Module rustc_middle::ty
source · Expand description
Defines how the compiler represents types internally.
Two important entities in this module are:
rustc_middle::ty::Ty, used to represent the semantics of a type.rustc_middle::ty::TyCtxt, the central data structure in the compiler.
For more information, see “The ty module: representing types” in the rustc-dev-guide.
Re-exports
pub use self::fold::FallibleTypeFolder;pub use self::fold::TypeFoldable;pub use self::fold::TypeFolder;pub use self::fold::TypeSuperFoldable;pub use self::visit::TypeSuperVisitable;pub use self::visit::TypeVisitable;pub use self::visit::TypeVisitor;pub use self::binding::BindingMode;pub use self::trait_def::TraitDef;pub use self::AssocItemContainer::*;pub use self::BorrowKind::*;pub use self::IntVarValue::*;pub use self::Variance::*;pub use self::AssocItemContainer::*;pub use subst::*;pub use vtable::*;pub use rustc_type_ir::AliasKind::*;pub use rustc_type_ir::DynKind::*;pub use rustc_type_ir::InferTy::*;pub use rustc_type_ir::RegionKind::*;pub use rustc_type_ir::TyKind::*;pub use self::binding::BindingMode::*;pub use self::sty::BoundRegionKind::*;Modules
A subset of a mir body used for const evaluatability checking.
adt 🔒
assoc 🔒
closure 🔒
This module contains some shared code for encoding and decoding various
things from the
ty module, and in particular implements support for
“shorthands” which allow to have pointers back into the already encoded
stream instead of re-encoding the same thing twice.consts 🔒
context 🔒
Type context book-keeping.
Diagnostics related methods for
Ty.A folding traversal mechanism for complex data structures that contain type
information.
generics 🔒
impls_ty 🔒
This module contains
HashStable implementations for various data types
from rustc_middle::ty in no particular order.This module contains logic for determining whether a type is inhabited or
uninhabited. The
InhabitedPredicate type captures the minimum
information needed to determine whether a type is inhabited given a
ParamEnv and module ID.instance 🔒
list 🔒
Methods for normalizing when you don’t care about regions (and
aren’t doing type inference). If either of those things don’t
apply to you, use
infcx.normalize(...).Generalized type relating mechanism.
This module contains implements of the
Lift and TypeFoldable
traits for various types in the Rust compiler. Most are written by
hand, though we’ve recently added some macros and proc-macros to help with the tedium.sty 🔒
This module contains
TyKind and its major components.Miscellaneous type-system utilities that are too small to deserve their own modules.
A visiting traversal mechanism for complex data structures that contain type
information.
An iterator over the type substructure.
WARNING: this does not keep track of the region depth.
Structs
The definition of a user-defined type, e.g., a
struct, enum, or union.Represents the projection of an associated type.
Information about an associated item
A list of
ty::AssocItems in definition order that allows for efficient lookup by name.Binder is a binder for higher-ranked lifetimes or types. It is part of the
compiler’s representation for things like
for<'a> Fn(&'a isize)
(which would be represented by the type PolyTraitRef == Binder<'tcx, TraitRef>). Note that when we instantiate,
erase, or otherwise “discharge” these bound vars, we change the
type from Binder<'tcx, T> to just T (see
e.g., liberate_late_bound_regions).Part of
MinCaptureInformationMap; describes the capture kind (&, &mut, move)
for a particular capture as well as identifying the part of the source code
that triggered this capture to occur.A composite describing a
Place that is captured by a closure.A closure can be modeled as a struct that looks like:
Struct returned by
split().Encodes that we have to coerce from the
a type to the b type.Use this rather than
ConstS, whenever possible.A type for representing any integer. Only used for printing.
Typed constant value.
