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rust-analyzer/crates/hir-ty/src/method_resolution.rs
dfireBird 8a4261aca8
implement basic inferring of lifetimes
2024-08-16 16:40:32 +05:30

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//! This module is concerned with finding methods that a given type provides.
//! For details about how this works in rustc, see the method lookup page in the
//! [rustc guide](https://rust-lang.github.io/rustc-guide/method-lookup.html)
//! and the corresponding code mostly in rustc_hir_analysis/check/method/probe.rs.
use std::ops::ControlFlow;
use base_db::CrateId;
use chalk_ir::{cast::Cast, UniverseIndex, WithKind};
use hir_def::{
data::{adt::StructFlags, ImplData},
nameres::DefMap,
AssocItemId, BlockId, ConstId, FunctionId, HasModule, ImplId, ItemContainerId, Lookup,
ModuleId, TraitId,
};
use hir_expand::name::Name;
use intern::sym;
use rustc_hash::{FxHashMap, FxHashSet};
use smallvec::{smallvec, SmallVec};
use stdx::never;
use triomphe::Arc;
use crate::{
autoderef::{self, AutoderefKind},
db::HirDatabase,
error_lifetime, from_chalk_trait_id, from_foreign_def_id,
infer::{unify::InferenceTable, Adjust, Adjustment, OverloadedDeref, PointerCast},
lang_items::is_box,
primitive::{FloatTy, IntTy, UintTy},
to_chalk_trait_id,
utils::all_super_traits,
AdtId, Canonical, CanonicalVarKinds, DebruijnIndex, DynTyExt, ForeignDefId, GenericArgData,
Goal, Guidance, InEnvironment, Interner, Mutability, Scalar, Solution, Substitution,
TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyExt, TyKind, TyVariableKind,
VariableKind, WhereClause,
};
/// This is used as a key for indexing impls.
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub enum TyFingerprint {
// These are lang item impls:
Str,
Slice,
Array,
Never,
RawPtr(Mutability),
Scalar(Scalar),
// These can have user-defined impls:
Adt(hir_def::AdtId),
Dyn(TraitId),
ForeignType(ForeignDefId),
// These only exist for trait impls
Unit,
Unnameable,
Function(u32),
}
impl TyFingerprint {
/// Creates a TyFingerprint for looking up an inherent impl. Only certain
/// types can have inherent impls: if we have some `struct S`, we can have
/// an `impl S`, but not `impl &S`. Hence, this will return `None` for
/// reference types and such.
pub fn for_inherent_impl(ty: &Ty) -> Option<TyFingerprint> {
let fp = match ty.kind(Interner) {
TyKind::Str => TyFingerprint::Str,
TyKind::Never => TyFingerprint::Never,
TyKind::Slice(..) => TyFingerprint::Slice,
TyKind::Array(..) => TyFingerprint::Array,
TyKind::Scalar(scalar) => TyFingerprint::Scalar(*scalar),
TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt),
TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability),
TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id),
TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?,
_ => return None,
};
Some(fp)
}
/// Creates a TyFingerprint for looking up a trait impl.
pub fn for_trait_impl(ty: &Ty) -> Option<TyFingerprint> {
let fp = match ty.kind(Interner) {
TyKind::Str => TyFingerprint::Str,
TyKind::Never => TyFingerprint::Never,
TyKind::Slice(..) => TyFingerprint::Slice,
TyKind::Array(..) => TyFingerprint::Array,
TyKind::Scalar(scalar) => TyFingerprint::Scalar(*scalar),
TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt),
TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability),
TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id),
TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?,
TyKind::Ref(_, _, ty) => return TyFingerprint::for_trait_impl(ty),
TyKind::Tuple(_, subst) => {
let first_ty = subst.interned().first().map(|arg| arg.assert_ty_ref(Interner));
match first_ty {
Some(ty) => return TyFingerprint::for_trait_impl(ty),
None => TyFingerprint::Unit,
}
}
TyKind::AssociatedType(_, _)
| TyKind::OpaqueType(_, _)
| TyKind::FnDef(_, _)
| TyKind::Closure(_, _)
| TyKind::Coroutine(..)
| TyKind::CoroutineWitness(..) => TyFingerprint::Unnameable,
TyKind::Function(fn_ptr) => {
TyFingerprint::Function(fn_ptr.substitution.0.len(Interner) as u32)
}
TyKind::Alias(_)
| TyKind::Placeholder(_)
| TyKind::BoundVar(_)
| TyKind::InferenceVar(_, _)
| TyKind::Error => return None,
};
Some(fp)
}
}
pub(crate) const ALL_INT_FPS: [TyFingerprint; 12] = [
TyFingerprint::Scalar(Scalar::Int(IntTy::I8)),
TyFingerprint::Scalar(Scalar::Int(IntTy::I16)),
TyFingerprint::Scalar(Scalar::Int(IntTy::I32)),
TyFingerprint::Scalar(Scalar::Int(IntTy::I64)),
TyFingerprint::Scalar(Scalar::Int(IntTy::I128)),
TyFingerprint::Scalar(Scalar::Int(IntTy::Isize)),
TyFingerprint::Scalar(Scalar::Uint(UintTy::U8)),
TyFingerprint::Scalar(Scalar::Uint(UintTy::U16)),
TyFingerprint::Scalar(Scalar::Uint(UintTy::U32)),
TyFingerprint::Scalar(Scalar::Uint(UintTy::U64)),
TyFingerprint::Scalar(Scalar::Uint(UintTy::U128)),
TyFingerprint::Scalar(Scalar::Uint(UintTy::Usize)),
];
pub(crate) const ALL_FLOAT_FPS: [TyFingerprint; 4] = [
TyFingerprint::Scalar(Scalar::Float(FloatTy::F16)),
TyFingerprint::Scalar(Scalar::Float(FloatTy::F32)),
TyFingerprint::Scalar(Scalar::Float(FloatTy::F64)),
TyFingerprint::Scalar(Scalar::Float(FloatTy::F128)),
];
type TraitFpMap = FxHashMap<TraitId, FxHashMap<Option<TyFingerprint>, Box<[ImplId]>>>;
type TraitFpMapCollector = FxHashMap<TraitId, FxHashMap<Option<TyFingerprint>, Vec<ImplId>>>;
/// Trait impls defined or available in some crate.
