Struct rustc_middle::ty::TyS[][src]

pub struct TyS<'tcx> {
    kind: TyKind<'tcx>,
    flags: TypeFlags,
    outer_exclusive_binder: DebruijnIndex,
}

Fields

kind: TyKind<'tcx>

This field shouldn’t be used directly and may be removed in the future. Use TyS::kind() instead.

flags: TypeFlags

This field shouldn’t be used directly and may be removed in the future. Use TyS::flags() instead.

outer_exclusive_binder: DebruijnIndex

This is a kind of confusing thing: it stores the smallest binder such that

(a) the binder itself captures nothing but (b) all the late-bound things within the type are captured by some sub-binder.

So, for a type without any late-bound things, like u32, this will be innermost, because that is the innermost binder that captures nothing. But for a type &'D u32, where 'D is a late-bound region with De Bruijn index D, this would be D + 1 – the binder itself does not capture D, but D is captured by an inner binder.

We call this concept an “exclusive” binder D because all De Bruijn indices within the type are contained within 0..D (exclusive).

Implementations

Calculates the forest of DefIds from which this type is visibly uninhabited.

Returns the maximum value for the given numeric type (including chars) or returns None if the type is not numeric.

Returns the minimum value for the given numeric type (including chars) or returns None if the type is not numeric.

Checks whether values of this type T are moved or copied when referenced – this amounts to a check for whether T: Copy, but note that we don’t consider lifetimes when doing this check. This means that we may generate MIR which does copies even when the type actually doesn’t satisfy the full requirements for the Copy trait (cc #29149) – this winds up being reported as an error during NLL borrow check.

Checks whether values of this type T have a size known at compile time (i.e., whether T: Sized). Lifetimes are ignored for the purposes of this check, so it can be an over-approximation in generic contexts, where one can have strange rules like <T as Foo<'static>>::Bar: Sized that actually carry lifetime requirements.

Checks whether values of this type T implement the Freeze trait – frozen types are those that do not contain an UnsafeCell anywhere. This is a language concept used to distinguish “true immutability”, which is relevant to optimization as well as the rules around static values. Note that the Freeze trait is not exposed to end users and is effectively an implementation detail.

Fast path helper for testing if a type is Freeze.

Returning true means the type is known to be Freeze. Returning false means nothing – could be Freeze, might not be.

Checks whether values of this type T implement the Unpin trait.

Fast path helper for testing if a type is Unpin.

Returning true means the type is known to be Unpin. Returning false means nothing – could be Unpin, might not be.

If ty.needs_drop(...) returns true, then ty is definitely non-copy and might have a destructor attached; if it returns false, then ty definitely has no destructor (i.e., no drop glue).

(Note that this implies that if ty has a destructor attached, then needs_drop will definitely return true for ty.)

Note that this method is used to check eligible types in unions.

Checks if ty has has a significant drop.

Note that this method can return false even if ty has a destructor attached; even if that is the case then the adt has been marked with the attribute rustc_insignificant_dtor.

Note that this method is used to check for change in drop order for 2229 drop reorder migration analysis.

Returns true if equality for this type is both reflexive and structural.

Reflexive equality for a type is indicated by an Eq impl for that type.

Primitive types (u32, str) have structural equality by definition. For composite data types, equality for the type as a whole is structural when it is the same as equality between all components (fields, array elements, etc.) of that type. For ADTs, structural equality is indicated by an implementation of PartialStructuralEq and StructuralEq for that type.

This function is “shallow” because it may return true for a composite type whose fields are not StructuralEq. For example, [T; 4] has structural equality regardless of T because equality for arrays is determined by the equality of each array element. If you want to know whether a given call to PartialEq::eq will proceed structurally all the way down, you will need to use a type visitor.

Peel off all reference types in this type until there are none left.

This method is idempotent, i.e. ty.peel_refs().peel_refs() == ty.peel_refs().

Examples

  • u8 -> u8
  • &'a mut u8 -> u8
  • &'a &'b u8 -> u8
  • &'a *const &'b u8 -> *const &'b u8

Iterator that walks self and any types reachable from self, in depth-first order. Note that just walks the types that appear in self, it does not descend into the fields of structs or variants. For example:

isize => { isize }
Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
[isize] => { [isize], isize }

Similar to TyS::is_primitive, but also considers inferred numeric values to be primitive.

Whether the type is succinctly representable as a type instead of just referred to with a description in error messages. This is used in the main error message.

Whether the type is succinctly representable as a type instead of just referred to with a description in error messages. This is used in the primary span label. Beyond what is_simple_ty includes, it also accepts ADTs with no type arguments and references to ADTs with no type arguments.

Whether the type can be safely suggested during error recovery.

Type utilities

Returns true if this type is a str.

Get the mutability of the reference or None when not a reference

Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).

Panics if called on any type other than Box<T>.

A scalar type is one that denotes an atomic datum, with no sub-components. (A RawPtr is scalar because it represents a non-managed pointer, so its contents are abstract to rustc.)

Returns true if this type is a floating point type.

Returns the type and mutability of *ty.

The parameter explicit indicates if this is an explicit dereference. Some types – notably unsafe ptrs – can only be dereferenced explicitly.

Returns the type of ty[i].

Iterates over tuple fields. Panics when called on anything but a tuple.

Get the i-th element of a tuple. Panics when called on anything but a tuple.

If the type contains variants, returns the valid range of variant indices.

If the type contains variants, returns the variant for variant_index. Panics if variant_index is out of range.

Returns the type of the discriminant of this type.

Returns the type of metadata for (potentially fat) pointers to this type.

When we create a closure, we record its kind (i.e., what trait it implements) into its ClosureSubsts using a type parameter. This is kind of a phantom type, except that the most convenient thing for us to are the integral types. This function converts such a special type into the closure kind. To go the other way, use tcx.closure_kind_ty(closure_kind).

Note that during type checking, we use an inference variable to represent the closure kind, because it has not yet been inferred. Once upvar inference (in rustc_typeck/src/check/upvar.rs) is complete, that type variable will be unified.

Fast path helper for testing if a type is Sized.

Returning true means the type is known to be sized. Returning false means nothing – could be sized, might not be.

Note that we could never rely on the fact that a type such as [_] is trivially !Sized because we could be in a type environment with a bound such as [_]: Copy. A function with such a bound obviously never can be called, but that doesn’t mean it shouldn’t typecheck. This is why this method doesn’t return Option<bool>.

A constructor used only for internal testing.

Trait Implementations

Performs the conversion.

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 40 bytes