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stop categorizing inference variables as diverging when created
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Instead, we now rely on the code that looks for a NeverToAny adjustment.
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@nikomatsakis @Mark-Simulacrum
nikomatsakis authored and Mark-Simulacrum committed Sep 17, 2021
1 parent 1c004f2 commit bc2ece2
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Showing 5 changed files with 17 additions and 63 deletions.
15 changes: 8 additions & 7 deletions compiler/rustc_infer/src/infer/combine.rs
View file
Expand Up @@ -22,14 +22,14 @@
// is also useful to track which value is the "expected" value in
// terms of error reporting.

use super::equate::Equate;
use super::glb::Glb;
use super::lub::Lub;
use super::sub::Sub;
use super::type_variable::TypeVariableValue;
use super::unify_key::replace_if_possible;
use super::unify_key::{ConstVarValue, ConstVariableValue};
use super::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
use super::{equate::Equate, type_variable::Diverging};
use super::{InferCtxt, MiscVariable, TypeTrace};

use crate::traits::{Obligation, PredicateObligations};
Expand Down Expand Up @@ -645,7 +645,7 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
.inner
.borrow_mut()
.type_variables()
.new_var(self.for_universe, Diverging::NotDiverging, origin);
.new_var(self.for_universe, origin);
let u = self.tcx().mk_ty_var(new_var_id);

// Record that we replaced `vid` with `new_var_id` as part of a generalization
Expand Down Expand Up @@ -885,11 +885,12 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {

let origin =
*self.infcx.inner.borrow_mut().type_variables().var_origin(vid);
let new_var_id = self.infcx.inner.borrow_mut().type_variables().new_var(
self.for_universe,
Diverging::NotDiverging,
origin,
);
let new_var_id = self
.infcx
.inner
.borrow_mut()
.type_variables()
.new_var(self.for_universe, origin);
let u = self.tcx().mk_ty_var(new_var_id);
debug!(
"ConstInferUnifier: replacing original vid={:?} with new={:?}",
Expand Down
36 changes: 5 additions & 31 deletions compiler/rustc_infer/src/infer/mod.rs
View file
Expand Up @@ -46,7 +46,7 @@ use self::region_constraints::{GenericKind, RegionConstraintData, VarInfos, Veri
use self::region_constraints::{
RegionConstraintCollector, RegionConstraintStorage, RegionSnapshot,
};
use self::type_variable::{Diverging, TypeVariableOrigin, TypeVariableOriginKind};
use self::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};

pub mod at;
pub mod canonical;
Expand Down Expand Up @@ -701,23 +701,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
t.fold_with(&mut self.freshener())
}

/// Returns whether `ty` is a diverging type variable or not.
/// (If `ty` is not a type variable at all, returns not diverging.)
///
/// No attempt is made to resolve `ty`.
pub fn type_var_diverges(&'a self, ty: Ty<'_>) -> Diverging {
match *ty.kind() {
ty::Infer(ty::TyVar(vid)) => self.ty_vid_diverges(vid),
_ => Diverging::NotDiverging,
}
}

/// Returns true if the type inference variable `vid` was created
/// as a diverging type variable. No attempt is made to resolve `vid`.
pub fn ty_vid_diverges(&'a self, vid: ty::TyVid) -> Diverging {
self.inner.borrow_mut().type_variables().var_diverges(vid)
}

/// Returns the origin of the type variable identified by `vid`, or `None`
/// if this is not a type variable.
///
Expand Down Expand Up @@ -1081,31 +1064,23 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
self.inner.borrow_mut().type_variables().num_vars()
}

pub fn next_ty_var_id(&self, diverging: Diverging, origin: TypeVariableOrigin) -> TyVid {
self.inner.borrow_mut().type_variables().new_var(self.universe(), diverging, origin)
pub fn next_ty_var_id(&self, origin: TypeVariableOrigin) -> TyVid {
self.inner.borrow_mut().type_variables().new_var(self.universe(), origin)
}

pub fn next_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
self.tcx.mk_ty_var(self.next_ty_var_id(Diverging::NotDiverging, origin))
self.tcx.mk_ty_var(self.next_ty_var_id(origin))
}

