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oli-obkoli-obk
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Add an error variance, but don't use it yet
1 parent b745423 commit 3b07bf1

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11 files changed

+36
-15
lines changed

11 files changed

+36
-15
lines changed

‎compiler/rustc_borrowck/src/type_check/relate_tys.rs

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -106,14 +106,14 @@ impl<'me, 'bccx, 'tcx> NllTypeRelating<'me, 'bccx, 'tcx> {
106106
fn ambient_covariance(&self) -> bool {
107107
match self.ambient_variance {
108108
ty::Variance::Covariant | ty::Variance::Invariant => true,
109-
ty::Variance::Contravariant | ty::Variance::Bivariant => false,
109+
ty::Variance::Contravariant | ty::Variance::Bivariant | ty::Errvariant(_) => false,
110110
}
111111
}
112112

113113
fn ambient_contravariance(&self) -> bool {
114114
match self.ambient_variance {
115115
ty::Variance::Contravariant | ty::Variance::Invariant => true,
116-
ty::Variance::Covariant | ty::Variance::Bivariant => false,
116+
ty::Variance::Covariant | ty::Variance::Bivariant | ty::Errvariant(_) => false,
117117
}
118118
}
119119

@@ -526,7 +526,7 @@ impl<'bccx, 'tcx> TypeRelation<'tcx> for NllTypeRelating<'_, 'bccx, 'tcx> {
526526
})?;
527527
}
528528

529-
ty::Variance::Bivariant => {}
529+
ty::Variance::Errvariant(_) | ty::Variance::Bivariant => {}
530530
}
531531

532532
Ok(a)
@@ -591,7 +591,7 @@ impl<'bccx, 'tcx> ObligationEmittingRelation<'tcx> for NllTypeRelating<'_, 'bccx
591591
b.into(),
592592
ty::AliasRelationDirection::Equate,
593593
),
594-
ty::Variance::Bivariant => {
594+
ty::Variance::Errvariant(_) | ty::Variance::Bivariant => {
595595
unreachable!("cannot defer an alias-relate goal with Bivariant variance (yet?)")
596596
}
597597
})]);

‎compiler/rustc_hir_analysis/src/variance/constraints.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -174,6 +174,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
174174
ty::Invariant => self.invariant,
175175
ty::Contravariant => self.contravariant,
176176
ty::Bivariant => self.bivariant,
177+
ty::Errvariant(_) => &*self.terms_cx.arena.alloc(ConstantTerm(v)),
177178
}
178179
}
179180

‎compiler/rustc_hir_analysis/src/variance/xform.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,7 @@ pub fn glb(v1: ty::Variance, v2: ty::Variance) -> ty::Variance {
88
// - +
99
// o
1010
match (v1, v2) {
11+
(ty::Errvariant(guar), _) | (_, ty::Errvariant(guar)) => ty::Errvariant(guar),
1112
(ty::Invariant, _) | (_, ty::Invariant) => ty::Invariant,
1213

1314
(ty::Covariant, ty::Contravariant) => ty::Invariant,

‎compiler/rustc_infer/src/infer/at.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -207,6 +207,7 @@ impl<'a, 'tcx> At<'a, 'tcx> {
207207
ty::Variance::Covariant => self.sub(define_opaque_types, expected, actual),
208208
ty::Variance::Invariant => self.eq(define_opaque_types, expected, actual),
209209
ty::Variance::Contravariant => self.sup(define_opaque_types, expected, actual),
210+
ty::Variance::Errvariant(_) => unreachable!(),
210211

211212
// We could make this make sense but it's not readily
212213
// exposed and I don't feel like dealing with it. Note

‎compiler/rustc_infer/src/infer/relate/generalize.rs

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -91,6 +91,7 @@ impl<'tcx> InferCtxt<'tcx> {
9191
ty::Variance::Contravariant => {
9292
(source_ty.into(), generalized_ty.into(), AliasRelationDirection::Subtype)
9393
}
94+
ty::Errvariant(_) => unreachable!(),
9495
ty::Variance::Bivariant => unreachable!("bivariant generalization"),
9596
};
9697

@@ -495,7 +496,7 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
495496

496497
// Co/contravariant: this will be
497498
// sufficiently constrained later on.
498-
ty::Covariant | ty::Contravariant => (),
499+
ty::Errvariant(_) | ty::Covariant | ty::Contravariant => (),
499500
}
500501

501502
let origin = inner.type_variables().var_origin(vid);

‎compiler/rustc_infer/src/infer/relate/glb.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -40,6 +40,8 @@ impl<'tcx> TypeRelation<'tcx> for Glb<'_, '_, 'tcx> {
4040
match variance {
4141
ty::Invariant => self.fields.equate(StructurallyRelateAliases::No).relate(a, b),
4242
ty::Covariant => self.relate(a, b),
43+
// TODO: report a new error kind
44+
ty::Errvariant(_) => Ok(a),
4345
// FIXME(#41044) -- not correct, need test
4446
ty::Bivariant => Ok(a),
4547
ty::Contravariant => self.fields.lub().relate(a, b),

‎compiler/rustc_infer/src/infer/relate/lub.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -40,6 +40,8 @@ impl<'tcx> TypeRelation<'tcx> for Lub<'_, '_, 'tcx> {
4040
match variance {
4141
ty::Invariant => self.fields.equate(StructurallyRelateAliases::No).relate(a, b),
4242
ty::Covariant => self.relate(a, b),
43+
// TODO: report a new kind of type error that preserves the `ErrorGuaranteed`?
44+
ty::Errvariant(_) => Ok(a),
4345
// FIXME(#41044) -- not correct, need test
4446
ty::Bivariant => Ok(a),
4547
ty::Contravariant => self.fields.glb().relate(a, b),

