1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! See the Book for more information.
13 pub use self::LateBoundRegionConversionTime
::*;
14 pub use self::RegionVariableOrigin
::*;
15 pub use self::SubregionOrigin
::*;
16 pub use self::ValuePairs
::*;
17 pub use ty
::IntVarValue
;
18 pub use self::freshen
::TypeFreshener
;
19 pub use self::region_inference
::{GenericKind, VerifyBound}
;
21 use hir
::def_id
::DefId
;
23 use middle
::free_region
::{FreeRegionMap, RegionRelations}
;
24 use middle
::region
::RegionMaps
;
25 use middle
::mem_categorization
as mc
;
26 use middle
::mem_categorization
::McResult
;
27 use middle
::lang_items
;
28 use mir
::tcx
::LvalueTy
;
29 use ty
::subst
::{Kind, Subst, Substs}
;
30 use ty
::{TyVid, IntVid, FloatVid}
;
31 use ty
::{self, Ty, TyCtxt}
;
32 use ty
::error
::{ExpectedFound, TypeError, UnconstrainedNumeric}
;
33 use ty
::fold
::{TypeFoldable, TypeFolder, TypeVisitor}
;
34 use ty
::relate
::RelateResult
;
35 use traits
::{self, ObligationCause, PredicateObligations, Reveal}
;
36 use rustc_data_structures
::unify
::{self, UnificationTable}
;
37 use std
::cell
::{Cell, RefCell, Ref, RefMut}
;
41 use errors
::DiagnosticBuilder
;
42 use syntax_pos
::{self, Span, DUMMY_SP}
;
43 use util
::nodemap
::{FxHashMap, FxHashSet}
;
44 use arena
::DroplessArena
;
46 use self::combine
::CombineFields
;
47 use self::higher_ranked
::HrMatchResult
;
48 use self::region_inference
::{RegionVarBindings, RegionSnapshot}
;
49 use self::type_variable
::TypeVariableOrigin
;
50 use self::unify_key
::ToType
;
55 pub mod error_reporting
;
61 pub mod region_inference
;
65 pub mod type_variable
;
69 pub struct InferOk
<'tcx
, T
> {
71 pub obligations
: PredicateObligations
<'tcx
>,
73 pub type InferResult
<'tcx
, T
> = Result
<InferOk
<'tcx
, T
>, TypeError
<'tcx
>>;
75 pub type Bound
<T
> = Option
<T
>;
76 pub type UnitResult
<'tcx
> = RelateResult
<'tcx
, ()>; // "unify result"
77 pub type FixupResult
<T
> = Result
<T
, FixupError
>; // "fixup result"
79 /// A version of &ty::TypeckTables which can be `Missing` (not needed),
80 /// `InProgress` (during typeck) or `Interned` (result of typeck).
81 /// Only the `InProgress` version supports `borrow_mut`.
82 #[derive(Copy, Clone)]
83 pub enum InferTables
<'a
, 'gcx
: 'a
+'tcx
, 'tcx
: 'a
> {
84 Interned(&'a ty
::TypeckTables
<'gcx
>),
85 InProgress(&'a RefCell
<ty
::TypeckTables
<'tcx
>>),
89 pub enum InferTablesRef
<'a
, 'gcx
: 'a
+'tcx
, 'tcx
: 'a
> {
90 Interned(&'a ty
::TypeckTables
<'gcx
>),
91 InProgress(Ref
<'a
, ty
::TypeckTables
<'tcx
>>)
94 impl<'a
, 'gcx
, 'tcx
> Deref
for InferTablesRef
<'a
, 'gcx
, 'tcx
> {
95 type Target
= ty
::TypeckTables
<'tcx
>;
96 fn deref(&self) -> &Self::Target
{
98 InferTablesRef
::Interned(tables
) => tables
,
99 InferTablesRef
::InProgress(ref tables
) => tables
104 impl<'a
, 'gcx
, 'tcx
> InferTables
<'a
, 'gcx
, 'tcx
> {
105 pub fn borrow(self) -> InferTablesRef
<'a
, 'gcx
, 'tcx
> {
107 InferTables
::Interned(tables
) => InferTablesRef
::Interned(tables
),
108 InferTables
::InProgress(tables
) => InferTablesRef
::InProgress(tables
.borrow()),
109 InferTables
::Missing
=> {
110 bug
!("InferTables: infcx.tables.borrow() with no tables")
115 pub fn expect_interned(self) -> &'a ty
::TypeckTables
<'gcx
> {
117 InferTables
::Interned(tables
) => tables
,
118 InferTables
::InProgress(_
) => {
119 bug
!("InferTables: infcx.tables.expect_interned() during type-checking");
121 InferTables
::Missing
=> {
122 bug
!("InferTables: infcx.tables.expect_interned() with no tables")
127 pub fn borrow_mut(self) -> RefMut
<'a
, ty
::TypeckTables
<'tcx
>> {
129 InferTables
::Interned(_
) => {
130 bug
!("InferTables: infcx.tables.borrow_mut() outside of type-checking");
132 InferTables
::InProgress(tables
) => tables
.borrow_mut(),
133 InferTables
::Missing
=> {
134 bug
!("InferTables: infcx.tables.borrow_mut() with no tables")
140 pub struct InferCtxt
<'a
, 'gcx
: 'a
+'tcx
, 'tcx
: 'a
> {
141 pub tcx
: TyCtxt
<'a
, 'gcx
, 'tcx
>,
143 pub tables
: InferTables
<'a
, 'gcx
, 'tcx
>,
145 // Cache for projections. This cache is snapshotted along with the
148 // Public so that `traits::project` can use it.
149 pub projection_cache
: RefCell
<traits
::ProjectionCache
<'tcx
>>,
151 // We instantiate UnificationTable with bounds<Ty> because the
152 // types that might instantiate a general type variable have an
153 // order, represented by its upper and lower bounds.
154 pub type_variables
: RefCell
<type_variable
::TypeVariableTable
<'tcx
>>,
156 // Map from integral variable to the kind of integer it represents
157 int_unification_table
: RefCell
<UnificationTable
<ty
::IntVid
>>,
159 // Map from floating variable to the kind of float it represents
160 float_unification_table
: RefCell
<UnificationTable
<ty
::FloatVid
>>,
162 // For region variables.
163 region_vars
: RegionVarBindings
<'a
, 'gcx
, 'tcx
>,
165 /// Caches the results of trait selection. This cache is used
166 /// for things that have to do with the parameters in scope.
167 pub selection_cache
: traits
::SelectionCache
<'tcx
>,
169 /// Caches the results of trait evaluation.
170 pub evaluation_cache
: traits
::EvaluationCache
<'tcx
>,
172 // the set of predicates on which errors have been reported, to
173 // avoid reporting the same error twice.
174 pub reported_trait_errors
: RefCell
<FxHashSet
<traits
::TraitErrorKey
<'tcx
>>>,
176 // When an error occurs, we want to avoid reporting "derived"
177 // errors that are due to this original failure. Normally, we
178 // handle this with the `err_count_on_creation` count, which
179 // basically just tracks how many errors were reported when we
180 // started type-checking a fn and checks to see if any new errors
181 // have been reported since then. Not great, but it works.
183 // However, when errors originated in other passes -- notably
184 // resolve -- this heuristic breaks down. Therefore, we have this
185 // auxiliary flag that one can set whenever one creates a
186 // type-error that is due to an error in a prior pass.
188 // Don't read this flag directly, call `is_tainted_by_errors()`
189 // and `set_tainted_by_errors()`.
190 tainted_by_errors_flag
: Cell
<bool
>,
192 // Track how many errors were reported when this infcx is created.
193 // If the number of errors increases, that's also a sign (line
194 // `tained_by_errors`) to avoid reporting certain kinds of errors.
