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rust-analyzer/crates/hir-ty/src/lower.rs
Chayim Refael Friedman 4317927231 Avoid interior mutability in TyLoweringContext 
This requires some serious code juggling.
2024-10-30 21:24:19 +02:00

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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.
use std::{
cell::OnceCell,
iter, mem,
ops::{self, Not as _},
};
use base_db::{ra_salsa::Cycle, CrateId};
use chalk_ir::{
cast::Cast,
fold::{Shift, TypeFoldable},
interner::HasInterner,
Mutability, Safety, TypeOutlives,
};
use either::Either;
use hir_def::{
builtin_type::BuiltinType,
data::adt::StructKind,
expander::Expander,
generics::{
GenericParamDataRef, TypeOrConstParamData, TypeParamProvenance, WherePredicate,
WherePredicateTypeTarget,
},
lang_item::LangItem,
nameres::MacroSubNs,
path::{GenericArg, GenericArgs, ModPath, Path, PathKind, PathSegment, PathSegments},
resolver::{HasResolver, LifetimeNs, Resolver, TypeNs},
type_ref::{
ConstRef, LifetimeRef, TraitBoundModifier, TraitRef as HirTraitRef, TypeBound, TypeRef,
TypeRefId, TypesMap, TypesSourceMap,
},
AdtId, AssocItemId, CallableDefId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId,
FunctionId, GenericDefId, GenericParamId, HasModule, ImplId, InTypeConstLoc, ItemContainerId,
LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeOrConstParamId,
TypeOwnerId, UnionId, VariantId,
};
use hir_expand::{name::Name, ExpandResult};
use la_arena::{Arena, ArenaMap};
use rustc_hash::FxHashSet;
use rustc_pattern_analysis::Captures;
use smallvec::SmallVec;
use stdx::{impl_from, never};
use syntax::ast;
use triomphe::Arc;
use crate::{
all_super_traits,
consteval::{
intern_const_ref, intern_const_scalar, path_to_const, unknown_const,
unknown_const_as_generic,
},
db::HirDatabase,
error_lifetime,
generics::{generics, trait_self_param_idx, Generics},
make_binders,
mapping::{from_chalk_trait_id, lt_to_placeholder_idx, ToChalk},
static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
utils::{
all_super_trait_refs, associated_type_by_name_including_super_traits, InTypeConstIdMetadata,
},
AliasEq, AliasTy, Binders, BoundVar, CallableSig, Const, ConstScalar, DebruijnIndex, DynTy,
FnAbi, FnPointer, FnSig, FnSubst, ImplTrait, ImplTraitId, ImplTraits, Interner, Lifetime,
LifetimeData, LifetimeOutlives, ParamKind, PolyFnSig, ProgramClause, ProjectionTy,
QuantifiedWhereClause, QuantifiedWhereClauses, Substitution, TraitEnvironment, TraitRef,
TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
};
#[derive(Debug, Default)]
struct ImplTraitLoweringState {
/// 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>,
param_and_variable_counter: u16,
}
impl ImplTraitLoweringState {
fn new(mode: ImplTraitLoweringMode) -> ImplTraitLoweringState {
Self { mode, opaque_type_data: Arena::new(), param_and_variable_counter: 0 }
}
fn param(counter: u16) -> Self {
Self {
mode: ImplTraitLoweringMode::Param,
opaque_type_data: Arena::new(),
param_and_variable_counter: counter,
}
}
fn variable(counter: u16) -> Self {
Self {
mode: ImplTraitLoweringMode::Variable,
opaque_type_data: Arena::new(),
param_and_variable_counter: counter,
}
}
}
#[derive(Debug)]
pub struct TyLoweringContext<'a> {
pub db: &'a dyn HirDatabase,
resolver: &'a Resolver,
generics: OnceCell<Option<Generics>>,
types_map: &'a TypesMap,
/// If this is set, that means we're in a context of a freshly expanded macro, and that means
/// we should not use `TypeRefId` in diagnostics because the caller won't have the `TypesMap`,
/// instead we need to put `TypeSource` from the source map.
types_source_map: Option<&'a TypesSourceMap>,
in_binders: DebruijnIndex,
// FIXME: Should not be an `Option` but `Resolver` currently does not return owners in all cases
// where expected
owner: Option<TypeOwnerId>,
/// Note: Conceptually, it's thinkable that we could be in a location where
/// some type params should be represented as placeholders, and others
/// should be converted to variables. I think in practice, this isn't
/// possible currently, so this should be fine for now.
pub type_param_mode: ParamLoweringMode,
impl_trait_mode: ImplTraitLoweringState,
expander: Option<Expander>,
/// Tracks types with explicit `?Sized` bounds.
pub(crate) unsized_types: FxHashSet<Ty>,
}
impl<'a> TyLoweringContext<'a> {
pub fn new(
db: &'a dyn HirDatabase,
resolver: &'a Resolver,
types_map: &'a TypesMap,
owner: TypeOwnerId,
) -> Self {
Self::new_maybe_unowned(db, resolver, types_map, None, Some(owner))
}
pub fn new_maybe_unowned(
db: &'a dyn HirDatabase,
resolver: &'a Resolver,
types_map: &'a TypesMap,
types_source_map: Option<&'a TypesSourceMap>,
owner: Option<TypeOwnerId>,
) -> Self {
let impl_trait_mode = ImplTraitLoweringState::new(ImplTraitLoweringMode::Disallowed);
let type_param_mode = ParamLoweringMode::Placeholder;
let in_binders = DebruijnIndex::INNERMOST;
Self {
db,
resolver,
generics: OnceCell::new(),
types_map,
types_source_map,
owner,
in_binders,
impl_trait_mode,
type_param_mode,
expander: None,
unsized_types: FxHashSet::default(),
}
}
pub fn with_debruijn<T>(
&mut self,
debruijn: DebruijnIndex,
f: impl FnOnce(&mut TyLoweringContext<'_>) -> T,
) -> T {
let old_debruijn = mem::replace(&mut self.in_binders, debruijn);
let result = f(self);
self.in_binders = old_debruijn;
result
}
pub fn with_shifted_in<T>(
&mut self,
debruijn: DebruijnIndex,
f: impl FnOnce(&mut TyLoweringContext<'_>) -> T,
) -> T {
self.with_debruijn(self.in_binders.shifted_in_from(debruijn), f)
}
pub fn with_impl_trait_mode(self, impl_trait_mode: ImplTraitLoweringMode) -> Self {
Self { impl_trait_mode: ImplTraitLoweringState::new(impl_trait_mode), ..self }
}
pub fn with_type_param_mode(self, type_param_mode: ParamLoweringMode) -> Self {
Self { type_param_mode, ..self }
}
pub fn impl_trait_mode(&mut self, impl_trait_mode: ImplTraitLoweringMode) -> &mut Self {
self.impl_trait_mode = ImplTraitLoweringState::new(impl_trait_mode);
self
}
pub fn type_param_mode(&mut self, type_param_mode: ParamLoweringMode) -> &mut Self {
self.type_param_mode = type_param_mode;
self
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Default)]
pub 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` gets lowered into a type variable. Used for argument
/// position impl Trait when inside the respective function, since it allows
/// us to support that without Chalk.
Param,
/// `impl Trait` gets lowered into a variable that can unify with some
/// type. This is used in places where values flow 'in', i.e. for arguments
/// of functions we're calling, and the return type of the function we're
/// currently checking.
Variable,
/// `impl Trait` is disallowed and will be an error.
