1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693
use std::ops::ControlFlow;
use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_errors::codes::*;
use rustc_errors::struct_span_code_err;
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_middle::bug;
use rustc_middle::ty::{self as ty, IsSuggestable, Ty, TyCtxt};
use rustc_span::symbol::Ident;
use rustc_span::{sym, ErrorGuaranteed, Span, Symbol};
use rustc_trait_selection::traits;
use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor};
use smallvec::SmallVec;
use tracing::{debug, instrument};
use crate::bounds::Bounds;
use crate::errors;
use crate::hir_ty_lowering::{
AssocItemQSelf, HirTyLowerer, OnlySelfBounds, PredicateFilter, RegionInferReason,
};
impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
/// Add a `Sized` bound to the `bounds` if appropriate.
///
/// Doesn't add the bound if the HIR bounds contain any of `Sized`, `?Sized` or `!Sized`.
pub(crate) fn add_sized_bound(
&self,
bounds: &mut Bounds<'tcx>,
self_ty: Ty<'tcx>,
hir_bounds: &'tcx [hir::GenericBound<'tcx>],
self_ty_where_predicates: Option<(LocalDefId, &'tcx [hir::WherePredicate<'tcx>])>,
span: Span,
) {
let tcx = self.tcx();
let sized_def_id = tcx.lang_items().sized_trait();
let mut seen_negative_sized_bound = false;
let mut seen_positive_sized_bound = false;
// Try to find an unbound in bounds.
let mut unbounds: SmallVec<[_; 1]> = SmallVec::new();
let mut search_bounds = |hir_bounds: &'tcx [hir::GenericBound<'tcx>]| {
for hir_bound in hir_bounds {
let hir::GenericBound::Trait(ptr, modifier) = hir_bound else {
continue;
};
match modifier {
hir::TraitBoundModifier::Maybe => unbounds.push(ptr),
hir::TraitBoundModifier::Negative => {
if let Some(sized_def_id) = sized_def_id
&& ptr.trait_ref.path.res == Res::Def(DefKind::Trait, sized_def_id)
{
seen_negative_sized_bound = true;
}
}
hir::TraitBoundModifier::None => {
if let Some(sized_def_id) = sized_def_id
&& ptr.trait_ref.path.res == Res::Def(DefKind::Trait, sized_def_id)
{
seen_positive_sized_bound = true;
}
}
_ => {}
}
}
};
search_bounds(hir_bounds);
if let Some((self_ty, where_clause)) = self_ty_where_predicates {
for clause in where_clause {
if let hir::WherePredicate::BoundPredicate(pred) = clause
&& pred.is_param_bound(self_ty.to_def_id())
{
search_bounds(pred.bounds);
}
}
}
let mut unique_bounds = FxIndexSet::default();
let mut seen_repeat = false;
for unbound in &unbounds {
if let Res::Def(DefKind::Trait, unbound_def_id) = unbound.trait_ref.path.res {
seen_repeat |= !unique_bounds.insert(unbound_def_id);
}
}
if unbounds.len() > 1 {
let err = errors::MultipleRelaxedDefaultBounds {
spans: unbounds.iter().map(|ptr| ptr.span).collect(),
};
if seen_repeat {
self.dcx().emit_err(err);
} else if !tcx.features().more_maybe_bounds {
self.tcx().sess.create_feature_err(err, sym::more_maybe_bounds).emit();
};
}
let mut seen_sized_unbound = false;
for unbound in unbounds {
if let Some(sized_def_id) = sized_def_id
&& unbound.trait_ref.path.res == Res::Def(DefKind::Trait, sized_def_id)
{
seen_sized_unbound = true;
continue;
}
// There was a `?Trait` bound, but it was not `?Sized`; warn.
self.dcx().span_warn(
unbound.span,
"relaxing a default bound only does something for `?Sized`; \
all other traits are not bound by default",
);
}
if seen_sized_unbound || seen_negative_sized_bound || seen_positive_sized_bound {
// There was in fact a `?Sized`, `!Sized` or explicit `Sized` bound;
// we don't need to do anything.