195 err_count_on_creation
: usize,
197 // This flag is true while there is an active snapshot.
198 in_snapshot
: Cell
<bool
>,
201 /// A map returned by `skolemize_late_bound_regions()` indicating the skolemized
202 /// region that each late-bound region was replaced with.
203 pub type SkolemizationMap
<'tcx
> = FxHashMap
<ty
::BoundRegion
, ty
::Region
<'tcx
>>;
205 /// See `error_reporting` module for more details
206 #[derive(Clone, Debug)]
207 pub enum ValuePairs
<'tcx
> {
208 Types(ExpectedFound
<Ty
<'tcx
>>),
209 TraitRefs(ExpectedFound
<ty
::TraitRef
<'tcx
>>),
210 PolyTraitRefs(ExpectedFound
<ty
::PolyTraitRef
<'tcx
>>),
213 /// The trace designates the path through inference that we took to
214 /// encounter an error or subtyping constraint.
216 /// See `error_reporting` module for more details.
218 pub struct TypeTrace
<'tcx
> {
219 cause
: ObligationCause
<'tcx
>,
220 values
: ValuePairs
<'tcx
>,
223 /// The origin of a `r1 <= r2` constraint.
225 /// See `error_reporting` module for more details
226 #[derive(Clone, Debug)]
227 pub enum SubregionOrigin
<'tcx
> {
228 // Arose from a subtyping relation
229 Subtype(TypeTrace
<'tcx
>),
231 // Stack-allocated closures cannot outlive innermost loop
232 // or function so as to ensure we only require finite stack
233 InfStackClosure(Span
),
235 // Invocation of closure must be within its lifetime
238 // Dereference of reference must be within its lifetime
241 // Closure bound must not outlive captured free variables
242 FreeVariable(Span
, ast
::NodeId
),
244 // Index into slice must be within its lifetime
247 // When casting `&'a T` to an `&'b Trait` object,
248 // relating `'a` to `'b`
249 RelateObjectBound(Span
),
251 // Some type parameter was instantiated with the given type,
252 // and that type must outlive some region.
253 RelateParamBound(Span
, Ty
<'tcx
>),
255 // The given region parameter was instantiated with a region
256 // that must outlive some other region.
257 RelateRegionParamBound(Span
),
259 // A bound placed on type parameters that states that must outlive
260 // the moment of their instantiation.
261 RelateDefaultParamBound(Span
, Ty
<'tcx
>),
263 // Creating a pointer `b` to contents of another reference
266 // Creating a pointer `b` to contents of an upvar
267 ReborrowUpvar(Span
, ty
::UpvarId
),
269 // Data with type `Ty<'tcx>` was borrowed
270 DataBorrowed(Ty
<'tcx
>, Span
),
272 // (&'a &'b T) where a >= b
273 ReferenceOutlivesReferent(Ty
<'tcx
>, Span
),
275 // Type or region parameters must be in scope.
276 ParameterInScope(ParameterOrigin
, Span
),
278 // The type T of an expression E must outlive the lifetime for E.
279 ExprTypeIsNotInScope(Ty
<'tcx
>, Span
),
281 // A `ref b` whose region does not enclose the decl site
282 BindingTypeIsNotValidAtDecl(Span
),
284 // Regions appearing in a method receiver must outlive method call
287 // Regions appearing in a function argument must outlive func call
290 // Region in return type of invoked fn must enclose call
293 // Operands must be in scope
296 // Region resulting from a `&` expr must enclose the `&` expr
299 // An auto-borrow that does not enclose the expr where it occurs
302 // Region constraint arriving from destructor safety
303 SafeDestructor(Span
),
305 // Comparing the signature and requirements of an impl method against
306 // the containing trait.
307 CompareImplMethodObligation
{
309 item_name
: ast
::Name
,
310 impl_item_def_id
: DefId
,
311 trait_item_def_id
: DefId
,
313 // this is `Some(_)` if this error arises from the bug fix for
314 // #18937. This is a temporary measure.
315 lint_id
: Option
<ast
::NodeId
>,
319 /// Places that type/region parameters can appear.
320 #[derive(Clone, Copy, Debug)]
321 pub enum ParameterOrigin
{
323 MethodCall
, // foo.bar() <-- parameters on impl providing bar()
324 OverloadedOperator
, // a + b when overloaded
325 OverloadedDeref
, // *a when overloaded
328 /// Times when we replace late-bound regions with variables:
329 #[derive(Clone, Copy, Debug)]
330 pub enum LateBoundRegionConversionTime
{
331 /// when a fn is called
334 /// when two higher-ranked types are compared
337 /// when projecting an associated type
338 AssocTypeProjection(ast
::Name
),
341 /// Reasons to create a region inference variable
343 /// See `error_reporting` module for more details
344 #[derive(Clone, Debug)]
345 pub enum RegionVariableOrigin
{
346 // Region variables created for ill-categorized reasons,
347 // mostly indicates places in need of refactoring
350 // Regions created by a `&P` or `[...]` pattern
353 // Regions created by `&` operator
356 // Regions created as part of an autoref of a method receiver
359 // Regions created as part of an automatic coercion
362 // Region variables created as the values for early-bound regions
363 EarlyBoundRegion(Span
, ast
::Name
, Option
<ty
::Issue32330
>),
365 // Region variables created for bound regions
366 // in a function or method that is called
367 LateBoundRegion(Span
, ty
::BoundRegion
, LateBoundRegionConversionTime
),
369 UpvarRegion(ty
::UpvarId
, Span
),
371 BoundRegionInCoherence(ast
::Name
),
374 #[derive(Copy, Clone, Debug)]
375 pub enum FixupError
{
376 UnresolvedIntTy(IntVid
),
377 UnresolvedFloatTy(FloatVid
),
381 impl fmt
::Display
for FixupError
{
382 fn fmt(&self, f
: &mut fmt
::Formatter
) -> fmt
::Result
{
383 use self::FixupError
::*;
386 UnresolvedIntTy(_
) => {
387 write
!(f
, "cannot determine the type of this integer; \
388 add a suffix to specify the type explicitly")
390 UnresolvedFloatTy(_
) => {
391 write
!(f
, "cannot determine the type of this number; \
392 add a suffix to specify the type explicitly")
394 UnresolvedTy(_
) => write
!(f
, "unconstrained type")
399 pub trait InferEnv
<'a
, 'tcx
> {
400 fn to_parts(self, tcx
: TyCtxt
<'a
, 'tcx
, 'tcx
>)
401 -> (Option
<&'a ty
::TypeckTables
<'tcx
>>,
402 Option
<ty
::TypeckTables
<'tcx
>>);
405 impl<'a
, 'tcx
> InferEnv
<'a
, 'tcx
> for () {
406 fn to_parts(self, _
: TyCtxt
<'a
, 'tcx
, 'tcx
>)
407 -> (Option
<&'a ty
::TypeckTables
<'tcx
>>,
408 Option
<ty
::TypeckTables
<'tcx
>>) {
413 impl<'a
, 'tcx
> InferEnv
<'a
, 'tcx
> for &'a ty
::TypeckTables
<'tcx
> {
414 fn to_parts(self, _
: TyCtxt
<'a
, 'tcx
, 'tcx
>)
415 -> (Option
<&'a ty
::TypeckTables
<'tcx
>>,
416 Option
<ty
::TypeckTables
<'tcx
>>) {
421 impl<'a
, 'tcx
> InferEnv
<'a
, 'tcx
> for ty
::TypeckTables
<'tcx
> {
422 fn to_parts(self, _
: TyCtxt
<'a
, 'tcx
, 'tcx
>)
423 -> (Option
<&'a ty
::TypeckTables
<'tcx
>>,
424 Option
<ty
::TypeckTables
<'tcx
>>) {
429 impl<'a
, 'tcx
> InferEnv
<'a
, 'tcx
> for hir
::BodyId
{
430 fn to_parts(self, tcx
: TyCtxt
<'a
, 'tcx
, 'tcx
>)
431 -> (Option
<&'a ty
::TypeckTables
<'tcx
>>,
432 Option
<ty
::TypeckTables
<'tcx
>>) {
433 let def_id
= tcx
.hir
.body_owner_def_id(self);
434 (Some(tcx
.typeck_tables_of(def_id
)), None
)
438 /// Helper type of a temporary returned by tcx.infer_ctxt(...).