#[default]
Disallowed,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum ParamLoweringMode {
Placeholder,
Variable,
}
impl<'a> TyLoweringContext<'a> {
pub fn lower_ty(&mut self, type_ref: TypeRefId) -> Ty {
self.lower_ty_ext(type_ref).0
}
pub fn lower_const(&mut self, const_ref: &ConstRef, const_type: Ty) -> Const {
let Some(owner) = self.owner else { return unknown_const(const_type) };
let debruijn = self.in_binders;
const_or_path_to_chalk(
self.db,
self.resolver,
owner,
const_type,
const_ref,
self.type_param_mode,
|| self.generics(),
debruijn,
)
}
fn generics(&self) -> Option<&Generics> {
self.generics
.get_or_init(|| self.resolver.generic_def().map(|def| generics(self.db.upcast(), def)))
.as_ref()
}
pub fn lower_ty_ext(&mut self, type_ref_id: TypeRefId) -> (Ty, Option<TypeNs>) {
let mut res = None;
let type_ref = &self.types_map[type_ref_id];
let ty = match type_ref {
TypeRef::Never => TyKind::Never.intern(Interner),
TypeRef::Tuple(inner) => {
let inner_tys = inner.iter().map(|&tr| self.lower_ty(tr));
TyKind::Tuple(inner_tys.len(), Substitution::from_iter(Interner, inner_tys))
.intern(Interner)
}
TypeRef::Path(path) => {
let (ty, res_) = self.lower_path(path);
res = res_;
ty
}
&TypeRef::RawPtr(inner, mutability) => {
let inner_ty = self.lower_ty(inner);
TyKind::Raw(lower_to_chalk_mutability(mutability), inner_ty).intern(Interner)
}
TypeRef::Array(array) => {
let inner_ty = self.lower_ty(array.ty);
let const_len = self.lower_const(&array.len, TyBuilder::usize());
TyKind::Array(inner_ty, const_len).intern(Interner)
}
&TypeRef::Slice(inner) => {
let inner_ty = self.lower_ty(inner);
TyKind::Slice(inner_ty).intern(Interner)
}
TypeRef::Reference(ref_) => {
let inner_ty = self.lower_ty(ref_.ty);
// FIXME: It should infer the eldided lifetimes instead of stubbing with static
let lifetime = ref_
.lifetime
.as_ref()
.map_or_else(error_lifetime, |lr| self.lower_lifetime(lr));
TyKind::Ref(lower_to_chalk_mutability(ref_.mutability), lifetime, inner_ty)
.intern(Interner)
}
TypeRef::Placeholder => TyKind::Error.intern(Interner),
TypeRef::Fn(fn_) => {
let substs = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
Substitution::from_iter(
Interner,
fn_.params().iter().map(|&(_, tr)| ctx.lower_ty(tr)),
)
});
TyKind::Function(FnPointer {
num_binders: 0, // FIXME lower `for<'a> fn()` correctly
sig: FnSig {
abi: fn_.abi().as_ref().map_or(FnAbi::Rust, FnAbi::from_symbol),
safety: if fn_.is_unsafe() { Safety::Unsafe } else { Safety::Safe },
variadic: fn_.is_varargs(),
},
substitution: FnSubst(substs),
})
.intern(Interner)
}
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 {
bounds: crate::make_single_type_binders(Vec::default()),
});
// 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::INNERMOST, |ctx| {
ctx.lower_impl_trait(bounds, self.resolver.krate())
});
self.impl_trait_mode.opaque_type_data[idx] = actual_opaque_type_data;
let impl_trait_id = origin.either(
|f| ImplTraitId::ReturnTypeImplTrait(f, idx),
|a| ImplTraitId::TypeAliasImplTrait(a, idx),
);
let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
let generics =
generics(self.db.upcast(), origin.either(|f| f.into(), |a| a.into()));
let parameters = generics.bound_vars_subst(self.db, self.in_binders);
TyKind::OpaqueType(opaque_ty_id, parameters).intern(Interner)
}
ImplTraitLoweringMode::Param => {
let idx = self.impl_trait_mode.param_and_variable_counter;
// Count the number of `impl Trait` things that appear within our bounds.
// Since those have been emitted as implicit type args already.
self.impl_trait_mode.param_and_variable_counter =
idx + self.count_impl_traits(type_ref_id) as u16;
let db = self.db;
let kind = self
.generics()
.expect("param impl trait lowering must be in a generic def")
.iter()
.filter_map(|(id, data)| match (id, data) {
(
GenericParamId::TypeParamId(id),
GenericParamDataRef::TypeParamData(data),
) if data.provenance == TypeParamProvenance::ArgumentImplTrait => {
Some(id)
}
_ => None,
})
.nth(idx as usize)
.map_or(TyKind::Error, |id| {
TyKind::Placeholder(to_placeholder_idx(db, id.into()))
});
kind.intern(Interner)
}
ImplTraitLoweringMode::Variable => {
let idx = self.impl_trait_mode.param_and_variable_counter;
// Count the number of `impl Trait` things that appear within our bounds.
// Since t hose have been emitted as implicit type args already.
self.impl_trait_mode.param_and_variable_counter =
idx + self.count_impl_traits(type_ref_id) as u16;
let debruijn = self.in_binders;
let kind = self
.generics()
.expect("variable impl trait lowering must be in a generic def")
.iter()
.enumerate()
.filter_map(|(i, (id, data))| match (id, data) {
(
GenericParamId::TypeParamId(_),
GenericParamDataRef::TypeParamData(data),
) if data.provenance == TypeParamProvenance::ArgumentImplTrait => {
Some(i)
}
_ => None,
})
.nth(idx as usize)
.map_or(TyKind::Error, |id| {
TyKind::BoundVar(BoundVar { debruijn, index: id })
});
kind.intern(Interner)
}
ImplTraitLoweringMode::Disallowed => {
// FIXME: report error
TyKind::Error.intern(Interner)
}
}
}
TypeRef::Macro(macro_call) => {
let (expander, recursion_start) = {
match &mut self.expander {
// There already is an expander here, this means we are already recursing
Some(expander) => (expander, false),
// No expander was created yet, so we are at the start of the expansion recursion
// and therefore have to create an expander.
None => {
let expander = self.expander.insert(Expander::new(
self.db.upcast(),
macro_call.file_id,
self.resolver.module(),
));
(expander, true)
}
}
};
let ty = {
let macro_call = macro_call.to_node(self.db.upcast());
let resolver = |path: &_| {
self.resolver
.resolve_path_as_macro(self.db.upcast(), path, Some(MacroSubNs::Bang))
.map(|(it, _)| it)
};
match expander.enter_expand::<ast::Type>(self.db.upcast(), macro_call, resolver)
{
Ok(ExpandResult { value: Some((mark, expanded)), .. }) => {
let (mut types_map, mut types_source_map) =
(TypesMap::default(), TypesSourceMap::default());
let mut ctx = expander.ctx(
self.db.upcast(),
&mut types_map,
&mut types_source_map,
);
// FIXME: Report syntax errors in expansion here
let type_ref = TypeRef::from_ast(&mut ctx, expanded.tree());
// Can't mutate `self`, must create a new instance, because of the lifetimes.
let mut inner_ctx = TyLoweringContext {
db: self.db,
resolver: self.resolver,
generics: self.generics.clone(),
types_map: &types_map,
types_source_map: Some(&types_source_map),
in_binders: self.in_binders,
owner: self.owner,
type_param_mode: self.type_param_mode,
impl_trait_mode: mem::take(&mut self.impl_trait_mode),
expander: self.expander.take(),
unsized_types: mem::take(&mut self.unsized_types),
};
let ty = inner_ctx.lower_ty(type_ref);
self.impl_trait_mode = inner_ctx.impl_trait_mode;
self.expander = inner_ctx.expander;
self.unsized_types = inner_ctx.unsized_types;
self.expander.as_mut().unwrap().exit(mark);
Some(ty)
}
_ => None,
}
};
// drop the expander, resetting it to pre-recursion state
if recursion_start {
self.expander = None;
}
ty.unwrap_or_else(|| TyKind::Error.intern(Interner))
}
TypeRef::Error => TyKind::Error.intern(Interner),
};
(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.types_map[type_ref];
let path = match type_ref {
TypeRef::Path(path) => path,
_ => 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.upcast(), path) {
Some((it, None, _)) => it,
_ => return None,
};
match resolution {
TypeNs::GenericParam(param_id) => Some(param_id.into()),
_ => None,
}
}
pub(crate) fn lower_ty_relative_path(
&mut self,
ty: Ty,
// We need the original resolution to lower `Self::AssocTy` correctly
res: Option<TypeNs>,
remaining_segments: PathSegments<'_>,
) -> (Ty, Option<TypeNs>) {
match remaining_segments.len() {
0 => (ty, res),
1 => {
// resolve unselected assoc types
let segment = remaining_segments.first().unwrap();
(self.select_associated_type(res, segment), None)
}
_ => {
// FIXME report error (ambiguous associated type)
(TyKind::Error.intern(Interner), None)
}
}
}
pub(crate) fn lower_partly_resolved_path(
&mut self,
resolution: TypeNs,
resolved_segment: PathSegment<'_>,
remaining_segments: PathSegments<'_>,
infer_args: bool,
) -> (Ty, Option<TypeNs>) {
let ty = match resolution {
TypeNs::TraitId(trait_) => {
let ty = match remaining_segments.len() {
1 => {
let trait_ref = self.lower_trait_ref_from_resolved_path(
trait_,
resolved_segment,
TyKind::Error.intern(Interner),
);
let segment = remaining_segments.first().unwrap();
let found = self
.db
.trait_data(trait_ref.hir_trait_id())
.associated_type_by_name(segment.name);
match found {
Some(associated_ty) => {
// FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent
// generic params. It's inefficient to splice the `Substitution`s, so we may want
// that method to optionally take parent `Substitution` as we already know them at
// this point (`trait_ref.substitution`).
let substitution = self.substs_from_path_segment(
segment,
Some(associated_ty.into()),
false,
None,
);
let len_self =
generics(self.db.upcast(), associated_ty.into()).len_self();
let substitution = Substitution::from_iter(
Interner,
substitution
.iter(Interner)
.take(len_self)
.chain(trait_ref.substitution.iter(Interner)),
);
TyKind::Alias(AliasTy::Projection(ProjectionTy {
associated_ty_id: to_assoc_type_id(associated_ty),
substitution,
}))
.intern(Interner)
}
None => {
// FIXME: report error (associated type not found)
TyKind::Error.intern(Interner)
}
}
}
0 => {
// Trait object type without dyn; this should be handled in upstream. See
// `lower_path()`.
stdx::never!("unexpected fully resolved trait path");
TyKind::Error.intern(Interner)
}
_ => {
// FIXME report error (ambiguous associated type)
TyKind::Error.intern(Interner)
}
};
return (ty, None);
}
TypeNs::TraitAliasId(_) => {
// FIXME(trait_alias): Implement trait alias.
return (TyKind::Error.intern(Interner), None);
}
TypeNs::GenericParam(param_id) => match self.type_param_mode {
ParamLoweringMode::Placeholder => {
TyKind::Placeholder(to_placeholder_idx(self.db, param_id.into()))
}
ParamLoweringMode::Variable => {
let idx = match self
.generics()
.expect("generics in scope")
.type_or_const_param_idx(param_id.into())
{
None => {
never!("no matching generics");
return (TyKind::Error.intern(Interner), None);
}
Some(idx) => idx,
};
TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
}
}
.intern(Interner),
TypeNs::SelfType(impl_id) => {
let generics = self.generics().expect("impl should have generic param scope");
match self.type_param_mode {
ParamLoweringMode::Placeholder => {
// `def` can be either impl itself or item within, and we need impl itself
// now.
let generics = generics.parent_or_self();
let subst = generics.placeholder_subst(self.db);
self.db.impl_self_ty(impl_id).substitute(Interner, &subst)
}
ParamLoweringMode::Variable => {
let starting_from = match generics.def() {
GenericDefId::ImplId(_) => 0,
// `def` is an item within impl. We need to substitute `BoundVar`s but
// remember that they are for parent (i.e. impl) generic params so they
// come after our own params.
