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Auto merge of #119989 - lcnr:sub_relations-bye-bye, r=compiler-errors
remove `sub_relations` from the `InferCtxt` While doing so, I tried to remove the `delay_span_bug` in `rematch_impl` again, which lead me to discover another `freshen` bug, fixing that one in the second commit. See commit descriptions for the reasoning behind each change. r? `@compiler-errors`
2 parents d9ae43c + c71484e commit 397937d

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47 files changed

+409
-455
lines changed

‎compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

+6-3
Original file line numberDiff line numberDiff line change
@@ -1522,10 +1522,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
15221522
if self.next_trait_solver()
15231523
&& let ty::Alias(..) = ty.kind()
15241524
{
1525-
match self
1525+
// We need to use a separate variable here as otherwise the temporary for
1526+
// `self.fulfillment_cx.borrow_mut()` is alive in the `Err` branch, resulting
1527+
// in a reentrant borrow, causing an ICE.
1528+
let result = self
15261529
.at(&self.misc(sp), self.param_env)
1527-
.structurally_normalize(ty, &mut **self.fulfillment_cx.borrow_mut())
1528-
{
1530+
.structurally_normalize(ty, &mut **self.fulfillment_cx.borrow_mut());
1531+
match result {
15291532
Ok(normalized_ty) => normalized_ty,
15301533
Err(errors) => {
15311534
let guar = self.err_ctxt().report_fulfillment_errors(errors);

‎compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

+7
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@ use rustc_hir as hir;
1111
use rustc_hir::def_id::{DefId, LocalDefId};
1212
use rustc_hir_analysis::astconv::AstConv;
1313
use rustc_infer::infer;
14+
use rustc_infer::infer::error_reporting::sub_relations::SubRelations;
1415
use rustc_infer::infer::error_reporting::TypeErrCtxt;
1516
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
1617
use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
@@ -155,8 +156,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
155156
///
156157
/// [`InferCtxt::err_ctxt`]: infer::InferCtxt::err_ctxt
157158
pub fn err_ctxt(&'a self) -> TypeErrCtxt<'a, 'tcx> {
159+
let mut sub_relations = SubRelations::default();
160+
sub_relations.add_constraints(
161+
self,
162+
self.fulfillment_cx.borrow_mut().pending_obligations().iter().map(|o| o.predicate),
163+
);
158164
TypeErrCtxt {
159165
infcx: &self.infcx,
166+
sub_relations: RefCell::new(sub_relations),
160167
typeck_results: Some(self.typeck_results.borrow()),
161168
fallback_has_occurred: self.fallback_has_occurred.get(),
162169
normalize_fn_sig: Box::new(|fn_sig| {

‎compiler/rustc_infer/src/infer/error_reporting/mod.rs

+3
Original file line numberDiff line numberDiff line change
@@ -88,6 +88,7 @@ mod note_and_explain;
8888
mod suggest;
8989

9090
pub(crate) mod need_type_info;
91+
pub mod sub_relations;
9192
pub use need_type_info::TypeAnnotationNeeded;
9293

9394
pub mod nice_region_error;
@@ -123,6 +124,8 @@ fn escape_literal(s: &str) -> String {
123124
/// methods which should not be used during the happy path.
124125
pub struct TypeErrCtxt<'a, 'tcx> {
125126
pub infcx: &'a InferCtxt<'tcx>,
127+
pub sub_relations: std::cell::RefCell<sub_relations::SubRelations>,
128+
126129
pub typeck_results: Option<std::cell::Ref<'a, ty::TypeckResults<'tcx>>>,
127130
pub fallback_has_occurred: bool,
128131

‎compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

+20-23
Original file line numberDiff line numberDiff line change
@@ -502,7 +502,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
502502
parent_name,
503503
});
504504

505-
let args = if self.infcx.tcx.get_diagnostic_item(sym::iterator_collect_fn)
505+
let args = if self.tcx.get_diagnostic_item(sym::iterator_collect_fn)
506506
== Some(generics_def_id)
507507
{
508508
"Vec<_>".to_string()
@@ -710,7 +710,7 @@ struct InsertableGenericArgs<'tcx> {
710710
/// While doing so, the currently best spot is stored in `infer_source`.
711711
/// For details on how we rank spots, see [Self::source_cost]
712712
struct FindInferSourceVisitor<'a, 'tcx> {
713-
infcx: &'a InferCtxt<'tcx>,
713+
tecx: &'a TypeErrCtxt<'a, 'tcx>,
714714
typeck_results: &'a TypeckResults<'tcx>,
715715

716716
target: GenericArg<'tcx>,
@@ -722,12 +722,12 @@ struct FindInferSourceVisitor<'a, 'tcx> {
722722

723723
impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
724724
fn new(
725-
infcx: &'a InferCtxt<'tcx>,
725+
tecx: &'a TypeErrCtxt<'a, 'tcx>,
726726
typeck_results: &'a TypeckResults<'tcx>,
727727
target: GenericArg<'tcx>,
728728
) -> Self {
729729
FindInferSourceVisitor {
730-
infcx,
730+
tecx,
731731
typeck_results,
732732

