `Self` constructor can only be used with tuple or unit structs");
3945 if let Some(adt_def) = adt_def {
3946 match adt_def.adt_kind() {
3948 err.help("did you mean to use one of the enum's variants?");
3952 err.span_suggestion(
3954 "use curly brackets",
3955 String::from("Self { /* fields */ }"),
3956 Applicability::HasPlaceholders,
3971 // Instantiates the given path, which must refer to an item with the given
3972 // number of type parameters and type.
3973 pub fn instantiate_value_path(&self,
3974 segments: &[hir::PathSegment],
3975 self_ty: Option<Ty<'tcx>>,
3979 -> (Ty<'tcx>, Res) {
3981 "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})",
3990 let res = match self.rewrite_self_ctor(res, span) {
3992 Err(ErrorReported) => return (tcx.types.err, res),
3994 let path_segs = match res {
3995 Res::Local(_) => vec![],
3996 Res::Def(kind, def_id) =>
3997 AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id),
3998 _ => bug!("instantiate_value_path on {:?}", res),
4001 let mut user_self_ty = None;
4002 let mut is_alias_variant_ctor = false;
4004 Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => {
4005 if let Some(self_ty) = self_ty {
4006 let adt_def = self_ty.ty_adt_def().unwrap();
4007 user_self_ty = Some(UserSelfTy {
4008 impl_def_id: adt_def.did,
4011 is_alias_variant_ctor = true;
4014 Res::Def(DefKind::Method, def_id)
4015 | Res::Def(DefKind::AssocConst, def_id) => {
4016 let container = tcx.associated_item(def_id).container;
4017 debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container);
4019 ty::TraitContainer(trait_did) => {
4020 callee::check_legal_trait_for_method_call(tcx, span, trait_did)
4022 ty::ImplContainer(impl_def_id) => {
4023 if segments.len() == 1 {
4024 // `<T>::assoc` will end up here, and so
4025 // can `T::assoc`. It this came from an
4026 // inherent impl, we need to record the
4027 // `T` for posterity (see `UserSelfTy` for
4029 let self_ty = self_ty.expect("UFCS sugared assoc missing Self");
4030 user_self_ty = Some(UserSelfTy {
4041 // Now that we have categorized what space the parameters for each
4042 // segment belong to, let's sort out the parameters that the user
4043 // provided (if any) into their appropriate spaces. We'll also report
4044 // errors if type parameters are provided in an inappropriate place.
4046 let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect();
4047 let generics_has_err = AstConv::prohibit_generics(
4048 self, segments.iter().enumerate().filter_map(|(index, seg)| {
4049 if !generic_segs.contains(&index) || is_alias_variant_ctor {
4056 if let Res::Local(hid) = res {
4057 let ty = self.local_ty(span, hid).decl_ty;
4058 let ty = self.normalize_associated_types_in(span, &ty);
4059 self.write_ty(hir_id, ty);
4063 if generics_has_err {
4064 // Don't try to infer type parameters when prohibited generic arguments were given.
4065 user_self_ty = None;
4068 // Now we have to compare the types that the user *actually*
4069 // provided against the types that were *expected*. If the user
4070 // did not provide any types, then we want to substitute inference
4071 // variables. If the user provided some types, we may still need
4072 // to add defaults. If the user provided *too many* types, that's
4075 let mut infer_args_for_err = FxHashSet::default();
4076 for &PathSeg(def_id, index) in &path_segs {
4077 let seg = &segments[index];
4078 let generics = tcx.generics_of(def_id);
4079 // Argument-position `impl Trait` is treated as a normal generic
4080 // parameter internally, but we don't allow users to specify the
4081 // parameter's value explicitly, so we have to do some error-
4083 let suppress_errors = AstConv::check_generic_arg_count_for_call(
4088 false, // `is_method_call`
4090 if suppress_errors {
4091 infer_args_for_err.insert(index);
4092 self.set_tainted_by_errors(); // See issue #53251.
4096 let has_self = path_segs.last().map(|PathSeg(def_id, _)| {
4097 tcx.generics_of(*def_id).has_self
4098 }).unwrap_or(false);
4100 let def_id = res.def_id();
4102 // The things we are substituting into the type should not contain
4103 // escaping late-bound regions, and nor should the base type scheme.
