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fuchsia / third_party / github.com / rust-lang / rust-analyzer / refs/heads/main / . / crates / hir-ty / src / lower.rs
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//! Methods for lowering the HIR to types. There are two main cases here:
//!
//! - Lowering a type reference like `&usize` or `Option<foo::bar::Baz>` to a
//! type: The entry point for this is `TyLoweringContext::lower_ty`.
//! - Building the type for an item: This happens through the `ty` query.
//!
//! This usually involves resolving names, collecting generic arguments etc.
pub(crate) mod diagnostics;
pub(crate) mod path;
use std::{
cell::OnceCell,
iter, mem,
ops::{self, Deref, Not as _},
};
use base_db::Crate;
use either::Either;
use hir_def::{
AdtId, AssocItemId, CallableDefId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId,
FunctionId, GenericDefId, GenericParamId, HasModule, ImplId, ItemContainerId, LifetimeParamId,
LocalFieldId, Lookup, StaticId, StructId, TypeAliasId, TypeOrConstParamId, TypeParamId,
UnionId, VariantId,
builtin_type::BuiltinType,
expr_store::{ExpressionStore, HygieneId, path::Path},
hir::generics::{
GenericParamDataRef, TypeOrConstParamData, TypeParamProvenance, WherePredicate,
},
item_tree::FieldsShape,
lang_item::LangItem,
resolver::{HasResolver, LifetimeNs, Resolver, TypeNs, ValueNs},
signatures::{FunctionSignature, TraitFlags, TypeAliasFlags},
type_ref::{
ConstRef, LifetimeRefId, LiteralConstRef, PathId, TraitBoundModifier,
TraitRef as HirTraitRef, TypeBound, TypeRef, TypeRefId,
},
};
use hir_expand::name::Name;
use la_arena::{Arena, ArenaMap, Idx};
use path::{PathDiagnosticCallback, PathLoweringContext};
use rustc_ast_ir::Mutability;
use rustc_hash::FxHashSet;
use rustc_pattern_analysis::Captures;
use rustc_type_ir::{
AliasTyKind, BoundVarIndexKind, ConstKind, DebruijnIndex, ExistentialPredicate,
ExistentialProjection, ExistentialTraitRef, FnSig, OutlivesPredicate,
TyKind::{self},
TypeVisitableExt,
inherent::{GenericArg as _, GenericArgs as _, IntoKind as _, Region as _, SliceLike, Ty as _},
};
use salsa::plumbing::AsId;
use smallvec::{SmallVec, smallvec};
use stdx::{impl_from, never};
use triomphe::{Arc, ThinArc};
use crate::{
FnAbi, ImplTraitId, TraitEnvironment, TyLoweringDiagnostic, TyLoweringDiagnosticKind,
consteval::intern_const_ref,
db::HirDatabase,
generics::{Generics, generics, trait_self_param_idx},
next_solver::{
AliasTy, Binder, BoundExistentialPredicates, Clause, Clauses, Const, DbInterner,
EarlyBinder, EarlyParamRegion, ErrorGuaranteed, GenericArg, GenericArgs, ParamConst,
ParamEnv, PolyFnSig, Predicate, Region, SolverDefId, TraitPredicate, TraitRef, Ty, Tys,
UnevaluatedConst, abi::Safety,
},
};
pub(crate) struct PathDiagnosticCallbackData(pub(crate) TypeRefId);
#[derive(PartialEq, Eq, Debug, Hash)]
pub struct ImplTraits<'db> {
pub(crate) impl_traits: Arena<ImplTrait<'db>>,
}
#[derive(PartialEq, Eq, Debug, Hash)]
pub struct ImplTrait<'db> {
pub(crate) predicates: Vec<Clause<'db>>,
}
pub type ImplTraitIdx<'db> = Idx<ImplTrait<'db>>;
#[derive(Debug, Default)]
struct ImplTraitLoweringState<'db> {
/// When turning `impl Trait` into opaque types, we have to collect the
/// bounds at the same time to get the IDs correct (without becoming too
/// complicated).
mode: ImplTraitLoweringMode,
// This is structured as a struct with fields and not as an enum because it helps with the borrow checker.
opaque_type_data: Arena<ImplTrait<'db>>,
}
impl<'db> ImplTraitLoweringState<'db> {
fn new(mode: ImplTraitLoweringMode) -> ImplTraitLoweringState<'db> {
Self { mode, opaque_type_data: Arena::new() }
}
}
#[derive(Debug, Clone)]
pub enum LifetimeElisionKind<'db> {
/// Create a new anonymous lifetime parameter and reference it.
///
/// If `report_in_path`, report an error when encountering lifetime elision in a path:
/// ```compile_fail
/// struct Foo<'a> { x: &'a () }
/// async fn foo(x: Foo) {}
/// ```
///
/// Note: the error should not trigger when the elided lifetime is in a pattern or
/// expression-position path:
/// ```
/// struct Foo<'a> { x: &'a () }
/// async fn foo(Foo { x: _ }: Foo<'_>) {}
/// ```
AnonymousCreateParameter { report_in_path: bool },
/// Replace all anonymous lifetimes by provided lifetime.
Elided(Region<'db>),
/// Give a hard error when either `&` or `'_` is written. Used to
/// rule out things like `where T: Foo<'_>`. Does not imply an
/// error on default object bounds (e.g., `Box<dyn Foo>`).
AnonymousReportError,
/// Resolves elided lifetimes to `'static` if there are no other lifetimes in scope,
/// otherwise give a warning that the previous behavior of introducing a new early-bound
/// lifetime is a bug and will be removed (if `only_lint` is enabled).
StaticIfNoLifetimeInScope { only_lint: bool },
/// Signal we cannot find which should be the anonymous lifetime.
ElisionFailure,
/// Infer all elided lifetimes.
Infer,
}
impl<'db> LifetimeElisionKind<'db> {
#[inline]
pub(crate) fn for_const(
interner: DbInterner<'db>,
const_parent: ItemContainerId,
) -> LifetimeElisionKind<'db> {
match const_parent {
ItemContainerId::ExternBlockId(_) | ItemContainerId::ModuleId(_) => {
LifetimeElisionKind::Elided(Region::new_static(interner))
}
ItemContainerId::ImplId(_) => {
LifetimeElisionKind::StaticIfNoLifetimeInScope { only_lint: true }
}
ItemContainerId::TraitId(_) => {
LifetimeElisionKind::StaticIfNoLifetimeInScope { only_lint: false }
}
}
}
#[inline]
pub(crate) fn for_fn_params(data: &FunctionSignature) -> LifetimeElisionKind<'db> {
LifetimeElisionKind::AnonymousCreateParameter { report_in_path: data.is_async() }
}
#[inline]
pub(crate) fn for_fn_ret(interner: DbInterner<'db>) -> LifetimeElisionKind<'db> {
// FIXME: We should use the elided lifetime here, or `ElisionFailure`.
LifetimeElisionKind::Elided(Region::error(interner))
}
}
#[derive(Debug)]
pub struct TyLoweringContext<'db, 'a> {
pub db: &'db dyn HirDatabase,
interner: DbInterner<'db>,
resolver: &'a Resolver<'db>,
store: &'a ExpressionStore,
def: GenericDefId,
generics: OnceCell<Generics>,
in_binders: DebruijnIndex,
impl_trait_mode: ImplTraitLoweringState<'db>,
/// Tracks types with explicit `?Sized` bounds.
pub(crate) unsized_types: FxHashSet<Ty<'db>>,
pub(crate) diagnostics: Vec<TyLoweringDiagnostic>,
lifetime_elision: LifetimeElisionKind<'db>,
/// When lowering the defaults for generic params, this contains the index of the currently lowered param.
/// We disallow referring to later params, or to ADT's `Self`.
lowering_param_default: Option<u32>,
}
impl<'db, 'a> TyLoweringContext<'db, 'a> {
pub fn new(
db: &'db dyn HirDatabase,
resolver: &'a Resolver<'db>,
store: &'a ExpressionStore,
def: GenericDefId,
lifetime_elision: LifetimeElisionKind<'db>,
) -> Self {
let impl_trait_mode = ImplTraitLoweringState::new(ImplTraitLoweringMode::Disallowed);
let in_binders = DebruijnIndex::ZERO;
Self {
db,
interner: DbInterner::new_with(db, Some(resolver.krate()), None),
resolver,
def,
generics: Default::default(),
store,
in_binders,
impl_trait_mode,
unsized_types: FxHashSet::default(),
diagnostics: Vec::new(),
lifetime_elision,
lowering_param_default: None,
}
}
pub(crate) fn set_lifetime_elision(&mut self, lifetime_elision: LifetimeElisionKind<'db>) {
self.lifetime_elision = lifetime_elision;
}
pub(crate) fn with_debruijn<T>(
&mut self,
debruijn: DebruijnIndex,
f: impl FnOnce(&mut TyLoweringContext<'db, '_>) -> T,
) -> T {
let old_debruijn = mem::replace(&mut self.in_binders, debruijn);
let result = f(self);
self.in_binders = old_debruijn;
result
}
pub(crate) fn with_shifted_in<T>(
&mut self,
debruijn: DebruijnIndex,
f: impl FnOnce(&mut TyLoweringContext<'db, '_>) -> T,
) -> T {
self.with_debruijn(self.in_binders.shifted_in(debruijn.as_u32()), f)
}
pub(crate) fn with_impl_trait_mode(self, impl_trait_mode: ImplTraitLoweringMode) -> Self {
Self { impl_trait_mode: ImplTraitLoweringState::new(impl_trait_mode), ..self }
}
pub(crate) fn impl_trait_mode(&mut self, impl_trait_mode: ImplTraitLoweringMode) -> &mut Self {
self.impl_trait_mode = ImplTraitLoweringState::new(impl_trait_mode);
self
}
pub(crate) fn lowering_param_default(&mut self, index: u32) {
self.lowering_param_default = Some(index);
}
pub(crate) fn push_diagnostic(&mut self, type_ref: TypeRefId, kind: TyLoweringDiagnosticKind) {
self.diagnostics.push(TyLoweringDiagnostic { source: type_ref, kind });
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Default)]
pub(crate) enum ImplTraitLoweringMode {
/// `impl Trait` gets lowered into an opaque type that doesn't unify with
/// anything except itself. This is used in places where values flow 'out',
/// i.e. for arguments of the function we're currently checking, and return
/// types of functions we're calling.