#[derive(Debug, Eq, PartialEq)]
pub struct TraitImpls {
// If the `Option<TyFingerprint>` is `None`, the impl may apply to any self type.
map: TraitFpMap,
}
impl TraitImpls {
pub(crate) fn trait_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> {
let _p = tracing::info_span!("trait_impls_in_crate_query", ?krate).entered();
let mut impls = FxHashMap::default();
Self::collect_def_map(db, &mut impls, &db.crate_def_map(krate));
Arc::new(Self::finish(impls))
}
pub(crate) fn trait_impls_in_block_query(
db: &dyn HirDatabase,
block: BlockId,
) -> Option<Arc<Self>> {
let _p = tracing::info_span!("trait_impls_in_block_query").entered();
let mut impls = FxHashMap::default();
Self::collect_def_map(db, &mut impls, &db.block_def_map(block));
if impls.is_empty() {
None
} else {
Some(Arc::new(Self::finish(impls)))
}
}
pub(crate) fn trait_impls_in_deps_query(
db: &dyn HirDatabase,
krate: CrateId,
) -> Arc<[Arc<Self>]> {
let _p = tracing::info_span!("trait_impls_in_deps_query", ?krate).entered();
let crate_graph = db.crate_graph();
Arc::from_iter(
crate_graph.transitive_deps(krate).map(|krate| db.trait_impls_in_crate(krate)),
)
}
fn finish(map: TraitFpMapCollector) -> TraitImpls {
TraitImpls {
map: map
.into_iter()
.map(|(k, v)| (k, v.into_iter().map(|(k, v)| (k, v.into_boxed_slice())).collect()))
.collect(),
}
}
fn collect_def_map(db: &dyn HirDatabase, map: &mut TraitFpMapCollector, def_map: &DefMap) {
for (_module_id, module_data) in def_map.modules() {
for impl_id in module_data.scope.impls() {
// Reservation impls should be ignored during trait resolution, so we never need
// them during type analysis. See rust-lang/rust#64631 for details.
//
// FIXME: Reservation impls should be considered during coherence checks. If we are
// (ever) to implement coherence checks, this filtering should be done by the trait
// solver.
if db.attrs(impl_id.into()).by_key(&sym::rustc_reservation_impl).exists() {
continue;
}
let target_trait = match db.impl_trait(impl_id) {
Some(tr) => tr.skip_binders().hir_trait_id(),
None => continue,
};
let self_ty = db.impl_self_ty(impl_id);
let self_ty_fp = TyFingerprint::for_trait_impl(self_ty.skip_binders());
map.entry(target_trait).or_default().entry(self_ty_fp).or_default().push(impl_id);
}
// To better support custom derives, collect impls in all unnamed const items.
// const _: () = { ... };
for konst in module_data.scope.unnamed_consts() {
let body = db.body(konst.into());
for (_, block_def_map) in body.blocks(db.upcast()) {
Self::collect_def_map(db, map, &block_def_map);
}
}
}
}
/// Queries all trait impls for the given type.
pub fn for_self_ty_without_blanket_impls(
&self,
fp: TyFingerprint,
) -> impl Iterator<Item = ImplId> + '_ {
self.map
.values()
.flat_map(move |impls| impls.get(&Some(fp)).into_iter())
.flat_map(|it| it.iter().copied())
}
/// Queries all impls of the given trait.
pub fn for_trait(&self, trait_: TraitId) -> impl Iterator<Item = ImplId> + '_ {
self.map
.get(&trait_)
.into_iter()
.flat_map(|map| map.values().flat_map(|v| v.iter().copied()))
}
/// Queries all impls of `trait_` that may apply to `self_ty`.
pub fn for_trait_and_self_ty(
&self,
trait_: TraitId,
self_ty: TyFingerprint,
) -> impl Iterator<Item = ImplId> + '_ {
self.map
.get(&trait_)
.into_iter()
.flat_map(move |map| map.get(&Some(self_ty)).into_iter().chain(map.get(&None)))
.flat_map(|v| v.iter().copied())
}
/// Queries whether `self_ty` has potentially applicable implementations of `trait_`.
pub fn has_impls_for_trait_and_self_ty(&self, trait_: TraitId, self_ty: TyFingerprint) -> bool {
self.for_trait_and_self_ty(trait_, self_ty).next().is_some()
}
pub fn all_impls(&self) -> impl Iterator<Item = ImplId> + '_ {
self.map.values().flat_map(|map| map.values().flat_map(|v| v.iter().copied()))
}
}
/// Inherent impls defined in some crate.
///
/// Inherent impls can only be defined in the crate that also defines the self type of the impl
/// (note that some primitives are considered to be defined by both libcore and liballoc).
///
/// This makes inherent impl lookup easier than trait impl lookup since we only have to consider a
/// single crate.
#[derive(Debug, Eq, PartialEq)]
pub struct InherentImpls {
map: FxHashMap<TyFingerprint, Vec<ImplId>>,
invalid_impls: Vec<ImplId>,
}
impl InherentImpls {
pub(crate) fn inherent_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> {
let _p = tracing::info_span!("inherent_impls_in_crate_query", ?krate).entered();
let mut impls = Self { map: FxHashMap::default(), invalid_impls: Vec::default() };
let crate_def_map = db.crate_def_map(krate);
impls.collect_def_map(db, &crate_def_map);
impls.shrink_to_fit();
Arc::new(impls)
}
pub(crate) fn inherent_impls_in_block_query(
db: &dyn HirDatabase,
block: BlockId,
) -> Option<Arc<Self>> {
let _p = tracing::info_span!("inherent_impls_in_block_query").entered();
let mut impls = Self { map: FxHashMap::default(), invalid_impls: Vec::default() };
let block_def_map = db.block_def_map(block);
impls.collect_def_map(db, &block_def_map);
impls.shrink_to_fit();
if impls.map.is_empty() && impls.invalid_impls.is_empty() {
None
} else {
Some(Arc::new(impls))
}
}
fn shrink_to_fit(&mut self) {
self.map.values_mut().for_each(Vec::shrink_to_fit);
self.map.shrink_to_fit();
}
fn collect_def_map(&mut self, db: &dyn HirDatabase, def_map: &DefMap) {
for (_module_id, module_data) in def_map.modules() {
for impl_id in module_data.scope.impls() {
let data = db.impl_data(impl_id);
if data.target_trait.is_some() {
continue;
}
let self_ty = db.impl_self_ty(impl_id);
let self_ty = self_ty.skip_binders();
match is_inherent_impl_coherent(db, def_map, &data, self_ty) {
true => {
// `fp` should only be `None` in error cases (either erroneous code or incomplete name resolution)
if let Some(fp) = TyFingerprint::for_inherent_impl(self_ty) {
self.map.entry(fp).or_default().push(impl_id);
}
}
false => self.invalid_impls.push(impl_id),
}
}
// To better support custom derives, collect impls in all unnamed const items.