4104 let ty = tcx.type_of(def_id);
4106 let substs = AstConv::create_substs_for_generic_args(
4112 // Provide the generic args, and whether types should be inferred.
4114 if let Some(&PathSeg(_, index)) = path_segs.iter().find(|&PathSeg(did, _)| {
4117 // If we've encountered an `impl Trait`-related error, we're just
4118 // going to infer the arguments for better error messages.
4119 if !infer_args_for_err.contains(&index) {
4120 // Check whether the user has provided generic arguments.
4121 if let Some(ref data) = segments[index].args {
4122 return (Some(data), segments[index].infer_args);
4125 return (None, segments[index].infer_args);
4130 // Provide substitutions for parameters for which (valid) arguments have been provided.
4132 match (¶m.kind, arg) {
4133 (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
4134 AstConv::ast_region_to_region(self, lt, Some(param)).into()
4136 (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
4137 self.to_ty(ty).into()
4139 (GenericParamDefKind::Const, GenericArg::Const(ct)) => {
4140 self.to_const(&ct.value, self.tcx.type_of(param.def_id)).into()
4142 _ => unreachable!(),
4145 // Provide substitutions for parameters for which arguments are inferred.
4146 |substs, param, infer_args| {
4148 GenericParamDefKind::Lifetime => {
4149 self.re_infer(Some(param), span).unwrap().into()
4151 GenericParamDefKind::Type { has_default, .. } => {
4152 if !infer_args && has_default {
4153 // If we have a default, then we it doesn't matter that we're not
4154 // inferring the type arguments: we provide the default where any
4156 let default = tcx.type_of(param.def_id);
4159 default.subst_spanned(tcx, substs.unwrap(), Some(span))
4162 // If no type arguments were provided, we have to infer them.
4163 // This case also occurs as a result of some malformed input, e.g.
4164 // a lifetime argument being given instead of a type parameter.
4165 // Using inference instead of `Error` gives better error messages.
4166 self.var_for_def(span, param)
4169 GenericParamDefKind::Const => {
4170 // FIXME(const_generics:defaults)
4171 // No const parameters were provided, we have to infer them.
4172 self.var_for_def(span, param)
4177 assert!(!substs.has_escaping_bound_vars());
4178 assert!(!ty.has_escaping_bound_vars());
4180 // First, store the "user substs" for later.
4181 self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty);
4183 // Add all the obligations that are required, substituting and
4184 // normalized appropriately.
4185 let bounds = self.instantiate_bounds(span, def_id, &substs);
4186 self.add_obligations_for_parameters(
4187 traits::ObligationCause::new(span, self.body_id, traits::ItemObligation(def_id)),
4190 // Substitute the values for the type parameters into the type of
4191 // the referenced item.
4192 let ty_substituted = self.instantiate_type_scheme(span, &substs, &ty);
4194 if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
4195 // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
4196 // is inherent, there is no `Self` parameter; instead, the impl needs
4197 // type parameters, which we can infer by unifying the provided `Self`
4198 // with the substituted impl type.
4199 // This also occurs for an enum variant on a type alias.
4200 let ty = tcx.type_of(impl_def_id);
4202 let impl_ty = self.instantiate_type_scheme(span, &substs, &ty);
4203 match self.at(&self.misc(span), self.param_env).sup(impl_ty, self_ty) {
4204 Ok(ok) => self.register_infer_ok_obligations(ok),
4206 self.tcx.sess.delay_span_bug(span, &format!(
4207 "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?",
4215 self.check_rustc_args_require_const(def_id, hir_id, span);
4217 debug!("instantiate_value_path: type of {:?} is {:?}",
4220 self.write_substs(hir_id, substs);
4222 (ty_substituted, res)
4225 fn check_rustc_args_require_const(&self,
4229 // We're only interested in functions tagged with
4230 // #[rustc_args_required_const], so ignore anything that's not.
4231 if !self.tcx.has_attr(def_id, sym::rustc_args_required_const) {
4235 // If our calling expression is indeed the function itself, we're good!
4236 // If not, generate an error that this can only be called directly.
4237 if let Node::Expr(expr) = self.tcx.hir().get_by_hir_id(
4238 self.tcx.hir().get_parent_node_by_hir_id(hir_id))
4240 if let ExprKind::Call(ref callee, ..) = expr.node {
4241 if callee.hir_id == hir_id {
4247 self.tcx.sess.span_err(span, "this function can only be invoked \
4248 directly, not through a function pointer");
4251 // Resolves `typ` by a single level if `typ` is a type variable.