439 /// Necessary because we can't write the following bound:
440 /// F: for<'b, 'tcx> where 'gcx: 'tcx FnOnce(InferCtxt<'b, 'gcx, 'tcx>).
441 pub struct InferCtxtBuilder
<'a
, 'gcx
: 'a
+'tcx
, 'tcx
: 'a
> {
442 global_tcx
: TyCtxt
<'a
, 'gcx
, 'gcx
>,
443 arena
: DroplessArena
,
444 fresh_tables
: Option
<RefCell
<ty
::TypeckTables
<'tcx
>>>,
445 tables
: Option
<&'a ty
::TypeckTables
<'gcx
>>,
448 impl<'a
, 'gcx
, 'tcx
> TyCtxt
<'a
, 'gcx
, 'gcx
> {
449 pub fn infer_ctxt
<E
: InferEnv
<'a
, 'gcx
>>(self, env
: E
) -> InferCtxtBuilder
<'a
, 'gcx
, 'tcx
> {
450 let (tables
, fresh_tables
) = env
.to_parts(self);
453 arena
: DroplessArena
::new(),
454 fresh_tables
: fresh_tables
.map(RefCell
::new
),
459 /// Fake InferCtxt with the global tcx. Used by pre-MIR borrowck
460 /// for MemCategorizationContext/ExprUseVisitor.
461 /// If any inference functionality is used, ICEs will occur.
462 pub fn borrowck_fake_infer_ctxt(self, body
: hir
::BodyId
)
463 -> InferCtxt
<'a
, 'gcx
, 'gcx
> {
464 let (tables
, _
) = body
.to_parts(self);
467 tables
: InferTables
::Interned(tables
.unwrap()),
468 type_variables
: RefCell
::new(type_variable
::TypeVariableTable
::new()),
469 int_unification_table
: RefCell
::new(UnificationTable
::new()),
470 float_unification_table
: RefCell
::new(UnificationTable
::new()),
471 region_vars
: RegionVarBindings
::new(self),
472 selection_cache
: traits
::SelectionCache
::new(),
473 evaluation_cache
: traits
::EvaluationCache
::new(),
474 projection_cache
: RefCell
::new(traits
::ProjectionCache
::new()),
475 reported_trait_errors
: RefCell
::new(FxHashSet()),
476 tainted_by_errors_flag
: Cell
::new(false),
477 err_count_on_creation
: self.sess
.err_count(),
478 in_snapshot
: Cell
::new(false),
483 impl<'a
, 'gcx
, 'tcx
> InferCtxtBuilder
<'a
, 'gcx
, 'tcx
> {
484 pub fn enter
<F
, R
>(&'tcx
mut self, f
: F
) -> R
485 where F
: for<'b
> FnOnce(InferCtxt
<'b
, 'gcx
, 'tcx
>) -> R
487 let InferCtxtBuilder
{
493 let tables
= tables
.map(InferTables
::Interned
).unwrap_or_else(|| {
494 fresh_tables
.as_ref().map_or(InferTables
::Missing
, InferTables
::InProgress
)
496 global_tcx
.enter_local(arena
, |tcx
| f(InferCtxt
{
499 projection_cache
: RefCell
::new(traits
::ProjectionCache
::new()),
500 type_variables
: RefCell
::new(type_variable
::TypeVariableTable
::new()),
501 int_unification_table
: RefCell
::new(UnificationTable
::new()),
502 float_unification_table
: RefCell
::new(UnificationTable
::new()),
503 region_vars
: RegionVarBindings
::new(tcx
),
504 selection_cache
: traits
::SelectionCache
::new(),
505 evaluation_cache
: traits
::EvaluationCache
::new(),
506 reported_trait_errors
: RefCell
::new(FxHashSet()),
507 tainted_by_errors_flag
: Cell
::new(false),
508 err_count_on_creation
: tcx
.sess
.err_count(),
509 in_snapshot
: Cell
::new(false),
514 impl<T
> ExpectedFound
<T
> {
515 pub fn new(a_is_expected
: bool
, a
: T
, b
: T
) -> Self {
517 ExpectedFound {expected: a, found: b}
519 ExpectedFound {expected: b, found: a}
524 impl<'tcx
, T
> InferOk
<'tcx
, T
> {
525 pub fn unit(self) -> InferOk
<'tcx
, ()> {
526 InferOk { value: (), obligations: self.obligations }
530 #[must_use = "once you start a snapshot, you should always consume it"]
531 pub struct CombinedSnapshot
<'a
, 'tcx
:'a
> {
532 projection_cache_snapshot
: traits
::ProjectionCacheSnapshot
,
533 type_snapshot
: type_variable
::Snapshot
,
534 int_snapshot
: unify
::Snapshot
<ty
::IntVid
>,
535 float_snapshot
: unify
::Snapshot
<ty
::FloatVid
>,
536 region_vars_snapshot
: RegionSnapshot
,
537 was_in_snapshot
: bool
,
538 _in_progress_tables
: Option
<Ref
<'a
, ty
::TypeckTables
<'tcx
>>>,
541 /// Helper trait for shortening the lifetimes inside a
542 /// value for post-type-checking normalization.
543 pub trait TransNormalize
<'gcx
>: TypeFoldable
<'gcx
> {
544 fn trans_normalize
<'a
, 'tcx
>(&self,
545 infcx
: &InferCtxt
<'a
, 'gcx
, 'tcx
>,
546 param_env
: ty
::ParamEnv
<'tcx
>)
550 macro_rules
! items { ($($item:item)+) => ($($item)+) }
551 macro_rules
! impl_trans_normalize
{
552 ($lt_gcx
:tt
, $
($ty
:ty
),+) => {
553 items
!($
(impl<$lt_gcx
> TransNormalize
<$lt_gcx
> for $ty
{
554 fn trans_normalize
<'a
, 'tcx
>(&self,
555 infcx
: &InferCtxt
<'a
, $lt_gcx
, 'tcx
>,
556 param_env
: ty
::ParamEnv
<'tcx
>)
558 infcx
.normalize_projections_in(param_env
, self)
564 impl_trans_normalize
!('gcx
,
569 ty
::ClosureSubsts
<'gcx
>,
570 ty
::PolyTraitRef
<'gcx
>,
571 ty
::ExistentialTraitRef
<'gcx
>
574 impl<'gcx
> TransNormalize
<'gcx
> for LvalueTy
<'gcx
> {
575 fn trans_normalize
<'a
, 'tcx
>(&self,
576 infcx
: &InferCtxt
<'a
, 'gcx
, 'tcx
>,
577 param_env
: ty
::ParamEnv
<'tcx
>)
580 LvalueTy
::Ty { ty }
=> LvalueTy
::Ty { ty: ty.trans_normalize(infcx, param_env) }
,
581 LvalueTy
::Downcast { adt_def, substs, variant_index }
=> {
584 substs
: substs
.trans_normalize(infcx
, param_env
),
585 variant_index
: variant_index
592 // NOTE: Callable from trans only!