pub fn next_ty_var_in_universe(
&self,
origin: TypeVariableOrigin,
universe: ty::UniverseIndex,
) -> Ty<'tcx> {
let vid = self.inner.borrow_mut().type_variables().new_var(
universe,
Diverging::NotDiverging,
origin,
);
let vid = self.inner.borrow_mut().type_variables().new_var(universe, origin);
self.tcx.mk_ty_var(vid)
}

pub fn next_diverging_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
self.tcx.mk_ty_var(self.next_ty_var_id(Diverging::Diverges, origin))
}

pub fn next_const_var(
&self,
ty: Ty<'tcx>,
Expand Down Expand Up @@ -1217,7 +1192,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// as the substitutions for the default, `(T, U)`.
let ty_var_id = self.inner.borrow_mut().type_variables().new_var(
self.universe(),
Diverging::NotDiverging,
TypeVariableOrigin {
kind: TypeVariableOriginKind::TypeParameterDefinition(
param.name,
Expand Down
4 changes: 1 addition & 3 deletions compiler/rustc_infer/src/infer/nll_relate/mod.rs
View file
Expand Up @@ -22,7 +22,6 @@
//! constituents)

use crate::infer::combine::ConstEquateRelation;
use crate::infer::type_variable::Diverging;
use crate::infer::InferCtxt;
use crate::infer::{ConstVarValue, ConstVariableValue};
use rustc_data_structures::fx::FxHashMap;
Expand Down Expand Up @@ -927,8 +926,7 @@ where
// Replacing with a new variable in the universe `self.universe`,
// it will be unified later with the original type variable in
// the universe `_universe`.
let new_var_id =
variables.new_var(self.universe, Diverging::NotDiverging, origin);
let new_var_id = variables.new_var(self.universe, origin);

let u = self.tcx().mk_ty_var(new_var_id);
debug!("generalize: replacing original vid={:?} with new={:?}", vid, u);
Expand Down
23 changes: 2 additions & 21 deletions compiler/rustc_infer/src/infer/type_variable.rs
View file
Expand Up @@ -139,13 +139,6 @@ pub enum TypeVariableOriginKind {

pub(crate) struct TypeVariableData {
origin: TypeVariableOrigin,
diverging: Diverging,
}

#[derive(Copy, Clone, Debug)]
pub enum Diverging {
NotDiverging,
Diverges,
}

#[derive(Copy, Clone, Debug)]
Expand Down Expand Up @@ -195,14 +188,6 @@ impl<'tcx> TypeVariableStorage<'tcx> {
}

impl<'tcx> TypeVariableTable<'_, 'tcx> {
/// 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_diverges(&self, vid: ty::TyVid) -> Diverging {
self.storage.values.get(vid.index()).diverging
}

/// Returns the origin that was given when `vid` was created.
///
/// Note that this function does not return care whether
Expand Down Expand Up @@ -264,21 +249,17 @@ impl<'tcx> TypeVariableTable<'_, 'tcx> {
pub fn new_var(
&mut self,
universe: ty::UniverseIndex,
diverging: Diverging,
origin: TypeVariableOrigin,
) -> ty::TyVid {
let eq_key = self.eq_relations().new_key(TypeVariableValue::Unknown { universe });

let sub_key = self.sub_relations().new_key(());
assert_eq!(eq_key.vid, sub_key);

let index = self.values().push(TypeVariableData { origin, diverging });
let index = self.values().push(TypeVariableData { origin });
assert_eq!(eq_key.vid.as_u32(), index as u32);

debug!(
"new_var(index={:?}, universe={:?}, diverging={:?}, origin={:?}",
eq_key.vid, universe, diverging, origin,
);
debug!("new_var(index={:?}, universe={:?}, origin={:?}", eq_key.vid, universe, origin,);

eq_key.vid
}
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_typeck/src/check/expr.rs
View file
Expand Up @@ -77,7 +77,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
!self.typeck_results.borrow().adjustments().contains_key(expr.hir_id),
"expression with never type wound up being adjusted"
);
let adj_ty = self.next_diverging_ty_var(TypeVariableOrigin {
let adj_ty = self.next_ty_var(TypeVariableOrigin {
kind: TypeVariableOriginKind::AdjustmentType,
span: expr.span,
});
Expand Down

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