_ => generics.len_self(),
};
TyBuilder::impl_self_ty(self.db, impl_id)
.fill_with_bound_vars(self.in_binders, starting_from)
.build()
}
}
}
TypeNs::AdtSelfType(adt) => {
let generics = generics(self.db.upcast(), adt.into());
let substs = match self.type_param_mode {
ParamLoweringMode::Placeholder => generics.placeholder_subst(self.db),
ParamLoweringMode::Variable => {
generics.bound_vars_subst(self.db, self.in_binders)
}
};
self.db.ty(adt.into()).substitute(Interner, &substs)
}
TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args),
TypeNs::BuiltinType(it) => {
self.lower_path_inner(resolved_segment, it.into(), infer_args)
}
TypeNs::TypeAliasId(it) => {
self.lower_path_inner(resolved_segment, it.into(), infer_args)
}
// FIXME: report error
TypeNs::EnumVariantId(_) => return (TyKind::Error.intern(Interner), None),
};
self.lower_ty_relative_path(ty, Some(resolution), remaining_segments)
}
pub(crate) fn lower_path(&mut self, path: &Path) -> (Ty, 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);
return self.lower_ty_relative_path(ty, res, path.segments());
}
let (resolution, remaining_index, _) =
match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path) {
Some(it) => it,
None => return (TyKind::Error.intern(Interner), None),
};
if matches!(resolution, TypeNs::TraitId(_)) && remaining_index.is_none() {
// trait object type without dyn
let bound = TypeBound::Path(path.clone(), TraitBoundModifier::None);
let ty = self.lower_dyn_trait(&[bound]);
return (ty, None);
}
let (resolved_segment, remaining_segments) = match remaining_index {
None => (
path.segments().last().expect("resolved path has at least one element"),
PathSegments::EMPTY,
),
Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)),
};
self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false)
}
fn select_associated_type(&mut self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty {
let Some((generics, res)) = self.generics().zip(res) else {
return TyKind::Error.intern(Interner);
};
let ty = named_associated_type_shorthand_candidates(
self.db,
generics.def(),
res,
Some(segment.name.clone()),
move |name, t, associated_ty| {
let generics = self.generics().unwrap();
if name != segment.name {
return None;
}
let parent_subst = t.substitution.clone();
let parent_subst = match self.type_param_mode {
ParamLoweringMode::Placeholder => {
// if we're lowering to placeholders, we have to put them in now.
let s = generics.placeholder_subst(self.db);
s.apply(parent_subst, Interner)
}
ParamLoweringMode::Variable => {
// We need to shift in the bound vars, since
// `named_associated_type_shorthand_candidates` does not do that.
parent_subst.shifted_in_from(Interner, self.in_binders)
}
};
// FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent
// generic params. It's inefficient to splice the `Substitution`s, so we may want
// that method to optionally take parent `Substitution` as we already know them at
// this point (`t.substitution`).
let substs = self.substs_from_path_segment(
segment.clone(),
Some(associated_ty.into()),
false,
None,
);
let len_self =
crate::generics::generics(self.db.upcast(), associated_ty.into()).len_self();
let substs = Substitution::from_iter(
Interner,
substs.iter(Interner).take(len_self).chain(parent_subst.iter(Interner)),
);
Some(
TyKind::Alias(AliasTy::Projection(ProjectionTy {
associated_ty_id: to_assoc_type_id(associated_ty),
substitution: substs,
}))
.intern(Interner),
)
},
);
ty.unwrap_or_else(|| TyKind::Error.intern(Interner))
}
fn lower_path_inner(
&mut self,
segment: PathSegment<'_>,
typeable: TyDefId,
infer_args: bool,
) -> Ty {
let generic_def = match typeable {
TyDefId::BuiltinType(_) => None,
TyDefId::AdtId(it) => Some(it.into()),
TyDefId::TypeAliasId(it) => Some(it.into()),
};
let substs = self.substs_from_path_segment(segment, generic_def, infer_args, None);
self.db.ty(typeable).substitute(Interner, &substs)
}
/// Collect generic arguments from a path into a `Substs`. See also
/// `create_substs_for_ast_path` and `def_to_ty` in rustc.
pub(super) fn substs_from_path(
&mut self,
path: &Path,
// Note that we don't call `db.value_type(resolved)` here,
// `ValueTyDefId` is just a convenient way to pass generics and
// special-case enum variants
resolved: ValueTyDefId,
infer_args: bool,
) -> Substitution {
let last = path.segments().last();
let (segment, generic_def) = match resolved {
ValueTyDefId::FunctionId(it) => (last, Some(it.into())),
ValueTyDefId::StructId(it) => (last, Some(it.into())),
ValueTyDefId::UnionId(it) => (last, Some(it.into())),
ValueTyDefId::ConstId(it) => (last, Some(it.into())),
ValueTyDefId::StaticId(_) => (last, None),
ValueTyDefId::EnumVariantId(var) => {
// the generic args for an enum variant may be either specified
// on the segment referring to the enum, or on the segment
// referring to the variant. So `Option::<T>::None` and
// `Option::None::<T>` are both allowed (though the former is
// preferred). See also `def_ids_for_path_segments` in rustc.
let len = path.segments().len();
let penultimate = len.checked_sub(2).and_then(|idx| path.segments().get(idx));
let segment = match penultimate {
Some(segment) if segment.args_and_bindings.is_some() => Some(segment),
_ => last,
};
(segment, Some(var.lookup(self.db.upcast()).parent.into()))
}
};
if let Some(segment) = segment {
self.substs_from_path_segment(segment, generic_def, infer_args, None)
} else if let Some(generic_def) = generic_def {
// lang item
self.substs_from_args_and_bindings(None, Some(generic_def), infer_args, None)
} else {
Substitution::empty(Interner)
}
}
pub(super) fn substs_from_path_segment(
&mut self,
segment: PathSegment<'_>,
def: Option<GenericDefId>,
infer_args: bool,
explicit_self_ty: Option<Ty>,
) -> Substitution {
self.substs_from_args_and_bindings(
segment.args_and_bindings,
def,
infer_args,
explicit_self_ty,
)
}
fn substs_from_args_and_bindings(
&mut self,
args_and_bindings: Option<&GenericArgs>,
def: Option<GenericDefId>,
infer_args: bool,
explicit_self_ty: Option<Ty>,
) -> Substitution {
let Some(def) = def else { return Substitution::empty(Interner) };
// Order is
// - Optional Self parameter
// - Lifetime parameters
// - Type or Const parameters
// - Parent parameters
let def_generics = generics(self.db.upcast(), def);
let (
parent_params,
self_param,
type_params,
const_params,
impl_trait_params,
lifetime_params,
) = def_generics.provenance_split();
let item_len =
self_param as usize + type_params + const_params + impl_trait_params + lifetime_params;
let total_len = parent_params + item_len;
let mut substs = Vec::new();
// we need to iterate the lifetime and type/const params separately as our order of them
// differs from the supplied syntax
let ty_error = || TyKind::Error.intern(Interner).cast(Interner);
let mut def_toc_iter = def_generics.iter_self_type_or_consts_id();
let fill_self_param = || {
if self_param {
let self_ty = explicit_self_ty.map(|x| x.cast(Interner)).unwrap_or_else(ty_error);
if let Some(id) = def_toc_iter.next() {
assert!(matches!(id, GenericParamId::TypeParamId(_)));
substs.push(self_ty);
}
}
};
let mut had_explicit_args = false;
if let Some(&GenericArgs { ref args, has_self_type, .. }) = args_and_bindings {
// Fill in the self param first
if has_self_type && self_param {
had_explicit_args = true;
if let Some(id) = def_toc_iter.next() {
assert!(matches!(id, GenericParamId::TypeParamId(_)));
had_explicit_args = true;
if let GenericArg::Type(ty) = &args[0] {
substs.push(self.lower_ty(*ty).cast(Interner));
}
}
} else {
fill_self_param()
};
// Then fill in the supplied lifetime args, or error lifetimes if there are too few
// (default lifetimes aren't a thing)
for arg in args
.iter()
.filter_map(|arg| match arg {
GenericArg::Lifetime(arg) => Some(self.lower_lifetime(arg)),
_ => None,
})
.chain(iter::repeat(error_lifetime()))
.take(lifetime_params)
{
substs.push(arg.cast(Interner));
}
let skip = if has_self_type { 1 } else { 0 };
// Fill in supplied type and const args
// Note if non-lifetime args are provided, it should be all of them, but we can't rely on that
for (arg, id) in args
.iter()
.filter(|arg| !matches!(arg, GenericArg::Lifetime(_)))
.skip(skip)
.take(type_params + const_params)
.zip(def_toc_iter)
{
had_explicit_args = true;
let arg = generic_arg_to_chalk(
self.db,
id,
arg,
self,
self.types_map,
|this, type_ref| this.lower_ty(type_ref),
|this, const_ref, ty| this.lower_const(const_ref, ty),
|this, lifetime_ref| this.lower_lifetime(lifetime_ref),
);
substs.push(arg);
}
} else {
fill_self_param();
}
let param_to_err = |id| match id {
GenericParamId::ConstParamId(x) => unknown_const_as_generic(self.db.const_param_ty(x)),
GenericParamId::TypeParamId(_) => ty_error(),
GenericParamId::LifetimeParamId(_) => error_lifetime().cast(Interner),
};
// handle defaults. In expression or pattern path segments without
// explicitly specified type arguments, missing type arguments are inferred
// (i.e. defaults aren't used).