593 impl<'a
, 'tcx
> TyCtxt
<'a
, 'tcx
, 'tcx
> {
594 /// Currently, higher-ranked type bounds inhibit normalization. Therefore,
595 /// each time we erase them in translation, we need to normalize
597 pub fn erase_late_bound_regions_and_normalize
<T
>(self, value
: &ty
::Binder
<T
>)
599 where T
: TransNormalize
<'tcx
>
601 assert
!(!value
.needs_subst());
602 let value
= self.erase_late_bound_regions(value
);
603 self.normalize_associated_type(&value
)
606 /// Fully normalizes any associated types in `value`, using an
607 /// empty environment and `Reveal::All` mode (therefore, suitable
608 /// only for monomorphized code during trans, basically).
609 pub fn normalize_associated_type
<T
>(self, value
: &T
) -> T
610 where T
: TransNormalize
<'tcx
>
612 debug
!("normalize_associated_type(t={:?})", value
);
614 let param_env
= ty
::ParamEnv
::empty(Reveal
::All
);
615 let value
= self.erase_regions(value
);
617 if !value
.has_projection_types() {
621 self.infer_ctxt(()).enter(|infcx
| {
622 value
.trans_normalize(&infcx
, param_env
)
626 /// Does a best-effort to normalize any associated types in
627 /// `value`; this includes revealing specializable types, so this
628 /// should be not be used during type-checking, but only during
629 /// optimization and code generation.
630 pub fn normalize_associated_type_in_env
<T
>(
631 self, value
: &T
, env
: ty
::ParamEnv
<'tcx
>
633 where T
: TransNormalize
<'tcx
>
635 debug
!("normalize_associated_type_in_env(t={:?})", value
);
637 let value
= self.erase_regions(value
);
639 if !value
.has_projection_types() {
643 self.infer_ctxt(()).enter(|infcx
| {
644 value
.trans_normalize(&infcx
, env
.reveal_all())
649 impl<'a
, 'gcx
, 'tcx
> InferCtxt
<'a
, 'gcx
, 'tcx
> {
650 fn normalize_projections_in
<T
>(&self, param_env
: ty
::ParamEnv
<'tcx
>, value
: &T
) -> T
::Lifted
651 where T
: TypeFoldable
<'tcx
> + ty
::Lift
<'gcx
>
653 let mut selcx
= traits
::SelectionContext
::new(self);
654 let cause
= traits
::ObligationCause
::dummy();
655 let traits
::Normalized { value: result, obligations }
=
656 traits
::normalize(&mut selcx
, param_env
, cause
, value
);
658 debug
!("normalize_projections_in: result={:?} obligations={:?}",
659 result
, obligations
);
661 let mut fulfill_cx
= traits
::FulfillmentContext
::new();
663 for obligation
in obligations
{
664 fulfill_cx
.register_predicate_obligation(self, obligation
);
667 self.drain_fulfillment_cx_or_panic(DUMMY_SP
, &mut fulfill_cx
, &result
)
670 /// Finishes processes any obligations that remain in the
671 /// fulfillment context, and then returns the result with all type
672 /// variables removed and regions erased. Because this is intended
673 /// for use after type-check has completed, if any errors occur,
674 /// it will panic. It is used during normalization and other cases
675 /// where processing the obligations in `fulfill_cx` may cause
676 /// type inference variables that appear in `result` to be
677 /// unified, and hence we need to process those obligations to get
678 /// the complete picture of the type.
679 pub fn drain_fulfillment_cx_or_panic
<T
>(&self,
681 fulfill_cx
: &mut traits
::FulfillmentContext
<'tcx
>,
684 where T
: TypeFoldable
<'tcx
> + ty
::Lift
<'gcx
>
686 debug
!("drain_fulfillment_cx_or_panic()");
688 // In principle, we only need to do this so long as `result`
689 // contains unbound type parameters. It could be a slight
690 // optimization to stop iterating early.
691 match fulfill_cx
.select_all_or_error(self) {
694 span_bug
!(span
, "Encountered errors `{:?}` resolving bounds after type-checking",
699 let result
= self.resolve_type_vars_if_possible(result
);
700 let result
= self.tcx
.erase_regions(&result
);
702 match self.tcx
.lift_to_global(&result
) {
703 Some(result
) => result
,
705 span_bug
!(span
, "Uninferred types/regions in `{:?}`", result
);
710 pub fn is_in_snapshot(&self) -> bool
{
711 self.in_snapshot
.get()
714 pub fn freshen
<T
:TypeFoldable
<'tcx
>>(&self, t
: T
) -> T
{
715 t
.fold_with(&mut self.freshener())
718 pub fn type_var_diverges(&'a
self, ty
: Ty
) -> bool
{
720 ty
::TyInfer(ty
::TyVar(vid
)) => self.type_variables
.borrow().var_diverges(vid
),
725 pub fn freshener
<'b
>(&'b
self) -> TypeFreshener
<'b
, 'gcx
, 'tcx
> {
726 freshen
::TypeFreshener
::new(self)
729 pub fn type_is_unconstrained_numeric(&'a
self, ty
: Ty
) -> UnconstrainedNumeric
{
730 use ty
::error
::UnconstrainedNumeric
::Neither
;
731 use ty
::error
::UnconstrainedNumeric
::{UnconstrainedInt, UnconstrainedFloat}
;
733 ty
::TyInfer(ty
::IntVar(vid
)) => {
734 if self.int_unification_table
.borrow_mut().has_value(vid
) {
740 ty
::TyInfer(ty
::FloatVar(vid
)) => {
741 if self.float_unification_table
.borrow_mut().has_value(vid
) {
751 /// Returns a type variable's default fallback if any exists. A default
752 /// must be attached to the variable when created, if it is created
753 /// without a default, this will return None.
755 /// This code does not apply to integral or floating point variables,
756 /// only to use declared defaults.
758 /// See `new_ty_var_with_default` to create a type variable with a default.
759 /// See `type_variable::Default` for details about what a default entails.
760 pub fn default(&self, ty
: Ty
<'tcx
>) -> Option
<type_variable
::Default
<'tcx
>> {
762 ty
::TyInfer(ty
::TyVar(vid
)) => self.type_variables
.borrow().default(vid
),
767 pub fn unsolved_variables(&self) -> Vec
<ty
::Ty
<'tcx
>> {
768 let mut variables
= Vec
::new();
770 let unbound_ty_vars
= self.type_variables
772 .unsolved_variables()
774 .map(|t
| self.tcx
.mk_var(t
));
776 let unbound_int_vars
= self.int_unification_table
778 .unsolved_variables()
780 .map(|v
| self.tcx
.mk_int_var(v
));
782 let unbound_float_vars
= self.float_unification_table
784 .unsolved_variables()
786 .map(|v
| self.tcx
.mk_float_var(v
));
788 variables
.extend(unbound_ty_vars
);
789 variables
.extend(unbound_int_vars
);
790 variables
.extend(unbound_float_vars
);
795 fn combine_fields(&'a
self, trace
: TypeTrace
<'tcx
>, param_env
: ty
::ParamEnv
<'tcx
>)
796 -> CombineFields
<'a
, 'gcx
, 'tcx
> {
802 obligations
: PredicateObligations
::new(),
806 // Clear the "currently in a snapshot" flag, invoke the closure,
807 // then restore the flag to its original value. This flag is a
808 // debugging measure designed to detect cases where we start a
809 // snapshot, create type variables, and register obligations
810 // which may involve those type variables in the fulfillment cx,
811 // potentially leaving "dangling type variables" behind.
812 // In such cases, an assertion will fail when attempting to
813 // register obligations, within a snapshot. Very useful, much
814 // better than grovelling through megabytes of RUST_LOG output.
816 // HOWEVER, in some cases the flag is unhelpful. In particular, we
817 // sometimes create a "mini-fulfilment-cx" in which we enroll
818 // obligations. As long as this fulfillment cx is fully drained
819 // before we return, this is not a problem, as there won't be any
820 // escaping obligations in the main cx. In those cases, you can
821 // use this function.