‎compiler/rustc_infer/src/infer/relate/type_relating.rs

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -117,7 +117,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
117117
ty::Invariant => {
118118
infcx.inner.borrow_mut().type_variables().equate(a_id, b_id);
119119
}
120-
ty::Bivariant => {
120+
ty::Errvariant(_) | ty::Bivariant => {
121121
unreachable!("Expected bivariance to be handled in relate_with_variance")
122122
}
123123
}
@@ -204,7 +204,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
204204
.unwrap_region_constraints()
205205
.make_eqregion(origin, a, b);
206206
}
207-
ty::Bivariant => {
207+
ty::Errvariant(_) | ty::Bivariant => {
208208
unreachable!("Expected bivariance to be handled in relate_with_variance")
209209
}
210210
}
@@ -289,7 +289,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
289289
self.relate(a, b)
290290
})?;
291291
}
292-
ty::Bivariant => {
292+
ty::Errvariant(_) | ty::Bivariant => {
293293
unreachable!("Expected bivariance to be handled in relate_with_variance")
294294
}
295295
}
@@ -341,7 +341,7 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
341341
b.into(),
342342
ty::AliasRelationDirection::Equate,
343343
),
344-
ty::Variance::Bivariant => {
344+
ty::Variance::Errvariant(_) | ty::Variance::Bivariant => {
345345
unreachable!("Expected bivariance to be handled in relate_with_variance")
346346
}
347347
})]);

‎compiler/rustc_smir/src/rustc_smir/convert/ty.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -870,6 +870,7 @@ impl<'tcx> Stable<'tcx> for ty::Variance {
870870
ty::Variance::Contravariant => stable_mir::mir::Variance::Contravariant,
871871
ty::Variance::Covariant => stable_mir::mir::Variance::Covariant,
872872
ty::Variance::Invariant => stable_mir::mir::Variance::Invariant,
873+
ty::Variance::Errvariant(_) => stable_mir::mir::Variance::Bivariant,
873874
}
874875
}
875876
}

‎compiler/rustc_span/src/lib.rs

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -39,7 +39,7 @@
3939
extern crate self as rustc_span;
4040

4141
use rustc_data_structures::{outline, AtomicRef};
42-
use rustc_macros::{Decodable, Encodable, HashStable_Generic};
42+
use rustc_macros::{Decodable, Encodable, HashStable_Generic, HashStable_NoContext};
4343
use rustc_serialize::opaque::{FileEncoder, MemDecoder};
4444
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
4545
use tracing::debug;
@@ -2573,7 +2573,7 @@ where
25732573
/// The `()` field is necessary: it is non-`pub`, which means values of this
25742574
/// type cannot be constructed outside of this crate.
25752575
#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
2576-
#[derive(HashStable_Generic)]
2576+
#[derive(HashStable_NoContext)]
25772577
pub struct ErrorGuaranteed(());
25782578

25792579
impl ErrorGuaranteed {

‎compiler/rustc_type_ir/src/lib.rs

Lines changed: 16 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@ use rustc_data_structures::sso::SsoHashSet;
1414
use rustc_data_structures::sync::Lrc;
1515
#[cfg(feature = "nightly")]
1616
use rustc_macros::{Decodable, Encodable, HashStable_NoContext};
17+
use rustc_span::ErrorGuaranteed;
1718
#[cfg(not(feature = "nightly"))]
1819
use std::collections::HashSet as SsoHashSet;
1920
use std::fmt;
@@ -200,10 +201,16 @@ pub fn debug_bound_var<T: std::fmt::Write>(
200201
#[cfg_attr(feature = "nightly", derive(Decodable, Encodable, Hash, HashStable_NoContext))]
201202
#[cfg_attr(feature = "nightly", rustc_pass_by_value)]
202203
pub enum Variance {
203-
Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
204-
Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
205-
Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
206-
Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
204+
/// T<A> <: T<B> iff A <: B -- e.g., function return type
205+
Covariant,
206+
/// T<A> <: T<B> iff B == A -- e.g., type of mutable cell
207+
Invariant,
208+
/// T<A> <: T<B> iff B <: A -- e.g., function param type
209+
Contravariant,
210+
/// T<A> <: T<B> -- e.g., unused type parameter
211+
Bivariant,
212+
/// Oddly named since these are all glob exported in various places in the compiler
213+
Errvariant(ErrorGuaranteed),
207214
}
208215

209216
impl Variance {
@@ -245,6 +252,10 @@ impl Variance {
245252
/// Combining Definition- and Use-Site Variance" published in PLDI'11.
246253
pub fn xform(self, v: Variance) -> Variance {
247254
match (self, v) {
255+
(Variance::Errvariant(guar), _) | (_, Variance::Errvariant(guar)) => {
256+
Variance::Errvariant(guar)
257+
}
258+
248259
// Figure 1, column 1.
249260
(Variance::Covariant, Variance::Covariant) => Variance::Covariant,
250261
(Variance::Covariant, Variance::Contravariant) => Variance::Contravariant,
@@ -273,6 +284,7 @@ impl fmt::Debug for Variance {
273284
Variance::Contravariant => "-",
274285
Variance::Invariant => "o",
275286
Variance::Bivariant => "*",
287+
Variance::Errvariant(_) => "💥",
276288
})
277289
}
278290
}

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