| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! See the Book for more information. |
| |
| pub use self::LateBoundRegionConversionTime::*; |
| pub use self::RegionVariableOrigin::*; |
| pub use self::SubregionOrigin::*; |
| pub use self::ValuePairs::*; |
| pub use ty::IntVarValue; |
| pub use self::freshen::TypeFreshener; |
| pub use self::region_inference::{GenericKind, VerifyBound}; |
| |
| use hir::def_id::DefId; |
| use hir; |
| use middle::free_region::FreeRegionMap; |
| use middle::mem_categorization as mc; |
| use middle::mem_categorization::McResult; |
| use middle::region::CodeExtent; |
| use mir::tcx::LvalueTy; |
| use ty::subst; |
| use ty::subst::Substs; |
| use ty::subst::Subst; |
| use ty::adjustment; |
| use ty::{TyVid, IntVid, FloatVid}; |
| use ty::{self, Ty, TyCtxt}; |
| use ty::error::{ExpectedFound, TypeError, UnconstrainedNumeric}; |
| use ty::fold::TypeFoldable; |
| use ty::relate::{Relate, RelateResult, TypeRelation}; |
| use traits::{self, PredicateObligations, ProjectionMode}; |
| use rustc_data_structures::unify::{self, UnificationTable}; |
| use std::cell::{Cell, RefCell, Ref, RefMut}; |
| use std::fmt; |
| use syntax::ast; |
| use errors::DiagnosticBuilder; |
| use syntax_pos::{self, Span, DUMMY_SP}; |
| use util::nodemap::{FnvHashMap, FnvHashSet, NodeMap}; |
| |
| use self::combine::CombineFields; |
| use self::higher_ranked::HrMatchResult; |
| use self::region_inference::{RegionVarBindings, RegionSnapshot}; |
| use self::unify_key::ToType; |
| |
| pub mod bivariate; |
| pub mod combine; |
| pub mod equate; |
| pub mod error_reporting; |
| pub mod glb; |
| mod higher_ranked; |
| pub mod lattice; |
| pub mod lub; |
| pub mod region_inference; |
| pub mod resolve; |
| mod freshen; |
| pub mod sub; |
| pub mod type_variable; |
| pub mod unify_key; |
| |
| #[must_use] |
| pub struct InferOk<'tcx, T> { |
| pub value: T, |
| pub obligations: PredicateObligations<'tcx>, |
| } |
| pub type InferResult<'tcx, T> = Result<InferOk<'tcx, T>, TypeError<'tcx>>; |
| |
| pub type Bound<T> = Option<T>; |
| pub type UnitResult<'tcx> = RelateResult<'tcx, ()>; // "unify result" |
| pub type FixupResult<T> = Result<T, FixupError>; // "fixup result" |
| |
| /// A version of &ty::Tables which can be global or local. |
| /// Only the local version supports borrow_mut. |
| #[derive(Copy, Clone)] |
| pub enum InferTables<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
| Global(&'a RefCell<ty::Tables<'gcx>>), |
| Local(&'a RefCell<ty::Tables<'tcx>>) |
| } |
| |
| impl<'a, 'gcx, 'tcx> InferTables<'a, 'gcx, 'tcx> { |
| pub fn borrow(self) -> Ref<'a, ty::Tables<'tcx>> { |
| match self { |
| InferTables::Global(tables) => tables.borrow(), |
| InferTables::Local(tables) => tables.borrow() |
| } |
| } |
| |
| pub fn borrow_mut(self) -> RefMut<'a, ty::Tables<'tcx>> { |
| match self { |
| InferTables::Global(_) => { |
| bug!("InferTables: infcx.tables.borrow_mut() outside of type-checking"); |
| } |
| InferTables::Local(tables) => tables.borrow_mut() |
| } |
| } |
| } |
| |
| pub struct InferCtxt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
| pub tcx: TyCtxt<'a, 'gcx, 'tcx>, |
| |
| pub tables: InferTables<'a, 'gcx, 'tcx>, |
| |
| // Cache for projections. This cache is snapshotted along with the |
| // infcx. |
| // |
| // Public so that `traits::project` can use it. |
| pub projection_cache: RefCell<traits::ProjectionCache<'tcx>>, |
| |
| // We instantiate UnificationTable with bounds<Ty> because the |
| // types that might instantiate a general type variable have an |
| // order, represented by its upper and lower bounds. |
| type_variables: RefCell<type_variable::TypeVariableTable<'tcx>>, |
| |
| // Map from integral variable to the kind of integer it represents |
| int_unification_table: RefCell<UnificationTable<ty::IntVid>>, |
| |
| // Map from floating variable to the kind of float it represents |
| float_unification_table: RefCell<UnificationTable<ty::FloatVid>>, |
| |
| // For region variables. |
| region_vars: RegionVarBindings<'a, 'gcx, 'tcx>, |
| |
| pub parameter_environment: ty::ParameterEnvironment<'gcx>, |
| |
| /// Caches the results of trait selection. This cache is used |
| /// for things that have to do with the parameters in scope. |
| pub selection_cache: traits::SelectionCache<'tcx>, |
| |
| /// Caches the results of trait evaluation. |
| pub evaluation_cache: traits::EvaluationCache<'tcx>, |
| |
| // the set of predicates on which errors have been reported, to |
| // avoid reporting the same error twice. |
| pub reported_trait_errors: RefCell<FnvHashSet<traits::TraitErrorKey<'tcx>>>, |
| |
| // This is a temporary field used for toggling on normalization in the inference context, |
| // as we move towards the approach described here: |
| // https://internals.rust-lang.org/t/flattening-the-contexts-for-fun-and-profit/2293 |
| // At a point sometime in the future normalization will be done by the typing context |
| // directly. |
| normalize: bool, |
| |
| // Sadly, the behavior of projection varies a bit depending on the |
| // stage of compilation. The specifics are given in the |
| // documentation for `ProjectionMode`. |
| projection_mode: ProjectionMode, |
| |
| // When an error occurs, we want to avoid reporting "derived" |
| // errors that are due to this original failure. Normally, we |
| // handle this with the `err_count_on_creation` count, which |
| // basically just tracks how many errors were reported when we |
| // started type-checking a fn and checks to see if any new errors |
| // have been reported since then. Not great, but it works. |
| // |
| // However, when errors originated in other passes -- notably |
| // resolve -- this heuristic breaks down. Therefore, we have this |
| // auxiliary flag that one can set whenever one creates a |
| // type-error that is due to an error in a prior pass. |
| // |
| // Don't read this flag directly, call `is_tainted_by_errors()` |
| // and `set_tainted_by_errors()`. |
| tainted_by_errors_flag: Cell<bool>, |
| |
| // Track how many errors were reported when this infcx is created. |
| // If the number of errors increases, that's also a sign (line |
| // `tained_by_errors`) to avoid reporting certain kinds of errors. |
| err_count_on_creation: usize, |
| |
| // This flag is used for debugging, and is set to true if there are |
| // any obligations set during the current snapshot. In that case, the |
| // snapshot can't be rolled back. |
| pub obligations_in_snapshot: Cell<bool>, |
| } |
| |
| /// A map returned by `skolemize_late_bound_regions()` indicating the skolemized |
| /// region that each late-bound region was replaced with. |
| pub type SkolemizationMap = FnvHashMap<ty::BoundRegion, ty::Region>; |
| |
| /// Why did we require that the two types be related? |
| /// |
| /// See `error_reporting.rs` for more details |
| #[derive(Clone, Copy, Debug)] |
| pub enum TypeOrigin { |
| // Not yet categorized in a better way |
| Misc(Span), |
| |
| // Checking that method of impl is compatible with trait |
| MethodCompatCheck(Span), |
| |
| // Checking that this expression can be assigned where it needs to be |
| // FIXME(eddyb) #11161 is the original Expr required? |
| ExprAssignable(Span), |
| |
| // Relating trait refs when resolving vtables |
| RelateTraitRefs(Span), |
| |
| // Relating self types when resolving vtables |
| RelateSelfType(Span), |
| |
| // Relating trait type parameters to those found in impl etc |
| RelateOutputImplTypes(Span), |
| |