Opaque,
/// `impl Trait` is disallowed and will be an error.
#[default]
Disallowed,
}
impl<'db, 'a> TyLoweringContext<'db, 'a> {
pub fn lower_ty(&mut self, type_ref: TypeRefId) -> Ty<'db> {
self.lower_ty_ext(type_ref).0
}
pub(crate) fn lower_const(&mut self, const_ref: ConstRef, const_type: Ty<'db>) -> Const<'db> {
let const_ref = &self.store[const_ref.expr];
match const_ref {
hir_def::hir::Expr::Path(path) => {
self.path_to_const(path).unwrap_or_else(|| unknown_const(const_type))
}
hir_def::hir::Expr::Literal(literal) => intern_const_ref(
self.db,
&match *literal {
hir_def::hir::Literal::Float(_, _)
| hir_def::hir::Literal::String(_)
| hir_def::hir::Literal::ByteString(_)
| hir_def::hir::Literal::CString(_) => LiteralConstRef::Unknown,
hir_def::hir::Literal::Char(c) => LiteralConstRef::Char(c),
hir_def::hir::Literal::Bool(b) => LiteralConstRef::Bool(b),
hir_def::hir::Literal::Int(val, _) => LiteralConstRef::Int(val),
hir_def::hir::Literal::Uint(val, _) => LiteralConstRef::UInt(val),
},
const_type,
self.resolver.krate(),
),
hir_def::hir::Expr::UnaryOp { expr: inner_expr, op: hir_def::hir::UnaryOp::Neg } => {
if let hir_def::hir::Expr::Literal(literal) = &self.store[*inner_expr] {
// Only handle negation for signed integers and floats
match literal {
hir_def::hir::Literal::Int(_, _) | hir_def::hir::Literal::Float(_, _) => {
if let Some(negated_literal) = literal.clone().negate() {
intern_const_ref(
self.db,
&negated_literal.into(),
const_type,
self.resolver.krate(),
)
} else {
unknown_const(const_type)
}
}
// For unsigned integers, chars, bools, etc., negation is not meaningful
_ => unknown_const(const_type),
}
} else {
unknown_const(const_type)
}
}
_ => unknown_const(const_type),
}
}
pub(crate) fn path_to_const(&mut self, path: &Path) -> Option<Const<'db>> {
match self.resolver.resolve_path_in_value_ns_fully(self.db, path, HygieneId::ROOT) {
Some(ValueNs::GenericParam(p)) => {
let args = self.generics();
match args.type_or_const_param_idx(p.into()) {
Some(idx) => Some(self.const_param(p, idx as u32)),
None => {
never!(
"Generic list doesn't contain this param: {:?}, {:?}, {:?}",
args,
path,
p
);
None
}
}
}
Some(ValueNs::ConstId(c)) => {
let args = GenericArgs::new_from_iter(self.interner, []);
Some(Const::new(
self.interner,
rustc_type_ir::ConstKind::Unevaluated(UnevaluatedConst::new(
SolverDefId::ConstId(c),
args,
)),
))
}
_ => None,
}
}
pub(crate) fn lower_path_as_const(&mut self, path: &Path, const_type: Ty<'db>) -> Const<'db> {
self.path_to_const(path).unwrap_or_else(|| unknown_const(const_type))
}
fn generics(&self) -> &Generics {
self.generics.get_or_init(|| generics(self.db, self.def))
}
fn param_index_is_disallowed(&self, index: u32) -> bool {
self.lowering_param_default
.is_some_and(|disallow_params_after| index >= disallow_params_after)
}
fn type_param(&mut self, id: TypeParamId, index: u32) -> Ty<'db> {
if self.param_index_is_disallowed(index) {
// FIXME: Report an error.
Ty::new_error(self.interner, ErrorGuaranteed)
} else {
Ty::new_param(self.interner, id, index)
}
}
fn const_param(&mut self, id: ConstParamId, index: u32) -> Const<'db> {
if self.param_index_is_disallowed(index) {
// FIXME: Report an error.
Const::error(self.interner)
} else {
Const::new_param(self.interner, ParamConst { id, index })
}
}
fn region_param(&mut self, id: LifetimeParamId, index: u32) -> Region<'db> {
if self.param_index_is_disallowed(index) {
// FIXME: Report an error.
Region::error(self.interner)
} else {
Region::new_early_param(self.interner, EarlyParamRegion { id, index })
}
}
#[tracing::instrument(skip(self), ret)]
pub fn lower_ty_ext(&mut self, type_ref_id: TypeRefId) -> (Ty<'db>, Option<TypeNs>) {
let interner = self.interner;
let mut res = None;
let type_ref = &self.store[type_ref_id];
tracing::debug!(?type_ref);
let ty = match type_ref {
TypeRef::Never => Ty::new(interner, TyKind::Never),
TypeRef::Tuple(inner) => {
let inner_tys = inner.iter().map(|&tr| self.lower_ty(tr));
Ty::new_tup_from_iter(interner, inner_tys)
}
TypeRef::Path(path) => {
let (ty, res_) =
self.lower_path(path, PathId::from_type_ref_unchecked(type_ref_id));
res = res_;
ty
}
&TypeRef::TypeParam(type_param_id) => {
res = Some(TypeNs::GenericParam(type_param_id));
let generics = self.generics();
let (idx, _data) =
generics.type_or_const_param(type_param_id.into()).expect("matching generics");
self.type_param(type_param_id, idx as u32)
}
&TypeRef::RawPtr(inner, mutability) => {
let inner_ty = self.lower_ty(inner);
Ty::new(interner, TyKind::RawPtr(inner_ty, lower_mutability(mutability)))
}
TypeRef::Array(array) => {
let inner_ty = self.lower_ty(array.ty);
let const_len = self.lower_const(array.len, Ty::new_usize(interner));
Ty::new_array_with_const_len(interner, inner_ty, const_len)
}
&TypeRef::Slice(inner) => {
let inner_ty = self.lower_ty(inner);
Ty::new_slice(interner, inner_ty)
}
TypeRef::Reference(ref_) => {
let inner_ty = self.lower_ty(ref_.ty);
// FIXME: It should infer the eldided lifetimes instead of stubbing with error
let lifetime = ref_
.lifetime
.map_or_else(|| Region::error(interner), |lr| self.lower_lifetime(lr));
Ty::new_ref(interner, lifetime, inner_ty, lower_mutability(ref_.mutability))
}
TypeRef::Placeholder => Ty::new_error(interner, ErrorGuaranteed),
TypeRef::Fn(fn_) => {
let substs = self.with_shifted_in(
DebruijnIndex::from_u32(1),
|ctx: &mut TyLoweringContext<'_, '_>| {
Tys::new_from_iter(
interner,
fn_.params.iter().map(|&(_, tr)| ctx.lower_ty(tr)),
)
},
);
Ty::new_fn_ptr(
interner,
Binder::dummy(FnSig {
abi: fn_.abi.as_ref().map_or(FnAbi::Rust, FnAbi::from_symbol),
safety: if fn_.is_unsafe { Safety::Unsafe } else { Safety::Safe },
c_variadic: fn_.is_varargs,
inputs_and_output: substs,
}),
)
}
TypeRef::DynTrait(bounds) => self.lower_dyn_trait(bounds),
TypeRef::ImplTrait(bounds) => {
match self.impl_trait_mode.mode {
ImplTraitLoweringMode::Opaque => {
let origin = match self.resolver.generic_def() {
Some(GenericDefId::FunctionId(it)) => Either::Left(it),
Some(GenericDefId::TypeAliasId(it)) => Either::Right(it),
_ => panic!(
"opaque impl trait lowering must be in function or type alias"
),
};
// this dance is to make sure the data is in the right
// place even if we encounter more opaque types while
// lowering the bounds
let idx = self
.impl_trait_mode
.opaque_type_data
.alloc(ImplTrait { predicates: Vec::default() });
let impl_trait_id = origin.either(
|f| ImplTraitId::ReturnTypeImplTrait(f, idx),
|a| ImplTraitId::TypeAliasImplTrait(a, idx),
);
let opaque_ty_id: SolverDefId =
self.db.intern_impl_trait_id(impl_trait_id).into();
// We don't want to lower the bounds inside the binders
// we're currently in, because they don't end up inside
// those binders. E.g. when we have `impl Trait<impl
// OtherTrait<T>>`, the `impl OtherTrait<T>` can't refer
// to the self parameter from `impl Trait`, and the
// bounds aren't actually stored nested within each
// other, but separately. So if the `T` refers to a type
// parameter of the outer function, it's just one binder
// away instead of two.
let actual_opaque_type_data = self
.with_debruijn(DebruijnIndex::ZERO, |ctx| {
ctx.lower_impl_trait(opaque_ty_id, bounds, self.resolver.krate())
});
self.impl_trait_mode.opaque_type_data[idx] = actual_opaque_type_data;
let args = GenericArgs::identity_for_item(self.interner, opaque_ty_id);
Ty::new_alias(
self.interner,
AliasTyKind::Opaque,
AliasTy::new_from_args(self.interner, opaque_ty_id, args),
)
}
ImplTraitLoweringMode::Disallowed => {
// FIXME: report error
Ty::new_error(self.interner, ErrorGuaranteed)
}
}
}
TypeRef::Error => Ty::new_error(self.interner, ErrorGuaranteed),
};
(ty, res)
}
/// This is only for `generic_predicates_for_param`, where we can't just
/// lower the self types of the predicates since that could lead to cycles.