} else if sized_def_id.is_some() {
// There was no `?Sized`, `!Sized` or explicit `Sized` bound;
// add `Sized` if it's available.
bounds.push_sized(tcx, self_ty, span);
}
}
/// Lower HIR bounds into `bounds` given the self type `param_ty` and the overarching late-bound vars if any.
///
/// ### Examples
///
/// ```ignore (illustrative)
/// fn foo<T>() where for<'a> T: Trait<'a> + Copy {}
/// // ^^^^^^^ ^ ^^^^^^^^^^^^^^^^ `hir_bounds`, in HIR form
/// // | |
/// // | `param_ty`, in ty form
/// // `bound_vars`, in ty form
///
/// fn bar<T>() where T: for<'a> Trait<'a> + Copy {} // no overarching `bound_vars` here!
/// // ^ ^^^^^^^^^^^^^^^^^^^^^^^^ `hir_bounds`, in HIR form
/// // |
/// // `param_ty`, in ty form
/// ```
///
/// ### A Note on Binders
///
/// There is an implied binder around `param_ty` and `hir_bounds`.
/// See `lower_poly_trait_ref` for more details.
#[instrument(level = "debug", skip(self, hir_bounds, bounds))]
pub(crate) fn lower_poly_bounds<'hir, I: Iterator<Item = &'hir hir::GenericBound<'tcx>>>(
&self,
param_ty: Ty<'tcx>,
hir_bounds: I,
bounds: &mut Bounds<'tcx>,
bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
only_self_bounds: OnlySelfBounds,
) where
'tcx: 'hir,
{
for hir_bound in hir_bounds {
match hir_bound {
hir::GenericBound::Trait(poly_trait_ref, modifier) => {
let (constness, polarity) = match modifier {
hir::TraitBoundModifier::Const => {
(ty::BoundConstness::Const, ty::PredicatePolarity::Positive)
}
hir::TraitBoundModifier::MaybeConst => {
(ty::BoundConstness::ConstIfConst, ty::PredicatePolarity::Positive)
}
hir::TraitBoundModifier::None => {
(ty::BoundConstness::NotConst, ty::PredicatePolarity::Positive)
}
hir::TraitBoundModifier::Negative => {
(ty::BoundConstness::NotConst, ty::PredicatePolarity::Negative)
}
hir::TraitBoundModifier::Maybe => continue,
};
let _ = self.lower_poly_trait_ref(
&poly_trait_ref.trait_ref,
poly_trait_ref.span,
constness,
polarity,
param_ty,
bounds,
only_self_bounds,
);
}
hir::GenericBound::Outlives(lifetime) => {
let region = self.lower_lifetime(lifetime, RegionInferReason::OutlivesBound);
bounds.push_region_bound(
self.tcx(),
ty::Binder::bind_with_vars(
ty::OutlivesPredicate(param_ty, region),
bound_vars,
),
lifetime.ident.span,
);
}
hir::GenericBound::Use(..) => {
// We don't actually lower `use` into the type layer.
}
}
}
}
/// Lower HIR bounds into `bounds` given the self type `param_ty` and *no* overarching late-bound vars.
///
/// ### Example
///
/// ```ignore (illustrative)
/// fn foo<T: Bar + Baz>() { }
/// // ^ ^^^^^^^^^ hir_bounds
/// // param_ty
/// ```
pub(crate) fn lower_mono_bounds(
&self,
param_ty: Ty<'tcx>,
hir_bounds: &[hir::GenericBound<'tcx>],
filter: PredicateFilter,
) -> Bounds<'tcx> {
let mut bounds = Bounds::default();
let only_self_bounds = match filter {
PredicateFilter::All | PredicateFilter::SelfAndAssociatedTypeBounds => {
OnlySelfBounds(false)
}
PredicateFilter::SelfOnly | PredicateFilter::SelfThatDefines(_) => OnlySelfBounds(true),
};
self.lower_poly_bounds(
param_ty,
hir_bounds.iter().filter(|bound| match filter {
PredicateFilter::All
| PredicateFilter::SelfOnly
| PredicateFilter::SelfAndAssociatedTypeBounds => true,
PredicateFilter::SelfThatDefines(assoc_name) => {
if let Some(trait_ref) = bound.trait_ref()
&& let Some(trait_did) = trait_ref.trait_def_id()
&& self.tcx().trait_may_define_assoc_item(trait_did, assoc_name)
{
true
} else {
false
}
}
}),
&mut bounds,
ty::List::empty(),
only_self_bounds,
);
debug!(?bounds);
bounds
}
/// Lower an associated item constraint from the HIR into `bounds`.