| // Computing common supertype in the arms of a match expression |
| MatchExpressionArm(Span, Span, hir::MatchSource), |
| |
| // Computing common supertype in an if expression |
| IfExpression(Span), |
| |
| // Computing common supertype of an if expression with no else counter-part |
| IfExpressionWithNoElse(Span), |
| |
| // Computing common supertype in a range expression |
| RangeExpression(Span), |
| |
| // `where a == b` |
| EquatePredicate(Span), |
| } |
| |
| impl TypeOrigin { |
| fn as_str(&self) -> &'static str { |
| match self { |
| &TypeOrigin::Misc(_) | |
| &TypeOrigin::RelateSelfType(_) | |
| &TypeOrigin::RelateOutputImplTypes(_) | |
| &TypeOrigin::ExprAssignable(_) => "mismatched types", |
| &TypeOrigin::RelateTraitRefs(_) => "mismatched traits", |
| &TypeOrigin::MethodCompatCheck(_) => "method not compatible with trait", |
| &TypeOrigin::MatchExpressionArm(_, _, source) => match source { |
| hir::MatchSource::IfLetDesugar{..} => "`if let` arms have incompatible types", |
| _ => "match arms have incompatible types", |
| }, |
| &TypeOrigin::IfExpression(_) => "if and else have incompatible types", |
| &TypeOrigin::IfExpressionWithNoElse(_) => "if may be missing an else clause", |
| &TypeOrigin::RangeExpression(_) => "start and end of range have incompatible types", |
| &TypeOrigin::EquatePredicate(_) => "equality predicate not satisfied", |
| } |
| } |
| } |
| |
| impl fmt::Display for TypeOrigin { |
| fn fmt(&self, f: &mut fmt::Formatter) -> Result<(),fmt::Error> { |
| fmt::Display::fmt(self.as_str(), f) |
| } |
| } |
| |
| /// See `error_reporting.rs` for more details |
| #[derive(Clone, Debug)] |
| pub enum ValuePairs<'tcx> { |
| Types(ExpectedFound<Ty<'tcx>>), |
| TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>), |
| PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>), |
| } |
| |
| /// The trace designates the path through inference that we took to |
| /// encounter an error or subtyping constraint. |
| /// |
| /// See `error_reporting.rs` for more details. |
| #[derive(Clone)] |
| pub struct TypeTrace<'tcx> { |
| origin: TypeOrigin, |
| values: ValuePairs<'tcx>, |
| } |
| |
| /// The origin of a `r1 <= r2` constraint. |
| /// |
| /// See `error_reporting.rs` for more details |
| #[derive(Clone, Debug)] |
| pub enum SubregionOrigin<'tcx> { |
| // Arose from a subtyping relation |
| Subtype(TypeTrace<'tcx>), |
| |
| // Stack-allocated closures cannot outlive innermost loop |
| // or function so as to ensure we only require finite stack |
| InfStackClosure(Span), |
| |
| // Invocation of closure must be within its lifetime |
| InvokeClosure(Span), |
| |
| // Dereference of reference must be within its lifetime |
| DerefPointer(Span), |
| |
| // Closure bound must not outlive captured free variables |
| FreeVariable(Span, ast::NodeId), |
| |
| // Index into slice must be within its lifetime |
| IndexSlice(Span), |
| |
| // When casting `&'a T` to an `&'b Trait` object, |
| // relating `'a` to `'b` |
| RelateObjectBound(Span), |
| |
| // Some type parameter was instantiated with the given type, |
| // and that type must outlive some region. |
| RelateParamBound(Span, Ty<'tcx>), |
| |
| // The given region parameter was instantiated with a region |
| // that must outlive some other region. |
| RelateRegionParamBound(Span), |
| |
| // A bound placed on type parameters that states that must outlive |
| // the moment of their instantiation. |
| RelateDefaultParamBound(Span, Ty<'tcx>), |
| |
| // Creating a pointer `b` to contents of another reference |
| Reborrow(Span), |
| |
| // Creating a pointer `b` to contents of an upvar |
| ReborrowUpvar(Span, ty::UpvarId), |
| |
| // Data with type `Ty<'tcx>` was borrowed |
| DataBorrowed(Ty<'tcx>, Span), |
| |
| // (&'a &'b T) where a >= b |
| ReferenceOutlivesReferent(Ty<'tcx>, Span), |
| |
| // Type or region parameters must be in scope. |
| ParameterInScope(ParameterOrigin, Span), |
| |
| // The type T of an expression E must outlive the lifetime for E. |
| ExprTypeIsNotInScope(Ty<'tcx>, Span), |
| |
| // A `ref b` whose region does not enclose the decl site |
| BindingTypeIsNotValidAtDecl(Span), |
| |
| // Regions appearing in a method receiver must outlive method call |
| CallRcvr(Span), |
| |
| // Regions appearing in a function argument must outlive func call |
| CallArg(Span), |
| |
| // Region in return type of invoked fn must enclose call |
| CallReturn(Span), |
| |
| // Operands must be in scope |
| Operand(Span), |
| |
| // Region resulting from a `&` expr must enclose the `&` expr |
| AddrOf(Span), |
| |
| // An auto-borrow that does not enclose the expr where it occurs |
| AutoBorrow(Span), |
| |
| // Region constraint arriving from destructor safety |
| SafeDestructor(Span), |
| } |
| |
| /// Places that type/region parameters can appear. |
| #[derive(Clone, Copy, Debug)] |
| pub enum ParameterOrigin { |
| Path, // foo::bar |
| MethodCall, // foo.bar() <-- parameters on impl providing bar() |
| OverloadedOperator, // a + b when overloaded |
| OverloadedDeref, // *a when overloaded |
| } |
| |
| /// Times when we replace late-bound regions with variables: |
| #[derive(Clone, Copy, Debug)] |
| pub enum LateBoundRegionConversionTime { |
| /// when a fn is called |
| FnCall, |
| |
| /// when two higher-ranked types are compared |
| HigherRankedType, |
| |
| /// when projecting an associated type |
| AssocTypeProjection(ast::Name), |
| } |
| |
| /// Reasons to create a region inference variable |
| /// |
| /// See `error_reporting.rs` for more details |
| #[derive(Clone, Debug)] |
| pub enum RegionVariableOrigin { |
| // Region variables created for ill-categorized reasons, |
| // mostly indicates places in need of refactoring |
| MiscVariable(Span), |
| |
| // Regions created by a `&P` or `[...]` pattern |
| PatternRegion(Span), |
| |
| // Regions created by `&` operator |
| AddrOfRegion(Span), |
| |
| // Regions created as part of an autoref of a method receiver |
| Autoref(Span), |
| |
| // Regions created as part of an automatic coercion |
| Coercion(Span), |
| |
| // Region variables created as the values for early-bound regions |
| EarlyBoundRegion(Span, ast::Name), |
| |
| // Region variables created for bound regions |
| // in a function or method that is called |
| LateBoundRegion(Span, ty::BoundRegion, LateBoundRegionConversionTime), |
| |
| UpvarRegion(ty::UpvarId, Span), |
| |
| BoundRegionInCoherence(ast::Name), |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| pub enum FixupError { |
| UnresolvedIntTy(IntVid), |
| UnresolvedFloatTy(FloatVid), |
| UnresolvedTy(TyVid) |
| } |
| |
| impl fmt::Display for FixupError { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| use self::FixupError::*; |
| |
| match *self { |
| UnresolvedIntTy(_) => { |
| write!(f, "cannot determine the type of this integer; \ |
| add a suffix to specify the type explicitly") |
| } |
| UnresolvedFloatTy(_) => { |
| write!(f, "cannot determine the type of this number; \ |
| add a suffix to specify the type explicitly") |
| } |
| UnresolvedTy(_) => write!(f, "unconstrained type") |
| } |
| } |
| } |
| |
| /// Helper type of a temporary returned by tcx.infer_ctxt(...). |
| /// Necessary because we can't write the following bound: |
| /// F: for<'b, 'tcx> where 'gcx: 'tcx FnOnce(InferCtxt<'b, 'gcx, 'tcx>). |
| pub struct InferCtxtBuilder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
| global_tcx: TyCtxt<'a, 'gcx, 'gcx>, |
| arenas: ty::CtxtArenas<'tcx>, |
| tables: Option<RefCell<ty::Tables<'tcx>>>, |