/// So we just check here if the `type_ref` resolves to a generic param, and which.
fn lower_ty_only_param(&self, type_ref: TypeRefId) -> Option<TypeOrConstParamId> {
let type_ref = &self.store[type_ref];
let path = match type_ref {
TypeRef::Path(path) => path,
&TypeRef::TypeParam(idx) => return Some(idx.into()),
_ => return None,
};
if path.type_anchor().is_some() {
return None;
}
if path.segments().len() > 1 {
return None;
}
let resolution = match self.resolver.resolve_path_in_type_ns(self.db, path) {
Some((it, None, _)) => it,
_ => return None,
};
match resolution {
TypeNs::GenericParam(param_id) => Some(param_id.into()),
_ => None,
}
}
#[inline]
fn on_path_diagnostic_callback<'b>(type_ref: TypeRefId) -> PathDiagnosticCallback<'b, 'db> {
PathDiagnosticCallback {
data: Either::Left(PathDiagnosticCallbackData(type_ref)),
callback: |data, this, diag| {
let type_ref = data.as_ref().left().unwrap().0;
this.push_diagnostic(type_ref, TyLoweringDiagnosticKind::PathDiagnostic(diag))
},
}
}
#[inline]
fn at_path(&mut self, path_id: PathId) -> PathLoweringContext<'_, 'a, 'db> {
PathLoweringContext::new(
self,
Self::on_path_diagnostic_callback(path_id.type_ref()),
&self.store[path_id],
)
}
pub(crate) fn lower_path(&mut self, path: &Path, path_id: PathId) -> (Ty<'db>, Option<TypeNs>) {
// Resolve the path (in type namespace)
if let Some(type_ref) = path.type_anchor() {
let (ty, res) = self.lower_ty_ext(type_ref);
let mut ctx = self.at_path(path_id);
return ctx.lower_ty_relative_path(ty, res, false);
}
let mut ctx = self.at_path(path_id);
let (resolution, remaining_index) = match ctx.resolve_path_in_type_ns() {
Some(it) => it,
None => return (Ty::new_error(self.interner, ErrorGuaranteed), None),
};
if matches!(resolution, TypeNs::TraitId(_)) && remaining_index.is_none() {
// trait object type without dyn
let bound = TypeBound::Path(path_id, TraitBoundModifier::None);
let ty = self.lower_dyn_trait(&[bound]);
return (ty, None);
}
ctx.lower_partly_resolved_path(resolution, false)
}
fn lower_trait_ref_from_path(
&mut self,
path_id: PathId,
explicit_self_ty: Ty<'db>,
) -> Option<(TraitRef<'db>, PathLoweringContext<'_, 'a, 'db>)> {
let mut ctx = self.at_path(path_id);
let resolved = match ctx.resolve_path_in_type_ns_fully()? {
// FIXME(trait_alias): We need to handle trait alias here.
TypeNs::TraitId(tr) => tr,
_ => return None,
};
Some((ctx.lower_trait_ref_from_resolved_path(resolved, explicit_self_ty, false), ctx))
}
fn lower_trait_ref(
&mut self,
trait_ref: &HirTraitRef,
explicit_self_ty: Ty<'db>,
) -> Option<TraitRef<'db>> {
self.lower_trait_ref_from_path(trait_ref.path, explicit_self_ty).map(|it| it.0)
}
pub(crate) fn lower_where_predicate<'b>(
&'b mut self,
where_predicate: &'b WherePredicate,
ignore_bindings: bool,
generics: &Generics,
predicate_filter: PredicateFilter,
) -> impl Iterator<Item = Clause<'db>> + use<'a, 'b, 'db> {
match where_predicate {
WherePredicate::ForLifetime { target, bound, .. }
| WherePredicate::TypeBound { target, bound } => {
if let PredicateFilter::SelfTrait = predicate_filter {
let target_type = &self.store[*target];
let self_type = 'is_self: {
if let TypeRef::Path(path) = target_type
&& path.is_self_type()
{
break 'is_self true;
}
if let TypeRef::TypeParam(param) = target_type
&& generics[param.local_id()].is_trait_self()
{
break 'is_self true;
}
false
};
if !self_type {
return Either::Left(Either::Left(iter::empty()));
}
}
let self_ty = self.lower_ty(*target);
Either::Left(Either::Right(self.lower_type_bound(bound, self_ty, ignore_bindings)))
}
&WherePredicate::Lifetime { bound, target } => {
Either::Right(iter::once(Clause(Predicate::new(
self.interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::RegionOutlives(OutlivesPredicate(
self.lower_lifetime(bound),
self.lower_lifetime(target),
)),
)),
))))
}
}
.into_iter()
}
pub(crate) fn lower_type_bound<'b>(
&'b mut self,
bound: &'b TypeBound,
self_ty: Ty<'db>,
ignore_bindings: bool,
) -> impl Iterator<Item = Clause<'db>> + use<'b, 'a, 'db> {
let interner = self.interner;
let mut assoc_bounds = None;
let mut clause = None;
match bound {
&TypeBound::Path(path, TraitBoundModifier::None) | &TypeBound::ForLifetime(_, path) => {
// FIXME Don't silently drop the hrtb lifetimes here
if let Some((trait_ref, mut ctx)) = self.lower_trait_ref_from_path(path, self_ty) {
// FIXME(sized-hierarchy): Remove this bound modifications once we have implemented
// sized-hierarchy correctly.
let meta_sized = LangItem::MetaSized
.resolve_trait(ctx.ty_ctx().db, ctx.ty_ctx().resolver.krate());
let pointee_sized = LangItem::PointeeSized
.resolve_trait(ctx.ty_ctx().db, ctx.ty_ctx().resolver.krate());
if meta_sized.is_some_and(|it| it == trait_ref.def_id.0) {
// Ignore this bound
} else if pointee_sized.is_some_and(|it| it == trait_ref.def_id.0) {
// Regard this as `?Sized` bound
ctx.ty_ctx().unsized_types.insert(self_ty);
} else {
if !ignore_bindings {
assoc_bounds = ctx.assoc_type_bindings_from_type_bound(trait_ref);
}
clause = Some(Clause(Predicate::new(
interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::Trait(TraitPredicate {
trait_ref,
polarity: rustc_type_ir::PredicatePolarity::Positive,
}),
)),
)));
}
}
}
&TypeBound::Path(path, TraitBoundModifier::Maybe) => {
let sized_trait = LangItem::Sized.resolve_trait(self.db, self.resolver.krate());
// Don't lower associated type bindings as the only possible relaxed trait bound
// `?Sized` has no of them.
// If we got another trait here ignore the bound completely.
let trait_id = self
.lower_trait_ref_from_path(path, self_ty)
.map(|(trait_ref, _)| trait_ref.def_id.0);
if trait_id == sized_trait {
self.unsized_types.insert(self_ty);
}
}
&TypeBound::Lifetime(l) => {
let lifetime = self.lower_lifetime(l);
clause = Some(Clause(Predicate::new(
self.interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::TypeOutlives(OutlivesPredicate(
self_ty, lifetime,
)),
)),
)));
}
TypeBound::Use(_) | TypeBound::Error => {}
}
clause.into_iter().chain(assoc_bounds.into_iter().flatten())
}
fn lower_dyn_trait(&mut self, bounds: &[TypeBound]) -> Ty<'db> {
let interner = self.interner;
// FIXME: we should never create non-existential predicates in the first place
// For now, use an error type so we don't run into dummy binder issues
let self_ty = Ty::new_error(interner, ErrorGuaranteed);
// INVARIANT: The principal trait bound, if present, must come first. Others may be in any
// order but should be in the same order for the same set but possibly different order of
// bounds in the input.
// INVARIANT: If this function returns `DynTy`, there should be at least one trait bound.