// const _: () = { ... };
for konst in module_data.scope.unnamed_consts() {
let body = db.body(konst.into());
for (_, block_def_map) in body.blocks(db.upcast()) {
self.collect_def_map(db, &block_def_map);
}
}
}
}
pub fn for_self_ty(&self, self_ty: &Ty) -> &[ImplId] {
match TyFingerprint::for_inherent_impl(self_ty) {
Some(fp) => self.map.get(&fp).map(|vec| vec.as_ref()).unwrap_or(&[]),
None => &[],
}
}
pub fn all_impls(&self) -> impl Iterator<Item = ImplId> + '_ {
self.map.values().flat_map(|v| v.iter().copied())
}
pub fn invalid_impls(&self) -> &[ImplId] {
&self.invalid_impls
}
}
pub(crate) fn incoherent_inherent_impl_crates(
db: &dyn HirDatabase,
krate: CrateId,
fp: TyFingerprint,
) -> SmallVec<[CrateId; 2]> {
let _p = tracing::info_span!("incoherent_inherent_impl_crates").entered();
let mut res = SmallVec::new();
let crate_graph = db.crate_graph();
// should pass crate for finger print and do reverse deps
for krate in crate_graph.transitive_deps(krate) {
let impls = db.inherent_impls_in_crate(krate);
if impls.map.get(&fp).map_or(false, |v| !v.is_empty()) {
res.push(krate);
}
}
res
}
pub fn def_crates(
db: &dyn HirDatabase,
ty: &Ty,
cur_crate: CrateId,
) -> Option<SmallVec<[CrateId; 2]>> {
match ty.kind(Interner) {
&TyKind::Adt(AdtId(def_id), _) => {
let rustc_has_incoherent_inherent_impls = match def_id {
hir_def::AdtId::StructId(id) => db
.struct_data(id)
.flags
.contains(StructFlags::IS_RUSTC_HAS_INCOHERENT_INHERENT_IMPL),
hir_def::AdtId::UnionId(id) => db
.union_data(id)
.flags
.contains(StructFlags::IS_RUSTC_HAS_INCOHERENT_INHERENT_IMPL),
hir_def::AdtId::EnumId(id) => db.enum_data(id).rustc_has_incoherent_inherent_impls,
};
Some(if rustc_has_incoherent_inherent_impls {
db.incoherent_inherent_impl_crates(cur_crate, TyFingerprint::Adt(def_id))
} else {
smallvec![def_id.module(db.upcast()).krate()]
})
}
&TyKind::Foreign(id) => {
let alias = from_foreign_def_id(id);
Some(if db.type_alias_data(alias).rustc_has_incoherent_inherent_impls {
db.incoherent_inherent_impl_crates(cur_crate, TyFingerprint::ForeignType(id))
} else {
smallvec![alias.module(db.upcast()).krate()]
})
}
TyKind::Dyn(_) => {
let trait_id = ty.dyn_trait()?;
Some(if db.trait_data(trait_id).rustc_has_incoherent_inherent_impls {
db.incoherent_inherent_impl_crates(cur_crate, TyFingerprint::Dyn(trait_id))
} else {
smallvec![trait_id.module(db.upcast()).krate()]
})
}
// for primitives, there may be impls in various places (core and alloc
// mostly). We just check the whole crate graph for crates with impls
// (cached behind a query).
TyKind::Scalar(_)
| TyKind::Str
| TyKind::Slice(_)
| TyKind::Array(..)
| TyKind::Raw(..) => Some(db.incoherent_inherent_impl_crates(
cur_crate,
TyFingerprint::for_inherent_impl(ty).expect("fingerprint for primitive"),
)),
_ => None,
}
}
/// Look up the method with the given name.
pub(crate) fn lookup_method(
db: &dyn HirDatabase,
ty: &Canonical<Ty>,
env: Arc<TraitEnvironment>,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: &Name,
) -> Option<(ReceiverAdjustments, FunctionId, bool)> {
let mut not_visible = None;
let res = iterate_method_candidates(
ty,
db,
env,
traits_in_scope,
visible_from_module,
Some(name),
LookupMode::MethodCall,
|adjustments, f, visible| match f {
AssocItemId::FunctionId(f) if visible => Some((adjustments, f, true)),
AssocItemId::FunctionId(f) if not_visible.is_none() => {
not_visible = Some((adjustments, f, false));
None
}
_ => None,
},
);
res.or(not_visible)
}
/// Whether we're looking up a dotted method call (like `v.len()`) or a path
/// (like `Vec::new`).
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum LookupMode {
/// Looking up a method call like `v.len()`: We only consider candidates
/// that have a `self` parameter, and do autoderef.
MethodCall,
/// Looking up a path like `Vec::new` or `Vec::default`: We consider all
/// candidates including associated constants, but don't do autoderef.
Path,
}
#[derive(Clone, Copy)]
pub enum VisibleFromModule {
/// Filter for results that are visible from the given module
Filter(ModuleId),
/// Include impls from the given block.
