Struct rustc_infer::infer::type_variable::TypeVariableTable

pub struct TypeVariableTable<'a, 'tcx> {
    storage: &'a mut TypeVariableStorage<'tcx>,
    undo_log: &'a mut InferCtxtUndoLogs<'tcx>,
}

Fields

storage: &'a mut TypeVariableStorage<'tcx>

undo_log: &'a mut InferCtxtUndoLogs<'tcx>

Implementations

impl<'tcx, '_> TypeVariableTable<'_, 'tcx>

pub fn var_diverges(&self, vid: TyVid) -> bool

Returns the diverges flag given when vid was created.

Note that this function does not return care whether vid has been unified with something else or not.

pub fn var_origin(&self, vid: TyVid) -> &TypeVariableOrigin

Returns the origin that was given when vid was created.

Note that this function does not return care whether vid has been unified with something else or not.

pub fn equate(&mut self, a: TyVid, b: TyVid)

Records that a == b, depending on dir.

Precondition: neither a nor b are known.

pub fn sub(&mut self, a: TyVid, b: TyVid)

Records that a <: b, depending on dir.

Precondition: neither a nor b are known.

pub fn instantiate(&mut self, vid: TyVid, ty: Ty<'tcx>)

Instantiates vid with the type ty.

Precondition: vid must not have been previously instantiated.

pub fn new_var(
    &mut self,
    universe: UniverseIndex,
    diverging: bool,
    origin: TypeVariableOrigin
) -> TyVid

Creates a new type variable.

• diverging: indicates if this is a "diverging" type variable, e.g., one created as the type of a return expression. The code in this module doesn't care if a variable is diverging, but the main Rust type-checker will sometimes "unify" such variables with the ! or () types.
• origin: indicates why the type variable was created. The code in this module doesn't care, but it can be useful for improving error messages.

pub fn num_vars(&self) -> usize

Returns the number of type variables created thus far.

pub fn root_var(&mut self, vid: TyVid) -> TyVid

Returns the "root" variable of vid in the eq_relations equivalence table. All type variables that have been equated will yield the same root variable (per the union-find algorithm), so root_var(a) == root_var(b) implies that a == b (transitively).

pub fn sub_root_var(&mut self, vid: TyVid) -> TyVid

Returns the "root" variable of vid in the sub_relations equivalence table. All type variables that have been are related via equality or subtyping will yield the same root variable (per the union-find algorithm), so sub_root_var(a) == sub_root_var(b) implies that:

exists X. (a <: X || X <: a) && (b <: X || X <: b)

pub fn sub_unified(&mut self, a: TyVid, b: TyVid) -> bool

Returns true if a and b have same "sub-root" (i.e., exists some type X such that forall i in {a, b}. (i <: X || X <: i).

pub fn probe(&mut self, vid: TyVid) -> TypeVariableValue<'tcx>

Retrieves the type to which vid has been instantiated, if any.

pub fn inlined_probe(&mut self, vid: TyVid) -> TypeVariableValue<'tcx>

An always-inlined variant of probe, for very hot call sites.

pub fn replace_if_possible(&mut self, t: Ty<'tcx>) -> Ty<'tcx>

If t is a type-inference variable, and it has been instantiated, then return the with which it was instantiated. Otherwise, returns t.

pub(in infer::type_variable) fn values(
    &mut self
) -> SnapshotVec<Delegate, &mut Vec<TypeVariableData>, &mut InferCtxtUndoLogs<'tcx>>

pub(in infer::type_variable) fn eq_relations(
    &mut self
) -> UnificationTable<InPlace<TyVidEqKey<'tcx>, &'_ mut UnificationStorage<TyVidEqKey<'tcx>>, &'_ mut InferCtxtUndoLogs<'tcx>>>

pub(in infer::type_variable) fn sub_relations(
    &mut self
) -> UnificationTable<InPlace<TyVid, &'_ mut UnificationStorage<TyVid>, &'_ mut InferCtxtUndoLogs<'tcx>>>

pub fn vars_since_snapshot(
    &mut self,
    value_count: usize
) -> (Range<TyVid>, Vec<TypeVariableOrigin>)

Returns a range of the type variables created during the snapshot.

pub fn types_escaping_snapshot(&mut self, s: &Snapshot<'tcx>) -> Vec<Ty<'tcx>>

Finds the set of type variables that existed before s but which have only been unified since s started, and return the types with which they were unified. So if we had a type variable V0, then we started the snapshot, then we created a type variable V1, unified V0 with T0, and unified V1 with T1, this function would return {T0}.

pub fn unsolved_variables(&mut self) -> Vec<TyVid>

Returns indices of all variables that are not yet instantiated.