// These invariants are utilized by `TyExt::dyn_trait()` and chalk.
let mut lifetime = None;
let bounds = self.with_shifted_in(DebruijnIndex::from_u32(1), |ctx| {
let mut lowered_bounds: Vec<
rustc_type_ir::Binder<DbInterner<'db>, ExistentialPredicate<DbInterner<'db>>>,
> = Vec::new();
for b in bounds {
let db = ctx.db;
ctx.lower_type_bound(b, self_ty, false).for_each(|b| {
if let Some(bound) = b
.kind()
.map_bound(|c| match c {
rustc_type_ir::ClauseKind::Trait(t) => {
let id = t.def_id();
let is_auto =
db.trait_signature(id.0).flags.contains(TraitFlags::AUTO);
if is_auto {
Some(ExistentialPredicate::AutoTrait(t.def_id()))
} else {
Some(ExistentialPredicate::Trait(
ExistentialTraitRef::new_from_args(
interner,
t.def_id(),
GenericArgs::new_from_iter(
interner,
t.trait_ref.args.iter().skip(1),
),
),
))
}
}
rustc_type_ir::ClauseKind::Projection(p) => {
Some(ExistentialPredicate::Projection(
ExistentialProjection::new_from_args(
interner,
p.def_id(),
GenericArgs::new_from_iter(
interner,
p.projection_term.args.iter().skip(1),
),
p.term,
),
))
}
rustc_type_ir::ClauseKind::TypeOutlives(outlives_predicate) => {
lifetime = Some(outlives_predicate.1);
None
}
rustc_type_ir::ClauseKind::RegionOutlives(_)
| rustc_type_ir::ClauseKind::ConstArgHasType(_, _)
| rustc_type_ir::ClauseKind::WellFormed(_)
| rustc_type_ir::ClauseKind::ConstEvaluatable(_)
| rustc_type_ir::ClauseKind::HostEffect(_)
| rustc_type_ir::ClauseKind::UnstableFeature(_) => unreachable!(),
})
.transpose()
{
lowered_bounds.push(bound);
}
})
}
let mut multiple_regular_traits = false;
let mut multiple_same_projection = false;
lowered_bounds.sort_unstable_by(|lhs, rhs| {
use std::cmp::Ordering;
match ((*lhs).skip_binder(), (*rhs).skip_binder()) {
(ExistentialPredicate::Trait(_), ExistentialPredicate::Trait(_)) => {
multiple_regular_traits = true;
// Order doesn't matter - we error
Ordering::Equal
}
(
ExistentialPredicate::AutoTrait(lhs_id),
ExistentialPredicate::AutoTrait(rhs_id),
) => lhs_id.0.cmp(&rhs_id.0),
(ExistentialPredicate::Trait(_), _) => Ordering::Less,
(_, ExistentialPredicate::Trait(_)) => Ordering::Greater,
(ExistentialPredicate::AutoTrait(_), _) => Ordering::Less,
(_, ExistentialPredicate::AutoTrait(_)) => Ordering::Greater,
(
ExistentialPredicate::Projection(lhs),
ExistentialPredicate::Projection(rhs),
) => {
let lhs_id = match lhs.def_id {
SolverDefId::TypeAliasId(id) => id,
_ => unreachable!(),
};
let rhs_id = match rhs.def_id {
SolverDefId::TypeAliasId(id) => id,
_ => unreachable!(),
};
// We only compare the `associated_ty_id`s. We shouldn't have
// multiple bounds for an associated type in the correct Rust code,
// and if we do, we error out.
if lhs_id == rhs_id {
multiple_same_projection = true;
}
lhs_id.as_id().index().cmp(&rhs_id.as_id().index())
}
}
});
if multiple_regular_traits || multiple_same_projection {
return None;
}
if !lowered_bounds.first().map_or(false, |b| {
matches!(
b.as_ref().skip_binder(),
ExistentialPredicate::Trait(_) | ExistentialPredicate::AutoTrait(_)
)
}) {
return None;
}
// As multiple occurrences of the same auto traits *are* permitted, we deduplicate the
// bounds. We shouldn't have repeated elements besides auto traits at this point.
lowered_bounds.dedup();
Some(BoundExistentialPredicates::new_from_iter(interner, lowered_bounds))
});
if let Some(bounds) = bounds {
let region = match lifetime {
Some(it) => match it.kind() {
rustc_type_ir::RegionKind::ReBound(BoundVarIndexKind::Bound(db), var) => {
Region::new_bound(
self.interner,
db.shifted_out_to_binder(DebruijnIndex::from_u32(2)),
var,
)
}
_ => it,
},
None => Region::new_static(self.interner),
};
Ty::new_dynamic(self.interner, bounds, region)
} else {
// FIXME: report error
// (additional non-auto traits, associated type rebound, or no resolved trait)
Ty::new_error(self.interner, ErrorGuaranteed)
}
}
fn lower_impl_trait(
&mut self,
def_id: SolverDefId,
bounds: &[TypeBound],
krate: Crate,
) -> ImplTrait<'db> {
let interner = self.interner;
cov_mark::hit!(lower_rpit);
let args = GenericArgs::identity_for_item(interner, def_id);
let self_ty = Ty::new_alias(
self.interner,
rustc_type_ir::AliasTyKind::Opaque,
AliasTy::new_from_args(interner, def_id, args),
);
let predicates = self.with_shifted_in(DebruijnIndex::from_u32(1), |ctx| {
let mut predicates = Vec::new();
for b in bounds {
predicates.extend(ctx.lower_type_bound(b, self_ty, false));
}
if !ctx.unsized_types.contains(&self_ty) {
let sized_trait = LangItem::Sized.resolve_trait(self.db, krate);
let sized_clause = sized_trait.map(|trait_id| {
let trait_ref = TraitRef::new_from_args(
interner,
trait_id.into(),
GenericArgs::new_from_iter(interner, [self_ty.into()]),
);
Clause(Predicate::new(
interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::Trait(TraitPredicate {
trait_ref,
polarity: rustc_type_ir::PredicatePolarity::Positive,
}),
)),
))
});
predicates.extend(sized_clause);
}
predicates.shrink_to_fit();
predicates
});
ImplTrait { predicates }
}
pub(crate) fn lower_lifetime(&mut self, lifetime: LifetimeRefId) -> Region<'db> {
match self.resolver.resolve_lifetime(&self.store[lifetime]) {
Some(resolution) => match resolution {
LifetimeNs::Static => Region::new_static(self.interner),
LifetimeNs::LifetimeParam(id) => {
let idx = match self.generics().lifetime_idx(id) {
None => return Region::error(self.interner),
Some(idx) => idx,
};
self.region_param(id, idx as u32)
}
},
None => Region::error(self.interner),
}
}
}
pub(crate) fn lower_mutability(m: hir_def::type_ref::Mutability) -> Mutability {
match m {
hir_def::type_ref::Mutability::Shared => Mutability::Not,
hir_def::type_ref::Mutability::Mut => Mutability::Mut,
}
}
fn unknown_const(_ty: Ty<'_>) -> Const<'_> {
Const::new(DbInterner::conjure(), ConstKind::Error(ErrorGuaranteed))
}
pub(crate) type Diagnostics = Option<ThinArc<(), TyLoweringDiagnostic>>;
pub(crate) fn create_diagnostics(diagnostics: Vec<TyLoweringDiagnostic>) -> Diagnostics {
(!diagnostics.is_empty()).then(|| ThinArc::from_header_and_iter((), diagnostics.into_iter()))
}
pub(crate) fn impl_trait_query<'db>(
db: &'db dyn HirDatabase,
impl_id: ImplId,
) -> Option<EarlyBinder<'db, TraitRef<'db>>> {
db.impl_trait_with_diagnostics(impl_id).map(|it| it.0)
}
pub(crate) fn impl_trait_with_diagnostics_query<'db>(
db: &'db dyn HirDatabase,
impl_id: ImplId,
) -> Option<(EarlyBinder<'db, TraitRef<'db>>, Diagnostics)> {
let impl_data = db.impl_signature(impl_id);
let resolver = impl_id.resolver(db);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&impl_data.store,
impl_id.into(),
LifetimeElisionKind::AnonymousCreateParameter { report_in_path: true },
);
let self_ty = db.impl_self_ty(impl_id).skip_binder();
let target_trait = impl_data.target_trait.as_ref()?;
let trait_ref = EarlyBinder::bind(ctx.lower_trait_ref(target_trait, self_ty)?);
Some((trait_ref, create_diagnostics(ctx.diagnostics)))
}
pub(crate) fn return_type_impl_traits<'db>(
db: &'db dyn HirDatabase,
def: hir_def::FunctionId,
) -> Option<Arc<EarlyBinder<'db, ImplTraits<'db>>>> {
// FIXME unify with fn_sig_for_fn instead of doing lowering twice, maybe
let data = db.function_signature(def);
let resolver = def.resolver(db);
let mut ctx_ret =
TyLoweringContext::new(db, &resolver, &data.store, def.into(), LifetimeElisionKind::Infer)
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque);
if let Some(ret_type) = data.ret_type {
let _ret = ctx_ret.lower_ty(ret_type);
}
let return_type_impl_traits =
ImplTraits { impl_traits: ctx_ret.impl_trait_mode.opaque_type_data };
if return_type_impl_traits.impl_traits.is_empty() {
None
} else {
Some(Arc::new(EarlyBinder::bind(return_type_impl_traits)))
}
}
pub(crate) fn type_alias_impl_traits<'db>(
db: &'db dyn HirDatabase,
def: hir_def::TypeAliasId,
) -> Option<Arc<EarlyBinder<'db, ImplTraits<'db>>>> {
let data = db.type_alias_signature(def);
let resolver = def.resolver(db);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&data.store,
def.into(),
LifetimeElisionKind::AnonymousReportError,
)
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque);
if let Some(type_ref) = data.ty {
let _ty = ctx.lower_ty(type_ref);
}
let type_alias_impl_traits = ImplTraits { impl_traits: ctx.impl_trait_mode.opaque_type_data };
if type_alias_impl_traits.impl_traits.is_empty() {
None
} else {
Some(Arc::new(EarlyBinder::bind(type_alias_impl_traits)))
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum TyDefId {
BuiltinType(BuiltinType),
AdtId(AdtId),
TypeAliasId(TypeAliasId),
}
impl_from!(BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId for TyDefId);
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, salsa_macros::Supertype)]
pub enum ValueTyDefId {
FunctionId(FunctionId),
StructId(StructId),
UnionId(UnionId),
EnumVariantId(EnumVariantId),
ConstId(ConstId),
StaticId(StaticId),
}
impl_from!(FunctionId, StructId, UnionId, EnumVariantId, ConstId, StaticId for ValueTyDefId);
impl ValueTyDefId {
pub(crate) fn to_generic_def_id(self, db: &dyn HirDatabase) -> GenericDefId {
match self {
Self::FunctionId(id) => id.into(),
Self::StructId(id) => id.into(),
Self::UnionId(id) => id.into(),
Self::EnumVariantId(var) => var.lookup(db).parent.into(),
Self::ConstId(id) => id.into(),
Self::StaticId(id) => id.into(),
}
}
}
/// Build the declared type of an item. This depends on the namespace; e.g. for
/// `struct Foo(usize)`, we have two types: The type of the struct itself, and
/// the constructor function `(usize) -> Foo` which lives in the values
/// namespace.