822 pub fn save_and_restore_in_snapshot_flag
<F
, R
>(&self, func
: F
) -> R
823 where F
: FnOnce(&Self) -> R
825 let flag
= self.in_snapshot
.get();
826 self.in_snapshot
.set(false);
827 let result
= func(self);
828 self.in_snapshot
.set(flag
);
832 fn start_snapshot
<'b
>(&'b
self) -> CombinedSnapshot
<'b
, 'tcx
> {
833 debug
!("start_snapshot()");
835 let in_snapshot
= self.in_snapshot
.get();
836 self.in_snapshot
.set(true);
839 projection_cache_snapshot
: self.projection_cache
.borrow_mut().snapshot(),
840 type_snapshot
: self.type_variables
.borrow_mut().snapshot(),
841 int_snapshot
: self.int_unification_table
.borrow_mut().snapshot(),
842 float_snapshot
: self.float_unification_table
.borrow_mut().snapshot(),
843 region_vars_snapshot
: self.region_vars
.start_snapshot(),
844 was_in_snapshot
: in_snapshot
,
845 // Borrow tables "in progress" (i.e. during typeck)
846 // to ban writes from within a snapshot to them.
847 _in_progress_tables
: match self.tables
{
848 InferTables
::InProgress(ref tables
) => tables
.try_borrow().ok(),
854 fn rollback_to(&self, cause
: &str, snapshot
: CombinedSnapshot
) {
855 debug
!("rollback_to(cause={})", cause
);
856 let CombinedSnapshot
{ projection_cache_snapshot
,
860 region_vars_snapshot
,
862 _in_progress_tables
} = snapshot
;
864 self.in_snapshot
.set(was_in_snapshot
);
866 self.projection_cache
868 .rollback_to(projection_cache_snapshot
);
871 .rollback_to(type_snapshot
);
872 self.int_unification_table
874 .rollback_to(int_snapshot
);
875 self.float_unification_table
877 .rollback_to(float_snapshot
);
879 .rollback_to(region_vars_snapshot
);
882 fn commit_from(&self, snapshot
: CombinedSnapshot
) {
883 debug
!("commit_from()");
884 let CombinedSnapshot
{ projection_cache_snapshot
,
888 region_vars_snapshot
,
890 _in_progress_tables
} = snapshot
;
892 self.in_snapshot
.set(was_in_snapshot
);
894 self.projection_cache
896 .commit(projection_cache_snapshot
);
899 .commit(type_snapshot
);
900 self.int_unification_table
902 .commit(int_snapshot
);
903 self.float_unification_table
905 .commit(float_snapshot
);
907 .commit(region_vars_snapshot
);
910 /// Execute `f` and commit the bindings
911 pub fn commit_unconditionally
<R
, F
>(&self, f
: F
) -> R
where
915 let snapshot
= self.start_snapshot();
917 self.commit_from(snapshot
);
921 /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)`
922 pub fn commit_if_ok
<T
, E
, F
>(&self, f
: F
) -> Result
<T
, E
> where
923 F
: FnOnce(&CombinedSnapshot
) -> Result
<T
, E
>
925 debug
!("commit_if_ok()");
926 let snapshot
= self.start_snapshot();
927 let r
= f(&snapshot
);
928 debug
!("commit_if_ok() -- r.is_ok() = {}", r
.is_ok());
930 Ok(_
) => { self.commit_from(snapshot); }
931 Err(_
) => { self.rollback_to("commit_if_ok -- error", snapshot); }
936 // Execute `f` in a snapshot, and commit the bindings it creates
937 pub fn in_snapshot
<T
, F
>(&self, f
: F
) -> T
where
938 F
: FnOnce(&CombinedSnapshot
) -> T
940 debug
!("in_snapshot()");
941 let snapshot
= self.start_snapshot();
942 let r
= f(&snapshot
);
943 self.commit_from(snapshot
);
947 /// Execute `f` then unroll any bindings it creates
948 pub fn probe
<R
, F
>(&self, f
: F
) -> R
where
949 F
: FnOnce(&CombinedSnapshot
) -> R
,
952 let snapshot
= self.start_snapshot();
953 let r
= f(&snapshot
);
954 self.rollback_to("probe", snapshot
);
958 pub fn add_given(&self,
959 sub
: ty
::Region
<'tcx
>,
962 self.region_vars
.add_given(sub
, sup
);
965 pub fn can_sub
<T
>(&self,
966 param_env
: ty
::ParamEnv
<'tcx
>,
970 where T
: at
::ToTrace
<'tcx
>
972 let origin
= &ObligationCause
::dummy();
974 self.at(origin
, param_env
).sub(a
, b
).map(|InferOk { obligations: _, .. }
| {
975 // Ignore obligations, since we are unrolling
976 // everything anyway.
981 pub fn can_eq
<T
>(&self,
982 param_env
: ty
::ParamEnv
<'tcx
>,
986 where T
: at
::ToTrace
<'tcx
>
988 let origin
= &ObligationCause
::dummy();
990 self.at(origin
, param_env
).eq(a
, b
).map(|InferOk { obligations: _, .. }
| {
991 // Ignore obligations, since we are unrolling
992 // everything anyway.
997 pub fn sub_regions(&self,
998 origin
: SubregionOrigin
<'tcx
>,
1000 b
: ty
::Region
<'tcx
>) {
1001 debug
!("sub_regions({:?} <: {:?})", a
, b
);
1002 self.region_vars
.make_subregion(origin
, a
, b
);
1005 pub fn equality_predicate(&self,
1006 cause
: &ObligationCause
<'tcx
>,
1007 param_env
: ty
::ParamEnv
<'tcx
>,
1008 predicate
: &ty
::PolyEquatePredicate
<'tcx
>)
1009 -> InferResult
<'tcx
, ()>
1011 self.commit_if_ok(|snapshot
| {
1012 let (ty
::EquatePredicate(a
, b
), skol_map
) =
1013 self.skolemize_late_bound_regions(predicate
, snapshot
);
1014 let cause_span
= cause
.span
;
1015 let eqty_ok
= self.at(cause
, param_env
).eq(b
, a
)?
;
1016 self.leak_check(false, cause_span
, &skol_map
, snapshot
)?
;
1017 self.pop_skolemized(skol_map
, snapshot
);
1022 pub fn subtype_predicate(&self,
1023 cause
: &ObligationCause
<'tcx
>,
1024 param_env
: ty
::ParamEnv
<'tcx
>,
1025 predicate
: &ty
::PolySubtypePredicate
<'tcx
>)
1026 -> Option
<InferResult
<'tcx
, ()>>
1028 // Subtle: it's ok to skip the binder here and resolve because
1029 // `shallow_resolve` just ignores anything that is not a type
1030 // variable, and because type variable's can't (at present, at
1031 // least) capture any of the things bound by this binder.
1033 // Really, there is no *particular* reason to do this
1034 // `shallow_resolve` here except as a
1035 // micro-optimization. Naturally I could not
1036 // resist. -nmatsakis
1037 let two_unbound_type_vars
= {
1038 let a
= self.shallow_resolve(predicate
.skip_binder().a
);
1039 let b
= self.shallow_resolve(predicate
.skip_binder().b
);
1040 a
.is_ty_var() && b
.is_ty_var()
1043 if two_unbound_type_vars
{
1044 // Two unbound type variables? Can't make progress.
1048 Some(self.commit_if_ok(|snapshot
| {
1049 let (ty
::SubtypePredicate { a_is_expected, a, b}
, skol_map
) =
1050 self.skolemize_late_bound_regions(predicate
, snapshot
);
1052 let cause_span
= cause
.span
;
1053 let ok
= self.at(cause
, param_env
).sub_exp(a_is_expected
, a
, b
)?
;
1054 self.leak_check(false, cause_span
, &skol_map
, snapshot
)?