733733
target,
@@ -778,7 +778,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
778778
}
779779

780780
// The sources are listed in order of preference here.
781-
let tcx = self.infcx.tcx;
781+
let tcx = self.tecx.tcx;
782782
let ctx = CostCtxt { tcx };
783783
match source.kind {
784784
InferSourceKind::LetBinding { ty, .. } => ctx.ty_cost(ty),
@@ -829,12 +829,12 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
829829

830830
fn node_args_opt(&self, hir_id: HirId) -> Option<GenericArgsRef<'tcx>> {
831831
let args = self.typeck_results.node_args_opt(hir_id);
832-
self.infcx.resolve_vars_if_possible(args)
832+
self.tecx.resolve_vars_if_possible(args)
833833
}
834834

835835
fn opt_node_type(&self, hir_id: HirId) -> Option<Ty<'tcx>> {
836836
let ty = self.typeck_results.node_type_opt(hir_id);
837-
self.infcx.resolve_vars_if_possible(ty)
837+
self.tecx.resolve_vars_if_possible(ty)
838838
}
839839

840840
// Check whether this generic argument is the inference variable we
@@ -849,20 +849,17 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
849849
use ty::{Infer, TyVar};
850850
match (inner_ty.kind(), target_ty.kind()) {
851851
(&Infer(TyVar(a_vid)), &Infer(TyVar(b_vid))) => {
852-
self.infcx.inner.borrow_mut().type_variables().sub_unified(a_vid, b_vid)
852+
self.tecx.sub_relations.borrow_mut().unified(self.tecx, a_vid, b_vid)
853853
}
854854
_ => false,
855855
}
856856
}
857857
(GenericArgKind::Const(inner_ct), GenericArgKind::Const(target_ct)) => {
858858
use ty::InferConst::*;
859859
match (inner_ct.kind(), target_ct.kind()) {
860-
(ty::ConstKind::Infer(Var(a_vid)), ty::ConstKind::Infer(Var(b_vid))) => self
861-
.infcx
862-
.inner
863-
.borrow_mut()
864-
.const_unification_table()
865-
.unioned(a_vid, b_vid),
860+
(ty::ConstKind::Infer(Var(a_vid)), ty::ConstKind::Infer(Var(b_vid))) => {
861+
self.tecx.inner.borrow_mut().const_unification_table().unioned(a_vid, b_vid)
862+
}
866863
_ => false,
867864
}
868865
}
@@ -917,7 +914,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
917914
&self,
918915
expr: &'tcx hir::Expr<'tcx>,
919916
) -> Box<dyn Iterator<Item = InsertableGenericArgs<'tcx>> + 'a> {
920-
let tcx = self.infcx.tcx;
917+
let tcx = self.tecx.tcx;
921918
match expr.kind {
922919
hir::ExprKind::Path(ref path) => {
923920
if let Some(args) = self.node_args_opt(expr.hir_id) {
@@ -980,7 +977,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
980977
path: &'tcx hir::Path<'tcx>,
981978
args: GenericArgsRef<'tcx>,
982979
) -> impl Iterator<Item = InsertableGenericArgs<'tcx>> + 'a {
983-
let tcx = self.infcx.tcx;
980+
let tcx = self.tecx.tcx;
984981
let have_turbofish = path.segments.iter().any(|segment| {
985982
segment.args.is_some_and(|args| args.args.iter().any(|arg| arg.is_ty_or_const()))
986983
});
@@ -1034,7 +1031,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
10341031
args: GenericArgsRef<'tcx>,
10351032
qpath: &'tcx hir::QPath<'tcx>,
10361033
) -> Box<dyn Iterator<Item = InsertableGenericArgs<'tcx>> + 'a> {
1037-
let tcx = self.infcx.tcx;
1034+
let tcx = self.tecx.tcx;
10381035
match qpath {
10391036
hir::QPath::Resolved(_self_ty, path) => {
10401037
Box::new(self.resolved_path_inferred_arg_iter(path, args))
@@ -1107,7 +1104,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
11071104
type NestedFilter = nested_filter::OnlyBodies;
11081105

11091106
fn nested_visit_map(&mut self) -> Self::Map {
1110-
self.infcx.tcx.hir()
1107+
self.tecx.tcx.hir()
11111108
}
11121109

11131110
fn visit_local(&mut self, local: &'tcx Local<'tcx>) {
@@ -1163,7 +1160,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
11631160

