Struct TypeVariableStorage 

pub(crate) struct TypeVariableStorage<'tcx> {
    values: IndexVec<TyVid, TypeVariableData>,
    eq_relations: UnificationTableStorage<TyVidEqKey<'tcx>>,
    sub_unification_table: UnificationTableStorage<TyVidSubKey>,
}

Fields

values: IndexVec<TyVid, TypeVariableData>

The origins of each type variable.

eq_relations: UnificationTableStorage<TyVidEqKey<'tcx>>

Two variables are unified in eq_relations when we have a constraint ?X == ?Y. This table also stores, for each key, the known value.

sub_unification_table: UnificationTableStorage<TyVidSubKey>

Only used by -Znext-solver and for diagnostics. Tracks whether type variables are related via subtyping at all, ignoring which of the two is the subtype.

When reporting ambiguity errors, we sometimes want to treat all inference vars which are subtypes of each others as if they are equal. For this case we compute the transitive closure of our subtype obligations here.

E.g. when encountering ambiguity errors, we want to suggest specifying some method argument or to add a type annotation to a local variable. Because subtyping cannot change the shape of a type, it’s fine if the cause of the ambiguity error is only related to the suggested variable via subtyping.

Even for something like let x = returns_arg(); x.method(); the type of x is only a supertype of the argument of returns_arg. We still want to suggest specifying the type of the argument.

Implementations

impl<'tcx> TypeVariableStorage<'tcx>

pub(crate) fn with_log<'a>( &'a mut self, undo_log: &'a mut InferCtxtUndoLogs<'tcx>, ) -> TypeVariableTable<'a, 'tcx>

pub(crate) fn eq_relations_ref( &self, ) -> &UnificationTableStorage<TyVidEqKey<'tcx>>

pub(super) fn finalize_rollback(&mut self)

Trait Implementations

impl<'tcx> Clone for TypeVariableStorage<'tcx>

fn clone(&self) -> TypeVariableStorage<'tcx>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'tcx> Default for TypeVariableStorage<'tcx>

fn default() -> TypeVariableStorage<'tcx>

Returns the “default value” for a type.

impl<'tcx> Rollback<UndoLog<'tcx>> for TypeVariableStorage<'tcx>

fn reverse(&mut self, undo: UndoLog<'tcx>)

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: 72 bytes