| param_env: Option<ty::ParameterEnvironment<'gcx>>, |
| projection_mode: ProjectionMode, |
| normalize: bool |
| } |
| |
| impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'gcx> { |
| pub fn infer_ctxt(self, |
| tables: Option<ty::Tables<'tcx>>, |
| param_env: Option<ty::ParameterEnvironment<'gcx>>, |
| projection_mode: ProjectionMode) |
| -> InferCtxtBuilder<'a, 'gcx, 'tcx> { |
| InferCtxtBuilder { |
| global_tcx: self, |
| arenas: ty::CtxtArenas::new(), |
| tables: tables.map(RefCell::new), |
| param_env: param_env, |
| projection_mode: projection_mode, |
| normalize: false |
| } |
| } |
| |
| pub fn normalizing_infer_ctxt(self, projection_mode: ProjectionMode) |
| -> InferCtxtBuilder<'a, 'gcx, 'tcx> { |
| InferCtxtBuilder { |
| global_tcx: self, |
| arenas: ty::CtxtArenas::new(), |
| tables: None, |
| param_env: None, |
| projection_mode: projection_mode, |
| normalize: false |
| } |
| } |
| |
| /// Fake InferCtxt with the global tcx. Used by pre-MIR borrowck |
| /// for MemCategorizationContext/ExprUseVisitor. |
| /// If any inference functionality is used, ICEs will occur. |
| pub fn borrowck_fake_infer_ctxt(self, param_env: ty::ParameterEnvironment<'gcx>) |
| -> InferCtxt<'a, 'gcx, 'gcx> { |
| InferCtxt { |
| tcx: self, |
| tables: InferTables::Global(&self.tables), |
| type_variables: RefCell::new(type_variable::TypeVariableTable::new()), |
| int_unification_table: RefCell::new(UnificationTable::new()), |
| float_unification_table: RefCell::new(UnificationTable::new()), |
| region_vars: RegionVarBindings::new(self), |
| parameter_environment: param_env, |
| selection_cache: traits::SelectionCache::new(), |
| evaluation_cache: traits::EvaluationCache::new(), |
| projection_cache: RefCell::new(traits::ProjectionCache::new()), |
| reported_trait_errors: RefCell::new(FnvHashSet()), |
| normalize: false, |
| projection_mode: ProjectionMode::AnyFinal, |
| tainted_by_errors_flag: Cell::new(false), |
| err_count_on_creation: self.sess.err_count(), |
| obligations_in_snapshot: Cell::new(false), |
| } |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> InferCtxtBuilder<'a, 'gcx, 'tcx> { |
| pub fn enter<F, R>(&'tcx mut self, f: F) -> R |
| where F: for<'b> FnOnce(InferCtxt<'b, 'gcx, 'tcx>) -> R |
| { |
| let InferCtxtBuilder { |
| global_tcx, |
| ref arenas, |
| ref tables, |
| ref mut param_env, |
| projection_mode, |
| normalize |
| } = *self; |
| let tables = if let Some(ref tables) = *tables { |
| InferTables::Local(tables) |
| } else { |
| InferTables::Global(&global_tcx.tables) |
| }; |
| let param_env = param_env.take().unwrap_or_else(|| { |
| global_tcx.empty_parameter_environment() |
| }); |
| global_tcx.enter_local(arenas, |tcx| f(InferCtxt { |
| tcx: tcx, |
| tables: tables, |
| projection_cache: RefCell::new(traits::ProjectionCache::new()), |
| type_variables: RefCell::new(type_variable::TypeVariableTable::new()), |
| int_unification_table: RefCell::new(UnificationTable::new()), |
| float_unification_table: RefCell::new(UnificationTable::new()), |
| region_vars: RegionVarBindings::new(tcx), |
| parameter_environment: param_env, |
| selection_cache: traits::SelectionCache::new(), |
| evaluation_cache: traits::EvaluationCache::new(), |
| reported_trait_errors: RefCell::new(FnvHashSet()), |
| normalize: normalize, |
| projection_mode: projection_mode, |
| tainted_by_errors_flag: Cell::new(false), |
| err_count_on_creation: tcx.sess.err_count(), |
| obligations_in_snapshot: Cell::new(false), |
| })) |
| } |
| } |
| |
| impl<T> ExpectedFound<T> { |
| fn new(a_is_expected: bool, a: T, b: T) -> Self { |
| if a_is_expected { |
| ExpectedFound {expected: a, found: b} |
| } else { |
| ExpectedFound {expected: b, found: a} |
| } |
| } |
| } |
| |
| impl<'tcx, T> InferOk<'tcx, T> { |
| pub fn unit(self) -> InferOk<'tcx, ()> { |
| InferOk { value: (), obligations: self.obligations } |
| } |
| } |
| |
| #[must_use = "once you start a snapshot, you should always consume it"] |
| pub struct CombinedSnapshot { |
| projection_cache_snapshot: traits::ProjectionCacheSnapshot, |
| type_snapshot: type_variable::Snapshot, |
| int_snapshot: unify::Snapshot<ty::IntVid>, |
| float_snapshot: unify::Snapshot<ty::FloatVid>, |
| region_vars_snapshot: RegionSnapshot, |
| obligations_in_snapshot: bool, |
| } |
| |
| /// Helper trait for shortening the lifetimes inside a |
| /// value for post-type-checking normalization. |
| pub trait TransNormalize<'gcx>: TypeFoldable<'gcx> { |
| fn trans_normalize<'a, 'tcx>(&self, infcx: &InferCtxt<'a, 'gcx, 'tcx>) -> Self; |
| } |
| |
| macro_rules! items { ($($item:item)+) => ($($item)+) } |
| macro_rules! impl_trans_normalize { |
| ($lt_gcx:tt, $($ty:ty),+) => { |
| items!($(impl<$lt_gcx> TransNormalize<$lt_gcx> for $ty { |
| fn trans_normalize<'a, 'tcx>(&self, |
| infcx: &InferCtxt<'a, $lt_gcx, 'tcx>) |
| -> Self { |
| infcx.normalize_projections_in(self) |
| } |
| })+); |
| } |
| } |
| |
| impl_trans_normalize!('gcx, |
| Ty<'gcx>, |
| &'gcx Substs<'gcx>, |
| ty::FnSig<'gcx>, |
| ty::FnOutput<'gcx>, |
| &'gcx ty::BareFnTy<'gcx>, |
| ty::ClosureSubsts<'gcx>, |
| ty::PolyTraitRef<'gcx> |
| ); |
| |
| impl<'gcx> TransNormalize<'gcx> for LvalueTy<'gcx> { |
| fn trans_normalize<'a, 'tcx>(&self, infcx: &InferCtxt<'a, 'gcx, 'tcx>) -> Self { |
| match *self { |
| LvalueTy::Ty { ty } => LvalueTy::Ty { ty: ty.trans_normalize(infcx) }, |
| LvalueTy::Downcast { adt_def, substs, variant_index } => { |
| LvalueTy::Downcast { |
| adt_def: adt_def, |
| substs: substs.trans_normalize(infcx), |
| variant_index: variant_index |
| } |
| } |
| } |
| } |
| } |
| |
| // NOTE: Callable from trans only! |
| impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> { |
| pub fn normalize_associated_type<T>(self, value: &T) -> T |
| where T: TransNormalize<'tcx> |
| { |
| debug!("normalize_associated_type(t={:?})", value); |
| |
| let value = self.erase_regions(value); |
| |
| if !value.has_projection_types() { |
| return value; |
| } |
| |
| self.infer_ctxt(None, None, ProjectionMode::Any).enter(|infcx| { |
| value.trans_normalize(&infcx) |
| }) |
| } |
| |
| pub fn normalize_associated_type_in_env<T>( |
| self, value: &T, env: &'a ty::ParameterEnvironment<'tcx> |
| ) -> T |
| where T: TransNormalize<'tcx> |
| { |
| debug!("normalize_associated_type_in_env(t={:?})", value); |
| |
| let value = self.erase_regions(value); |
| |
| if !value.has_projection_types() { |
| return value; |
| } |
| |
| self.infer_ctxt(None, Some(env.clone()), ProjectionMode::Any).enter(|infcx| { |
| value.trans_normalize(&infcx) |
| }) |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { |
| fn normalize_projections_in<T>(&self, value: &T) -> T::Lifted |
| where T: TypeFoldable<'tcx> + ty::Lift<'gcx> |
| { |
| let mut selcx = traits::SelectionContext::new(self); |
| let cause = traits::ObligationCause::dummy(); |
| let traits::Normalized { value: result, obligations } = |
| traits::normalize(&mut selcx, cause, value); |
| |
| debug!("normalize_projections_in: result={:?} obligations={:?}", |
| result, obligations); |
| |
| let mut fulfill_cx = traits::FulfillmentContext::new(); |
| |
| for obligation in obligations { |
| fulfill_cx.register_predicate_obligation(self, obligation); |
| } |
| |
| self.drain_fulfillment_cx_or_panic(DUMMY_SP, &mut fulfill_cx, &result) |
| } |
| |
| pub fn drain_fulfillment_cx_or_panic<T>(&self, |
| span: Span, |
| fulfill_cx: &mut traits::FulfillmentContext<'tcx>, |
| result: &T) |
| -> T::Lifted |
| where T: TypeFoldable<'tcx> + ty::Lift<'gcx> |