pub(crate) fn ty_query<'db>(db: &'db dyn HirDatabase, def: TyDefId) -> EarlyBinder<'db, Ty<'db>> {
let interner = DbInterner::new_with(db, None, None);
match def {
TyDefId::BuiltinType(it) => EarlyBinder::bind(Ty::from_builtin_type(interner, it)),
TyDefId::AdtId(it) => EarlyBinder::bind(Ty::new_adt(
interner,
it,
GenericArgs::identity_for_item(interner, it.into()),
)),
TyDefId::TypeAliasId(it) => db.type_for_type_alias_with_diagnostics(it).0,
}
}
/// Build the declared type of a function. This should not need to look at the
/// function body.
fn type_for_fn<'db>(db: &'db dyn HirDatabase, def: FunctionId) -> EarlyBinder<'db, Ty<'db>> {
let interner = DbInterner::new_with(db, None, None);
EarlyBinder::bind(Ty::new_fn_def(
interner,
CallableDefId::FunctionId(def).into(),
GenericArgs::identity_for_item(interner, def.into()),
))
}
/// Build the declared type of a const.
fn type_for_const<'db>(db: &'db dyn HirDatabase, def: ConstId) -> EarlyBinder<'db, Ty<'db>> {
let resolver = def.resolver(db);
let data = db.const_signature(def);
let parent = def.loc(db).container;
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&data.store,
def.into(),
LifetimeElisionKind::AnonymousReportError,
);
ctx.set_lifetime_elision(LifetimeElisionKind::for_const(ctx.interner, parent));
EarlyBinder::bind(ctx.lower_ty(data.type_ref))
}
/// Build the declared type of a static.
fn type_for_static<'db>(db: &'db dyn HirDatabase, def: StaticId) -> EarlyBinder<'db, Ty<'db>> {
let resolver = def.resolver(db);
let data = db.static_signature(def);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&data.store,
def.into(),
LifetimeElisionKind::AnonymousReportError,
);
ctx.set_lifetime_elision(LifetimeElisionKind::Elided(Region::new_static(ctx.interner)));
EarlyBinder::bind(ctx.lower_ty(data.type_ref))
}
/// Build the type of a tuple struct constructor.
fn type_for_struct_constructor<'db>(
db: &'db dyn HirDatabase,
def: StructId,
) -> Option<EarlyBinder<'db, Ty<'db>>> {
let struct_data = def.fields(db);
match struct_data.shape {
FieldsShape::Record => None,
FieldsShape::Unit => Some(type_for_adt(db, def.into())),
FieldsShape::Tuple => {
let interner = DbInterner::new_with(db, None, None);
Some(EarlyBinder::bind(Ty::new_fn_def(
interner,
CallableDefId::StructId(def).into(),
GenericArgs::identity_for_item(interner, def.into()),
)))
}
}
}
/// Build the type of a tuple enum variant constructor.
fn type_for_enum_variant_constructor<'db>(
db: &'db dyn HirDatabase,
def: EnumVariantId,
) -> Option<EarlyBinder<'db, Ty<'db>>> {
let struct_data = def.fields(db);
match struct_data.shape {
FieldsShape::Record => None,
FieldsShape::Unit => Some(type_for_adt(db, def.loc(db).parent.into())),
FieldsShape::Tuple => {
let interner = DbInterner::new_with(db, None, None);
Some(EarlyBinder::bind(Ty::new_fn_def(
interner,
CallableDefId::EnumVariantId(def).into(),
GenericArgs::identity_for_item(interner, def.loc(db).parent.into()),
)))
}
}
}
pub(crate) fn value_ty_query<'db>(
db: &'db dyn HirDatabase,
def: ValueTyDefId,
) -> Option<EarlyBinder<'db, Ty<'db>>> {
match def {
ValueTyDefId::FunctionId(it) => Some(type_for_fn(db, it)),
ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
ValueTyDefId::UnionId(it) => Some(type_for_adt(db, it.into())),
ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
ValueTyDefId::ConstId(it) => Some(type_for_const(db, it)),
ValueTyDefId::StaticId(it) => Some(type_for_static(db, it)),
}
}
pub(crate) fn type_for_type_alias_with_diagnostics_query<'db>(
db: &'db dyn HirDatabase,
t: TypeAliasId,
) -> (EarlyBinder<'db, Ty<'db>>, Diagnostics) {
let type_alias_data = db.type_alias_signature(t);
let mut diags = None;
let resolver = t.resolver(db);
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
let inner = if type_alias_data.flags.contains(TypeAliasFlags::IS_EXTERN) {
EarlyBinder::bind(Ty::new_foreign(interner, t.into()))
} else {
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&type_alias_data.store,
t.into(),
LifetimeElisionKind::AnonymousReportError,
)
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque);
let res = EarlyBinder::bind(
type_alias_data
.ty
.map(|type_ref| ctx.lower_ty(type_ref))
.unwrap_or_else(|| Ty::new_error(interner, ErrorGuaranteed)),
);
diags = create_diagnostics(ctx.diagnostics);
res
};
(inner, diags)
}
pub(crate) fn type_for_type_alias_with_diagnostics_cycle_result<'db>(
db: &'db dyn HirDatabase,
_adt: TypeAliasId,
) -> (EarlyBinder<'db, Ty<'db>>, Diagnostics) {
(EarlyBinder::bind(Ty::new_error(DbInterner::new_with(db, None, None), ErrorGuaranteed)), None)
}
pub(crate) fn impl_self_ty_query<'db>(
db: &'db dyn HirDatabase,
impl_id: ImplId,
) -> EarlyBinder<'db, Ty<'db>> {
db.impl_self_ty_with_diagnostics(impl_id).0
}
pub(crate) fn impl_self_ty_with_diagnostics_query<'db>(
db: &'db dyn HirDatabase,
impl_id: ImplId,
) -> (EarlyBinder<'db, Ty<'db>>, Diagnostics) {
let resolver = impl_id.resolver(db);
let impl_data = db.impl_signature(impl_id);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&impl_data.store,
impl_id.into(),
LifetimeElisionKind::AnonymousCreateParameter { report_in_path: true },
);
let ty = ctx.lower_ty(impl_data.self_ty);
assert!(!ty.has_escaping_bound_vars());
(EarlyBinder::bind(ty), create_diagnostics(ctx.diagnostics))
}
pub(crate) fn impl_self_ty_with_diagnostics_cycle_result(
db: &dyn HirDatabase,
_impl_id: ImplId,
) -> (EarlyBinder<'_, Ty<'_>>, Diagnostics) {
(EarlyBinder::bind(Ty::new_error(DbInterner::new_with(db, None, None), ErrorGuaranteed)), None)
}
pub(crate) fn const_param_ty_query<'db>(db: &'db dyn HirDatabase, def: ConstParamId) -> Ty<'db> {
db.const_param_ty_with_diagnostics(def).0
}
// returns None if def is a type arg
pub(crate) fn const_param_ty_with_diagnostics_query<'db>(
db: &'db dyn HirDatabase,
def: ConstParamId,
) -> (Ty<'db>, Diagnostics) {
let (parent_data, store) = db.generic_params_and_store(def.parent());
let data = &parent_data[def.local_id()];
let resolver = def.parent().resolver(db);
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&store,
def.parent(),
LifetimeElisionKind::AnonymousReportError,
);
let ty = match data {
TypeOrConstParamData::TypeParamData(_) => {
never!();
Ty::new_error(interner, ErrorGuaranteed)
}
TypeOrConstParamData::ConstParamData(d) => ctx.lower_ty(d.ty),
};
(ty, create_diagnostics(ctx.diagnostics))
}
pub(crate) fn const_param_ty_with_diagnostics_cycle_result<'db>(
db: &'db dyn HirDatabase,
_: crate::db::HirDatabaseData,
def: ConstParamId,
) -> (Ty<'db>, Diagnostics) {
let resolver = def.parent().resolver(db);
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
(Ty::new_error(interner, ErrorGuaranteed), None)
}
pub(crate) fn field_types_query<'db>(
db: &'db dyn HirDatabase,
variant_id: VariantId,
) -> Arc<ArenaMap<LocalFieldId, EarlyBinder<'db, Ty<'db>>>> {
db.field_types_with_diagnostics(variant_id).0
}
/// Build the type of all specific fields of a struct or enum variant.
pub(crate) fn field_types_with_diagnostics_query<'db>(
db: &'db dyn HirDatabase,
variant_id: VariantId,
) -> (Arc<ArenaMap<LocalFieldId, EarlyBinder<'db, Ty<'db>>>>, Diagnostics) {
let var_data = variant_id.fields(db);
let fields = var_data.fields();
if fields.is_empty() {
return (Arc::new(ArenaMap::default()), None);
}
let (resolver, def): (_, GenericDefId) = match variant_id {
VariantId::StructId(it) => (it.resolver(db), it.into()),
VariantId::UnionId(it) => (it.resolver(db), it.into()),
VariantId::EnumVariantId(it) => (it.resolver(db), it.lookup(db).parent.into()),
};
let mut res = ArenaMap::default();
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&var_data.store,
def,
LifetimeElisionKind::AnonymousReportError,
);
for (field_id, field_data) in var_data.fields().iter() {
res.insert(field_id, EarlyBinder::bind(ctx.lower_ty(field_data.type_ref)));
}
(Arc::new(res), create_diagnostics(ctx.diagnostics))
}
/// This query exists only to be used when resolving short-hand associated types
/// like `T::Item`.