// Generic parameters for associated types are not supposed to have defaults, so we just
// ignore them.
let is_assoc_ty = || match def {
GenericDefId::TypeAliasId(id) => {
matches!(id.lookup(self.db.upcast()).container, ItemContainerId::TraitId(_))
}
_ => false,
};
let fill_defaults = (!infer_args || had_explicit_args) && !is_assoc_ty();
if fill_defaults {
let defaults = &*self.db.generic_defaults(def);
let (item, _parent) = defaults.split_at(item_len);
let parent_from = item_len - substs.len();
let mut rem =
def_generics.iter_id().skip(substs.len()).map(param_to_err).collect::<Vec<_>>();
// Fill in defaults for type/const params
for (idx, default_ty) in item[substs.len()..].iter().enumerate() {
// each default can depend on the previous parameters
let substs_so_far = Substitution::from_iter(
Interner,
substs.iter().cloned().chain(rem[idx..].iter().cloned()),
);
substs.push(default_ty.clone().substitute(Interner, &substs_so_far));
}
// Fill in remaining parent params
substs.extend(rem.drain(parent_from..));
} else {
// Fill in remaining def params and parent params
substs.extend(def_generics.iter_id().skip(substs.len()).map(param_to_err));
}
assert_eq!(substs.len(), total_len, "expected {} substs, got {}", total_len, substs.len());
Substitution::from_iter(Interner, substs)
}
pub(crate) fn lower_trait_ref_from_resolved_path(
&mut self,
resolved: TraitId,
segment: PathSegment<'_>,
explicit_self_ty: Ty,
) -> TraitRef {
let substs = self.trait_ref_substs_from_path(segment, resolved, explicit_self_ty);
TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
}
fn lower_trait_ref_from_path(&mut self, path: &Path, explicit_self_ty: Ty) -> Option<TraitRef> {
let resolved = match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path)? {
// FIXME(trait_alias): We need to handle trait alias here.
TypeNs::TraitId(tr) => tr,
_ => return None,
};
let segment = path.segments().last().expect("path should have at least one segment");
Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty))
}
fn lower_trait_ref(
&mut self,
trait_ref: &HirTraitRef,
explicit_self_ty: Ty,
) -> Option<TraitRef> {
self.lower_trait_ref_from_path(&trait_ref.path, explicit_self_ty)
}
fn trait_ref_substs_from_path(
&mut self,
segment: PathSegment<'_>,
resolved: TraitId,
explicit_self_ty: Ty,
) -> Substitution {
self.substs_from_path_segment(segment, Some(resolved.into()), false, Some(explicit_self_ty))
}
pub(crate) fn lower_where_predicate<'b>(
&'b mut self,
where_predicate: &'b WherePredicate,
&def: &GenericDefId,
ignore_bindings: bool,
) -> impl Iterator<Item = QuantifiedWhereClause> + use<'a, 'b> {
match where_predicate {
WherePredicate::ForLifetime { target, bound, .. }
| WherePredicate::TypeBound { target, bound } => {
let self_ty = match target {
WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(*type_ref),
&WherePredicateTypeTarget::TypeOrConstParam(local_id) => {
let param_id = hir_def::TypeOrConstParamId { parent: def, local_id };
match self.type_param_mode {
ParamLoweringMode::Placeholder => {
TyKind::Placeholder(to_placeholder_idx(self.db, param_id))
}
ParamLoweringMode::Variable => {
let idx = generics(self.db.upcast(), def)
.type_or_const_param_idx(param_id)
.expect("matching generics");
TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, idx))
}
}
.intern(Interner)
}
};
Either::Left(self.lower_type_bound(bound, self_ty, ignore_bindings))
}
WherePredicate::Lifetime { bound, target } => Either::Right(iter::once(
crate::wrap_empty_binders(WhereClause::LifetimeOutlives(LifetimeOutlives {
a: self.lower_lifetime(bound),
b: self.lower_lifetime(target),
})),
)),
}
.into_iter()
}
pub(crate) fn lower_type_bound<'b>(
&'b mut self,
bound: &'b TypeBound,
self_ty: Ty,
ignore_bindings: bool,
) -> impl Iterator<Item = QuantifiedWhereClause> + use<'b, 'a> {
let mut trait_ref = None;
let clause = match bound {
TypeBound::Path(path, TraitBoundModifier::None) => {
trait_ref = self.lower_trait_ref_from_path(path, self_ty);
trait_ref.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
}
TypeBound::Path(path, TraitBoundModifier::Maybe) => {
let sized_trait = self
.db
.lang_item(self.resolver.krate(), LangItem::Sized)
.and_then(|lang_item| lang_item.as_trait());
// 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.clone())
.map(|trait_ref| trait_ref.hir_trait_id());
if trait_id == sized_trait {
self.unsized_types.insert(self_ty);
}
None
}
TypeBound::ForLifetime(_, path) => {
// FIXME Don't silently drop the hrtb lifetimes here
trait_ref = self.lower_trait_ref_from_path(path, self_ty);
trait_ref.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
}
TypeBound::Lifetime(l) => {
let lifetime = self.lower_lifetime(l);
Some(crate::wrap_empty_binders(WhereClause::TypeOutlives(TypeOutlives {
ty: self_ty,
lifetime,
})))
}
TypeBound::Use(_) | TypeBound::Error => None,
};
clause.into_iter().chain(
trait_ref
.filter(move |_| !ignore_bindings)
.map(move |tr| self.assoc_type_bindings_from_type_bound(bound, tr))
.into_iter()
.flatten(),
)
}
fn assoc_type_bindings_from_type_bound<'b>(
&'b mut self,
bound: &'b TypeBound,
trait_ref: TraitRef,
) -> impl Iterator<Item = QuantifiedWhereClause> + use<'b, 'a> {
let last_segment = match bound {
TypeBound::Path(path, TraitBoundModifier::None) | TypeBound::ForLifetime(_, path) => {
path.segments().last()
}
TypeBound::Path(_, TraitBoundModifier::Maybe)
| TypeBound::Use(_)
| TypeBound::Error
| TypeBound::Lifetime(_) => None,
};
last_segment
.into_iter()
.filter_map(|segment| segment.args_and_bindings)
.flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
.flat_map(move |binding| {
let found = associated_type_by_name_including_super_traits(
self.db,
trait_ref.clone(),
&binding.name,
);
let (super_trait_ref, associated_ty) = match found {
None => return SmallVec::new(),
Some(t) => t,
};
// FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent
// generic params. It's inefficient to splice the `Substitution`s, so we may want
// that method to optionally take parent `Substitution` as we already know them at
// this point (`super_trait_ref.substitution`).
let substitution = self.substs_from_path_segment(
// FIXME: This is hack. We shouldn't really build `PathSegment` directly.
PathSegment { name: &binding.name, args_and_bindings: binding.args.as_ref() },
Some(associated_ty.into()),
false, // this is not relevant
Some(super_trait_ref.self_type_parameter(Interner)),
);
let self_params = generics(self.db.upcast(), associated_ty.into()).len_self();
let substitution = Substitution::from_iter(
Interner,
substitution
.iter(Interner)
.take(self_params)
.chain(super_trait_ref.substitution.iter(Interner)),
);
let projection_ty = ProjectionTy {
associated_ty_id: to_assoc_type_id(associated_ty),
substitution,
};
let mut predicates: SmallVec<[_; 1]> = SmallVec::with_capacity(
binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
);
if let Some(type_ref) = binding.type_ref {
match (&self.types_map[type_ref], self.impl_trait_mode.mode) {
(TypeRef::ImplTrait(_), ImplTraitLoweringMode::Disallowed) => (),
(_, ImplTraitLoweringMode::Disallowed | ImplTraitLoweringMode::Opaque) => {
let ty = self.lower_ty(type_ref);
let alias_eq =
AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
predicates
.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
}
(_, ImplTraitLoweringMode::Param | ImplTraitLoweringMode::Variable) => {
// Find the generic index for the target of our `bound`
let target_param_idx = self
.resolver
.where_predicates_in_scope()
.find_map(|(p, _)| match p {
WherePredicate::TypeBound {
target: WherePredicateTypeTarget::TypeOrConstParam(idx),
bound: b,
} if b == bound => Some(idx),
_ => None,
});
let ty = if let Some(target_param_idx) = target_param_idx {
let mut counter = 0;
let generics = self.generics().expect("generics in scope");
for (idx, data) in generics.iter_self_type_or_consts() {
// Count the number of `impl Trait` things that appear before
// the target of our `bound`.