A
const variable ID.A map for the local crate mapping each type to a vector of its
inherent impls. This is not meant to be used outside of coherence;
rather, you should request the vector for a specific type via
tcx.inherent_impls(def_id) so as to minimize your dependencies
(constructing this map requires touching the entire crate).The crate outlives map is computed during typeck and contains the
outlives of every item in the local crate. You should not use it
directly, because to do so will make your pass dependent on the
HIR of every item in the local crate. Instead, use
tcx.inferred_outlives_of() to get the outlives for a particular
item.The crate variances map is computed during typeck and contains the
variance of every item in the local crate. You should not use it
directly, because to do so will make your pass dependent on the
HIR of every item in the local crate. Instead, use
tcx.variances_of() to get the variance for a particular
item.A De Bruijn index is a standard means of representing
regions (and perhaps later types) in a higher-ranked setting. In
particular, imagine a type like this:
Parameter attributes that can only be determined by examining the body of a function instead
of just its signature.
The constituent parts of a type level constant of kind ADT or array.
A
ProjectionPredicate for an ExistentialTraitRef.An existential reference to a trait, where
Self is erased.
For example, the trait object Trait<'a, 'b, X, Y> is:An floating-point (
f32 or f64) type variable ID.Signature of a function type, which we have arbitrarily
decided to use to refer to the input/output types.
A “free” region
fr can be interpreted as “some region
at least as big as the scope fr.scope”.This struct contains information regarding the
ReFree(FreeRegion) corresponding to a lifetime
conflict.Whenever a value may be live across a generator yield, the type of that value winds up in the
GeneratorInteriorTypeCause struct. This struct adds additional information about such
captured types that can be useful for diagnostics. In particular, it stores the span that
caused a given type to be recorded, along with the scope that enclosed the value (which can
be used to find the await that the value is live across).Similar to
ClosureSubsts; see the above documentation for more.Bounds on generics.
Information about the formal type/lifetime parameters associated
with an item or method. Analogous to
hir::Generics.The “header” of an impl is everything outside the body: a Self type, a trait
ref (in the case of a trait impl), and a set of predicates (from the
bounds / where-clauses).
An inline const is modeled like
Struct returned by
split().A monomorphized
InstanceDef.Represents the bounds declared on a particular set of type
parameters. Should eventually be generalized into a flag list of
where-clauses. You can obtain an
InstantiatedPredicates list from a
GenericPredicates by using the instantiate method. Note that this method
reflects an important semantic invariant of InstantiatedPredicates: while
the GenericPredicates are expressed in terms of the bound type
parameters of the impl/trait/whatever, an InstantiatedPredicates instance
represented a set of bounds for some particular instantiation,
meaning that the generic parameters have been substituted with
their values.An integral (
u32, i32, usize, etc.) type variable ID.List<T> is a bit like &[T], but with some critical differences.When type checking, we use the
ParamEnv to track
details about the set of where-clauses that are in scope at this
particular point.ParamTag 🔒
The “placeholder index” fully defines a placeholder region, type, or const. Placeholders are
identified by both a universe, as well as a name residing within that universe. Distinct bound
regions/types/consts within the same universe simply have an unknown relationship to one
another.
Use this rather than
PredicateKind, whenever possible.This kind of predicate has no direct correspondent in the
syntax, but it roughly corresponds to the syntactic forms:
Use this rather than
RegionKind, whenever possible.A region (lifetime) variable ID.
Represents the repr options provided by the user,
Resolutions that should only be used for lowering.
This struct is meant to be consumed by lowering.
RvalueScopes is a mapping from sub-expressions to extended lifetime as determined by
rules laid out in rustc_hir_analysis::check::rvalue_scopes.The raw bytes of a simple value.
Collect al types that have an implicit
'static obligation that we could suggest '_ for.Encodes that
a must be a subtype of b. The a_is_expected flag indicates
whether the a type is the type that we should label as “expected” when
presenting user diagnostics.Collect al types that have an implicit
'static obligation that we could suggest '_ for.A complete reference to a trait. These take numerous guises in syntax,
but perhaps the most recognizable form is in a where-clause:
Use this rather than
TyKind, whenever possible.The central data structure of the compiler. It stores references
to the various arenas and also houses the results of the
various compiler queries that have been performed. See the
rustc dev guide for more details.