///
/// See the analogous query in rustc and its comment:
/// <https://github.com/rust-lang/rust/blob/9150f844e2624eb013ec78ca08c1d416e6644026/src/librustc_typeck/astconv.rs#L46>
/// This is a query mostly to handle cycles somewhat gracefully; e.g. the
/// following bounds are disallowed: `T: Foo<U::Item>, U: Foo<T::Item>`, but
/// these are fine: `T: Foo<U::Item>, U: Foo<()>`.
#[tracing::instrument(skip(db), ret)]
pub(crate) fn generic_predicates_for_param_query<'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
param_id: TypeOrConstParamId,
assoc_name: Option<Name>,
) -> GenericPredicates<'db> {
let generics = generics(db, def);
let interner = DbInterner::new_with(db, None, None);
let resolver = def.resolver(db);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
generics.store(),
def,
LifetimeElisionKind::AnonymousReportError,
);
// we have to filter out all other predicates *first*, before attempting to lower them
let predicate = |pred: &_, ctx: &mut TyLoweringContext<'_, '_>| match pred {
WherePredicate::ForLifetime { target, bound, .. }
| WherePredicate::TypeBound { target, bound, .. } => {
let invalid_target = { ctx.lower_ty_only_param(*target) != Some(param_id) };
if invalid_target {
// FIXME(sized-hierarchy): Revisit and adjust this properly once we have implemented
// sized-hierarchy correctly.
// If this is filtered out without lowering, `?Sized` or `PointeeSized` is not gathered into
// `ctx.unsized_types`
let lower = || -> bool {
match bound {
TypeBound::Path(_, TraitBoundModifier::Maybe) => true,
TypeBound::Path(path, _) | TypeBound::ForLifetime(_, path) => {
let TypeRef::Path(path) = &ctx.store[path.type_ref()] else {
return false;
};
let Some(pointee_sized) =
LangItem::PointeeSized.resolve_trait(ctx.db, ctx.resolver.krate())
else {
return false;
};
// Lower the path directly with `Resolver` instead of PathLoweringContext`
// to prevent diagnostics duplications.
ctx.resolver.resolve_path_in_type_ns_fully(ctx.db, path).is_some_and(
|it| matches!(it, TypeNs::TraitId(tr) if tr == pointee_sized),
)
}
_ => false,
}
}();
if lower {
ctx.lower_where_predicate(pred, true, &generics, PredicateFilter::All)
.for_each(drop);
}
return false;
}
match bound {
&TypeBound::ForLifetime(_, path) | &TypeBound::Path(path, _) => {
// Only lower the bound if the trait could possibly define the associated
// type we're looking for.
let path = &ctx.store[path];
let Some(assoc_name) = &assoc_name else { return true };
let Some(TypeNs::TraitId(tr)) =
resolver.resolve_path_in_type_ns_fully(db, path)
else {
return false;
};
rustc_type_ir::elaborate::supertrait_def_ids(interner, tr.into()).any(|tr| {
tr.0.trait_items(db).items.iter().any(|(name, item)| {
matches!(item, AssocItemId::TypeAliasId(_)) && name == assoc_name
})
})
}
TypeBound::Use(_) | TypeBound::Lifetime(_) | TypeBound::Error => false,
}
}
WherePredicate::Lifetime { .. } => false,
};
let mut predicates = Vec::new();
for maybe_parent_generics in
std::iter::successors(Some(&generics), |generics| generics.parent_generics())
{
ctx.store = maybe_parent_generics.store();
for pred in maybe_parent_generics.where_predicates() {
if predicate(pred, &mut ctx) {
predicates.extend(ctx.lower_where_predicate(
pred,
true,
maybe_parent_generics,
PredicateFilter::All,
));
}
}
}
let args = GenericArgs::identity_for_item(interner, def.into());
if !args.is_empty() {
let explicitly_unsized_tys = ctx.unsized_types;
if let Some(implicitly_sized_predicates) =
implicitly_sized_clauses(db, param_id.parent, &explicitly_unsized_tys, &args, &resolver)
{
predicates.extend(implicitly_sized_predicates);
};
}
GenericPredicates(predicates.is_empty().not().then(|| predicates.into()))
}
pub(crate) fn generic_predicates_for_param_cycle_result(
_db: &dyn HirDatabase,
_def: GenericDefId,
_param_id: TypeOrConstParamId,
_assoc_name: Option<Name>,
) -> GenericPredicates<'_> {
GenericPredicates(None)
}
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct GenericPredicates<'db>(Option<Arc<[Clause<'db>]>>);
impl<'db> GenericPredicates<'db> {
#[inline]
pub fn instantiate(
&self,
interner: DbInterner<'db>,
args: GenericArgs<'db>,
) -> Option<impl Iterator<Item = Clause<'db>>> {
self.0
.as_ref()
.map(|it| EarlyBinder::bind(it.iter().copied()).iter_instantiated(interner, args))
}
#[inline]
pub fn instantiate_identity(&self) -> Option<impl Iterator<Item = Clause<'db>>> {
self.0.as_ref().map(|it| it.iter().copied())
}
}
impl<'db> ops::Deref for GenericPredicates<'db> {
type Target = [Clause<'db>];
fn deref(&self) -> &Self::Target {
self.0.as_deref().unwrap_or(&[])
}
}
pub(crate) fn trait_environment_for_body_query(
db: &dyn HirDatabase,
def: DefWithBodyId,
) -> Arc<TraitEnvironment<'_>> {
let Some(def) = def.as_generic_def_id(db) else {
let krate = def.module(db).krate();
return TraitEnvironment::empty(krate);
};
db.trait_environment(def)
}
pub(crate) fn trait_environment_query<'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
) -> Arc<TraitEnvironment<'db>> {
let generics = generics(db, def);
if generics.has_no_predicates() && generics.is_empty() {
return TraitEnvironment::empty(def.krate(db));
}
let resolver = def.resolver(db);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
generics.store(),
def,
LifetimeElisionKind::AnonymousReportError,
);
let mut traits_in_scope = Vec::new();
let mut clauses = Vec::new();
for maybe_parent_generics in
std::iter::successors(Some(&generics), |generics| generics.parent_generics())
{
ctx.store = maybe_parent_generics.store();
for pred in maybe_parent_generics.where_predicates() {
for pred in ctx.lower_where_predicate(pred, false, &generics, PredicateFilter::All) {
if let rustc_type_ir::ClauseKind::Trait(tr) = pred.kind().skip_binder() {
traits_in_scope.push((tr.self_ty(), tr.def_id().0));
}
clauses.push(pred);
}
}
}
if let Some(trait_id) = def.assoc_trait_container(db) {
// add `Self: Trait<T1, T2, ...>` to the environment in trait
// function default implementations (and speculative code
// inside consts or type aliases)
cov_mark::hit!(trait_self_implements_self);
let trait_ref = TraitRef::identity(ctx.interner, trait_id.into());
let clause = Clause(Predicate::new(
ctx.interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(rustc_type_ir::ClauseKind::Trait(
TraitPredicate { trait_ref, polarity: rustc_type_ir::PredicatePolarity::Positive },
))),
));
clauses.push(clause);
}
let explicitly_unsized_tys = ctx.unsized_types;
let sized_trait = LangItem::Sized.resolve_trait(db, resolver.krate());
if let Some(sized_trait) = sized_trait {
let (mut generics, mut def_id) =
(crate::next_solver::generics::generics(db, def.into()), def);
loop {
let self_idx = trait_self_param_idx(db, def_id);
for (idx, p) in generics.own_params.iter().enumerate() {
if let Some(self_idx) = self_idx
&& p.index() as usize == self_idx
{
continue;
}
let GenericParamId::TypeParamId(param_id) = p.id else {
continue;
};
let idx = idx as u32 + generics.parent_count as u32;
let param_ty = Ty::new_param(ctx.interner, param_id, idx);
if explicitly_unsized_tys.contains(&param_ty) {
continue;
}
let trait_ref = TraitRef::new_from_args(
ctx.interner,
sized_trait.into(),
GenericArgs::new_from_iter(ctx.interner, [param_ty.into()]),
);
let clause = Clause(Predicate::new(
ctx.interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::Trait(TraitPredicate {
trait_ref,
polarity: rustc_type_ir::PredicatePolarity::Positive,
}),
)),
));
clauses.push(clause);
}
if let Some(g) = generics.parent {
generics = crate::next_solver::generics::generics(db, g.into());
def_id = g;
} else {
break;
}
}
}
let clauses = rustc_type_ir::elaborate::elaborate(ctx.interner, clauses);
let clauses = Clauses::new_from_iter(ctx.interner, clauses);
let env = ParamEnv { clauses };
TraitEnvironment::new(resolver.krate(), None, traits_in_scope.into_boxed_slice(), env)
}
#[derive(Copy, Clone, Debug)]
pub(crate) enum PredicateFilter {
SelfTrait,
All,
}
/// Resolve the where clause(s) of an item with generics.