11641161
#[instrument(level = "debug", skip(self))]
11651162
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
1166-
let tcx = self.infcx.tcx;
1163+
let tcx = self.tecx.tcx;
11671164
match expr.kind {
11681165
// When encountering `func(arg)` first look into `arg` and then `func`,
11691166
// as `arg` is "more specific".
@@ -1194,7 +1191,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
11941191
if generics.parent.is_none() && generics.has_self {
11951192
argument_index += 1;
11961193
}
1197-
let args = self.infcx.resolve_vars_if_possible(args);
1194+
let args = self.tecx.resolve_vars_if_possible(args);
11981195
let generic_args =
11991196
&generics.own_args_no_defaults(tcx, args)[generics.own_counts().lifetimes..];
12001197
let span = match expr.kind {
@@ -1224,7 +1221,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
12241221
{
12251222
let output = args.as_closure().sig().output().skip_binder();
12261223
if self.generic_arg_contains_target(output.into()) {
1227-
let body = self.infcx.tcx.hir().body(body);
1224+
let body = self.tecx.tcx.hir().body(body);
12281225
let should_wrap_expr = if matches!(body.value.kind, ExprKind::Block(..)) {
12291226
None
12301227
} else {
@@ -1252,12 +1249,12 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
12521249
&& let Some(args) = self.node_args_opt(expr.hir_id)
12531250
&& args.iter().any(|arg| self.generic_arg_contains_target(arg))
12541251
&& let Some(def_id) = self.typeck_results.type_dependent_def_id(expr.hir_id)
1255-
&& self.infcx.tcx.trait_of_item(def_id).is_some()
1252+
&& self.tecx.tcx.trait_of_item(def_id).is_some()
12561253
&& !has_impl_trait(def_id)
12571254
{
12581255
let successor =
12591256
method_args.get(0).map_or_else(|| (")", span.hi()), |arg| (", ", arg.span.lo()));
1260-
let args = self.infcx.resolve_vars_if_possible(args);
1257+
let args = self.tecx.resolve_vars_if_possible(args);
12611258
self.update_infer_source(InferSource {
12621259
span: path.ident.span,
12631260
kind: InferSourceKind::FullyQualifiedMethodCall {

‎compiler/rustc_infer/src/infer/error_reporting/sub_relations.rs

+81
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,81 @@
1+
use rustc_data_structures::fx::FxHashMap;
2+
use rustc_data_structures::undo_log::NoUndo;
3+
use rustc_data_structures::unify as ut;
4+
use rustc_middle::ty;
5+
6+
use crate::infer::InferCtxt;
7+
8+
#[derive(Debug, Copy, Clone, PartialEq)]
9+
struct SubId(u32);
10+
impl ut::UnifyKey for SubId {
11+
type Value = ();
12+
#[inline]
13+
fn index(&self) -> u32 {
14+
self.0
15+
}
16+
#[inline]
17+
fn from_index(i: u32) -> SubId {
18+
SubId(i)
19+
}
20+
fn tag() -> &'static str {
21+
"SubId"
22+
}
23+
}
24+
25+
/// When reporting ambiguity errors, we sometimes want to
26+
/// treat all inference vars which are subtypes of each
27+
/// others as if they are equal. For this case we compute
28+
/// the transitive closure of our subtype obligations here.
29+
///
30+
/// E.g. when encountering ambiguity errors, we want to suggest
31+
/// specifying some method argument or to add a type annotation
32+
/// to a local variable. Because subtyping cannot change the
33+
/// shape of a type, it's fine if the cause of the ambiguity error
34+
/// is only related to the suggested variable via subtyping.
35+
///
36+
/// Even for something like `let x = returns_arg(); x.method();` the
37+
/// type of `x` is only a supertype of the argument of `returns_arg`. We
38+
/// still want to suggest specifying the type of the argument.
39+
#[derive(Default)]
40+
pub struct SubRelations {
41+
map: FxHashMap<ty::TyVid, SubId>,
42+
table: ut::UnificationTableStorage<SubId>,
43+
}
44+
45+
impl SubRelations {
46+
fn get_id<'tcx>(&mut self, infcx: &InferCtxt<'tcx>, vid: ty::TyVid) -> SubId {
47+
let root_vid = infcx.root_var(vid);
48+
*self.map.entry(root_vid).or_insert_with(|| self.table.with_log(&mut NoUndo).new_key(()))
49+
}
50+
51+
pub fn add_constraints<'tcx>(
52+
&mut self,
53+
infcx: &InferCtxt<'tcx>,
54+
obls: impl IntoIterator<Item = ty::Predicate<'tcx>>,
55+
) {
56+
for p in obls {
57+
let (a, b) = match p.kind().skip_binder() {
58+
ty::PredicateKind::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
59+
(a, b)
60+
}
61+
ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => (a, b),
62+
_ => continue,
63+
};
64+
65+
match (a.kind(), b.kind()) {
66+
(&ty::Infer(ty::TyVar(a_vid)), &ty::Infer(ty::TyVar(b_vid))) => {
67+
let a = self.get_id(infcx, a_vid);
68+
let b = self.get_id(infcx, b_vid);
69+
self.table.with_log(&mut NoUndo).unify_var_var(a, b).unwrap();
70+
}
71+
_ => continue,
72+
}
73+
}
74+
}
75+
76+
pub fn unified<'tcx>(&mut self, infcx: &InferCtxt<'tcx>, a: ty::TyVid, b: ty::TyVid) -> bool {
77+
let a = self.get_id(infcx, a);
78+
let b = self.get_id(infcx, b);
79+
self.table.with_log(&mut NoUndo).unioned(a, b)
80+
}
81+
}

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