| { |
| debug!("drain_fulfillment_cx_or_panic()"); |
| |
| let when = "resolving bounds after type-checking"; |
| let v = match self.drain_fulfillment_cx(fulfill_cx, result) { |
| Ok(v) => v, |
| Err(errors) => { |
| span_bug!(span, "Encountered errors `{:?}` {}", errors, when); |
| } |
| }; |
| |
| match self.tcx.lift_to_global(&v) { |
| Some(v) => v, |
| None => { |
| span_bug!(span, "Uninferred types/regions in `{:?}` {}", v, when); |
| } |
| } |
| } |
| |
| /// Finishes processes any obligations that remain in the fulfillment |
| /// context, and then "freshens" and returns `result`. This is |
| /// primarily used during normalization and other cases where |
| /// processing the obligations in `fulfill_cx` may cause type |
| /// inference variables that appear in `result` to be unified, and |
| /// hence we need to process those obligations to get the complete |
| /// picture of the type. |
| pub fn drain_fulfillment_cx<T>(&self, |
| fulfill_cx: &mut traits::FulfillmentContext<'tcx>, |
| result: &T) |
| -> Result<T,Vec<traits::FulfillmentError<'tcx>>> |
| where T : TypeFoldable<'tcx> |
| { |
| debug!("drain_fulfillment_cx(result={:?})", |
| result); |
| |
| // In principle, we only need to do this so long as `result` |
| // contains unbound type parameters. It could be a slight |
| // optimization to stop iterating early. |
| fulfill_cx.select_all_or_error(self)?; |
| |
| let result = self.resolve_type_vars_if_possible(result); |
| Ok(self.tcx.erase_regions(&result)) |
| } |
| |
| pub fn projection_mode(&self) -> ProjectionMode { |
| self.projection_mode |
| } |
| |
| pub fn freshen<T:TypeFoldable<'tcx>>(&self, t: T) -> T { |
| t.fold_with(&mut self.freshener()) |
| } |
| |
| pub fn type_var_diverges(&'a self, ty: Ty) -> bool { |
| match ty.sty { |
| ty::TyInfer(ty::TyVar(vid)) => self.type_variables.borrow().var_diverges(vid), |
| _ => false |
| } |
| } |
| |
| pub fn freshener<'b>(&'b self) -> TypeFreshener<'b, 'gcx, 'tcx> { |
| freshen::TypeFreshener::new(self) |
| } |
| |
| pub fn type_is_unconstrained_numeric(&'a self, ty: Ty) -> UnconstrainedNumeric { |
| use ty::error::UnconstrainedNumeric::Neither; |
| use ty::error::UnconstrainedNumeric::{UnconstrainedInt, UnconstrainedFloat}; |
| match ty.sty { |
| ty::TyInfer(ty::IntVar(vid)) => { |
| if self.int_unification_table.borrow_mut().has_value(vid) { |
| Neither |
| } else { |
| UnconstrainedInt |
| } |
| }, |
| ty::TyInfer(ty::FloatVar(vid)) => { |
| if self.float_unification_table.borrow_mut().has_value(vid) { |
| Neither |
| } else { |
| UnconstrainedFloat |
| } |
| }, |
| _ => Neither, |
| } |
| } |
| |
| /// Returns a type variable's default fallback if any exists. A default |
| /// must be attached to the variable when created, if it is created |
| /// without a default, this will return None. |
| /// |
| /// This code does not apply to integral or floating point variables, |
| /// only to use declared defaults. |
| /// |
| /// See `new_ty_var_with_default` to create a type variable with a default. |
| /// See `type_variable::Default` for details about what a default entails. |
| pub fn default(&self, ty: Ty<'tcx>) -> Option<type_variable::Default<'tcx>> { |
| match ty.sty { |
| ty::TyInfer(ty::TyVar(vid)) => self.type_variables.borrow().default(vid), |
| _ => None |
| } |
| } |
| |
| pub fn unsolved_variables(&self) -> Vec<ty::Ty<'tcx>> { |
| let mut variables = Vec::new(); |
| |
| let unbound_ty_vars = self.type_variables |
| .borrow_mut() |
| .unsolved_variables() |
| .into_iter() |
| .map(|t| self.tcx.mk_var(t)); |
| |
| let unbound_int_vars = self.int_unification_table |
| .borrow_mut() |
| .unsolved_variables() |
| .into_iter() |
| .map(|v| self.tcx.mk_int_var(v)); |
| |
| let unbound_float_vars = self.float_unification_table |
| .borrow_mut() |
| .unsolved_variables() |
| .into_iter() |
| .map(|v| self.tcx.mk_float_var(v)); |
| |
| variables.extend(unbound_ty_vars); |
| variables.extend(unbound_int_vars); |
| variables.extend(unbound_float_vars); |
| |
| return variables; |
| } |
| |
| fn combine_fields(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>) |
| -> CombineFields<'a, 'gcx, 'tcx> { |
| CombineFields { |
| infcx: self, |
| a_is_expected: a_is_expected, |
| trace: trace, |
| cause: None, |
| obligations: PredicateObligations::new(), |
| } |
| } |
| |
| pub fn equate<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T) |
| -> InferResult<'tcx, T> |
| where T: Relate<'tcx> |
| { |
| let mut equate = self.combine_fields(a_is_expected, trace).equate(); |
| let result = equate.relate(a, b); |
| result.map(|t| InferOk { value: t, obligations: equate.obligations() }) |
| } |
| |
| pub fn sub<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T) |
| -> InferResult<'tcx, T> |
| where T: Relate<'tcx> |
| { |
| let mut sub = self.combine_fields(a_is_expected, trace).sub(); |
| let result = sub.relate(a, b); |
| result.map(|t| InferOk { value: t, obligations: sub.obligations() }) |
| } |
| |
| pub fn lub<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T) |
| -> InferResult<'tcx, T> |
| where T: Relate<'tcx> |
| { |
| let mut lub = self.combine_fields(a_is_expected, trace).lub(); |
| let result = lub.relate(a, b); |
| result.map(|t| InferOk { value: t, obligations: lub.obligations() }) |
| } |
| |
| pub fn glb<T>(&'a self, a_is_expected: bool, trace: TypeTrace<'tcx>, a: &T, b: &T) |
| -> InferResult<'tcx, T> |
| where T: Relate<'tcx> |
| { |
| let mut glb = self.combine_fields(a_is_expected, trace).glb(); |
| let result = glb.relate(a, b); |
| result.map(|t| InferOk { value: t, obligations: glb.obligations() }) |
| } |
| |
| fn start_snapshot(&self) -> CombinedSnapshot { |
| debug!("start_snapshot()"); |
| |
| let obligations_in_snapshot = self.obligations_in_snapshot.get(); |
| self.obligations_in_snapshot.set(false); |
| |
| CombinedSnapshot { |
| projection_cache_snapshot: self.projection_cache.borrow_mut().snapshot(), |
| type_snapshot: self.type_variables.borrow_mut().snapshot(), |
| int_snapshot: self.int_unification_table.borrow_mut().snapshot(), |
| float_snapshot: self.float_unification_table.borrow_mut().snapshot(), |
| region_vars_snapshot: self.region_vars.start_snapshot(), |
| obligations_in_snapshot: obligations_in_snapshot, |
| } |
| } |
| |
| fn rollback_to(&self, cause: &str, snapshot: CombinedSnapshot) { |
| debug!("rollback_to(cause={})", cause); |
| let CombinedSnapshot { projection_cache_snapshot, |
| type_snapshot, |
| int_snapshot, |
| float_snapshot, |
| region_vars_snapshot, |
| obligations_in_snapshot } = snapshot; |
| |
| assert!(!self.obligations_in_snapshot.get()); |
| self.obligations_in_snapshot.set(obligations_in_snapshot); |
| |
| self.projection_cache |
| .borrow_mut() |
| .rollback_to(projection_cache_snapshot); |
| self.type_variables |
| .borrow_mut() |
| .rollback_to(type_snapshot); |
| self.int_unification_table |
| .borrow_mut() |
| .rollback_to(int_snapshot); |
| self.float_unification_table |
| .borrow_mut() |
| .rollback_to(float_snapshot); |
| self.region_vars |
| .rollback_to(region_vars_snapshot); |
| } |
| |
| fn commit_from(&self, snapshot: CombinedSnapshot) { |
| debug!("commit_from()"); |
| let CombinedSnapshot { projection_cache_snapshot, |
| type_snapshot, |
| int_snapshot, |
| float_snapshot, |
| region_vars_snapshot, |
| obligations_in_snapshot } = snapshot; |
| |
| self.obligations_in_snapshot.set(obligations_in_snapshot); |
| |
| self.projection_cache |
| .borrow_mut() |
| .commit(projection_cache_snapshot); |