;
1055 self.pop_skolemized(skol_map
, snapshot
);
1060 pub fn region_outlives_predicate(&self,
1061 cause
: &traits
::ObligationCause
<'tcx
>,
1062 predicate
: &ty
::PolyRegionOutlivesPredicate
<'tcx
>)
1065 self.commit_if_ok(|snapshot
| {
1066 let (ty
::OutlivesPredicate(r_a
, r_b
), skol_map
) =
1067 self.skolemize_late_bound_regions(predicate
, snapshot
);
1069 SubregionOrigin
::from_obligation_cause(cause
,
1070 || RelateRegionParamBound(cause
.span
));
1071 self.sub_regions(origin
, r_b
, r_a
); // `b : a` ==> `a <= b`
1072 self.leak_check(false, cause
.span
, &skol_map
, snapshot
)?
;
1073 Ok(self.pop_skolemized(skol_map
, snapshot
))
1077 pub fn next_ty_var_id(&self, diverging
: bool
, origin
: TypeVariableOrigin
) -> TyVid
{
1080 .new_var(diverging
, origin
, None
)
1083 pub fn next_ty_var(&self, origin
: TypeVariableOrigin
) -> Ty
<'tcx
> {
1084 self.tcx
.mk_var(self.next_ty_var_id(false, origin
))
1087 pub fn next_diverging_ty_var(&self, origin
: TypeVariableOrigin
) -> Ty
<'tcx
> {
1088 self.tcx
.mk_var(self.next_ty_var_id(true, origin
))
1091 pub fn next_int_var_id(&self) -> IntVid
{
1092 self.int_unification_table
1097 pub fn next_float_var_id(&self) -> FloatVid
{
1098 self.float_unification_table
1103 pub fn next_region_var(&self, origin
: RegionVariableOrigin
)
1104 -> ty
::Region
<'tcx
> {
1105 self.tcx
.mk_region(ty
::ReVar(self.region_vars
.new_region_var(origin
)))
1108 /// Create a region inference variable for the given
1109 /// region parameter definition.
1110 pub fn region_var_for_def(&self,
1112 def
: &ty
::RegionParameterDef
)
1113 -> ty
::Region
<'tcx
> {
1114 self.next_region_var(EarlyBoundRegion(span
, def
.name
, def
.issue_32330
))
1117 /// Create a type inference variable for the given
1118 /// type parameter definition. The substitutions are
1119 /// for actual parameters that may be referred to by
1120 /// the default of this type parameter, if it exists.
1121 /// E.g. `struct Foo<A, B, C = (A, B)>(...);` when
1122 /// used in a path such as `Foo::<T, U>::new()` will
1123 /// use an inference variable for `C` with `[T, U]`
1124 /// as the substitutions for the default, `(T, U)`.
1125 pub fn type_var_for_def(&self,
1127 def
: &ty
::TypeParameterDef
,
1128 substs
: &[Kind
<'tcx
>])
1130 let default = if def
.has_default
{
1131 let default = self.tcx
.type_of(def
.def_id
);
1132 Some(type_variable
::Default
{
1133 ty
: default.subst_spanned(self.tcx
, substs
, Some(span
)),
1142 let ty_var_id
= self.type_variables
1145 TypeVariableOrigin
::TypeParameterDefinition(span
, def
.name
),
1148 self.tcx
.mk_var(ty_var_id
)
1151 /// Given a set of generics defined on a type or impl, returns a substitution mapping each
1152 /// type/region parameter to a fresh inference variable.
1153 pub fn fresh_substs_for_item(&self,
1156 -> &'tcx Substs
<'tcx
> {
1157 Substs
::for_item(self.tcx
, def_id
, |def
, _
| {
1158 self.region_var_for_def(span
, def
)
1160 self.type_var_for_def(span
, def
, substs
)
1164 pub fn fresh_bound_region(&self, debruijn
: ty
::DebruijnIndex
) -> ty
::Region
<'tcx
> {
1165 self.region_vars
.new_bound(debruijn
)
1168 /// True if errors have been reported since this infcx was
1169 /// created. This is sometimes used as a heuristic to skip
1170 /// reporting errors that often occur as a result of earlier
1171 /// errors, but where it's hard to be 100% sure (e.g., unresolved
1172 /// inference variables, regionck errors).
1173 pub fn is_tainted_by_errors(&self) -> bool
{
1174 debug
!("is_tainted_by_errors(err_count={}, err_count_on_creation={}, \
1175 tainted_by_errors_flag={})",
1176 self.tcx
.sess
.err_count(),
1177 self.err_count_on_creation
,
1178 self.tainted_by_errors_flag
.get());
1180 if self.tcx
.sess
.err_count() > self.err_count_on_creation
{
1181 return true; // errors reported since this infcx was made
1183 self.tainted_by_errors_flag
.get()
1186 /// Set the "tainted by errors" flag to true. We call this when we
1187 /// observe an error from a prior pass.
1188 pub fn set_tainted_by_errors(&self) {
1189 debug
!("set_tainted_by_errors()");
1190 self.tainted_by_errors_flag
.set(true)
1193 pub fn node_type(&self, id
: ast
::NodeId
) -> Ty
<'tcx
> {
1194 match self.tables
.borrow().node_types
.get(&id
) {
1197 None
if self.is_tainted_by_errors() =>
1200 bug
!("no type for node {}: {} in fcx",
1201 id
, self.tcx
.hir
.node_to_string(id
));
1206 pub fn expr_ty(&self, ex
: &hir
::Expr
) -> Ty
<'tcx
> {
1207 match self.tables
.borrow().node_types
.get(&ex
.id
) {
1210 bug
!("no type for expr in fcx");
1215 pub fn resolve_regions_and_report_errors(&self,
1216 region_context
: DefId
,
1217 region_map
: &RegionMaps
,
1218 free_regions
: &FreeRegionMap
<'tcx
>) {
1219 let region_rels
= RegionRelations
::new(self.tcx
,
1223 let errors
= self.region_vars
.resolve_regions(®ion_rels
);
1224 if !self.is_tainted_by_errors() {
1225 // As a heuristic, just skip reporting region errors
1226 // altogether if other errors have been reported while
1227 // this infcx was in use. This is totally hokey but
1228 // otherwise we have a hard time separating legit region
1229 // errors from silly ones.
1230 self.report_region_errors(&errors
); // see error_reporting module
1234 pub fn ty_to_string(&self, t
: Ty
<'tcx
>) -> String
{
1235 self.resolve_type_vars_if_possible(&t
).to_string()
1238 pub fn tys_to_string(&self, ts
: &[Ty
<'tcx
>]) -> String
{
1239 let tstrs
: Vec
<String
> = ts
.iter().map(|t
| self.ty_to_string(*t
)).collect();
1240 format
!("({})", tstrs
.join(", "))
1243 pub fn trait_ref_to_string(&self, t
: &ty
::TraitRef
<'tcx
>) -> String
{
1244 self.resolve_type_vars_if_possible(t
).to_string()
1247 pub fn shallow_resolve(&self, typ
: Ty
<'tcx
>) -> Ty
<'tcx
> {
1249 ty
::TyInfer(ty
::TyVar(v
)) => {
1250 // Not entirely obvious: if `typ` is a type variable,
1251 // it can be resolved to an int/float variable, which
1252 // can then be recursively resolved, hence the
1253 // recursion. Note though that we prevent type
1254 // variables from unifying to other type variables
1255 // directly (though they may be embedded
1256 // structurally), and we prevent cycles in any case,
1257 // so this recursion should always be of very limited
1259 self.type_variables
.borrow_mut()
1261 .map(|t
| self.shallow_resolve(t
))
1265 ty
::TyInfer(ty
::IntVar(v
)) => {
1266 self.int_unification_table
1269 .map(|v
| v
.to_type(self.tcx
))
1273 ty
::TyInfer(ty
::FloatVar(v
)) => {
1274 self.float_unification_table
1277 .map(|v
| v
.to_type(self.tcx
))
1287 pub fn resolve_type_vars_if_possible
<T
>(&self, value
: &T
) -> T
1288 where T
: TypeFoldable
<'tcx
>
1291 * Where possible, replaces type/int/float variables in
1292 * `value` with their final value. Note that region variables
1293 * are unaffected. If a type variable has not been unified, it
1294 * is left as is. This is an idempotent operation that does
1295 * not affect inference state in any way and so you can do it
1299 if !value
.needs_infer() {
1300 return value
.clone(); // avoid duplicated subst-folding
1302 let mut r
= resolve
::OpportunisticTypeResolver
::new(self);
1303 value
.fold_with(&mut r
)
1306 pub fn resolve_type_and_region_vars_if_possible
<T
>(&self, value
: &T
) -> T
1307 where T
: TypeFoldable
<'tcx
>
1309 let mut r
= resolve
::OpportunisticTypeAndRegionResolver
::new(self);
1310 value
.fold_with(&mut r
)
1313 /// Resolves all type variables in `t` and then, if any were left
1314 /// unresolved, substitutes an error type. This is used after the
1315 /// main checking when doing a second pass before writeback. The
1316 /// justification is that writeback will produce an error for
1317 /// these unconstrained type variables.