#[tracing::instrument(skip(db))]
pub(crate) fn generic_predicates_query<'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
) -> GenericPredicates<'db> {
generic_predicates_filtered_by(db, def, PredicateFilter::All, |_| true).0
}
pub(crate) fn generic_predicates_without_parent_query<'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
) -> GenericPredicates<'db> {
generic_predicates_filtered_by(db, def, PredicateFilter::All, |d| d == def).0
}
/// Resolve the where clause(s) of an item with generics,
/// except the ones inherited from the parent
pub(crate) fn generic_predicates_without_parent_with_diagnostics_query<'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
) -> (GenericPredicates<'db>, Diagnostics) {
generic_predicates_filtered_by(db, def, PredicateFilter::All, |d| d == def)
}
/// Resolve the where clause(s) of an item with generics,
/// with a given filter
#[tracing::instrument(skip(db, filter), ret)]
pub(crate) fn generic_predicates_filtered_by<'db, F>(
db: &'db dyn HirDatabase,
def: GenericDefId,
predicate_filter: PredicateFilter,
filter: F,
) -> (GenericPredicates<'db>, Diagnostics)
where
F: Fn(GenericDefId) -> bool,
{
let generics = generics(db, def);
let resolver = def.resolver(db);
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
generics.store(),
def,
LifetimeElisionKind::AnonymousReportError,
);
let mut predicates = Vec::new();
for maybe_parent_generics in
std::iter::successors(Some(&generics), |generics| generics.parent_generics())
{
ctx.store = maybe_parent_generics.store();
for pred in maybe_parent_generics.where_predicates() {
tracing::debug!(?pred);
if filter(maybe_parent_generics.def()) {
predicates.extend(ctx.lower_where_predicate(
pred,
false,
maybe_parent_generics,
predicate_filter,
));
}
}
}
let explicitly_unsized_tys = ctx.unsized_types;
let sized_trait = LangItem::Sized.resolve_trait(db, resolver.krate());
if let Some(sized_trait) = sized_trait {
let mut add_sized_clause = |param_idx, param_id, param_data| {
let (
GenericParamId::TypeParamId(param_id),
GenericParamDataRef::TypeParamData(param_data),
) = (param_id, param_data)
else {
return;
};
if param_data.provenance == TypeParamProvenance::TraitSelf {
return;
}
let param_ty = Ty::new_param(interner, param_id, param_idx);
if explicitly_unsized_tys.contains(&param_ty) {
return;
}
let trait_ref = TraitRef::new_from_args(
interner,
sized_trait.into(),
GenericArgs::new_from_iter(interner, [param_ty.into()]),
);
let clause = Clause(Predicate::new(
interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::Trait(TraitPredicate {
trait_ref,
polarity: rustc_type_ir::PredicatePolarity::Positive,
}),
)),
));
predicates.push(clause);
};
if generics.parent_generics().is_some_and(|parent| filter(parent.def())) {
generics.iter_parent().enumerate().for_each(|(param_idx, (param_id, param_data))| {
add_sized_clause(param_idx as u32, param_id, param_data);
});
}
if filter(def) {
let parent_params_len = generics.len_parent();
generics.iter_self().enumerate().for_each(|(param_idx, (param_id, param_data))| {
add_sized_clause((param_idx + parent_params_len) as u32, param_id, param_data);
});
}
}
// FIXME: rustc gathers more predicates by recursing through resulting trait predicates.
// See https://github.com/rust-lang/rust/blob/76c5ed2847cdb26ef2822a3a165d710f6b772217/compiler/rustc_hir_analysis/src/collect/predicates_of.rs#L689-L715
(
GenericPredicates(predicates.is_empty().not().then(|| predicates.into())),
create_diagnostics(ctx.diagnostics),
)
}
/// Generate implicit `: Sized` predicates for all generics that has no `?Sized` bound.
/// Exception is Self of a trait def.
fn implicitly_sized_clauses<'a, 'subst, 'db>(
db: &'db dyn HirDatabase,
def: GenericDefId,
explicitly_unsized_tys: &'a FxHashSet<Ty<'db>>,
args: &'subst GenericArgs<'db>,
resolver: &Resolver<'db>,
) -> Option<impl Iterator<Item = Clause<'db>> + Captures<'a> + Captures<'subst>> {
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
let sized_trait = LangItem::Sized.resolve_trait(db, resolver.krate())?;
let trait_self_idx = trait_self_param_idx(db, def);
Some(
args.iter()
.enumerate()
.filter_map(
move |(idx, generic_arg)| {
if Some(idx) == trait_self_idx { None } else { Some(generic_arg) }
},
)
.filter_map(|generic_arg| generic_arg.as_type())
.filter(move |self_ty| !explicitly_unsized_tys.contains(self_ty))
.map(move |self_ty| {
let trait_ref = TraitRef::new_from_args(
interner,
sized_trait.into(),
GenericArgs::new_from_iter(interner, [self_ty.into()]),
);
Clause(Predicate::new(
interner,
Binder::dummy(rustc_type_ir::PredicateKind::Clause(
rustc_type_ir::ClauseKind::Trait(TraitPredicate {
trait_ref,
polarity: rustc_type_ir::PredicatePolarity::Positive,
}),
)),
))
}),
)
}
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct GenericDefaults<'db>(Option<Arc<[Option<EarlyBinder<'db, GenericArg<'db>>>]>>);
impl<'db> GenericDefaults<'db> {
#[inline]
pub fn get(&self, idx: usize) -> Option<EarlyBinder<'db, GenericArg<'db>>> {
self.0.as_ref()?[idx]
}
}
pub(crate) fn generic_defaults_query(
db: &dyn HirDatabase,
def: GenericDefId,
) -> GenericDefaults<'_> {
db.generic_defaults_with_diagnostics(def).0
}
/// Resolve the default type params from generics.
///
/// Diagnostics are only returned for this `GenericDefId` (returned defaults include parents).
pub(crate) fn generic_defaults_with_diagnostics_query(
db: &dyn HirDatabase,
def: GenericDefId,
) -> (GenericDefaults<'_>, Diagnostics) {
let generic_params = generics(db, def);
if generic_params.is_empty() {
return (GenericDefaults(None), None);
}
let resolver = def.resolver(db);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
generic_params.store(),
def,
LifetimeElisionKind::AnonymousReportError,
)
.with_impl_trait_mode(ImplTraitLoweringMode::Disallowed);
let mut idx = 0;
let mut has_any_default = false;
let mut defaults = generic_params
.iter_parents_with_store()
.map(|((_id, p), store)| {
ctx.store = store;
let (result, has_default) = handle_generic_param(&mut ctx, idx, p);
has_any_default |= has_default;
idx += 1;
result
})
.collect::<Vec<_>>();
ctx.diagnostics.clear(); // Don't include diagnostics from the parent.
defaults.extend(generic_params.iter_self().map(|(_id, p)| {
let (result, has_default) = handle_generic_param(&mut ctx, idx, p);
has_any_default |= has_default;
idx += 1;
result
}));
let diagnostics = create_diagnostics(mem::take(&mut ctx.diagnostics));
let defaults = if has_any_default {
GenericDefaults(Some(Arc::from_iter(defaults)))
} else {
GenericDefaults(None)
};
return (defaults, diagnostics);
fn handle_generic_param<'db>(
ctx: &mut TyLoweringContext<'db, '_>,
idx: usize,
p: GenericParamDataRef<'_>,
) -> (Option<EarlyBinder<'db, GenericArg<'db>>>, bool) {
ctx.lowering_param_default(idx as u32);
match p {
GenericParamDataRef::TypeParamData(p) => {
let ty = p.default.map(|ty| ctx.lower_ty(ty));
(ty.map(|ty| EarlyBinder::bind(ty.into())), p.default.is_some())
}
GenericParamDataRef::ConstParamData(p) => {
let val = p.default.map(|c| {
let param_ty = ctx.lower_ty(p.ty);
let c = ctx.lower_const(c, param_ty);
c.into()
});
(val.map(EarlyBinder::bind), p.default.is_some())
}
GenericParamDataRef::LifetimeParamData(_) => (None, false),
}
}
}
pub(crate) fn generic_defaults_with_diagnostics_cycle_result(
_db: &dyn HirDatabase,
_def: GenericDefId,
) -> (GenericDefaults<'_>, Diagnostics) {
(GenericDefaults(None), None)
}
/// Build the signature of a callable item (function, struct or enum variant).