4252 // If no resolution is possible, then an error is reported.
4253 // Numeric inference variables may be left unresolved.
4254 pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
4255 let ty = self.resolve_type_vars_with_obligations(ty);
4256 if !ty.is_ty_var() {
4259 if !self.is_tainted_by_errors() {
4260 self.need_type_info_err((**self).body_id, sp, ty)
4261 .note("type must be known at this point")
4264 self.demand_suptype(sp, self.tcx.types.err, ty);
4269 fn with_breakable_ctxt<F: FnOnce() -> R, R>(
4272 ctxt: BreakableCtxt<'tcx>,
4274 ) -> (BreakableCtxt<'tcx>, R) {
4277 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
4278 index = enclosing_breakables.stack.len();
4279 enclosing_breakables.by_id.insert(id, index);
4280 enclosing_breakables.stack.push(ctxt);
4284 let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
4285 debug_assert!(enclosing_breakables.stack.len() == index + 1);
4286 enclosing_breakables.by_id.remove(&id).expect("missing breakable context");
4287 enclosing_breakables.stack.pop().expect("missing breakable context")
4292 /// Instantiate a QueryResponse in a probe context, without a
4293 /// good ObligationCause.
4294 fn probe_instantiate_query_response(
4297 original_values: &OriginalQueryValues<'tcx>,
4298 query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
4299 ) -> InferResult<'tcx, Ty<'tcx>>
4301 self.instantiate_query_response_and_region_obligations(
4302 &traits::ObligationCause::misc(span, self.body_id),
4308 /// Returns `true` if an expression is contained inside the LHS of an assignment expression.
4309 fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool {
4310 let mut contained_in_place = false;
4312 while let hir::Node::Expr(parent_expr) =
4313 self.tcx.hir().get_by_hir_id(self.tcx.hir().get_parent_node_by_hir_id(expr_id))
4315 match &parent_expr.node {
4316 hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => {
4317 if lhs.hir_id == expr_id {
4318 contained_in_place = true;
4324 expr_id = parent_expr.hir_id;
4331 pub fn check_bounds_are_used<'tcx>(tcx: TyCtxt<'tcx>, generics: &ty::Generics, ty: Ty<'tcx>) {
4332 let own_counts = generics.own_counts();
4334 "check_bounds_are_used(n_tys={}, n_cts={}, ty={:?})",
4340 if own_counts.types == 0 {
4344 // Make a vector of booleans initially false, set to true when used.
4345 let mut types_used = vec![false; own_counts.types];
4347 for leaf_ty in ty.walk() {
4348 if let ty::Param(ty::ParamTy { index, .. }) = leaf_ty.sty {
4349 debug!("Found use of ty param num {}", index);
4350 types_used[index as usize - own_counts.lifetimes] = true;
4351 } else if let ty::Error = leaf_ty.sty {
4352 // If there is already another error, do not emit
4353 // an error for not using a type Parameter.
4354 assert!(tcx.sess.err_count() > 0);
4359 let types = generics.params.iter().filter(|param| match param.kind {
4360 ty::GenericParamDefKind::Type { .. } => true,
4363 for (&used, param) in types_used.iter().zip(types) {
4365 let id = tcx.hir().as_local_hir_id(param.def_id).unwrap();
4366 let span = tcx.hir().span(id);
4367 struct_span_err!(tcx.sess, span, E0091, "type parameter `{}` is unused", param.name)
4368 .span_label(span, "unused type parameter")
4374 fn fatally_break_rust(sess: &Session) {
4375 let handler = sess.diagnostic();
4376 handler.span_bug_no_panic(
4378 "It looks like you're trying to break rust; would you like some ICE?",
4380 handler.note_without_error("the compiler expectedly panicked. this is a feature.");
4381 handler.note_without_error(
4382 "we would appreciate a joke overview: \
4383 https://github.com/rust-lang/rust/issues/43162#issuecomment-320764675"
4385 handler.note_without_error(&format!("rustc {} running on {}",
4386 option_env!("CFG_VERSION").unwrap_or("unknown_version"),
4387 crate::session::config::host_triple(),
4391 fn potentially_plural_count(count: usize, word: &str) -> String {
4392 format!("{} {}{}", count, word, if count == 1 { "" } else { "s" })