1318 fn resolve_type_vars_or_error(&self, t
: &Ty
<'tcx
>) -> mc
::McResult
<Ty
<'tcx
>> {
1319 let ty
= self.resolve_type_vars_if_possible(t
);
1320 if ty
.references_error() || ty
.is_ty_var() {
1321 debug
!("resolve_type_vars_or_error: error from {:?}", ty
);
1328 pub fn fully_resolve
<T
:TypeFoldable
<'tcx
>>(&self, value
: &T
) -> FixupResult
<T
> {
1330 * Attempts to resolve all type/region variables in
1331 * `value`. Region inference must have been run already (e.g.,
1332 * by calling `resolve_regions_and_report_errors`). If some
1333 * variable was never unified, an `Err` results.
1335 * This method is idempotent, but it not typically not invoked
1336 * except during the writeback phase.
1339 resolve
::fully_resolve(self, value
)
1342 // [Note-Type-error-reporting]
1343 // An invariant is that anytime the expected or actual type is TyError (the special
1344 // error type, meaning that an error occurred when typechecking this expression),
1345 // this is a derived error. The error cascaded from another error (that was already
1346 // reported), so it's not useful to display it to the user.
1347 // The following methods implement this logic.
1348 // They check if either the actual or expected type is TyError, and don't print the error
1349 // in this case. The typechecker should only ever report type errors involving mismatched
1350 // types using one of these methods, and should not call span_err directly for such
1353 pub fn type_error_message
<M
>(&self,
1356 actual_ty
: Ty
<'tcx
>)
1357 where M
: FnOnce(String
) -> String
,
1359 self.type_error_struct(sp
, mk_msg
, actual_ty
).emit();
1362 // FIXME: this results in errors without an error code. Deprecate?
1363 pub fn type_error_struct
<M
>(&self,
1366 actual_ty
: Ty
<'tcx
>)
1367 -> DiagnosticBuilder
<'tcx
>
1368 where M
: FnOnce(String
) -> String
,
1370 self.type_error_struct_with_diag(sp
, |actual_ty
| {
1371 self.tcx
.sess
.struct_span_err(sp
, &mk_msg(actual_ty
))
1375 pub fn type_error_struct_with_diag
<M
>(&self,
1378 actual_ty
: Ty
<'tcx
>)
1379 -> DiagnosticBuilder
<'tcx
>
1380 where M
: FnOnce(String
) -> DiagnosticBuilder
<'tcx
>,
1382 let actual_ty
= self.resolve_type_vars_if_possible(&actual_ty
);
1383 debug
!("type_error_struct_with_diag({:?}, {:?})", sp
, actual_ty
);
1385 // Don't report an error if actual type is TyError.
1386 if actual_ty
.references_error() {
1387 return self.tcx
.sess
.diagnostic().struct_dummy();
1390 mk_diag(self.ty_to_string(actual_ty
))
1393 pub fn report_mismatched_types(&self,
1394 cause
: &ObligationCause
<'tcx
>,
1397 err
: TypeError
<'tcx
>)
1398 -> DiagnosticBuilder
<'tcx
> {
1399 let trace
= TypeTrace
::types(cause
, true, expected
, actual
);
1400 self.report_and_explain_type_error(trace
, &err
)
1403 pub fn report_conflicting_default_types(&self,
1405 body_id
: ast
::NodeId
,
1406 expected
: type_variable
::Default
<'tcx
>,
1407 actual
: type_variable
::Default
<'tcx
>) {
1408 let trace
= TypeTrace
{
1409 cause
: ObligationCause
::misc(span
, body_id
),
1410 values
: Types(ExpectedFound
{
1411 expected
: expected
.ty
,
1416 self.report_and_explain_type_error(
1418 &TypeError
::TyParamDefaultMismatch(ExpectedFound
{
1425 pub fn replace_late_bound_regions_with_fresh_var
<T
>(
1428 lbrct
: LateBoundRegionConversionTime
,
1429 value
: &ty
::Binder
<T
>)
1430 -> (T
, FxHashMap
<ty
::BoundRegion
, ty
::Region
<'tcx
>>)
1431 where T
: TypeFoldable
<'tcx
>
1433 self.tcx
.replace_late_bound_regions(
1435 |br
| self.next_region_var(LateBoundRegion(span
, br
, lbrct
)))
1438 /// Given a higher-ranked projection predicate like:
1440 /// for<'a> <T as Fn<&'a u32>>::Output = &'a u32
1442 /// and a target trait-ref like:
1444 /// <T as Fn<&'x u32>>
1446 /// find a substitution `S` for the higher-ranked regions (here,
1447 /// `['a => 'x]`) such that the predicate matches the trait-ref,
1448 /// and then return the value (here, `&'a u32`) but with the
1449 /// substitution applied (hence, `&'x u32`).
1451 /// See `higher_ranked_match` in `higher_ranked/mod.rs` for more
1453 pub fn match_poly_projection_predicate(&self,
1454 cause
: ObligationCause
<'tcx
>,
1455 param_env
: ty
::ParamEnv
<'tcx
>,
1456 match_a
: ty
::PolyProjectionPredicate
<'tcx
>,
1457 match_b
: ty
::TraitRef
<'tcx
>)
1458 -> InferResult
<'tcx
, HrMatchResult
<Ty
<'tcx
>>>
1460 let span
= cause
.span
;
1461 let match_trait_ref
= match_a
.skip_binder().projection_ty
.trait_ref
;
1462 let trace
= TypeTrace
{
1464 values
: TraitRefs(ExpectedFound
::new(true, match_trait_ref
, match_b
))
1467 let match_pair
= match_a
.map_bound(|p
| (p
.projection_ty
.trait_ref
, p
.ty
));
1468 let mut combine
= self.combine_fields(trace
, param_env
);
1469 let result
= combine
.higher_ranked_match(span
, &match_pair
, &match_b
, true)?