///
/// ### A Note on Binders
///
/// Given something like `T: for<'a> Iterator<Item = &'a u32>`,
/// the `trait_ref` here will be `for<'a> T: Iterator`.
/// The `constraint` data however is from *inside* the binder
/// (e.g., `&'a u32`) and hence may reference bound regions.
#[instrument(level = "debug", skip(self, bounds, duplicates, path_span))]
pub(super) fn lower_assoc_item_constraint(
&self,
hir_ref_id: hir::HirId,
trait_ref: ty::PolyTraitRef<'tcx>,
constraint: &hir::AssocItemConstraint<'tcx>,
bounds: &mut Bounds<'tcx>,
duplicates: &mut FxIndexMap<DefId, Span>,
path_span: Span,
only_self_bounds: OnlySelfBounds,
) -> Result<(), ErrorGuaranteed> {
let tcx = self.tcx();
let assoc_kind = if constraint.gen_args.parenthesized
== hir::GenericArgsParentheses::ReturnTypeNotation
{
ty::AssocKind::Fn
} else if let hir::AssocItemConstraintKind::Equality { term: hir::Term::Const(_) } =
constraint.kind
{
ty::AssocKind::Const
} else {
ty::AssocKind::Type
};
// Given something like `U: Trait<T = X>`, we want to produce a predicate like
// `<U as Trait>::T = X`.
// This is somewhat subtle in the event that `T` is defined in a supertrait of `Trait`,
// because in that case we need to upcast. I.e., we want to produce
// `<B as SuperTrait<i32>>::T == X` for `B: SubTrait<T = X>` where
//
// trait SubTrait: SuperTrait<i32> {}
// trait SuperTrait<A> { type T; }
let candidate = if self.probe_trait_that_defines_assoc_item(
trait_ref.def_id(),
assoc_kind,
constraint.ident,
) {
// Simple case: The assoc item is defined in the current trait.
trait_ref
} else {
// Otherwise, we have to walk through the supertraits to find
// one that does define it.
self.probe_single_bound_for_assoc_item(
|| traits::supertraits(tcx, trait_ref),
AssocItemQSelf::Trait(trait_ref.def_id()),
assoc_kind,
constraint.ident,
path_span,
Some(constraint),
)?
};
let assoc_item = self
.probe_assoc_item(
constraint.ident,
assoc_kind,
hir_ref_id,
constraint.span,
candidate.def_id(),
)
.expect("failed to find associated item");
duplicates
.entry(assoc_item.def_id)
.and_modify(|prev_span| {
self.dcx().emit_err(errors::ValueOfAssociatedStructAlreadySpecified {
span: constraint.span,
prev_span: *prev_span,
item_name: constraint.ident,
def_path: tcx.def_path_str(assoc_item.container_id(tcx)),
});
})
.or_insert(constraint.span);
let projection_term = if let ty::AssocKind::Fn = assoc_kind {
let mut emitted_bad_param_err = None;
// If we have an method return type bound, then we need to instantiate
// the method's early bound params with suitable late-bound params.