// Our counter within `impl_trait_mode` should be that number
// to properly lower each types within `type_ref`
if data.type_param().is_some_and(|p| {
p.provenance == TypeParamProvenance::ArgumentImplTrait
}) {
counter += 1;
}
if idx == *target_param_idx {
break;
}
}
let mut ext = TyLoweringContext::new_maybe_unowned(
self.db,
self.resolver,
self.types_map,
self.types_source_map,
self.owner,
)
.with_type_param_mode(self.type_param_mode);
match self.impl_trait_mode.mode {
ImplTraitLoweringMode::Param => {
ext.impl_trait_mode =
ImplTraitLoweringState::param(counter);
}
ImplTraitLoweringMode::Variable => {
ext.impl_trait_mode =
ImplTraitLoweringState::variable(counter);
}
_ => unreachable!(),
}
ext.lower_ty(type_ref)
} else {
self.lower_ty(type_ref)
};
let alias_eq =
AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
predicates
.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
}
}
}
for bound in binding.bounds.iter() {
predicates.extend(self.lower_type_bound(
bound,
TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(Interner),
false,
));
}
predicates
})
}
fn lower_dyn_trait(&mut self, bounds: &[TypeBound]) -> Ty {
let self_ty = TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner);
// 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::ONE, |ctx| {
let mut lowered_bounds = Vec::new();
for b in bounds {
ctx.lower_type_bound(b, self_ty.clone(), false).for_each(|b| {
let filter = match b.skip_binders() {
WhereClause::Implemented(_) | WhereClause::AliasEq(_) => true,
WhereClause::LifetimeOutlives(_) => false,
WhereClause::TypeOutlives(t) => {
lifetime = Some(t.lifetime.clone());
false
}
};
if filter {
lowered_bounds.push(b);
}
});
}
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_binders(), rhs.skip_binders()) {
(WhereClause::Implemented(lhs), WhereClause::Implemented(rhs)) => {
let lhs_id = lhs.trait_id;
let lhs_is_auto = ctx.db.trait_data(from_chalk_trait_id(lhs_id)).is_auto;
let rhs_id = rhs.trait_id;
let rhs_is_auto = ctx.db.trait_data(from_chalk_trait_id(rhs_id)).is_auto;
if !lhs_is_auto && !rhs_is_auto {
multiple_regular_traits = true;
}
// Note that the ordering here is important; this ensures the invariant
// mentioned above.
(lhs_is_auto, lhs_id).cmp(&(rhs_is_auto, rhs_id))
}
(WhereClause::Implemented(_), _) => Ordering::Less,
(_, WhereClause::Implemented(_)) => Ordering::Greater,
(WhereClause::AliasEq(lhs), WhereClause::AliasEq(rhs)) => {
match (&lhs.alias, &rhs.alias) {
(AliasTy::Projection(lhs_proj), AliasTy::Projection(rhs_proj)) => {
// 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_proj.associated_ty_id == rhs_proj.associated_ty_id {
multiple_same_projection = true;
}
lhs_proj.associated_ty_id.cmp(&rhs_proj.associated_ty_id)
}
// We don't produce `AliasTy::Opaque`s yet.
_ => unreachable!(),
}
}
// `WhereClause::{TypeOutlives, LifetimeOutlives}` have been filtered out
_ => unreachable!(),
}
});
if multiple_regular_traits || multiple_same_projection {
return None;
}
lowered_bounds.first().and_then(|b| b.trait_id())?;
// 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(QuantifiedWhereClauses::from_iter(Interner, lowered_bounds))
});
if let Some(bounds) = bounds {
let bounds = crate::make_single_type_binders(bounds);
TyKind::Dyn(DynTy {
bounds,
lifetime: match lifetime {
Some(it) => match it.bound_var(Interner) {
Some(bound_var) => bound_var
.shifted_out_to(DebruijnIndex::new(2))
.map(|bound_var| LifetimeData::BoundVar(bound_var).intern(Interner))
.unwrap_or(it),
None => it,
},
None => static_lifetime(),
},
})
.intern(Interner)
} else {
// FIXME: report error
// (additional non-auto traits, associated type rebound, or no resolved trait)
TyKind::Error.intern(Interner)
}
}
fn lower_impl_trait(&mut self, bounds: &[TypeBound], krate: CrateId) -> ImplTrait {
cov_mark::hit!(lower_rpit);
let self_ty = TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner);
let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
let mut predicates = Vec::new();
for b in bounds {
predicates.extend(ctx.lower_type_bound(b, self_ty.clone(), false));
}
if !ctx.unsized_types.contains(&self_ty) {
let sized_trait = ctx
.db
.lang_item(krate, LangItem::Sized)
.and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id));
let sized_clause = sized_trait.map(|trait_id| {
let clause = WhereClause::Implemented(TraitRef {
trait_id,
substitution: Substitution::from1(Interner, self_ty.clone()),
});
crate::wrap_empty_binders(clause)
});
predicates.extend(sized_clause);
}
predicates.shrink_to_fit();
predicates
});
ImplTrait { bounds: crate::make_single_type_binders(predicates) }
}
pub fn lower_lifetime(&self, lifetime: &LifetimeRef) -> Lifetime {
match self.resolver.resolve_lifetime(lifetime) {
Some(resolution) => match resolution {
LifetimeNs::Static => static_lifetime(),
LifetimeNs::LifetimeParam(id) => match self.type_param_mode {
ParamLoweringMode::Placeholder => {
LifetimeData::Placeholder(lt_to_placeholder_idx(self.db, id))
}
ParamLoweringMode::Variable => {
let generics = self.generics().expect("generics in scope");
let idx = match generics.lifetime_idx(id) {
None => return error_lifetime(),
Some(idx) => idx,
};
LifetimeData::BoundVar(BoundVar::new(self.in_binders, idx))
}
}
.intern(Interner),
},
None => error_lifetime(),
}
}
// FIXME: This does not handle macros!
fn count_impl_traits(&self, type_ref: TypeRefId) -> usize {
let mut count = 0;
TypeRef::walk(type_ref, self.types_map, &mut |type_ref| {
if matches!(type_ref, TypeRef::ImplTrait(_)) {
count += 1;
}
});
count
}
}
/// Build the signature of a callable item (function, struct or enum variant).
pub(crate) fn callable_item_sig(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig {
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),
}
}
pub fn associated_type_shorthand_candidates<R>(
db: &dyn HirDatabase,
def: GenericDefId,
res: TypeNs,
mut cb: impl FnMut(&Name, TypeAliasId) -> Option<R>,
) -> Option<R> {
named_associated_type_shorthand_candidates(db, def, res, None, |name, _, id| cb(name, id))
}
fn named_associated_type_shorthand_candidates<R>(
db: &dyn HirDatabase,
// 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>,
// Do NOT let `cb` touch `TraitRef` outside of `TyLoweringContext`. Its substitution contains
// free `BoundVar`s that need to be shifted and only `TyLoweringContext` knows how to do that
// properly (see `TyLoweringContext::select_associated_type()`).
mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
) -> Option<R> {
let mut search = |t| {
all_super_trait_refs(db, t, |t| {
let data = db.trait_data(t.hir_trait_id());
for (name, assoc_id) in &data.items {
if let AssocItemId::TypeAliasId(alias) = assoc_id {
if let Some(result) = cb(name, &t, *alias) {
return Some(result);
}
}
}
None
})
};
match res {
TypeNs::SelfType(impl_id) => {
// we're _in_ the impl -- the binders get added back later. Correct,
// but it would be nice to make this more explicit
let trait_ref = db.impl_trait(impl_id)?.into_value_and_skipped_binders().0;
let impl_id_as_generic_def: GenericDefId = impl_id.into();
if impl_id_as_generic_def != def {
// `trait_ref` contains `BoundVar`s bound by impl's `Binders`, but here we need
// `BoundVar`s from `def`'s point of view.
// FIXME: A `HirDatabase` query may be handy if this process is needed in more
// places. It'd be almost identical as `impl_trait_query` where `resolver` would be
// of `def` instead of `impl_id`.
let starting_idx = generics(db.upcast(), def).len_self();
let subst = TyBuilder::subst_for_def(db, impl_id, None)
.fill_with_bound_vars(DebruijnIndex::INNERMOST, starting_idx)
.build();
let trait_ref = subst.apply(trait_ref, Interner);
search(trait_ref)
} else {
search(trait_ref)
}
}
TypeNs::GenericParam(param_id) => {
let predicates = db.generic_predicates_for_param(def, param_id.into(), assoc_name);
let res = predicates.iter().find_map(|pred| match pred.skip_binders().skip_binders() {
// FIXME: how to correctly handle higher-ranked bounds here?
WhereClause::Implemented(tr) => search(
tr.clone()
.shifted_out_to(Interner, DebruijnIndex::ONE)
.expect("FIXME unexpected higher-ranked trait bound"),
),
_ => None,
});
if res.is_some() {
return res;
}
// Handle `Self::Type` referring to own associated type in trait definitions
if let GenericDefId::TraitId(trait_id) = param_id.parent() {
let trait_generics = generics(db.upcast(), trait_id.into());
if trait_generics[param_id.local_id()].is_trait_self() {
let def_generics = generics(db.upcast(), def);
let starting_idx = match def {
GenericDefId::TraitId(_) => 0,
// `def` is an item within trait. We need to substitute `BoundVar`s but
// remember that they are for parent (i.e. trait) generic params so they
// come after our own params.