IncludeBlock(BlockId),
/// Do nothing special in regards visibility
None,
}
impl From<Option<ModuleId>> for VisibleFromModule {
fn from(module: Option<ModuleId>) -> Self {
match module {
Some(module) => Self::Filter(module),
None => Self::None,
}
}
}
impl From<Option<BlockId>> for VisibleFromModule {
fn from(block: Option<BlockId>) -> Self {
match block {
Some(block) => Self::IncludeBlock(block),
None => Self::None,
}
}
}
#[derive(Debug, Clone, Default)]
pub struct ReceiverAdjustments {
autoref: Option<Mutability>,
autoderefs: usize,
unsize_array: bool,
}
impl ReceiverAdjustments {
pub(crate) fn apply(&self, table: &mut InferenceTable<'_>, ty: Ty) -> (Ty, Vec<Adjustment>) {
let mut ty = table.resolve_ty_shallow(&ty);
let mut adjust = Vec::new();
for _ in 0..self.autoderefs {
match autoderef::autoderef_step(table, ty.clone(), true) {
None => {
never!("autoderef not possible for {:?}", ty);
ty = TyKind::Error.intern(Interner);
break;
}
Some((kind, new_ty)) => {
ty = new_ty.clone();
adjust.push(Adjustment {
kind: Adjust::Deref(match kind {
// FIXME should we know the mutability here, when autoref is `None`?
AutoderefKind::Overloaded => Some(OverloadedDeref(self.autoref)),
AutoderefKind::Builtin => None,
}),
target: new_ty,
});
}
}
}
if let Some(m) = self.autoref {
let lt = table.new_lifetime_var();
let a = Adjustment::borrow(m, ty, lt);
ty = a.target.clone();
adjust.push(a);
}
if self.unsize_array {
ty = 'it: {
if let TyKind::Ref(m, l, inner) = ty.kind(Interner) {
if let TyKind::Array(inner, _) = inner.kind(Interner) {
break 'it TyKind::Ref(
*m,
l.clone(),
TyKind::Slice(inner.clone()).intern(Interner),
)
.intern(Interner);
}
}
// FIXME: report diagnostic if array unsizing happens without indirection.
ty
};
adjust.push(Adjustment {
kind: Adjust::Pointer(PointerCast::Unsize),
target: ty.clone(),
});
}
(ty, adjust)
}
fn with_autoref(&self, m: Mutability) -> ReceiverAdjustments {
Self { autoref: Some(m), ..*self }
}
}
// This would be nicer if it just returned an iterator, but that runs into
// lifetime problems, because we need to borrow temp `CrateImplDefs`.
// FIXME add a context type here?
pub(crate) fn iterate_method_candidates<T>(
ty: &Canonical<Ty>,
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: Option<&Name>,
mode: LookupMode,
mut callback: impl FnMut(ReceiverAdjustments, AssocItemId, bool) -> Option<T>,
) -> Option<T> {
let mut slot = None;
iterate_method_candidates_dyn(
ty,
db,
env,
traits_in_scope,
visible_from_module,
name,
mode,
&mut |adj, item, visible| {
assert!(slot.is_none());
if let Some(it) = callback(adj, item, visible) {
slot = Some(it);
return ControlFlow::Break(());
}
ControlFlow::Continue(())
},
);
slot
}
pub fn lookup_impl_const(
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
const_id: ConstId,
subs: Substitution,
) -> (ConstId, Substitution) {
let trait_id = match const_id.lookup(db.upcast()).container {
ItemContainerId::TraitId(id) => id,
_ => return (const_id, subs),
};
let substitution = Substitution::from_iter(Interner, subs.iter(Interner));
let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution };
let const_data = db.const_data(const_id);
let name = match const_data.name.as_ref() {
Some(name) => name,
None => return (const_id, subs),
};
lookup_impl_assoc_item_for_trait_ref(trait_ref, db, env, name)
.and_then(
|assoc| if let (AssocItemId::ConstId(id), s) = assoc { Some((id, s)) } else { None },
)
.unwrap_or((const_id, subs))
}
/// Checks if the self parameter of `Trait` method is the `dyn Trait` and we should
/// call the method using the vtable.
pub fn is_dyn_method(
db: &dyn HirDatabase,
_env: Arc<TraitEnvironment>,
func: FunctionId,
fn_subst: Substitution,
) -> Option<usize> {
let ItemContainerId::TraitId(trait_id) = func.lookup(db.upcast()).container else {
return None;
};
let trait_params = db.generic_params(trait_id.into()).len();
let fn_params = fn_subst.len(Interner) - trait_params;
let trait_ref = TraitRef {
trait_id: to_chalk_trait_id(trait_id),
substitution: Substitution::from_iter(Interner, fn_subst.iter(Interner).skip(fn_params)),
};
let self_ty = trait_ref.self_type_parameter(Interner);
if let TyKind::Dyn(d) = self_ty.kind(Interner) {
let is_my_trait_in_bounds = d
.bounds
.skip_binders()
.as_slice(Interner)
.iter()
.map(|it| it.skip_binders())
.flat_map(|it| match it {
WhereClause::Implemented(tr) => {
all_super_traits(db.upcast(), from_chalk_trait_id(tr.trait_id))
}
_ => smallvec![],
})
// rustc doesn't accept `impl Foo<2> for dyn Foo<5>`, so if the trait id is equal, no matter
// what the generics are, we are sure that the method is come from the vtable.
.any(|x| x == trait_id);
if is_my_trait_in_bounds {
return Some(fn_params);
}
}
None
}
/// Looks up the impl method that actually runs for the trait method `func`.
///
/// Returns `func` if it's not a method defined in a trait or the lookup failed.