| self.type_variables |
| .borrow_mut() |
| .commit(type_snapshot); |
| self.int_unification_table |
| .borrow_mut() |
| .commit(int_snapshot); |
| self.float_unification_table |
| .borrow_mut() |
| .commit(float_snapshot); |
| self.region_vars |
| .commit(region_vars_snapshot); |
| } |
| |
| /// Execute `f` and commit the bindings |
| pub fn commit_unconditionally<R, F>(&self, f: F) -> R where |
| F: FnOnce() -> R, |
| { |
| debug!("commit()"); |
| let snapshot = self.start_snapshot(); |
| let r = f(); |
| self.commit_from(snapshot); |
| r |
| } |
| |
| /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)` |
| pub fn commit_if_ok<T, E, F>(&self, f: F) -> Result<T, E> where |
| F: FnOnce(&CombinedSnapshot) -> Result<T, E> |
| { |
| debug!("commit_if_ok()"); |
| let snapshot = self.start_snapshot(); |
| let r = f(&snapshot); |
| debug!("commit_if_ok() -- r.is_ok() = {}", r.is_ok()); |
| match r { |
| Ok(_) => { self.commit_from(snapshot); } |
| Err(_) => { self.rollback_to("commit_if_ok -- error", snapshot); } |
| } |
| r |
| } |
| |
| // Execute `f` in a snapshot, and commit the bindings it creates |
| pub fn in_snapshot<T, F>(&self, f: F) -> T where |
| F: FnOnce(&CombinedSnapshot) -> T |
| { |
| debug!("in_snapshot()"); |
| let snapshot = self.start_snapshot(); |
| let r = f(&snapshot); |
| self.commit_from(snapshot); |
| r |
| } |
| |
| /// Execute `f` and commit only the region bindings if successful. |
| /// The function f must be very careful not to leak any non-region |
| /// variables that get created. |
| pub fn commit_regions_if_ok<T, E, F>(&self, f: F) -> Result<T, E> where |
| F: FnOnce() -> Result<T, E> |
| { |
| debug!("commit_regions_if_ok()"); |
| let CombinedSnapshot { projection_cache_snapshot, |
| type_snapshot, |
| int_snapshot, |
| float_snapshot, |
| region_vars_snapshot, |
| obligations_in_snapshot } = self.start_snapshot(); |
| |
| let r = self.commit_if_ok(|_| f()); |
| |
| debug!("commit_regions_if_ok: rolling back everything but regions"); |
| |
| assert!(!self.obligations_in_snapshot.get()); |
| self.obligations_in_snapshot.set(obligations_in_snapshot); |
| |
| // Roll back any non-region bindings - they should be resolved |
| // inside `f`, with, e.g. `resolve_type_vars_if_possible`. |
| self.projection_cache |
| .borrow_mut() |
| .rollback_to(projection_cache_snapshot); |
| self.type_variables |
| .borrow_mut() |
| .rollback_to(type_snapshot); |
| self.int_unification_table |
| .borrow_mut() |
| .rollback_to(int_snapshot); |
| self.float_unification_table |
| .borrow_mut() |
| .rollback_to(float_snapshot); |
| |
| // Commit region vars that may escape through resolved types. |
| self.region_vars |
| .commit(region_vars_snapshot); |
| |
| r |
| } |
| |
| /// Execute `f` then unroll any bindings it creates |
| pub fn probe<R, F>(&self, f: F) -> R where |
| F: FnOnce(&CombinedSnapshot) -> R, |
| { |
| debug!("probe()"); |
| let snapshot = self.start_snapshot(); |
| let r = f(&snapshot); |
| self.rollback_to("probe", snapshot); |
| r |
| } |
| |
| pub fn add_given(&self, |
| sub: ty::FreeRegion, |
| sup: ty::RegionVid) |
| { |
| self.region_vars.add_given(sub, sup); |
| } |
| |
| pub fn sub_types(&self, |
| a_is_expected: bool, |
| origin: TypeOrigin, |
| a: Ty<'tcx>, |
| b: Ty<'tcx>) |
| -> InferResult<'tcx, ()> |
| { |
| debug!("sub_types({:?} <: {:?})", a, b); |
| self.commit_if_ok(|_| { |
| let trace = TypeTrace::types(origin, a_is_expected, a, b); |
| self.sub(a_is_expected, trace, &a, &b).map(|ok| ok.unit()) |
| }) |
| } |
| |
| pub fn can_sub_types(&self, |
| a: Ty<'tcx>, |
| b: Ty<'tcx>) |
| -> UnitResult<'tcx> |
| { |
| self.probe(|_| { |
| let origin = TypeOrigin::Misc(syntax_pos::DUMMY_SP); |
| let trace = TypeTrace::types(origin, true, a, b); |
| self.sub(true, trace, &a, &b).map(|_| ()) |
| }) |
| } |
| |
| pub fn eq_types(&self, |
| a_is_expected: bool, |
| origin: TypeOrigin, |
| a: Ty<'tcx>, |
| b: Ty<'tcx>) |
| -> InferResult<'tcx, ()> |
| { |
| self.commit_if_ok(|_| { |
| let trace = TypeTrace::types(origin, a_is_expected, a, b); |
| self.equate(a_is_expected, trace, &a, &b).map(|ok| ok.unit()) |
| }) |
| } |
| |
| pub fn eq_trait_refs(&self, |
| a_is_expected: bool, |
| origin: TypeOrigin, |
| a: ty::TraitRef<'tcx>, |
| b: ty::TraitRef<'tcx>) |
| -> InferResult<'tcx, ()> |
| { |
| debug!("eq_trait_refs({:?} = {:?})", a, b); |
| self.commit_if_ok(|_| { |
| let trace = TypeTrace { |
| origin: origin, |
| values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)) |
| }; |
| self.equate(a_is_expected, trace, &a, &b).map(|ok| ok.unit()) |
| }) |
| } |
| |
| pub fn eq_impl_headers(&self, |
| a_is_expected: bool, |
| origin: TypeOrigin, |
| a: &ty::ImplHeader<'tcx>, |
| b: &ty::ImplHeader<'tcx>) |
| -> InferResult<'tcx, ()> |
| { |
| debug!("eq_impl_header({:?} = {:?})", a, b); |
| match (a.trait_ref, b.trait_ref) { |
| (Some(a_ref), Some(b_ref)) => self.eq_trait_refs(a_is_expected, origin, a_ref, b_ref), |
| (None, None) => self.eq_types(a_is_expected, origin, a.self_ty, b.self_ty), |
| _ => bug!("mk_eq_impl_headers given mismatched impl kinds"), |
| } |
| } |
| |
| pub fn sub_poly_trait_refs(&self, |
| a_is_expected: bool, |
| origin: TypeOrigin, |
| a: ty::PolyTraitRef<'tcx>, |
| b: ty::PolyTraitRef<'tcx>) |
| -> InferResult<'tcx, ()> |
| { |
| debug!("sub_poly_trait_refs({:?} <: {:?})", a, b); |
| self.commit_if_ok(|_| { |
| let trace = TypeTrace { |
| origin: origin, |
| values: PolyTraitRefs(ExpectedFound::new(a_is_expected, a, b)) |
| }; |
| self.sub(a_is_expected, trace, &a, &b).map(|ok| ok.unit()) |
| }) |
| } |
| |
| pub fn sub_regions(&self, |
| origin: SubregionOrigin<'tcx>, |
| a: ty::Region, |
| b: ty::Region) { |
| debug!("sub_regions({:?} <: {:?})", a, b); |
| self.region_vars.make_subregion(origin, a, b); |
| } |
| |
| pub fn equality_predicate(&self, |
| span: Span, |
| predicate: &ty::PolyEquatePredicate<'tcx>) |
| -> InferResult<'tcx, ()> |
| { |
| self.commit_if_ok(|snapshot| { |
| let (ty::EquatePredicate(a, b), skol_map) = |
| self.skolemize_late_bound_regions(predicate, snapshot); |
| let origin = TypeOrigin::EquatePredicate(span); |
| let eqty_ok = self.eq_types(false, origin, a, b)?; |
| self.leak_check(false, span, &skol_map, snapshot)?; |
| self.pop_skolemized(skol_map, snapshot); |
| Ok(eqty_ok.unit()) |
| }) |
| } |
| |
| pub fn region_outlives_predicate(&self, |
| span: Span, |
| predicate: &ty::PolyRegionOutlivesPredicate) |
| -> UnitResult<'tcx> |
| { |
| self.commit_if_ok(|snapshot| { |
| let (ty::OutlivesPredicate(r_a, r_b), skol_map) = |
| self.skolemize_late_bound_regions(predicate, snapshot); |
| let origin = RelateRegionParamBound(span); |
| self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b` |
| self.leak_check(false, span, &skol_map, snapshot)?; |
| Ok(self.pop_skolemized(skol_map, snapshot)) |
| }) |
| } |
| |
| pub fn next_ty_var_id(&self, diverging: bool) -> TyVid { |
| self.type_variables |
| .borrow_mut() |
| .new_var(diverging, None) |
| } |
| |
| pub fn next_ty_var(&self) -> Ty<'tcx> { |
| self.tcx.mk_var(self.next_ty_var_id(false)) |
| } |
| |
| pub fn next_ty_var_with_default(&self, |
| default: Option<type_variable::Default<'tcx>>) -> Ty<'tcx> { |
| let ty_var_id = self.type_variables |
| .borrow_mut() |
| .new_var(false, default); |
| |
| self.tcx.mk_var(ty_var_id) |
| } |
| |
| pub fn next_diverging_ty_var(&self) -> Ty<'tcx> { |
| self.tcx.mk_var(self.next_ty_var_id(true)) |
| } |
| |
| pub fn next_ty_vars(&self, n: usize) -> Vec<Ty<'tcx>> { |