This struct should only be created by
create_def.A type variable ID.
Flags that we track on types. These flags are propagated upwards
through the type during type construction, so that we can quickly check
whether the type has various kinds of types in it without recursing
over the type itself.
An unevaluated (potentially generic) constant used in the type-system.
“Universes” are used during type- and trait-checking in the
presence of
for<..> binders to control what sets of names are
visible. Universes are arranged into a tree: the root universe
contains names that are always visible. Each child then adds a new
set of names that are visible, in addition to those of its parent.
We say that the child universe “extends” the parent universe with
new names.Upvars do not get their own
NodeId. Instead, we use the pair of
the original var ID (that is, the root variable that is referenced
by the upvar) and the ID of the closure expression.Definition of a variant – a struct’s fields or an enum variant.
A helper type that you can wrap round your own type in order to automatically
cache the stable hash, type flags and debruijn index on creation and
not recompute it whenever the information is needed.
This is only done in incremental mode. You can also opt out of caching by using
StableHash::ZERO for the hash, in which case the hash gets computed each time.
This is useful if you have values that you intern but never (can?) use for stable
hashing.
A
DefId which, in case it is a const argument, is potentially bundled with
the DefId of the generic parameter it instantiates.Enums
A clause is something that can appear in where bounds or be inferred
by implied bounds.
Represents the various closure traits in the language. This
will determine the type of the environment (
self, in the
desugaring) argument that the closure expects.Represents a constant in Rust.
Specifies how a trait object is represented.
An inference variable for a const, for use in const generics.
A placeholder for a type that hasn’t been inferred yet.
Representation of regions. Note that the NLL checker uses a distinct
representation of regions. For this reason, it internally replaces all the
regions with inference variables – the index of the variable is then used
to index into internal NLL data structures. See
rustc_const_eval::borrow_check
module for more information.Defines the kinds of types used by the type system.
Information describing the capture of an upvar. This is computed
during
typeck, specifically by regionck.A user-given type annotation attached to a constant. These arise
from constants that are named via paths, like
Foo::<A>::new and
so forth.This datastructure is used to represent the value of constants used in the type system.
Extra information about why we ended up with a particular variance.
This is only used to add more information to error messages, and
has no effect on soundness. While choosing the ‘wrong’
VarianceDiagInfo
may lead to confusing notes in error messages, it will never cause
a miscompilation or unsoundness.Constants
Captures are represented using fields inside a structure.
This represents accessing self in the closure structure
The shorthand encoding uses an enum’s variant index
usize
and is offset by this value so it never matches a real variant.
This offset is also chosen so that the first byte is never < 0x80.TAG_MASK 🔒
TYPE_TAG 🔒
Traits
Needed so we can use #[derive(HashStable_Generic)]
A trait implemented for all
X<'a> types that can be safely and
efficiently converted to X<'tcx> as long as they are part of the
provided TyCtxt<'tcx>.
This can be done, for example, for Ty<'tcx> or SubstsRef<'tcx>
by looking them up in their respective interners.Trait for decoding to a reference.
Functions
Return true if the
proj_possible_ancestor represents an ancestor path
to proj_capture or proj_possible_ancestor is same as proj_capture,
assuming they both start off of the same root variable.Yields the parent function’s
LocalDefId if def_id is an impl Trait definition.Suggest restricting a type param with a new bound.
Suggest restricting a type param with a new bound.
Type Definitions
Canonicalized user type annotation.
Mapping of type annotation indices to canonical user type annotations.
Given the closure DefId this map provides a map of root variables to minimum
set of
CapturedPlaces that need to be tracked to support all captures of that closure.Part of
MinCaptureInformationMap; List of CapturePlaces.Part of
MinCaptureInformationMap; Maps a root variable to the list of CapturedPlace.
Used to track the minimum set of Places that need to be captured to support all
Places captured by the closure starting at a given root variable.