pub(crate) fn lookup_impl_method_query(
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
func: FunctionId,
fn_subst: Substitution,
) -> (FunctionId, Substitution) {
let ItemContainerId::TraitId(trait_id) = func.lookup(db.upcast()).container else {
return (func, fn_subst);
};
let trait_params = db.generic_params(trait_id.into()).len();
let fn_params = fn_subst.len(Interner) - trait_params;
let trait_ref = TraitRef {
trait_id: to_chalk_trait_id(trait_id),
substitution: Substitution::from_iter(Interner, fn_subst.iter(Interner).skip(fn_params)),
};
let name = &db.function_data(func).name;
let Some((impl_fn, impl_subst)) =
lookup_impl_assoc_item_for_trait_ref(trait_ref, db, env, name).and_then(|assoc| {
if let (AssocItemId::FunctionId(id), subst) = assoc {
Some((id, subst))
} else {
None
}
})
else {
return (func, fn_subst);
};
(
impl_fn,
Substitution::from_iter(
Interner,
fn_subst.iter(Interner).take(fn_params).chain(impl_subst.iter(Interner)),
),
)
}
fn lookup_impl_assoc_item_for_trait_ref(
trait_ref: TraitRef,
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
name: &Name,
) -> Option<(AssocItemId, Substitution)> {
let hir_trait_id = trait_ref.hir_trait_id();
let self_ty = trait_ref.self_type_parameter(Interner);
let self_ty_fp = TyFingerprint::for_trait_impl(&self_ty)?;
let impls = db.trait_impls_in_deps(env.krate);
let self_impls = match self_ty.kind(Interner) {
TyKind::Adt(id, _) => {
id.0.module(db.upcast()).containing_block().and_then(|it| db.trait_impls_in_block(it))
}
_ => None,
};
let impls = impls
.iter()
.chain(self_impls.as_ref())
.flat_map(|impls| impls.for_trait_and_self_ty(hir_trait_id, self_ty_fp));
let table = InferenceTable::new(db, env);
let (impl_data, impl_subst) = find_matching_impl(impls, table, trait_ref)?;
let item = impl_data.items.iter().find_map(|&it| match it {
AssocItemId::FunctionId(f) => {
(db.function_data(f).name == *name).then_some(AssocItemId::FunctionId(f))
}
AssocItemId::ConstId(c) => db
.const_data(c)
.name
.as_ref()
.map(|n| n == name)
.and_then(|result| if result { Some(AssocItemId::ConstId(c)) } else { None }),
AssocItemId::TypeAliasId(_) => None,
})?;
Some((item, impl_subst))
}
fn find_matching_impl(
mut impls: impl Iterator<Item = ImplId>,
mut table: InferenceTable<'_>,
actual_trait_ref: TraitRef,
) -> Option<(Arc<ImplData>, Substitution)> {
let db = table.db;
impls.find_map(|impl_| {
table.run_in_snapshot(|table| {
let impl_data = db.impl_data(impl_);
let impl_substs =
TyBuilder::subst_for_def(db, impl_, None).fill_with_inference_vars(table).build();
let trait_ref = db
.impl_trait(impl_)
.expect("non-trait method in find_matching_impl")
.substitute(Interner, &impl_substs);
if !table.unify(&trait_ref, &actual_trait_ref) {
return None;
}
let wcs = crate::chalk_db::convert_where_clauses(db, impl_.into(), &impl_substs)
.into_iter()
.map(|b| b.cast(Interner));
let goal = crate::Goal::all(Interner, wcs);
table.try_obligation(goal.clone())?;
table.register_obligation(goal);
Some((impl_data, table.resolve_completely(impl_substs)))
})
})
}
fn is_inherent_impl_coherent(
db: &dyn HirDatabase,
def_map: &DefMap,
impl_data: &ImplData,
self_ty: &Ty,
) -> bool {
let self_ty = self_ty.kind(Interner);
let impl_allowed = match self_ty {
TyKind::Tuple(_, _)
| TyKind::FnDef(_, _)
| TyKind::Array(_, _)
| TyKind::Never
| TyKind::Raw(_, _)
| TyKind::Ref(_, _, _)
| TyKind::Slice(_)
| TyKind::Str
| TyKind::Scalar(_) => def_map.is_rustc_coherence_is_core(),
&TyKind::Adt(AdtId(adt), _) => adt.module(db.upcast()).krate() == def_map.krate(),
TyKind::Dyn(it) => it.principal().map_or(false, |trait_ref| {
from_chalk_trait_id(trait_ref.trait_id).module(db.upcast()).krate() == def_map.krate()
}),
_ => true,
};
impl_allowed || {
let rustc_has_incoherent_inherent_impls = match self_ty {
TyKind::Tuple(_, _)
| TyKind::FnDef(_, _)
| TyKind::Array(_, _)
| TyKind::Never
| TyKind::Raw(_, _)
| TyKind::Ref(_, _, _)
| TyKind::Slice(_)
| TyKind::Str
| TyKind::Scalar(_) => true,
&TyKind::Adt(AdtId(adt), _) => match adt {
hir_def::AdtId::StructId(id) => db
.struct_data(id)
.flags
.contains(StructFlags::IS_RUSTC_HAS_INCOHERENT_INHERENT_IMPL),
hir_def::AdtId::UnionId(id) => db
.union_data(id)
.flags
.contains(StructFlags::IS_RUSTC_HAS_INCOHERENT_INHERENT_IMPL),
hir_def::AdtId::EnumId(it) => db.enum_data(it).rustc_has_incoherent_inherent_impls,
},
TyKind::Dyn(it) => it.principal().map_or(false, |trait_ref| {
db.trait_data(from_chalk_trait_id(trait_ref.trait_id))
.rustc_has_incoherent_inherent_impls
}),
_ => false,
};
rustc_has_incoherent_inherent_impls
&& !impl_data.items.is_empty()
&& impl_data.items.iter().copied().all(|assoc| match assoc {
AssocItemId::FunctionId(it) => db.function_data(it).rustc_allow_incoherent_impl,
AssocItemId::ConstId(it) => db.const_data(it).rustc_allow_incoherent_impl,
AssocItemId::TypeAliasId(it) => db.type_alias_data(it).rustc_allow_incoherent_impl,
})
}
}
/// Checks whether the impl satisfies the orphan rules.
///
/// Given `impl<P1..=Pn> Trait<T1..=Tn> for T0`, an `impl`` is valid only if at least one of the following is true:
/// - Trait is a local trait
/// - All of
/// - At least one of the types `T0..=Tn`` must be a local type. Let `Ti`` be the first such type.