let mut num_bound_vars = candidate.bound_vars().len();
let args =
candidate.skip_binder().args.extend_to(tcx, assoc_item.def_id, |param, _| {
let arg = match param.kind {
ty::GenericParamDefKind::Lifetime => ty::Region::new_bound(
tcx,
ty::INNERMOST,
ty::BoundRegion {
var: ty::BoundVar::from_usize(num_bound_vars),
kind: ty::BoundRegionKind::BrNamed(param.def_id, param.name),
},
)
.into(),
ty::GenericParamDefKind::Type { .. } => {
let guar = *emitted_bad_param_err.get_or_insert_with(|| {
self.dcx().emit_err(
crate::errors::ReturnTypeNotationIllegalParam::Type {
span: path_span,
param_span: tcx.def_span(param.def_id),
},
)
});
Ty::new_error(tcx, guar).into()
}
ty::GenericParamDefKind::Const { .. } => {
let guar = *emitted_bad_param_err.get_or_insert_with(|| {
self.dcx().emit_err(
crate::errors::ReturnTypeNotationIllegalParam::Const {
span: path_span,
param_span: tcx.def_span(param.def_id),
},
)
});
ty::Const::new_error(tcx, guar).into()
}
};
num_bound_vars += 1;
arg
});
// Next, we need to check that the return-type notation is being used on
// an RPITIT (return-position impl trait in trait) or AFIT (async fn in trait).
let output = tcx.fn_sig(assoc_item.def_id).skip_binder().output();
let output = if let ty::Alias(ty::Projection, alias_ty) = *output.skip_binder().kind()
&& tcx.is_impl_trait_in_trait(alias_ty.def_id)
{
alias_ty.into()
} else {
return Err(self.dcx().emit_err(crate::errors::ReturnTypeNotationOnNonRpitit {
span: constraint.span,
ty: tcx.liberate_late_bound_regions(assoc_item.def_id, output),
fn_span: tcx.hir().span_if_local(assoc_item.def_id),
note: (),
}));
};
// Finally, move the fn return type's bound vars over to account for the early bound
// params (and trait ref's late bound params). This logic is very similar to
// `rustc_middle::ty::predicate::Clause::instantiate_supertrait`
// and it's no coincidence why.
let shifted_output = tcx.shift_bound_var_indices(num_bound_vars, output);
let instantiation_output = ty::EarlyBinder::bind(shifted_output).instantiate(tcx, args);
let bound_vars = tcx.late_bound_vars(constraint.hir_id);
ty::Binder::bind_with_vars(instantiation_output, bound_vars)
} else {
// Create the generic arguments for the associated type or constant by joining the
// parent arguments (the arguments of the trait) and the own arguments (the ones of
// the associated item itself) and construct an alias type using them.
let alias_term = candidate.map_bound(|trait_ref| {
let item_segment = hir::PathSegment {
ident: constraint.ident,
hir_id: constraint.hir_id,
res: Res::Err,
args: Some(constraint.gen_args),
infer_args: false,
};
let alias_args = self.lower_generic_args_of_assoc_item(
path_span,
assoc_item.def_id,
&item_segment,
trait_ref.args,
);
debug!(?alias_args);
ty::AliasTerm::new_from_args(tcx, assoc_item.def_id, alias_args)
});
// Provide the resolved type of the associated constant to `type_of(AnonConst)`.
if let Some(const_arg) = constraint.ct() {
if let hir::ConstArgKind::Anon(anon_const) = const_arg.kind {
let ty = alias_term
.map_bound(|alias| tcx.type_of(alias.def_id).instantiate(tcx, alias.args));
let ty = check_assoc_const_binding_type(
self,
constraint.ident,
ty,
constraint.hir_id,
);
tcx.feed_anon_const_type(anon_const.def_id, ty::EarlyBinder::bind(ty));
}
}
alias_term
};
match constraint.kind {
hir::AssocItemConstraintKind::Equality { .. } if let ty::AssocKind::Fn = assoc_kind => {
return Err(self.dcx().emit_err(crate::errors::ReturnTypeNotationEqualityBound {
span: constraint.span,
}));
}
// Lower an equality constraint like `Item = u32` as found in HIR bound `T: Iterator<Item = u32>`
// to a projection predicate: `<T as Iterator>::Item = u32`.
hir::AssocItemConstraintKind::Equality { term } => {
let term = match term {
hir::Term::Ty(ty) => self.lower_ty(ty).into(),
hir::Term::Const(ct) => {
ty::Const::from_const_arg(tcx, ct, ty::FeedConstTy::No).into()
}
};
// Find any late-bound regions declared in `ty` that are not
// declared in the trait-ref or assoc_item. These are not well-formed.