;
1470 Ok(InferOk { value: result, obligations: combine.obligations }
)
1473 /// See `verify_generic_bound` method in `region_inference`
1474 pub fn verify_generic_bound(&self,
1475 origin
: SubregionOrigin
<'tcx
>,
1476 kind
: GenericKind
<'tcx
>,
1477 a
: ty
::Region
<'tcx
>,
1478 bound
: VerifyBound
<'tcx
>) {
1479 debug
!("verify_generic_bound({:?}, {:?} <: {:?})",
1484 self.region_vars
.verify_generic_bound(origin
, kind
, a
, bound
);
1487 pub fn node_ty(&self, id
: ast
::NodeId
) -> McResult
<Ty
<'tcx
>> {
1488 let ty
= self.node_type(id
);
1489 self.resolve_type_vars_or_error(&ty
)
1492 pub fn expr_ty_adjusted(&self, expr
: &hir
::Expr
) -> McResult
<Ty
<'tcx
>> {
1493 let ty
= self.tables
.borrow().expr_ty_adjusted(expr
);
1494 self.resolve_type_vars_or_error(&ty
)
1497 pub fn type_moves_by_default(&self,
1498 param_env
: ty
::ParamEnv
<'tcx
>,
1502 let ty
= self.resolve_type_vars_if_possible(&ty
);
1503 if let Some((param_env
, ty
)) = self.tcx
.lift_to_global(&(param_env
, ty
)) {
1504 // Even if the type may have no inference variables, during
1505 // type-checking closure types are in local tables only.
1506 let local_closures
= match self.tables
{
1507 InferTables
::InProgress(_
) => ty
.has_closure_types(),
1510 if !local_closures
{
1511 return ty
.moves_by_default(self.tcx
.global_tcx(), param_env
, span
);
1515 let copy_def_id
= self.tcx
.require_lang_item(lang_items
::CopyTraitLangItem
);
1517 // this can get called from typeck (by euv), and moves_by_default
1518 // rightly refuses to work with inference variables, but
1519 // moves_by_default has a cache, which we want to use in other
1521 !traits
::type_known_to_meet_bound(self, param_env
, ty
, copy_def_id
, span
)
1524 pub fn upvar_capture(&self, upvar_id
: ty
::UpvarId
) -> Option
<ty
::UpvarCapture
<'tcx
>> {
1525 self.tables
.borrow().upvar_capture_map
.get(&upvar_id
).cloned()
1528 pub fn closure_kind(&self,
1530 -> Option
<ty
::ClosureKind
>
1532 if let InferTables
::InProgress(tables
) = self.tables
{
1533 if let Some(id
) = self.tcx
.hir
.as_local_node_id(def_id
) {
1534 return tables
.borrow()
1538 .map(|(kind
, _
)| kind
);
1542 // During typeck, ALL closures are local. But afterwards,
1543 // during trans, we see closure ids from other traits.
1544 // That may require loading the closure data out of the
1546 Some(self.tcx
.closure_kind(def_id
))
1549 pub fn closure_type(&self, def_id
: DefId
) -> ty
::PolyFnSig
<'tcx
> {
1550 if let InferTables
::InProgress(tables
) = self.tables
{
1551 if let Some(id
) = self.tcx
.hir
.as_local_node_id(def_id
) {
1552 if let Some(&ty
) = tables
.borrow().closure_tys
.get(&id
) {
1558 self.tcx
.closure_type(def_id
)
1562 impl<'a
, 'gcx
, 'tcx
> TypeTrace
<'tcx
> {
1563 pub fn span(&self) -> Span
{
1567 pub fn types(cause
: &ObligationCause
<'tcx
>,
1568 a_is_expected
: bool
,
1571 -> TypeTrace
<'tcx
> {
1573 cause
: cause
.clone(),
1574 values
: Types(ExpectedFound
::new(a_is_expected
, a
, b
))
1578 pub fn dummy(tcx
: TyCtxt
<'a
, 'gcx
, 'tcx
>) -> TypeTrace
<'tcx
> {
1580 cause
: ObligationCause
::dummy(),
1581 values
: Types(ExpectedFound
{
1582 expected
: tcx
.types
.err
,
1583 found
: tcx
.types
.err
,
1589 impl<'tcx
> fmt
::Debug
for TypeTrace
<'tcx
> {
1590 fn fmt(&self, f
: &mut fmt
::Formatter
) -> fmt
::Result
{
1591 write
!(f
, "TypeTrace({:?})", self.cause
)
1595 impl<'tcx
> SubregionOrigin
<'tcx
> {
1596 pub fn span(&self) -> Span
{
1598 Subtype(ref a
) => a
.span(),
1599 InfStackClosure(a
) => a
,
1600 InvokeClosure(a
) => a
,
1601 DerefPointer(a
) => a
,
1602 FreeVariable(a
, _
) => a
,
1604 RelateObjectBound(a
) => a
,
1605 RelateParamBound(a
, _
) => a
,
1606 RelateRegionParamBound(a
) => a
,
1607 RelateDefaultParamBound(a
, _
) => a
,
1609 ReborrowUpvar(a
, _
) => a
,
1610 DataBorrowed(_
, a
) => a
,
1611 ReferenceOutlivesReferent(_
, a
) => a
,
1612 ParameterInScope(_
, a
) => a
,
1613 ExprTypeIsNotInScope(_
, a
) => a
,
1614 BindingTypeIsNotValidAtDecl(a
) => a
,
1621 SafeDestructor(a
) => a
,
1622 CompareImplMethodObligation { span, .. }
=> span
,
1626 pub fn from_obligation_cause
<F
>(cause
: &traits
::ObligationCause
<'tcx
>,
1629 where F
: FnOnce() -> Self
1632 traits
::ObligationCauseCode
::ReferenceOutlivesReferent(ref_type
) =>
1633 SubregionOrigin
::ReferenceOutlivesReferent(ref_type
, cause
.span
),
1635 traits
::ObligationCauseCode
::CompareImplMethodObligation
{ item_name
,
1639 SubregionOrigin
::CompareImplMethodObligation
{
1641 item_name
: item_name
,
1642 impl_item_def_id
: impl_item_def_id
,
1643 trait_item_def_id
: trait_item_def_id
,
1652 impl RegionVariableOrigin
{
1653 pub fn span(&self) -> Span
{
1655 MiscVariable(a
) => a
,
1656 PatternRegion(a
) => a
,
1657 AddrOfRegion(a
) => a
,
1660 EarlyBoundRegion(a
, ..) => a
,
1661 LateBoundRegion(a
, ..) => a
,
1662 BoundRegionInCoherence(_
) => syntax_pos
::DUMMY_SP
,
1663 UpvarRegion(_
, a
) => a
1668 impl<'tcx
> TypeFoldable
<'tcx
> for ValuePairs
<'tcx
> {
1669 fn super_fold_with
<'gcx
: 'tcx
, F
: TypeFolder
<'gcx
, 'tcx
>>(&self, folder
: &mut F
) -> Self {
1671 ValuePairs
::Types(ref ef
) => {
1672 ValuePairs
::Types(ef
.fold_with(folder
))
1674 ValuePairs
::TraitRefs(ref ef
) => {
1675 ValuePairs
::TraitRefs(ef
.fold_with(folder
))
1677 ValuePairs
::PolyTraitRefs(ref ef
) => {
1678 ValuePairs
::PolyTraitRefs(ef
.fold_with(folder
))
1683 fn super_visit_with
<V
: TypeVisitor
<'tcx
>>(&self, visitor
: &mut V
) -> bool
{
1685 ValuePairs
::Types(ref ef
) => ef
.visit_with(visitor
),
1686 ValuePairs
::TraitRefs(ref ef
) => ef
.visit_with(visitor
),
1687 ValuePairs
::PolyTraitRefs(ref ef
) => ef
.visit_with(visitor
),
1692 impl<'tcx
> TypeFoldable
<'tcx
> for TypeTrace
<'tcx
> {
1693 fn super_fold_with
<'gcx
: 'tcx
, F
: TypeFolder
<'gcx
, 'tcx
>>(&self, folder
: &mut F
) -> Self {
1695 cause
: self.cause
.fold_with(folder
),
1696 values
: self.values
.fold_with(folder
)
1700 fn super_visit_with
<V
: TypeVisitor
<'tcx
>>(&self, visitor
: &mut V
) -> bool
{
1701 self.cause
.visit_with(visitor
) || self.values
.visit_with(visitor
)