/// - No uncovered type parameters `P1..=Pn` may appear in `T0..Ti`` (excluding `Ti`)
pub fn check_orphan_rules(db: &dyn HirDatabase, impl_: ImplId) -> bool {
let substs = TyBuilder::placeholder_subst(db, impl_);
let Some(impl_trait) = db.impl_trait(impl_) else {
// not a trait impl
return true;
};
let local_crate = impl_.lookup(db.upcast()).container.krate();
let is_local = |tgt_crate| tgt_crate == local_crate;
let trait_ref = impl_trait.substitute(Interner, &substs);
let trait_id = from_chalk_trait_id(trait_ref.trait_id);
if is_local(trait_id.module(db.upcast()).krate()) {
// trait to be implemented is local
return true;
}
let unwrap_fundamental = |ty: Ty| match ty.kind(Interner) {
TyKind::Ref(_, _, referenced) => referenced.clone(),
&TyKind::Adt(AdtId(hir_def::AdtId::StructId(s)), ref subs) => {
let struct_data = db.struct_data(s);
if struct_data.flags.contains(StructFlags::IS_FUNDAMENTAL) {
let next = subs.type_parameters(Interner).next();
match next {
Some(ty) => ty,
None => ty,
}
} else {
ty
}
}
_ => ty,
};
// - At least one of the types `T0..=Tn`` must be a local type. Let `Ti`` be the first such type.
let is_not_orphan = trait_ref.substitution.type_parameters(Interner).any(|ty| {
match unwrap_fundamental(ty).kind(Interner) {
&TyKind::Adt(AdtId(id), _) => is_local(id.module(db.upcast()).krate()),
TyKind::Error => true,
TyKind::Dyn(it) => it.principal().map_or(false, |trait_ref| {
is_local(from_chalk_trait_id(trait_ref.trait_id).module(db.upcast()).krate())
}),
_ => false,
}
});
// FIXME: param coverage
// - No uncovered type parameters `P1..=Pn` may appear in `T0..Ti`` (excluding `Ti`)
is_not_orphan
}
pub fn iterate_path_candidates(
ty: &Canonical<Ty>,
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: Option<&Name>,
callback: &mut dyn FnMut(AssocItemId) -> ControlFlow<()>,
) -> ControlFlow<()> {
iterate_method_candidates_dyn(
ty,
db,
env,
traits_in_scope,
visible_from_module,
name,
LookupMode::Path,
// the adjustments are not relevant for path lookup
&mut |_, id, _| callback(id),
)
}
pub fn iterate_method_candidates_dyn(
ty: &Canonical<Ty>,
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: Option<&Name>,
mode: LookupMode,
callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
let _p = tracing::info_span!(
"iterate_method_candidates_dyn",
?mode,
?name,
traits_in_scope_len = traits_in_scope.len()
)
.entered();
match mode {
LookupMode::MethodCall => {
// For method calls, rust first does any number of autoderef, and
// then one autoref (i.e. when the method takes &self or &mut self).
// Note that when we've got a receiver like &S, even if the method
// we find in the end takes &self, we still do the autoderef step
// (just as rustc does an autoderef and then autoref again).
// We have to be careful about the order we're looking at candidates
// in here. Consider the case where we're resolving `it.clone()`
// where `it: &Vec<_>`. This resolves to the clone method with self
// type `Vec<_>`, *not* `&_`. I.e. we need to consider methods where
// the receiver type exactly matches before cases where we have to
// do autoref. But in the autoderef steps, the `&_` self type comes
// up *before* the `Vec<_>` self type.
//
// On the other hand, we don't want to just pick any by-value method
// before any by-autoref method; it's just that we need to consider
// the methods by autoderef order of *receiver types*, not *self
// types*.
let mut table = InferenceTable::new(db, env);
let ty = table.instantiate_canonical(ty.clone());
let deref_chain = autoderef_method_receiver(&mut table, ty);
deref_chain.into_iter().try_for_each(|(receiver_ty, adj)| {
iterate_method_candidates_with_autoref(
&mut table,
receiver_ty,
adj,
traits_in_scope,
visible_from_module,
name,
callback,
)
})
}
LookupMode::Path => {
// No autoderef for path lookups
iterate_method_candidates_for_self_ty(
ty,
db,
env,
traits_in_scope,
visible_from_module,
name,
callback,
)
}
}
}
#[tracing::instrument(skip_all, fields(name = ?name))]
fn iterate_method_candidates_with_autoref(
table: &mut InferenceTable<'_>,
receiver_ty: Canonical<Ty>,
first_adjustment: ReceiverAdjustments,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: Option<&Name>,
mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
if receiver_ty.value.is_general_var(Interner, &receiver_ty.binders) {
// don't try to resolve methods on unknown types
return ControlFlow::Continue(());
}
let mut iterate_method_candidates_by_receiver = move |receiver_ty, first_adjustment| {
iterate_method_candidates_by_receiver(
table,
receiver_ty,
first_adjustment,
traits_in_scope,
visible_from_module,
name,
&mut callback,
)
};
let mut maybe_reborrowed = first_adjustment.clone();
if let Some((_, _, m)) = receiver_ty.value.as_reference() {
// Prefer reborrow of references to move
maybe_reborrowed.autoref = Some(m);
maybe_reborrowed.autoderefs += 1;
}
iterate_method_candidates_by_receiver(receiver_ty.clone(), maybe_reborrowed)?;
let refed = Canonical {
value: TyKind::Ref(Mutability::Not, error_lifetime(), receiver_ty.value.clone())
.intern(Interner),
binders: receiver_ty.binders.clone(),
};
iterate_method_candidates_by_receiver(refed, first_adjustment.with_autoref(Mutability::Not))?;
let ref_muted = Canonical {
value: TyKind::Ref(Mutability::Mut, error_lifetime(), receiver_ty.value.clone())
.intern(Interner),
binders: receiver_ty.binders,
};
iterate_method_candidates_by_receiver(ref_muted, first_adjustment.with_autoref(Mutability::Mut))
}
#[tracing::instrument(skip_all, fields(name = ?name))]
fn iterate_method_candidates_by_receiver(
table: &mut InferenceTable<'_>,
receiver_ty: Canonical<Ty>,
receiver_adjustments: ReceiverAdjustments,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: Option<&Name>,
mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
let receiver_ty = table.instantiate_canonical(receiver_ty);
// We're looking for methods with *receiver* type receiver_ty. These could
// be found in any of the derefs of receiver_ty, so we have to go through
// that, including raw derefs.
table.run_in_snapshot(|table| {
let mut autoderef = autoderef::Autoderef::new(table, receiver_ty.clone(), true);
while let Some((self_ty, _)) = autoderef.next() {
iterate_inherent_methods(
&self_ty,
autoderef.table,
name,
Some(&receiver_ty),
Some(receiver_adjustments.clone()),
visible_from_module,
&mut callback,
)?