//
// Example:
//
// for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad
// for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
let late_bound_in_projection_ty =
tcx.collect_constrained_late_bound_regions(projection_term);
let late_bound_in_term =
tcx.collect_referenced_late_bound_regions(trait_ref.rebind(term));
debug!(?late_bound_in_projection_ty);
debug!(?late_bound_in_term);
// FIXME: point at the type params that don't have appropriate lifetimes:
// struct S1<F: for<'a> Fn(&i32, &i32) -> &'a i32>(F);
// ---- ---- ^^^^^^^
// NOTE(associated_const_equality): This error should be impossible to trigger
// with associated const equality constraints.
self.validate_late_bound_regions(
late_bound_in_projection_ty,
late_bound_in_term,
|br_name| {
struct_span_code_err!(
self.dcx(),
constraint.span,
E0582,
"binding for associated type `{}` references {}, \
which does not appear in the trait input types",
constraint.ident,
br_name
)
},
);
bounds.push_projection_bound(
tcx,
projection_term.map_bound(|projection_term| ty::ProjectionPredicate {
projection_term,
term,
}),
constraint.span,
);
}
// Lower a constraint like `Item: Debug` as found in HIR bound `T: Iterator<Item: Debug>`
// to a bound involving a projection: `<T as Iterator>::Item: Debug`.
hir::AssocItemConstraintKind::Bound { bounds: hir_bounds } => {
// NOTE: If `only_self_bounds` is true, do NOT expand this associated type bound into
// a trait predicate, since we only want to add predicates for the `Self` type.
if !only_self_bounds.0 {
let projection_ty = projection_term
.map_bound(|projection_term| projection_term.expect_ty(self.tcx()));
// Calling `skip_binder` is okay, because `lower_bounds` expects the `param_ty`
// parameter to have a skipped binder.
let param_ty = Ty::new_alias(tcx, ty::Projection, projection_ty.skip_binder());
self.lower_poly_bounds(
param_ty,
hir_bounds.iter(),
bounds,
projection_ty.bound_vars(),
only_self_bounds,
);
}
}
}
Ok(())
}
}
/// Detect and reject early-bound & escaping late-bound generic params in the type of assoc const bindings.
///
/// FIXME(const_generics): This is a temporary and semi-artifical restriction until the
/// arrival of *generic const generics*[^1].
///
/// It might actually be possible that we can already support early-bound generic params
/// in such types if we just lifted some more checks in other places, too, for example
/// inside [`ty::Const::from_anon_const`]. However, even if that were the case, we should
/// probably gate this behind another feature flag.
///
/// [^1]: <https://github.com/rust-lang/project-const-generics/issues/28>.
fn check_assoc_const_binding_type<'tcx>(
cx: &dyn HirTyLowerer<'tcx>,
assoc_const: Ident,
ty: ty::Binder<'tcx, Ty<'tcx>>,
hir_id: hir::HirId,
) -> Ty<'tcx> {
// We can't perform the checks for early-bound params during name resolution unlike E0770
// because this information depends on *type* resolution.
// We can't perform these checks in `resolve_bound_vars` either for the same reason.
// Consider the trait ref `for<'a> Trait<'a, C = { &0 }>`. We need to know the fully
// resolved type of `Trait::C` in order to know if it references `'a` or not.