_ => def_generics.len_self(),
};
let trait_ref = TyBuilder::trait_ref(db, trait_id)
.fill_with_bound_vars(DebruijnIndex::INNERMOST, starting_idx)
.build();
return search(trait_ref);
}
}
None
}
_ => None,
}
}
/// Build the type of all specific fields of a struct or enum variant.
pub(crate) fn field_types_query(
db: &dyn HirDatabase,
variant_id: VariantId,
) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
let var_data = variant_id.variant_data(db.upcast());
let (resolver, def): (_, GenericDefId) = match variant_id {
VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()),
VariantId::UnionId(it) => (it.resolver(db.upcast()), it.into()),
VariantId::EnumVariantId(it) => {
(it.resolver(db.upcast()), it.lookup(db.upcast()).parent.into())
}
};
let generics = generics(db.upcast(), def);
let mut res = ArenaMap::default();
let mut ctx = TyLoweringContext::new(db, &resolver, var_data.types_map(), def.into())
.with_type_param_mode(ParamLoweringMode::Variable);
for (field_id, field_data) in var_data.fields().iter() {
res.insert(field_id, make_binders(db, &generics, ctx.lower_ty(field_data.type_ref)));
}
Arc::new(res)
}
/// 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<()>`.
pub(crate) fn generic_predicates_for_param_query(
db: &dyn HirDatabase,
def: GenericDefId,
param_id: TypeOrConstParamId,
assoc_name: Option<Name>,
) -> GenericPredicates {
let resolver = def.resolver(db.upcast());
let mut ctx = if let GenericDefId::FunctionId(_) = def {
TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Variable)
.with_type_param_mode(ParamLoweringMode::Variable)
} else {
TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
.with_type_param_mode(ParamLoweringMode::Variable)
};
let generics = generics(db.upcast(), def);
// we have to filter out all other predicates *first*, before attempting to lower them
let predicate = |pred: &_, def: &_, ctx: &mut TyLoweringContext<'_>| match pred {
WherePredicate::ForLifetime { target, bound, .. }
| WherePredicate::TypeBound { target, bound, .. } => {
let invalid_target = match target {
WherePredicateTypeTarget::TypeRef(type_ref) => {
ctx.lower_ty_only_param(*type_ref) != Some(param_id)
}
&WherePredicateTypeTarget::TypeOrConstParam(local_id) => {
let target_id = TypeOrConstParamId { parent: *def, local_id };
target_id != param_id
}
};
if invalid_target {
// If this is filtered out without lowering, `?Sized` is not gathered into `ctx.unsized_types`
if let TypeBound::Path(_, TraitBoundModifier::Maybe) = bound {
ctx.lower_where_predicate(pred, def, true).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 Some(assoc_name) = &assoc_name else { return true };
let Some(TypeNs::TraitId(tr)) =
resolver.resolve_path_in_type_ns_fully(db.upcast(), path)
else {
return false;
};
all_super_traits(db.upcast(), tr).iter().any(|tr| {
db.trait_data(*tr).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 (params, def) in resolver.all_generic_params() {
ctx.types_map = &params.types_map;
for pred in params.where_predicates() {
if predicate(pred, def, &mut ctx) {
predicates.extend(
ctx.lower_where_predicate(pred, def, true)
.map(|p| make_binders(db, &generics, p)),
);
}
}
}
let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
if !subst.is_empty(Interner) {
let explicitly_unsized_tys = ctx.unsized_types;
if let Some(implicitly_sized_predicates) = implicitly_sized_clauses(
db,
param_id.parent,
&explicitly_unsized_tys,
&subst,
&resolver,
) {
predicates.extend(
implicitly_sized_predicates
.map(|p| make_binders(db, &generics, crate::wrap_empty_binders(p))),
);
};
}
GenericPredicates(predicates.is_empty().not().then(|| predicates.into()))
}
pub(crate) fn generic_predicates_for_param_recover(
_db: &dyn HirDatabase,
_cycle: &Cycle,
_def: &GenericDefId,
_param_id: &TypeOrConstParamId,
_assoc_name: &Option<Name>,
) -> GenericPredicates {
GenericPredicates(None)
}
pub(crate) fn trait_environment_for_body_query(
db: &dyn HirDatabase,
def: DefWithBodyId,
) -> Arc<TraitEnvironment> {
let Some(def) = def.as_generic_def_id(db.upcast()) else {
let krate = def.module(db.upcast()).krate();
return TraitEnvironment::empty(krate);
};
db.trait_environment(def)
}
pub(crate) fn trait_environment_query(
db: &dyn HirDatabase,
def: GenericDefId,
) -> Arc<TraitEnvironment> {
let resolver = def.resolver(db.upcast());
let mut ctx = if let GenericDefId::FunctionId(_) = def {
TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Param)
.with_type_param_mode(ParamLoweringMode::Placeholder)
} else {
TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
.with_type_param_mode(ParamLoweringMode::Placeholder)
};
let mut traits_in_scope = Vec::new();
let mut clauses = Vec::new();
for (params, def) in resolver.all_generic_params() {
ctx.types_map = &params.types_map;
for pred in params.where_predicates() {
for pred in ctx.lower_where_predicate(pred, def, false) {
if let WhereClause::Implemented(tr) = pred.skip_binders() {
traits_in_scope
.push((tr.self_type_parameter(Interner).clone(), tr.hir_trait_id()));
}
let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(Interner);
clauses.push(program_clause.into_from_env_clause(Interner));
}
}
}
if let Some(trait_id) = def.assoc_trait_container(db.upcast()) {
// 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 substs = TyBuilder::placeholder_subst(db, trait_id);
let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
let pred = WhereClause::Implemented(trait_ref);
clauses.push(pred.cast::<ProgramClause>(Interner).into_from_env_clause(Interner));
}
let subst = generics(db.upcast(), def).placeholder_subst(db);
if !subst.is_empty(Interner) {
let explicitly_unsized_tys = ctx.unsized_types;
if let Some(implicitly_sized_clauses) =
implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver)
{
clauses.extend(
implicitly_sized_clauses.map(|pred| {
pred.cast::<ProgramClause>(Interner).into_from_env_clause(Interner)
}),
);
};
}
let env = chalk_ir::Environment::new(Interner).add_clauses(Interner, clauses);
TraitEnvironment::new(resolver.krate(), None, traits_in_scope.into_boxed_slice(), env)
}
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct GenericPredicates(Option<Arc<[Binders<QuantifiedWhereClause>]>>);
impl ops::Deref for GenericPredicates {
type Target = [Binders<crate::QuantifiedWhereClause>];
fn deref(&self) -> &Self::Target {
self.0.as_deref().unwrap_or(&[])
}
}
/// Resolve the where clause(s) of an item with generics.
pub(crate) fn generic_predicates_query(
db: &dyn HirDatabase,
def: GenericDefId,
) -> GenericPredicates {
generic_predicates_filtered_by(db, def, |_, _| true)
}
/// Resolve the where clause(s) of an item with generics,
/// except the ones inherited from the parent
pub(crate) fn generic_predicates_without_parent_query(
db: &dyn HirDatabase,
def: GenericDefId,
) -> GenericPredicates {
generic_predicates_filtered_by(db, def, |_, d| *d == def)
}
/// Resolve the where clause(s) of an item with generics,
/// except the ones inherited from the parent
fn generic_predicates_filtered_by<F>(
db: &dyn HirDatabase,
def: GenericDefId,
filter: F,
) -> GenericPredicates
where
F: Fn(&WherePredicate, &GenericDefId) -> bool,
{
let resolver = def.resolver(db.upcast());
let (impl_trait_lowering, param_lowering) = match def {
GenericDefId::FunctionId(_) => {
(ImplTraitLoweringMode::Variable, ParamLoweringMode::Variable)
}
_ => (ImplTraitLoweringMode::Disallowed, ParamLoweringMode::Variable),
};
let mut ctx = TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
.with_impl_trait_mode(impl_trait_lowering)
.with_type_param_mode(param_lowering);
let generics = generics(db.upcast(), def);
let mut predicates = Vec::new();
for (params, def) in resolver.all_generic_params() {
ctx.types_map = &params.types_map;
for pred in params.where_predicates() {
if filter(pred, def) {
predicates.extend(
ctx.lower_where_predicate(pred, def, false)
.map(|p| make_binders(db, &generics, p)),
);
}
}
}
if generics.len() > 0 {
let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
let explicitly_unsized_tys = ctx.unsized_types;
if let Some(implicitly_sized_predicates) =
implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver)
{
predicates.extend(
implicitly_sized_predicates
.map(|p| make_binders(db, &generics, crate::wrap_empty_binders(p))),
);
};
}
GenericPredicates(predicates.is_empty().not().then(|| predicates.into()))
}
/// 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: 'a>(
db: &dyn HirDatabase,
def: GenericDefId,
explicitly_unsized_tys: &'a FxHashSet<Ty>,
substitution: &'subst Substitution,
resolver: &Resolver,
) -> Option<impl Iterator<Item = WhereClause> + Captures<'a> + Captures<'subst>> {
let sized_trait = db
.lang_item(resolver.krate(), LangItem::Sized)
.and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id))?;
let trait_self_idx = trait_self_param_idx(db.upcast(), def);
Some(
substitution
.iter(Interner)
.enumerate()
.filter_map(
move |(idx, generic_arg)| {
if Some(idx) == trait_self_idx {
None
} else {
Some(generic_arg)
}
},
)
.filter_map(|generic_arg| generic_arg.ty(Interner))
.filter(move |&self_ty| !explicitly_unsized_tys.contains(self_ty))
.map(move |self_ty| {
WhereClause::Implemented(TraitRef {
trait_id: sized_trait,
substitution: Substitution::from1(Interner, self_ty.clone()),
})
}),
)
}
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct GenericDefaults(Option<Arc<[Binders<crate::GenericArg>]>>);
impl ops::Deref for GenericDefaults {
type Target = [Binders<crate::GenericArg>];
fn deref(&self) -> &Self::Target {
self.0.as_deref().unwrap_or(&[])
}
}
/// Resolve the default type params from generics
pub(crate) fn generic_defaults_query(db: &dyn HirDatabase, def: GenericDefId) -> GenericDefaults {
let generic_params = generics(db.upcast(), def);
if generic_params.len() == 0 {
return GenericDefaults(None);
}
let resolver = def.resolver(db.upcast());
let parent_start_idx = generic_params.len_self();
let mut ctx = TyLoweringContext::new(db, &resolver, TypesMap::EMPTY, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Disallowed)
.with_type_param_mode(ParamLoweringMode::Variable);
GenericDefaults(Some(Arc::from_iter(generic_params.iter_with_types_map().enumerate().map(
|(idx, ((id, p), types_map))| {
ctx.types_map = types_map;
match p {
GenericParamDataRef::TypeParamData(p) => {
let ty = p.default.as_ref().map_or(TyKind::Error.intern(Interner), |ty| {
// Each default can only refer to previous parameters.