| (0..n).map(|_i| self.next_ty_var()).collect() |
| } |
| |
| pub fn next_int_var_id(&self) -> IntVid { |
| self.int_unification_table |
| .borrow_mut() |
| .new_key(None) |
| } |
| |
| pub fn next_float_var_id(&self) -> FloatVid { |
| self.float_unification_table |
| .borrow_mut() |
| .new_key(None) |
| } |
| |
| pub fn next_region_var(&self, origin: RegionVariableOrigin) -> ty::Region { |
| ty::ReVar(self.region_vars.new_region_var(origin)) |
| } |
| |
| pub fn region_vars_for_defs(&self, |
| span: Span, |
| defs: &[ty::RegionParameterDef]) |
| -> Vec<ty::Region> { |
| defs.iter() |
| .map(|d| self.next_region_var(EarlyBoundRegion(span, d.name))) |
| .collect() |
| } |
| |
| // We have to take `&mut Substs` in order to provide the correct substitutions for defaults |
| // along the way, for this reason we don't return them. |
| pub fn type_vars_for_defs(&self, |
| span: Span, |
| space: subst::ParamSpace, |
| substs: &mut Substs<'tcx>, |
| defs: &[ty::TypeParameterDef<'tcx>]) { |
| |
| for def in defs.iter() { |
| let default = def.default.map(|default| { |
| type_variable::Default { |
| ty: default.subst_spanned(self.tcx, substs, Some(span)), |
| origin_span: span, |
| def_id: def.default_def_id |
| } |
| }); |
| |
| let ty_var = self.next_ty_var_with_default(default); |
| substs.types.push(space, ty_var); |
| } |
| } |
| |
| /// Given a set of generics defined on a type or impl, returns a substitution mapping each |
| /// type/region parameter to a fresh inference variable. |
| pub fn fresh_substs_for_generics(&self, |
| span: Span, |
| generics: &ty::Generics<'tcx>) |
| -> &'tcx subst::Substs<'tcx> |
| { |
| let type_params = subst::VecPerParamSpace::empty(); |
| |
| let region_params = |
| generics.regions.map( |
| |d| self.next_region_var(EarlyBoundRegion(span, d.name))); |
| |
| let mut substs = subst::Substs::new(type_params, region_params); |
| |
| for space in subst::ParamSpace::all().iter() { |
| self.type_vars_for_defs( |
| span, |
| *space, |
| &mut substs, |
| generics.types.get_slice(*space)); |
| } |
| |
| self.tcx.mk_substs(substs) |
| } |
| |
| /// Given a set of generics defined on a trait, returns a substitution mapping each output |
| /// type/region parameter to a fresh inference variable, and mapping the self type to |
| /// `self_ty`. |
| pub fn fresh_substs_for_trait(&self, |
| span: Span, |
| generics: &ty::Generics<'tcx>, |
| self_ty: Ty<'tcx>) |
| -> subst::Substs<'tcx> |
| { |
| |
| assert!(generics.types.len(subst::SelfSpace) == 1); |
| assert!(generics.types.len(subst::FnSpace) == 0); |
| assert!(generics.regions.len(subst::SelfSpace) == 0); |
| assert!(generics.regions.len(subst::FnSpace) == 0); |
| |
| let type_params = Vec::new(); |
| |
| let region_param_defs = generics.regions.get_slice(subst::TypeSpace); |
| let regions = self.region_vars_for_defs(span, region_param_defs); |
| |
| let mut substs = subst::Substs::new_trait(type_params, regions, self_ty); |
| |
| let type_parameter_defs = generics.types.get_slice(subst::TypeSpace); |
| self.type_vars_for_defs(span, subst::TypeSpace, &mut substs, type_parameter_defs); |
| |
| return substs; |
| } |
| |
| pub fn fresh_bound_region(&self, debruijn: ty::DebruijnIndex) -> ty::Region { |
| self.region_vars.new_bound(debruijn) |
| } |
| |
| /// Apply `adjustment` to the type of `expr` |
| pub fn adjust_expr_ty(&self, |
| expr: &hir::Expr, |
| adjustment: Option<&adjustment::AutoAdjustment<'tcx>>) |
| -> Ty<'tcx> |
| { |
| let raw_ty = self.expr_ty(expr); |
| let raw_ty = self.shallow_resolve(raw_ty); |
| let resolve_ty = |ty: Ty<'tcx>| self.resolve_type_vars_if_possible(&ty); |
| raw_ty.adjust(self.tcx, |
| expr.span, |
| expr.id, |
| adjustment, |
| |method_call| self.tables |
| .borrow() |
| .method_map |
| .get(&method_call) |
| .map(|method| resolve_ty(method.ty))) |
| } |
| |
| /// True if errors have been reported since this infcx was |
| /// created. This is sometimes used as a heuristic to skip |
| /// reporting errors that often occur as a result of earlier |
| /// errors, but where it's hard to be 100% sure (e.g., unresolved |
| /// inference variables, regionck errors). |
| pub fn is_tainted_by_errors(&self) -> bool { |
| debug!("is_tainted_by_errors(err_count={}, err_count_on_creation={}, \ |
| tainted_by_errors_flag={})", |
| self.tcx.sess.err_count(), |
| self.err_count_on_creation, |
| self.tainted_by_errors_flag.get()); |
| |
| if self.tcx.sess.err_count() > self.err_count_on_creation { |
| return true; // errors reported since this infcx was made |
| } |
| self.tainted_by_errors_flag.get() |
| } |
| |
| /// Set the "tainted by errors" flag to true. We call this when we |
| /// observe an error from a prior pass. |
| pub fn set_tainted_by_errors(&self) { |
| debug!("set_tainted_by_errors()"); |
| self.tainted_by_errors_flag.set(true) |
| } |
| |
| pub fn node_type(&self, id: ast::NodeId) -> Ty<'tcx> { |
| match self.tables.borrow().node_types.get(&id) { |
| Some(&t) => t, |
| // FIXME |
| None if self.is_tainted_by_errors() => |
| self.tcx.types.err, |
| None => { |
| bug!("no type for node {}: {} in fcx", |
| id, self.tcx.map.node_to_string(id)); |
| } |
| } |
| } |
| |
| pub fn expr_ty(&self, ex: &hir::Expr) -> Ty<'tcx> { |
| match self.tables.borrow().node_types.get(&ex.id) { |
| Some(&t) => t, |
| None => { |
| bug!("no type for expr in fcx"); |
| } |
| } |
| } |
| |
| pub fn resolve_regions_and_report_errors(&self, |
| free_regions: &FreeRegionMap, |
| subject_node_id: ast::NodeId) { |
| let errors = self.region_vars.resolve_regions(free_regions, subject_node_id); |
| if !self.is_tainted_by_errors() { |
| // As a heuristic, just skip reporting region errors |
| // altogether if other errors have been reported while |
| // this infcx was in use. This is totally hokey but |
| // otherwise we have a hard time separating legit region |
| // errors from silly ones. |
| self.report_region_errors(&errors); // see error_reporting.rs |
| } |
| } |
| |
| pub fn ty_to_string(&self, t: Ty<'tcx>) -> String { |
| self.resolve_type_vars_if_possible(&t).to_string() |
| } |
| |
| pub fn tys_to_string(&self, ts: &[Ty<'tcx>]) -> String { |
| let tstrs: Vec<String> = ts.iter().map(|t| self.ty_to_string(*t)).collect(); |
| format!("({})", tstrs.join(", ")) |
| } |
| |
| pub fn trait_ref_to_string(&self, t: &ty::TraitRef<'tcx>) -> String { |
| self.resolve_type_vars_if_possible(t).to_string() |
| } |
| |
| pub fn shallow_resolve(&self, typ: Ty<'tcx>) -> Ty<'tcx> { |
| match typ.sty { |
| ty::TyInfer(ty::TyVar(v)) => { |
| // Not entirely obvious: if `typ` is a type variable, |
| // it can be resolved to an int/float variable, which |
| // can then be recursively resolved, hence the |
| // recursion. Note though that we prevent type |
| // variables from unifying to other type variables |
| // directly (though they may be embedded |
| // structurally), and we prevent cycles in any case, |
| // so this recursion should always be of very limited |
| // depth. |
| self.type_variables.borrow_mut() |
| .probe(v) |
| .map(|t| self.shallow_resolve(t)) |
| .unwrap_or(typ) |
| } |
| |
| ty::TyInfer(ty::IntVar(v)) => { |
| self.int_unification_table |
| .borrow_mut() |
| .probe(v) |
| .map(|v| v.to_type(self.tcx)) |
| .unwrap_or(typ) |
| } |
| |
| ty::TyInfer(ty::FloatVar(v)) => { |
| self.float_unification_table |
| .borrow_mut() |
| .probe(v) |
| .map(|v| v.to_type(self.tcx)) |
| .unwrap_or(typ) |
| } |
| |
| _ => { |
| typ |
| } |
| } |
| } |
| |
| pub fn resolve_type_vars_if_possible<T>(&self, value: &T) -> T |