}
ControlFlow::Continue(())
})?;
table.run_in_snapshot(|table| {
let mut autoderef = autoderef::Autoderef::new(table, receiver_ty.clone(), true);
while let Some((self_ty, _)) = autoderef.next() {
if matches!(self_ty.kind(Interner), TyKind::InferenceVar(_, TyVariableKind::General)) {
// don't try to resolve methods on unknown types
return ControlFlow::Continue(());
}
iterate_trait_method_candidates(
&self_ty,
autoderef.table,
traits_in_scope,
name,
Some(&receiver_ty),
Some(receiver_adjustments.clone()),
&mut callback,
)?
}
ControlFlow::Continue(())
})
}
#[tracing::instrument(skip_all, fields(name = ?name))]
fn iterate_method_candidates_for_self_ty(
self_ty: &Canonical<Ty>,
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
traits_in_scope: &FxHashSet<TraitId>,
visible_from_module: VisibleFromModule,
name: Option<&Name>,
mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
let mut table = InferenceTable::new(db, env);
let self_ty = table.instantiate_canonical(self_ty.clone());
iterate_inherent_methods(
&self_ty,
&mut table,
name,
None,
None,
visible_from_module,
&mut callback,
)?;
iterate_trait_method_candidates(
&self_ty,
&mut table,
traits_in_scope,
name,
None,
None,
callback,
)
}
#[tracing::instrument(skip_all, fields(name = ?name, visible_from_module, receiver_ty))]
fn iterate_trait_method_candidates(
self_ty: &Ty,
table: &mut InferenceTable<'_>,
traits_in_scope: &FxHashSet<TraitId>,
name: Option<&Name>,
receiver_ty: Option<&Ty>,
receiver_adjustments: Option<ReceiverAdjustments>,
callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
let db = table.db;
let canonical_self_ty = table.canonicalize(self_ty.clone());
let TraitEnvironment { krate, block, .. } = *table.trait_env;
'traits: for &t in traits_in_scope {
let data = db.trait_data(t);
// Traits annotated with `#[rustc_skip_during_method_dispatch]` are skipped during
// method resolution, if the receiver is an array, and we're compiling for editions before
// 2021.
// This is to make `[a].into_iter()` not break code with the new `IntoIterator` impl for
// arrays.
if data.skip_array_during_method_dispatch
&& matches!(self_ty.kind(Interner), TyKind::Array(..))
{
// FIXME: this should really be using the edition of the method name's span, in case it
// comes from a macro
if !db.crate_graph()[krate].edition.at_least_2021() {
continue;
}
}
if data.skip_boxed_slice_during_method_dispatch
&& matches!(
self_ty.kind(Interner), TyKind::Adt(AdtId(def), subst)
if is_box(table.db, *def)
&& matches!(subst.at(Interner, 0).assert_ty_ref(Interner).kind(Interner), TyKind::Slice(..))
)
{
// FIXME: this should really be using the edition of the method name's span, in case it
// comes from a macro
if !db.crate_graph()[krate].edition.at_least_2024() {
continue;
}
}
// we'll be lazy about checking whether the type implements the
// trait, but if we find out it doesn't, we'll skip the rest of the
// iteration
let mut known_implemented = false;
for &(_, item) in data.items.iter() {
// Don't pass a `visible_from_module` down to `is_valid_candidate`,
// since only inherent methods should be included into visibility checking.
let visible =
match is_valid_trait_method_candidate(table, t, name, receiver_ty, item, self_ty) {
IsValidCandidate::Yes => true,
IsValidCandidate::NotVisible => false,
IsValidCandidate::No => continue,
};
if !known_implemented {
let goal = generic_implements_goal(db, &table.trait_env, t, &canonical_self_ty);
if db.trait_solve(krate, block, goal.cast(Interner)).is_none() {
continue 'traits;
}
}
known_implemented = true;
callback(receiver_adjustments.clone().unwrap_or_default(), item, visible)?;
}
}
ControlFlow::Continue(())
}
#[tracing::instrument(skip_all, fields(name = ?name, visible_from_module, receiver_ty))]
fn iterate_inherent_methods(
self_ty: &Ty,
table: &mut InferenceTable<'_>,
name: Option<&Name>,
receiver_ty: Option<&Ty>,
receiver_adjustments: Option<ReceiverAdjustments>,
visible_from_module: VisibleFromModule,
callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
let db = table.db;
let env = table.trait_env.clone();
// For trait object types and placeholder types with trait bounds, the methods of the trait and
// its super traits are considered inherent methods. This matters because these methods have
// higher priority than the other traits' methods, which would be considered in
// `iterate_trait_method_candidates()` only after this function.
match self_ty.kind(Interner) {
TyKind::Placeholder(_) => {
let env = table.trait_env.clone();
let traits = env
.traits_in_scope_from_clauses(self_ty.clone())
.flat_map(|t| all_super_traits(db.upcast(), t));
iterate_inherent_trait_methods(
self_ty,
table,
name,
receiver_ty,
receiver_adjustments.clone(),
callback,
traits,
)?;
}
TyKind::Dyn(_) => {
if let Some(principal_trait) = self_ty.dyn_trait() {
let traits = all_super_traits(db.upcast(), principal_trait);
iterate_inherent_trait_methods(
self_ty,
table,
name,
receiver_ty,
receiver_adjustments.clone(),
callback,
traits.into_iter(),
)?;
}
}
_ => {}
}
let def_crates = match def_crates(db, self_ty, env.krate) {
Some(k) => k,
None => return ControlFlow::Continue(()),
};
let (module, mut block) = match visible_from_module {
VisibleFromModule::Filter(module) => (Some(module), module.containing_block()),
VisibleFromModule::IncludeBlock(block) => (None, Some(block)),
VisibleFromModule::None => (None, None),
};
while let Some(block_id) = block {
if let Some(impls) = db.inherent_impls_in_block(block_id) {
impls_for_self_ty(
&impls,
self_ty,
table,
name,
receiver_ty,
receiver_adjustments.clone(),
module,
callback,
)?;
}
block = db.block_def_map(block_id).parent().and_then(|module| module.containing_block());
}
for krate in def_crates {
let impls = db.inherent_impls_in_crate(krate);
impls_for_self_ty(
&impls,
self_ty,
table,
name,
receiver_ty,
receiver_adjustments.clone(),
module,
callback,
)?;
}
return ControlFlow::Continue(());
#[tracing::instrument(skip_all, fields(name = ?name, visible_from_module, receiver_ty))]
fn iterate_inherent_trait_methods(
self_ty: &Ty,
table: &mut InferenceTable<'_>,
name: Option<&Name>,
receiver_ty: Option<&Ty>,
receiver_adjustments: Option<ReceiverAdjustments>,
callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
traits: impl Iterator<Item = TraitId>,
) -> ControlFlow<()> {
let db = table.db;
for t in traits {
let data = db.trait_data(t);
for &(_, item) in data.items.iter() {
// We don't pass `visible_from_module` as all trait items should be visible.