// Type variable default referring to parameter coming
// after it is forbidden (FIXME: report diagnostic)
fallback_bound_vars(ctx.lower_ty(*ty), idx, parent_start_idx)
});
crate::make_binders(db, &generic_params, ty.cast(Interner))
}
GenericParamDataRef::ConstParamData(p) => {
let GenericParamId::ConstParamId(id) = id else {
unreachable!("Unexpected lifetime or type argument")
};
let mut val = p.default.as_ref().map_or_else(
|| unknown_const_as_generic(db.const_param_ty(id)),
|c| {
let param_ty = ctx.lower_ty(p.ty);
let c = ctx.lower_const(c, param_ty);
c.cast(Interner)
},
);
// Each default can only refer to previous parameters, see above.
val = fallback_bound_vars(val, idx, parent_start_idx);
make_binders(db, &generic_params, val)
}
GenericParamDataRef::LifetimeParamData(_) => {
make_binders(db, &generic_params, error_lifetime().cast(Interner))
}
}
},
))))
}
pub(crate) fn generic_defaults_recover(
db: &dyn HirDatabase,
_cycle: &Cycle,
def: &GenericDefId,
) -> GenericDefaults {
let generic_params = generics(db.upcast(), *def);
if generic_params.len() == 0 {
return GenericDefaults(None);
}
// FIXME: this code is not covered in tests.
// we still need one default per parameter
GenericDefaults(Some(Arc::from_iter(generic_params.iter_id().map(|id| {
let val = match id {
GenericParamId::TypeParamId(_) => TyKind::Error.intern(Interner).cast(Interner),
GenericParamId::ConstParamId(id) => unknown_const_as_generic(db.const_param_ty(id)),
GenericParamId::LifetimeParamId(_) => error_lifetime().cast(Interner),
};
crate::make_binders(db, &generic_params, val)
}))))
}
fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
let data = db.function_data(def);
let resolver = def.resolver(db.upcast());
let mut ctx_params = TyLoweringContext::new(db, &resolver, &data.types_map, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Variable)
.with_type_param_mode(ParamLoweringMode::Variable);
let params = data.params.iter().map(|&tr| ctx_params.lower_ty(tr));
let mut ctx_ret = TyLoweringContext::new(db, &resolver, &data.types_map, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
.with_type_param_mode(ParamLoweringMode::Variable);
let ret = ctx_ret.lower_ty(data.ret_type);
let generics = generics(db.upcast(), def.into());
let sig = CallableSig::from_params_and_return(
params,
ret,
data.is_varargs(),
if data.is_unsafe() { Safety::Unsafe } else { Safety::Safe },
data.abi.as_ref().map_or(FnAbi::Rust, FnAbi::from_symbol),
);
make_binders(db, &generics, sig)
}
/// Build the declared type of a function. This should not need to look at the
/// function body.
fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders<Ty> {
let generics = generics(db.upcast(), def.into());
let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
make_binders(
db,
&generics,
TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(Interner),
)
}
/// Build the declared type of a const.
fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders<Ty> {
let data = db.const_data(def);
let generics = generics(db.upcast(), def.into());
let resolver = def.resolver(db.upcast());
let mut ctx = TyLoweringContext::new(db, &resolver, &data.types_map, def.into())
.with_type_param_mode(ParamLoweringMode::Variable);
make_binders(db, &generics, ctx.lower_ty(data.type_ref))
}
/// Build the declared type of a static.
fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders<Ty> {
let data = db.static_data(def);
let resolver = def.resolver(db.upcast());
let mut ctx = TyLoweringContext::new(db, &resolver, &data.types_map, def.into());
Binders::empty(Interner, ctx.lower_ty(data.type_ref))
}
fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig {
let struct_data = db.struct_data(def);
let fields = struct_data.variant_data.fields();
let resolver = def.resolver(db.upcast());
let mut ctx = TyLoweringContext::new(
db,
&resolver,
struct_data.variant_data.types_map(),
AdtId::from(def).into(),
)
.with_type_param_mode(ParamLoweringMode::Variable);
let params = fields.iter().map(|(_, field)| ctx.lower_ty(field.type_ref));
let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
Binders::new(
binders,
CallableSig::from_params_and_return(params, ret, false, Safety::Safe, FnAbi::RustCall),
)
}
/// Build the type of a tuple struct constructor.
fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Option<Binders<Ty>> {
let struct_data = db.struct_data(def);
match struct_data.variant_data.kind() {
StructKind::Record => None,
StructKind::Unit => Some(type_for_adt(db, def.into())),
StructKind::Tuple => {
let generics = generics(db.upcast(), AdtId::from(def).into());
let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
Some(make_binders(
db,
&generics,
TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(Interner),
))
}
}
}
fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig {
let var_data = db.enum_variant_data(def);
let fields = var_data.variant_data.fields();
let resolver = def.resolver(db.upcast());
let mut ctx = TyLoweringContext::new(
db,
&resolver,
var_data.variant_data.types_map(),
DefWithBodyId::VariantId(def).into(),
)
.with_type_param_mode(ParamLoweringMode::Variable);
let params = fields.iter().map(|(_, field)| ctx.lower_ty(field.type_ref));
let (ret, binders) =
type_for_adt(db, def.lookup(db.upcast()).parent.into()).into_value_and_skipped_binders();
Binders::new(
binders,
CallableSig::from_params_and_return(params, ret, false, Safety::Safe, FnAbi::RustCall),
)
}
/// Build the type of a tuple enum variant constructor.