| where T: TypeFoldable<'tcx> |
| { |
| /*! |
| * Where possible, replaces type/int/float variables in |
| * `value` with their final value. Note that region variables |
| * are unaffected. If a type variable has not been unified, it |
| * is left as is. This is an idempotent operation that does |
| * not affect inference state in any way and so you can do it |
| * at will. |
| */ |
| |
| if !value.needs_infer() { |
| return value.clone(); // avoid duplicated subst-folding |
| } |
| let mut r = resolve::OpportunisticTypeResolver::new(self); |
| value.fold_with(&mut r) |
| } |
| |
| pub fn resolve_type_and_region_vars_if_possible<T>(&self, value: &T) -> T |
| where T: TypeFoldable<'tcx> |
| { |
| let mut r = resolve::OpportunisticTypeAndRegionResolver::new(self); |
| value.fold_with(&mut r) |
| } |
| |
| /// Resolves all type variables in `t` and then, if any were left |
| /// unresolved, substitutes an error type. This is used after the |
| /// main checking when doing a second pass before writeback. The |
| /// justification is that writeback will produce an error for |
| /// these unconstrained type variables. |
| fn resolve_type_vars_or_error(&self, t: &Ty<'tcx>) -> mc::McResult<Ty<'tcx>> { |
| let ty = self.resolve_type_vars_if_possible(t); |
| if ty.references_error() || ty.is_ty_var() { |
| debug!("resolve_type_vars_or_error: error from {:?}", ty); |
| Err(()) |
| } else { |
| Ok(ty) |
| } |
| } |
| |
| pub fn fully_resolve<T:TypeFoldable<'tcx>>(&self, value: &T) -> FixupResult<T> { |
| /*! |
| * Attempts to resolve all type/region variables in |
| * `value`. Region inference must have been run already (e.g., |
| * by calling `resolve_regions_and_report_errors`). If some |
| * variable was never unified, an `Err` results. |
| * |
| * This method is idempotent, but it not typically not invoked |
| * except during the writeback phase. |
| */ |
| |
| resolve::fully_resolve(self, value) |
| } |
| |
| // [Note-Type-error-reporting] |
| // An invariant is that anytime the expected or actual type is TyError (the special |
| // error type, meaning that an error occurred when typechecking this expression), |
| // this is a derived error. The error cascaded from another error (that was already |
| // reported), so it's not useful to display it to the user. |
| // The following four methods -- type_error_message_str, type_error_message_str_with_expected, |
| // type_error_message, and report_mismatched_types -- implement this logic. |
| // They check if either the actual or expected type is TyError, and don't print the error |
| // in this case. The typechecker should only ever report type errors involving mismatched |
| // types using one of these four methods, and should not call span_err directly for such |
| // errors. |
| pub fn type_error_message_str<M>(&self, |
| sp: Span, |
| mk_msg: M, |
| actual_ty: String, |
| err: Option<&TypeError<'tcx>>) |
| where M: FnOnce(Option<String>, String) -> String, |
| { |
| self.type_error_message_str_with_expected(sp, mk_msg, None, actual_ty, err) |
| } |
| |
| pub fn type_error_struct_str<M>(&self, |
| sp: Span, |
| mk_msg: M, |
| actual_ty: String, |
| err: Option<&TypeError<'tcx>>) |
| -> DiagnosticBuilder<'tcx> |
| where M: FnOnce(Option<String>, String) -> String, |
| { |
| self.type_error_struct_str_with_expected(sp, mk_msg, None, actual_ty, err) |
| } |
| |
| pub fn type_error_message_str_with_expected<M>(&self, |
| sp: Span, |
| mk_msg: M, |
| expected_ty: Option<Ty<'tcx>>, |
| actual_ty: String, |
| err: Option<&TypeError<'tcx>>) |
| where M: FnOnce(Option<String>, String) -> String, |
| { |
| self.type_error_struct_str_with_expected(sp, mk_msg, expected_ty, actual_ty, err) |
| .emit(); |
| } |
| |
| pub fn type_error_struct_str_with_expected<M>(&self, |
| sp: Span, |
| mk_msg: M, |
| expected_ty: Option<Ty<'tcx>>, |
| actual_ty: String, |
| err: Option<&TypeError<'tcx>>) |
| -> DiagnosticBuilder<'tcx> |
| where M: FnOnce(Option<String>, String) -> String, |
| { |
| debug!("hi! expected_ty = {:?}, actual_ty = {}", expected_ty, actual_ty); |
| |
| let resolved_expected = expected_ty.map(|e_ty| self.resolve_type_vars_if_possible(&e_ty)); |
| |
| if !resolved_expected.references_error() { |
| let error_str = err.map_or("".to_string(), |t_err| { |
| format!(" ({})", t_err) |
| }); |
| |
| let mut db = self.tcx.sess.struct_span_err(sp, &format!("{}{}", |
| mk_msg(resolved_expected.map(|t| self.ty_to_string(t)), actual_ty), |
| error_str)); |
| |
| if let Some(err) = err { |
| self.tcx.note_and_explain_type_err(&mut db, err, sp); |
| } |
| db |
| } else { |
| self.tcx.sess.diagnostic().struct_dummy() |
| } |
| } |
| |
| pub fn type_error_message<M>(&self, |
| sp: Span, |
| mk_msg: M, |
| actual_ty: Ty<'tcx>, |
| err: Option<&TypeError<'tcx>>) |
| where M: FnOnce(String) -> String, |
| { |
| self.type_error_struct(sp, mk_msg, actual_ty, err).emit(); |
| } |
| |
| pub fn type_error_struct<M>(&self, |
| sp: Span, |
| mk_msg: M, |
| actual_ty: Ty<'tcx>, |
| err: Option<&TypeError<'tcx>>) |
| -> DiagnosticBuilder<'tcx> |
| where M: FnOnce(String) -> String, |
| { |
| let actual_ty = self.resolve_type_vars_if_possible(&actual_ty); |
| |
| // Don't report an error if actual type is TyError. |
| if actual_ty.references_error() { |
| return self.tcx.sess.diagnostic().struct_dummy(); |
| } |
| |
| self.type_error_struct_str(sp, |
| move |_e, a| { mk_msg(a) }, |
| self.ty_to_string(actual_ty), err) |
| } |
| |
| pub fn report_mismatched_types(&self, |
| origin: TypeOrigin, |
| expected: Ty<'tcx>, |
| actual: Ty<'tcx>, |
| err: TypeError<'tcx>) { |
| let trace = TypeTrace { |
| origin: origin, |
| values: Types(ExpectedFound { |
| expected: expected, |
| found: actual |
| }) |
| }; |
| self.report_and_explain_type_error(trace, &err).emit(); |
| } |
| |
| pub fn report_conflicting_default_types(&self, |
| span: Span, |
| expected: type_variable::Default<'tcx>, |
| actual: type_variable::Default<'tcx>) { |
| let trace = TypeTrace { |
| origin: TypeOrigin::Misc(span), |
| values: Types(ExpectedFound { |
| expected: expected.ty, |
| found: actual.ty |
| }) |
| }; |
| |
| self.report_and_explain_type_error( |
| trace, |
| &TypeError::TyParamDefaultMismatch(ExpectedFound { |
| expected: expected, |
| found: actual |
| })) |
| .emit(); |
| } |
| |
| pub fn replace_late_bound_regions_with_fresh_var<T>( |
| &self, |
| span: Span, |
| lbrct: LateBoundRegionConversionTime, |
| value: &ty::Binder<T>) |
| -> (T, FnvHashMap<ty::BoundRegion,ty::Region>) |
| where T : TypeFoldable<'tcx> |
| { |
| self.tcx.replace_late_bound_regions( |
| value, |
| |br| self.next_region_var(LateBoundRegion(span, br, lbrct))) |
| } |
| |
| /// Given a higher-ranked projection predicate like: |
| /// |
| /// for<'a> <T as Fn<&'a u32>>::Output = &'a u32 |
| /// |
| /// and a target trait-ref like: |
| /// |
| /// <T as Fn<&'x u32>> |
| /// |
| /// find a substitution `S` for the higher-ranked regions (here, |
| /// `['a => 'x]`) such that the predicate matches the trait-ref, |
| /// and then return the value (here, `&'a u32`) but with the |
| /// substitution applied (hence, `&'x u32`). |
| /// |
| /// See `higher_ranked_match` in `higher_ranked/mod.rs` for more |
| /// details. |
| pub fn match_poly_projection_predicate(&self, |
| origin: TypeOrigin, |
| match_a: ty::PolyProjectionPredicate<'tcx>, |
| match_b: ty::TraitRef<'tcx>) |
| -> InferResult<'tcx, HrMatchResult<Ty<'tcx>>> |
| { |
| let span = origin.span(); |