pub(crate) fn callable_item_signature_query<'db>(
db: &'db dyn HirDatabase,
def: CallableDefId,
) -> EarlyBinder<'db, PolyFnSig<'db>> {
match def {
CallableDefId::FunctionId(f) => fn_sig_for_fn(db, f),
CallableDefId::StructId(s) => fn_sig_for_struct_constructor(db, s),
CallableDefId::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e),
}
}
fn fn_sig_for_fn<'db>(
db: &'db dyn HirDatabase,
def: FunctionId,
) -> EarlyBinder<'db, PolyFnSig<'db>> {
let data = db.function_signature(def);
let resolver = def.resolver(db);
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
let mut ctx_params = TyLoweringContext::new(
db,
&resolver,
&data.store,
def.into(),
LifetimeElisionKind::for_fn_params(&data),
);
let params = data.params.iter().map(|&tr| ctx_params.lower_ty(tr));
let ret = match data.ret_type {
Some(ret_type) => {
let mut ctx_ret = TyLoweringContext::new(
db,
&resolver,
&data.store,
def.into(),
LifetimeElisionKind::for_fn_ret(interner),
)
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque);
ctx_ret.lower_ty(ret_type)
}
None => Ty::new_tup(interner, &[]),
};
let inputs_and_output = Tys::new_from_iter(interner, params.chain(Some(ret)));
// If/when we track late bound vars, we need to switch this to not be `dummy`
EarlyBinder::bind(rustc_type_ir::Binder::dummy(FnSig {
abi: data.abi.as_ref().map_or(FnAbi::Rust, FnAbi::from_symbol),
c_variadic: data.is_varargs(),
safety: if data.is_unsafe() { Safety::Unsafe } else { Safety::Safe },
inputs_and_output,
}))
}
fn type_for_adt<'db>(db: &'db dyn HirDatabase, adt: AdtId) -> EarlyBinder<'db, Ty<'db>> {
let interner = DbInterner::new_with(db, None, None);
let args = GenericArgs::identity_for_item(interner, adt.into());
let ty = Ty::new_adt(interner, adt, args);
EarlyBinder::bind(ty)
}
fn fn_sig_for_struct_constructor<'db>(
db: &'db dyn HirDatabase,
def: StructId,
) -> EarlyBinder<'db, PolyFnSig<'db>> {
let field_tys = db.field_types(def.into());
let params = field_tys.iter().map(|(_, ty)| ty.skip_binder());
let ret = type_for_adt(db, def.into()).skip_binder();
let inputs_and_output =
Tys::new_from_iter(DbInterner::new_with(db, None, None), params.chain(Some(ret)));
EarlyBinder::bind(Binder::dummy(FnSig {
abi: FnAbi::RustCall,
c_variadic: false,
safety: Safety::Safe,
inputs_and_output,
}))
}
fn fn_sig_for_enum_variant_constructor<'db>(
db: &'db dyn HirDatabase,
def: EnumVariantId,
) -> EarlyBinder<'db, PolyFnSig<'db>> {
let field_tys = db.field_types(def.into());
let params = field_tys.iter().map(|(_, ty)| ty.skip_binder());
let parent = def.lookup(db).parent;
let ret = type_for_adt(db, parent.into()).skip_binder();
let inputs_and_output =
Tys::new_from_iter(DbInterner::new_with(db, None, None), params.chain(Some(ret)));
EarlyBinder::bind(Binder::dummy(FnSig {
abi: FnAbi::RustCall,
c_variadic: false,
safety: Safety::Safe,
inputs_and_output,
}))
}
// FIXME(next-solver): should merge this with `explicit_item_bounds` in some way
pub(crate) fn associated_ty_item_bounds<'db>(
db: &'db dyn HirDatabase,
type_alias: TypeAliasId,
) -> EarlyBinder<'db, BoundExistentialPredicates<'db>> {
let type_alias_data = db.type_alias_signature(type_alias);
let resolver = hir_def::resolver::HasResolver::resolver(type_alias, db);
let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
let mut ctx = TyLoweringContext::new(
db,
&resolver,
&type_alias_data.store,
type_alias.into(),
LifetimeElisionKind::AnonymousReportError,
);
// FIXME: we should never create non-existential predicates in the first place
// For now, use an error type so we don't run into dummy binder issues
let self_ty = Ty::new_error(interner, ErrorGuaranteed);
let mut bounds = Vec::new();
for bound in &type_alias_data.bounds {
ctx.lower_type_bound(bound, self_ty, false).for_each(|pred| {
if let Some(bound) = pred
.kind()
.map_bound(|c| match c {
rustc_type_ir::ClauseKind::Trait(t) => {
let id = t.def_id();
let is_auto = db.trait_signature(id.0).flags.contains(TraitFlags::AUTO);
if is_auto {
Some(ExistentialPredicate::AutoTrait(t.def_id()))
} else {
Some(ExistentialPredicate::Trait(ExistentialTraitRef::new_from_args(
interner,
t.def_id(),
GenericArgs::new_from_iter(
interner,
t.trait_ref.args.iter().skip(1),
),
)))
}
}
rustc_type_ir::ClauseKind::Projection(p) => Some(
ExistentialPredicate::Projection(ExistentialProjection::new_from_args(
interner,
p.def_id(),
GenericArgs::new_from_iter(
interner,
p.projection_term.args.iter().skip(1),
),
p.term,
)),
),
rustc_type_ir::ClauseKind::TypeOutlives(_) => None,
rustc_type_ir::ClauseKind::RegionOutlives(_)
| rustc_type_ir::ClauseKind::ConstArgHasType(_, _)
| rustc_type_ir::ClauseKind::WellFormed(_)
| rustc_type_ir::ClauseKind::ConstEvaluatable(_)
| rustc_type_ir::ClauseKind::HostEffect(_)
| rustc_type_ir::ClauseKind::UnstableFeature(_) => unreachable!(),
})
.transpose()
{
bounds.push(bound);
}
});
}
if !ctx.unsized_types.contains(&self_ty)
&& let Some(sized_trait) = LangItem::Sized.resolve_trait(db, resolver.krate())
{
let sized_clause = Binder::dummy(ExistentialPredicate::Trait(ExistentialTraitRef::new(
interner,
sized_trait.into(),
[] as [GenericArg<'_>; 0],
)));
bounds.push(sized_clause);
}
EarlyBinder::bind(BoundExistentialPredicates::new_from_iter(interner, bounds))
}
pub(crate) fn associated_type_by_name_including_super_traits<'db>(
db: &'db dyn HirDatabase,
trait_ref: TraitRef<'db>,
name: &Name,
) -> Option<(TraitRef<'db>, TypeAliasId)> {
let interner = DbInterner::new_with(db, None, None);
rustc_type_ir::elaborate::supertraits(interner, Binder::dummy(trait_ref)).find_map(|t| {
let trait_id = t.as_ref().skip_binder().def_id.0;
let assoc_type = trait_id.trait_items(db).associated_type_by_name(name)?;
Some((t.skip_binder(), assoc_type))
})
}
pub fn associated_type_shorthand_candidates(
db: &dyn HirDatabase,
def: GenericDefId,
res: TypeNs,
mut cb: impl FnMut(&Name, TypeAliasId) -> bool,
) -> Option<TypeAliasId> {
let interner = DbInterner::new_with(db, None, None);
named_associated_type_shorthand_candidates(interner, def, res, None, |name, _, id| {
cb(name, id).then_some(id)
})
}
#[tracing::instrument(skip(interner, check_alias))]
fn named_associated_type_shorthand_candidates<'db, R>(
interner: DbInterner<'db>,
// If the type parameter is defined in an impl and we're in a method, there
// might be additional where clauses to consider
def: GenericDefId,
res: TypeNs,
assoc_name: Option<Name>,
mut check_alias: impl FnMut(&Name, TraitRef<'db>, TypeAliasId) -> Option<R>,
) -> Option<R> {
let db = interner.db;
let mut search = |t: TraitRef<'db>| -> Option<R> {
let mut checked_traits = FxHashSet::default();
let mut check_trait = |trait_ref: TraitRef<'db>| {
let trait_id = trait_ref.def_id.0;
let name = &db.trait_signature(trait_id).name;
tracing::debug!(?trait_id, ?name);
if !checked_traits.insert(trait_id) {
return None;
}
let data = trait_id.trait_items(db);
tracing::debug!(?data.items);
for (name, assoc_id) in &data.items {
if let &AssocItemId::TypeAliasId(alias) = assoc_id
&& let Some(ty) = check_alias(name, trait_ref, alias)
{
return Some(ty);
}
}
None
};
let mut stack: SmallVec<[_; 4]> = smallvec![t];
while let Some(trait_ref) = stack.pop() {
if let Some(alias) = check_trait(trait_ref) {
return Some(alias);
}
for pred in generic_predicates_filtered_by(
db,
GenericDefId::TraitId(trait_ref.def_id.0),
PredicateFilter::SelfTrait,
// We are likely in the midst of lowering generic predicates of `def`.
// So, if we allow `pred == def` we might fall into an infinite recursion.
// Actually, we have already checked for the case `pred == def` above as we started
// with a stack including `trait_id`
|pred| pred != def && pred == GenericDefId::TraitId(trait_ref.def_id.0),
)
.0
.deref()
{
tracing::debug!(?pred);
let sup_trait_ref = match pred.kind().skip_binder() {
rustc_type_ir::ClauseKind::Trait(pred) => pred.trait_ref,
_ => continue,
};
let sup_trait_ref =
EarlyBinder::bind(sup_trait_ref).instantiate(interner, trait_ref.args);
stack.push(sup_trait_ref);
}
tracing::debug!(?stack);
}
None
};
match res {
TypeNs::SelfType(impl_id) => {
let trait_ref = db.impl_trait(impl_id)?;
// FIXME(next-solver): same method in `lower` checks for impl or not
// Is that needed here?
// we're _in_ the impl -- the binders get added back later. Correct,
// but it would be nice to make this more explicit
search(trait_ref.skip_binder())
}
TypeNs::GenericParam(param_id) => {
// Handle `Self::Type` referring to own associated type in trait definitions
// This *must* be done first to avoid cycles with
// `generic_predicates_for_param`, but not sure that it's sufficient,
if let GenericDefId::TraitId(trait_id) = param_id.parent() {
let trait_name = &db.trait_signature(trait_id).name;
tracing::debug!(?trait_name);
let trait_generics = generics(db, trait_id.into());
tracing::debug!(?trait_generics);
if trait_generics[param_id.local_id()].is_trait_self() {
let args = GenericArgs::identity_for_item(interner, trait_id.into());
let trait_ref = TraitRef::new_from_args(interner, trait_id.into(), args);
tracing::debug!(?args, ?trait_ref);
return search(trait_ref);
}
}
let predicates =
db.generic_predicates_for_param(def, param_id.into(), assoc_name.clone());
predicates
.iter()
.find_map(|pred| match (*pred).kind().skip_binder() {
rustc_type_ir::ClauseKind::Trait(trait_predicate) => Some(trait_predicate),
_ => None,
})
.and_then(|trait_predicate| {
let trait_ref = trait_predicate.trait_ref;
assert!(
!trait_ref.has_escaping_bound_vars(),
"FIXME unexpected higher-ranked trait bound"
);
search(trait_ref)
})
}
_ => None,
}
}