fn type_for_enum_variant_constructor(
db: &dyn HirDatabase,
def: EnumVariantId,
) -> Option<Binders<Ty>> {
let e = def.lookup(db.upcast()).parent;
match db.enum_variant_data(def).variant_data.kind() {
StructKind::Record => None,
StructKind::Unit => Some(type_for_adt(db, e.into())),
StructKind::Tuple => {
let generics = generics(db.upcast(), e.into());
let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
Some(make_binders(
db,
&generics,
TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs)
.intern(Interner),
))
}
}
}
fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
let generics = generics(db.upcast(), adt.into());
let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
let ty = TyKind::Adt(crate::AdtId(adt), subst).intern(Interner);
make_binders(db, &generics, ty)
}
fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
let generics = generics(db.upcast(), t.into());
let resolver = t.resolver(db.upcast());
let type_alias_data = db.type_alias_data(t);
let mut ctx = TyLoweringContext::new(db, &resolver, &type_alias_data.types_map, t.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
.with_type_param_mode(ParamLoweringMode::Variable);
let inner = if type_alias_data.is_extern {
TyKind::Foreign(crate::to_foreign_def_id(t)).intern(Interner)
} else {
type_alias_data
.type_ref
.map(|type_ref| ctx.lower_ty(type_ref))
.unwrap_or_else(|| TyKind::Error.intern(Interner))
};
make_binders(db, &generics, inner)
}
#[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)]
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) -> Option<GenericDefId> {
match self {
Self::FunctionId(id) => Some(id.into()),
Self::StructId(id) => Some(id.into()),
Self::UnionId(id) => Some(id.into()),
Self::EnumVariantId(var) => Some(var.lookup(db.upcast()).parent.into()),
Self::ConstId(id) => Some(id.into()),
Self::StaticId(_) => None,
}
}
}
/// 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: &dyn HirDatabase, def: TyDefId) -> Binders<Ty> {
match def {
TyDefId::BuiltinType(it) => Binders::empty(Interner, TyBuilder::builtin(it)),
TyDefId::AdtId(it) => type_for_adt(db, it),
TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
}
}
pub(crate) fn ty_recover(db: &dyn HirDatabase, _cycle: &Cycle, def: &TyDefId) -> Binders<Ty> {
let generics = match *def {
TyDefId::BuiltinType(_) => return Binders::empty(Interner, TyKind::Error.intern(Interner)),
TyDefId::AdtId(it) => generics(db.upcast(), it.into()),
TyDefId::TypeAliasId(it) => generics(db.upcast(), it.into()),
};
make_binders(db, &generics, TyKind::Error.intern(Interner))
}
pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Option<Binders<Ty>> {
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 impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders<Ty> {
let impl_data = db.impl_data(impl_id);
let resolver = impl_id.resolver(db.upcast());
let generics = generics(db.upcast(), impl_id.into());
let mut ctx = TyLoweringContext::new(db, &resolver, &impl_data.types_map, impl_id.into())
.with_type_param_mode(ParamLoweringMode::Variable);
make_binders(db, &generics, ctx.lower_ty(impl_data.self_ty))
}
// returns None if def is a type arg
pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
let parent_data = db.generic_params(def.parent());
let data = &parent_data[def.local_id()];
let resolver = def.parent().resolver(db.upcast());
let mut ctx =
TyLoweringContext::new(db, &resolver, &parent_data.types_map, def.parent().into());
match data {
TypeOrConstParamData::TypeParamData(_) => {
never!();
Ty::new(Interner, TyKind::Error)
}
TypeOrConstParamData::ConstParamData(d) => ctx.lower_ty(d.ty),
}
}
pub(crate) fn impl_self_ty_recover(
db: &dyn HirDatabase,
_cycle: &Cycle,
impl_id: &ImplId,
) -> Binders<Ty> {
let generics = generics(db.upcast(), (*impl_id).into());
make_binders(db, &generics, TyKind::Error.intern(Interner))
}
pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<Binders<TraitRef>> {
let impl_data = db.impl_data(impl_id);
let resolver = impl_id.resolver(db.upcast());
let mut ctx = TyLoweringContext::new(db, &resolver, &impl_data.types_map, impl_id.into())
.with_type_param_mode(ParamLoweringMode::Variable);
let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders();
let target_trait = impl_data.target_trait.as_ref()?;
Some(Binders::new(binders, ctx.lower_trait_ref(target_trait, self_ty)?))
}
pub(crate) fn return_type_impl_traits(
db: &dyn HirDatabase,
def: hir_def::FunctionId,
) -> Option<Arc<Binders<ImplTraits>>> {
// FIXME unify with fn_sig_for_fn instead of doing lowering twice, maybe
let data = db.function_data(def);
let resolver = def.resolver(db.upcast());
let mut ctx_ret = TyLoweringContext::new(db, &resolver, &data.types_map, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
.with_type_param_mode(ParamLoweringMode::Variable);
let _ret = ctx_ret.lower_ty(data.ret_type);
let generics = generics(db.upcast(), def.into());
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(make_binders(db, &generics, return_type_impl_traits)))
}
}
pub(crate) fn type_alias_impl_traits(
db: &dyn HirDatabase,
def: hir_def::TypeAliasId,
) -> Option<Arc<Binders<ImplTraits>>> {
let data = db.type_alias_data(def);
let resolver = def.resolver(db.upcast());
let mut ctx = TyLoweringContext::new(db, &resolver, &data.types_map, def.into())
.with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
.with_type_param_mode(ParamLoweringMode::Variable);
if let Some(type_ref) = data.type_ref {
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 {
let generics = generics(db.upcast(), def.into());
Some(Arc::new(make_binders(db, &generics, type_alias_impl_traits)))
}
}
pub(crate) fn lower_to_chalk_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,
}
}
/// Checks if the provided generic arg matches its expected kind, then lower them via
/// provided closures. Use unknown if there was kind mismatch.
///
pub(crate) fn generic_arg_to_chalk<'a, T>(
db: &dyn HirDatabase,
kind_id: GenericParamId,
arg: &'a GenericArg,
this: &mut T,
types_map: &TypesMap,
for_type: impl FnOnce(&mut T, TypeRefId) -> Ty + 'a,
for_const: impl FnOnce(&mut T, &ConstRef, Ty) -> Const + 'a,
for_lifetime: impl FnOnce(&mut T, &LifetimeRef) -> Lifetime + 'a,
) -> crate::GenericArg {
let kind = match kind_id {
GenericParamId::TypeParamId(_) => ParamKind::Type,
GenericParamId::ConstParamId(id) => {
let ty = db.const_param_ty(id);
ParamKind::Const(ty)
}
GenericParamId::LifetimeParamId(_) => ParamKind::Lifetime,
};
match (arg, kind) {
(GenericArg::Type(type_ref), ParamKind::Type) => for_type(this, *type_ref).cast(Interner),
(GenericArg::Const(c), ParamKind::Const(c_ty)) => for_const(this, c, c_ty).cast(Interner),
(GenericArg::Lifetime(lifetime_ref), ParamKind::Lifetime) => {
for_lifetime(this, lifetime_ref).cast(Interner)
}
(GenericArg::Const(_), ParamKind::Type) => TyKind::Error.intern(Interner).cast(Interner),
(GenericArg::Lifetime(_), ParamKind::Type) => TyKind::Error.intern(Interner).cast(Interner),
(GenericArg::Type(t), ParamKind::Const(c_ty)) => {
// We want to recover simple idents, which parser detects them
// as types. Maybe here is not the best place to do it, but
// it works.
if let TypeRef::Path(p) = &types_map[*t] {
if let Some(p) = p.mod_path() {
if p.kind == PathKind::Plain {
if let [n] = p.segments() {
let c = ConstRef::Path(n.clone());
return for_const(this, &c, c_ty).cast(Interner);
}
}
}
}
unknown_const_as_generic(c_ty)
}
(GenericArg::Lifetime(_), ParamKind::Const(c_ty)) => unknown_const_as_generic(c_ty),
(GenericArg::Type(_), ParamKind::Lifetime) => error_lifetime().cast(Interner),
(GenericArg::Const(_), ParamKind::Lifetime) => error_lifetime().cast(Interner),
}
}
pub(crate) fn const_or_path_to_chalk<'g>(
db: &dyn HirDatabase,
resolver: &Resolver,
owner: TypeOwnerId,
expected_ty: Ty,
value: &ConstRef,
mode: ParamLoweringMode,
args: impl FnOnce() -> Option<&'g Generics>,
debruijn: DebruijnIndex,
) -> Const {
match value {
ConstRef::Scalar(s) => intern_const_ref(db, s, expected_ty, resolver.krate()),
ConstRef::Path(n) => {
let path = ModPath::from_segments(PathKind::Plain, Some(n.clone()));
path_to_const(
db,
resolver,
&Path::from_known_path_with_no_generic(path),
mode,
args,
debruijn,
expected_ty.clone(),
)
.unwrap_or_else(|| unknown_const(expected_ty))
}
&ConstRef::Complex(it) => {
let crate_data = &db.crate_graph()[resolver.krate()];
if crate_data.env.get("__ra_is_test_fixture").is_none() && crate_data.origin.is_local()
{
// FIXME: current `InTypeConstId` is very unstable, so we only use it in non local crate
// that are unlikely to be edited.
return unknown_const(expected_ty);
}
let c = db
.intern_in_type_const(InTypeConstLoc {
id: it,
owner,
expected_ty: Box::new(InTypeConstIdMetadata(expected_ty.clone())),
})
.into();
intern_const_scalar(
ConstScalar::UnevaluatedConst(c, Substitution::empty(Interner)),
expected_ty,
)
}
}
}
/// Replaces any 'free' `BoundVar`s in `s` by `TyKind::Error` from the perspective of generic
/// parameter whose index is `param_index`. A `BoundVar` is free when it is or (syntactically)
/// appears after the generic parameter of `param_index`.
fn fallback_bound_vars<T: TypeFoldable<Interner> + HasInterner<Interner = Interner>>(
s: T,
param_index: usize,
parent_start: usize,
) -> T {
// Keep in mind that parent generic parameters, if any, come *after* those of the item in
// question. In the diagrams below, `c*` and `p*` represent generic parameters of the item and
// its parent respectively.
let is_allowed = |index| {
if param_index < parent_start {
// The parameter of `param_index` is one from the item in question. Any parent generic
// parameters or the item's generic parameters that come before `param_index` is
// allowed.
// [c1, .., cj, .., ck, p1, .., pl] where cj is `param_index`
// ^^^^^^ ^^^^^^^^^^ these are allowed
!(param_index..parent_start).contains(&index)
} else {
// The parameter of `param_index` is one from the parent generics. Only parent generic
// parameters that come before `param_index` are allowed.
// [c1, .., ck, p1, .., pj, .., pl] where pj is `param_index`
// ^^^^^^ these are allowed
(parent_start..param_index).contains(&index)
}
};
crate::fold_free_vars(
s,
|bound, binders| {
if bound.index_if_innermost().map_or(true, is_allowed) {
bound.shifted_in_from(binders).to_ty(Interner)
} else {
TyKind::Error.intern(Interner)
}
},
|ty, bound, binders| {
if bound.index_if_innermost().map_or(true, is_allowed) {
bound.shifted_in_from(binders).to_const(Interner, ty)
} else {
unknown_const(ty)
}
},
)
}
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