| let match_trait_ref = match_a.skip_binder().projection_ty.trait_ref; |
| let trace = TypeTrace { |
| origin: origin, |
| values: TraitRefs(ExpectedFound::new(true, match_trait_ref, match_b)) |
| }; |
| |
| let match_pair = match_a.map_bound(|p| (p.projection_ty.trait_ref, p.ty)); |
| let combine = self.combine_fields(true, trace); |
| let result = combine.higher_ranked_match(span, &match_pair, &match_b)?; |
| Ok(InferOk { value: result, obligations: combine.obligations }) |
| } |
| |
| /// See `verify_generic_bound` method in `region_inference` |
| pub fn verify_generic_bound(&self, |
| origin: SubregionOrigin<'tcx>, |
| kind: GenericKind<'tcx>, |
| a: ty::Region, |
| bound: VerifyBound) { |
| debug!("verify_generic_bound({:?}, {:?} <: {:?})", |
| kind, |
| a, |
| bound); |
| |
| self.region_vars.verify_generic_bound(origin, kind, a, bound); |
| } |
| |
| pub fn can_equate<T>(&self, a: &T, b: &T) -> UnitResult<'tcx> |
| where T: Relate<'tcx> + fmt::Debug |
| { |
| debug!("can_equate({:?}, {:?})", a, b); |
| self.probe(|_| { |
| // Gin up a dummy trace, since this won't be committed |
| // anyhow. We should make this typetrace stuff more |
| // generic so we don't have to do anything quite this |
| // terrible. |
| self.equate(true, TypeTrace::dummy(self.tcx), a, b) |
| }).map(|_| ()) |
| } |
| |
| pub fn node_ty(&self, id: ast::NodeId) -> McResult<Ty<'tcx>> { |
| let ty = self.node_type(id); |
| self.resolve_type_vars_or_error(&ty) |
| } |
| |
| pub fn expr_ty_adjusted(&self, expr: &hir::Expr) -> McResult<Ty<'tcx>> { |
| let ty = self.adjust_expr_ty(expr, self.tables.borrow().adjustments.get(&expr.id)); |
| self.resolve_type_vars_or_error(&ty) |
| } |
| |
| pub fn type_moves_by_default(&self, ty: Ty<'tcx>, span: Span) -> bool { |
| let ty = self.resolve_type_vars_if_possible(&ty); |
| if let Some(ty) = self.tcx.lift_to_global(&ty) { |
| // Even if the type may have no inference variables, during |
| // type-checking closure types are in local tables only. |
| let local_closures = match self.tables { |
| InferTables::Local(_) => ty.has_closure_types(), |
| InferTables::Global(_) => false |
| }; |
| if !local_closures { |
| return ty.moves_by_default(self.tcx.global_tcx(), self.param_env(), span); |
| } |
| } |
| |
| // this can get called from typeck (by euv), and moves_by_default |
| // rightly refuses to work with inference variables, but |
| // moves_by_default has a cache, which we want to use in other |
| // cases. |
| !traits::type_known_to_meet_builtin_bound(self, ty, ty::BoundCopy, span) |
| } |
| |
| pub fn node_method_ty(&self, method_call: ty::MethodCall) |
| -> Option<Ty<'tcx>> { |
| self.tables |
| .borrow() |
| .method_map |
| .get(&method_call) |
| .map(|method| method.ty) |
| .map(|ty| self.resolve_type_vars_if_possible(&ty)) |
| } |
| |
| pub fn node_method_id(&self, method_call: ty::MethodCall) |
| -> Option<DefId> { |
| self.tables |
| .borrow() |
| .method_map |
| .get(&method_call) |
| .map(|method| method.def_id) |
| } |
| |
| pub fn adjustments(&self) -> Ref<NodeMap<adjustment::AutoAdjustment<'tcx>>> { |
| fn project_adjustments<'a, 'tcx>(tables: &'a ty::Tables<'tcx>) |
| -> &'a NodeMap<adjustment::AutoAdjustment<'tcx>> { |
| &tables.adjustments |
| } |
| |
| Ref::map(self.tables.borrow(), project_adjustments) |
| } |
| |
| pub fn is_method_call(&self, id: ast::NodeId) -> bool { |
| self.tables.borrow().method_map.contains_key(&ty::MethodCall::expr(id)) |
| } |
| |
| pub fn temporary_scope(&self, rvalue_id: ast::NodeId) -> Option<CodeExtent> { |
| self.tcx.region_maps.temporary_scope(rvalue_id) |
| } |
| |
| pub fn upvar_capture(&self, upvar_id: ty::UpvarId) -> Option<ty::UpvarCapture> { |
| self.tables.borrow().upvar_capture_map.get(&upvar_id).cloned() |
| } |
| |
| pub fn param_env(&self) -> &ty::ParameterEnvironment<'gcx> { |
| &self.parameter_environment |
| } |
| |
| pub fn closure_kind(&self, |
| def_id: DefId) |
| -> Option<ty::ClosureKind> |
| { |
| if def_id.is_local() { |
| self.tables.borrow().closure_kinds.get(&def_id).cloned() |
| } else { |
| // During typeck, ALL closures are local. But afterwards, |
| // during trans, we see closure ids from other traits. |
| // That may require loading the closure data out of the |
| // cstore. |
| Some(self.tcx.closure_kind(def_id)) |
| } |
| } |
| |
| pub fn closure_type(&self, |
| def_id: DefId, |
| substs: ty::ClosureSubsts<'tcx>) |
| -> ty::ClosureTy<'tcx> |
| { |
| if let InferTables::Local(tables) = self.tables { |
| if let Some(ty) = tables.borrow().closure_tys.get(&def_id) { |
| return ty.subst(self.tcx, substs.func_substs); |
| } |
| } |
| |
| let closure_ty = self.tcx.closure_type(def_id, substs); |
| if self.normalize { |
| let closure_ty = self.tcx.erase_regions(&closure_ty); |
| |
| if !closure_ty.has_projection_types() { |
| return closure_ty; |
| } |
| |
| self.normalize_projections_in(&closure_ty) |
| } else { |
| closure_ty |
| } |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> TypeTrace<'tcx> { |
| pub fn span(&self) -> Span { |
| self.origin.span() |
| } |
| |
| pub fn types(origin: TypeOrigin, |
| a_is_expected: bool, |
| a: Ty<'tcx>, |
| b: Ty<'tcx>) |
| -> TypeTrace<'tcx> { |
| TypeTrace { |
| origin: origin, |
| values: Types(ExpectedFound::new(a_is_expected, a, b)) |
| } |
| } |
| |
| pub fn dummy(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> TypeTrace<'tcx> { |
| TypeTrace { |
| origin: TypeOrigin::Misc(syntax_pos::DUMMY_SP), |
| values: Types(ExpectedFound { |
| expected: tcx.types.err, |
| found: tcx.types.err, |
| }) |
| } |
| } |
| } |
| |
| impl<'tcx> fmt::Debug for TypeTrace<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| write!(f, "TypeTrace({:?})", self.origin) |
| } |
| } |
| |
| impl TypeOrigin { |
| pub fn span(&self) -> Span { |
| match *self { |
| TypeOrigin::MethodCompatCheck(span) => span, |
| TypeOrigin::ExprAssignable(span) => span, |
| TypeOrigin::Misc(span) => span, |
| TypeOrigin::RelateTraitRefs(span) => span, |
| TypeOrigin::RelateSelfType(span) => span, |
| TypeOrigin::RelateOutputImplTypes(span) => span, |
| TypeOrigin::MatchExpressionArm(match_span, _, _) => match_span, |
| TypeOrigin::IfExpression(span) => span, |
| TypeOrigin::IfExpressionWithNoElse(span) => span, |
| TypeOrigin::RangeExpression(span) => span, |
| TypeOrigin::EquatePredicate(span) => span, |
| } |
| } |
| } |
| |
| impl<'tcx> SubregionOrigin<'tcx> { |
| pub fn span(&self) -> Span { |
| match *self { |
| Subtype(ref a) => a.span(), |
| InfStackClosure(a) => a, |
| InvokeClosure(a) => a, |
| DerefPointer(a) => a, |
| FreeVariable(a, _) => a, |
| IndexSlice(a) => a, |
| RelateObjectBound(a) => a, |
| RelateParamBound(a, _) => a, |
| RelateRegionParamBound(a) => a, |
| RelateDefaultParamBound(a, _) => a, |
| Reborrow(a) => a, |
| ReborrowUpvar(a, _) => a, |
| DataBorrowed(_, a) => a, |
| ReferenceOutlivesReferent(_, a) => a, |
| ParameterInScope(_, a) => a, |
| ExprTypeIsNotInScope(_, a) => a, |
| BindingTypeIsNotValidAtDecl(a) => a, |
| CallRcvr(a) => a, |
| CallArg(a) => a, |
| CallReturn(a) => a, |
| Operand(a) => a, |
| AddrOf(a) => a, |
| AutoBorrow(a) => a, |
| SafeDestructor(a) => a, |
| } |
| } |
| } |
| |
| impl RegionVariableOrigin { |
| pub fn span(&self) -> Span { |
| match *self { |
| MiscVariable(a) => a, |
| PatternRegion(a) => a, |
| AddrOfRegion(a) => a, |
| Autoref(a) => a, |
| Coercion(a) => a, |
| EarlyBoundRegion(a, _) => a, |
| LateBoundRegion(a, _, _) => a, |
| BoundRegionInCoherence(_) => syntax_pos::DUMMY_SP, |
| UpvarRegion(_, a) => a |
| } |
| } |
| } |