let ty = ty.skip_binder();
if !ty.has_param() && !ty.has_escaping_bound_vars() {
return ty;
}
let mut collector = GenericParamAndBoundVarCollector {
cx,
params: Default::default(),
vars: Default::default(),
depth: ty::INNERMOST,
};
let mut guar = ty.visit_with(&mut collector).break_value();
let tcx = cx.tcx();
let ty_note = ty
.make_suggestable(tcx, false, None)
.map(|ty| crate::errors::TyOfAssocConstBindingNote { assoc_const, ty });
let enclosing_item_owner_id = tcx
.hir()
.parent_owner_iter(hir_id)
.find_map(|(owner_id, parent)| parent.generics().map(|_| owner_id))
.unwrap();
let generics = tcx.generics_of(enclosing_item_owner_id);
for index in collector.params {
let param = generics.param_at(index as _, tcx);
let is_self_param = param.name == rustc_span::symbol::kw::SelfUpper;
guar.get_or_insert(cx.dcx().emit_err(crate::errors::ParamInTyOfAssocConstBinding {
span: assoc_const.span,
assoc_const,
param_name: param.name,
param_def_kind: tcx.def_descr(param.def_id),
param_category: if is_self_param {
"self"
} else if param.kind.is_synthetic() {
"synthetic"
} else {
"normal"
},
param_defined_here_label:
(!is_self_param).then(|| tcx.def_ident_span(param.def_id).unwrap()),
ty_note,
}));
}
for (var_def_id, var_name) in collector.vars {
guar.get_or_insert(cx.dcx().emit_err(
crate::errors::EscapingBoundVarInTyOfAssocConstBinding {
span: assoc_const.span,
assoc_const,
var_name,
var_def_kind: tcx.def_descr(var_def_id),
var_defined_here_label: tcx.def_ident_span(var_def_id).unwrap(),
ty_note,
},
));
}
let guar = guar.unwrap_or_else(|| bug!("failed to find gen params or bound vars in ty"));
Ty::new_error(tcx, guar)
}
struct GenericParamAndBoundVarCollector<'a, 'tcx> {
cx: &'a dyn HirTyLowerer<'tcx>,
params: FxIndexSet<u32>,
vars: FxIndexSet<(DefId, Symbol)>,
depth: ty::DebruijnIndex,
}
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for GenericParamAndBoundVarCollector<'_, 'tcx> {
type Result = ControlFlow<ErrorGuaranteed>;
fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
&mut self,
binder: &ty::Binder<'tcx, T>,
) -> Self::Result {
self.depth.shift_in(1);
let result = binder.super_visit_with(self);
self.depth.shift_out(1);
result
}
fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
match ty.kind() {
ty::Param(param) => {
self.params.insert(param.index);
}
ty::Bound(db, bt) if *db >= self.depth => {
self.vars.insert(match bt.kind {
ty::BoundTyKind::Param(def_id, name) => (def_id, name),
ty::BoundTyKind::Anon => {
let reported = self
.cx
.dcx()
.delayed_bug(format!("unexpected anon bound ty: {:?}", bt.var));
return ControlFlow::Break(reported);
}
});
}
_ if ty.has_param() || ty.has_bound_vars() => return ty.super_visit_with(self),
_ => {}
}
ControlFlow::Continue(())
}
fn visit_region(&mut self, re: ty::Region<'tcx>) -> Self::Result {
match re.kind() {
ty::ReEarlyParam(param) => {
self.params.insert(param.index);
}
ty::ReBound(db, br) if db >= self.depth => {
self.vars.insert(match br.kind {
ty::BrNamed(def_id, name) => (def_id, name),
ty::BrAnon | ty::BrEnv => {
let guar = self
.cx
.dcx()
.delayed_bug(format!("unexpected bound region kind: {:?}", br.kind));
return ControlFlow::Break(guar);
}
});
}
_ => {}
}
ControlFlow::Continue(())
}
fn visit_const(&mut self, ct: ty::Const<'tcx>) -> Self::Result {
match ct.kind() {
ty::ConstKind::Param(param) => {
self.params.insert(param.index);
}
ty::ConstKind::Bound(db, ty::BoundVar { .. }) if db >= self.depth => {
let guar = self.cx.dcx().delayed_bug("unexpected escaping late-bound const var");
return ControlFlow::Break(guar);
}
_ if ct.has_param() || ct.has_bound_vars() => return ct.super_visit_with(self),
_ => {}
}
ControlFlow::Continue(())
}
}