let visible = match is_valid_trait_method_candidate(
table,
t,
name,
receiver_ty,
item,
self_ty,
) {
IsValidCandidate::Yes => true,
IsValidCandidate::NotVisible => false,
IsValidCandidate::No => continue,
};
callback(receiver_adjustments.clone().unwrap_or_default(), item, visible)?;
}
}
ControlFlow::Continue(())
}
#[tracing::instrument(skip_all, fields(name = ?name, visible_from_module, receiver_ty))]
fn impls_for_self_ty(
impls: &InherentImpls,
self_ty: &Ty,
table: &mut InferenceTable<'_>,
name: Option<&Name>,
receiver_ty: Option<&Ty>,
receiver_adjustments: Option<ReceiverAdjustments>,
visible_from_module: Option<ModuleId>,
callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
) -> ControlFlow<()> {
for &impl_id in impls.for_self_ty(self_ty) {
for &item in table.db.impl_data(impl_id).items.iter() {
let visible = match is_valid_impl_method_candidate(
table,
self_ty,
receiver_ty,
visible_from_module,
name,
impl_id,
item,
) {
IsValidCandidate::Yes => true,
IsValidCandidate::NotVisible => false,
IsValidCandidate::No => continue,
};
callback(receiver_adjustments.clone().unwrap_or_default(), item, visible)?;
}
}
ControlFlow::Continue(())
}
}
/// Returns the receiver type for the index trait call.
pub(crate) fn resolve_indexing_op(
db: &dyn HirDatabase,
env: Arc<TraitEnvironment>,
ty: Canonical<Ty>,
index_trait: TraitId,
) -> Option<ReceiverAdjustments> {
let mut table = InferenceTable::new(db, env);
let ty = table.instantiate_canonical(ty);
let deref_chain = autoderef_method_receiver(&mut table, ty);
for (ty, adj) in deref_chain {
let goal = generic_implements_goal(db, &table.trait_env, index_trait, &ty);
if db
.trait_solve(table.trait_env.krate, table.trait_env.block, goal.cast(Interner))
.is_some()
{
return Some(adj);
}
}
None
}
// FIXME: Replace this with a `Try` impl once stable
macro_rules! check_that {
($cond:expr) => {
if !$cond {
return IsValidCandidate::No;
}
};
}
#[derive(Debug)]
enum IsValidCandidate {
Yes,
No,
NotVisible,
}
#[tracing::instrument(skip_all, fields(name))]
fn is_valid_impl_method_candidate(
table: &mut InferenceTable<'_>,
self_ty: &Ty,
receiver_ty: Option<&Ty>,
visible_from_module: Option<ModuleId>,
name: Option<&Name>,
impl_id: ImplId,
item: AssocItemId,
) -> IsValidCandidate {
match item {
AssocItemId::FunctionId(f) => is_valid_impl_fn_candidate(
table,
impl_id,
f,
name,
receiver_ty,
self_ty,
visible_from_module,
),
AssocItemId::ConstId(c) => {
let db = table.db;
check_that!(receiver_ty.is_none());
check_that!(name.map_or(true, |n| db.const_data(c).name.as_ref() == Some(n)));
if let Some(from_module) = visible_from_module {
if !db.const_visibility(c).is_visible_from(db.upcast(), from_module) {
cov_mark::hit!(const_candidate_not_visible);
return IsValidCandidate::NotVisible;
}
}
let self_ty_matches = table.run_in_snapshot(|table| {
let expected_self_ty =
TyBuilder::impl_self_ty(db, impl_id).fill_with_inference_vars(table).build();
table.unify(&expected_self_ty, self_ty)
});
if !self_ty_matches {
cov_mark::hit!(const_candidate_self_type_mismatch);
return IsValidCandidate::No;
}
IsValidCandidate::Yes
}
_ => IsValidCandidate::No,
}
}
/// Checks whether a given `AssocItemId` is applicable for `receiver_ty`.
#[tracing::instrument(skip_all, fields(name))]
fn is_valid_trait_method_candidate(
table: &mut InferenceTable<'_>,
trait_id: TraitId,
name: Option<&Name>,
receiver_ty: Option<&Ty>,
item: AssocItemId,
self_ty: &Ty,
) -> IsValidCandidate {
let db = table.db;
match item {
AssocItemId::FunctionId(fn_id) => {
let data = db.function_data(fn_id);
check_that!(name.map_or(true, |n| n == &data.name));
table.run_in_snapshot(|table| {
let impl_subst = TyBuilder::subst_for_def(db, trait_id, None)
.fill_with_inference_vars(table)
.build();
let expect_self_ty = impl_subst.at(Interner, 0).assert_ty_ref(Interner).clone();
check_that!(table.unify(&expect_self_ty, self_ty));
if let Some(receiver_ty) = receiver_ty {
check_that!(data.has_self_param());
let fn_subst = TyBuilder::subst_for_def(db, fn_id, Some(impl_subst))
.fill_with_inference_vars(table)
.build();
let sig = db.callable_item_signature(fn_id.into());
let expected_receiver =
sig.map(|s| s.params()[0].clone()).substitute(Interner, &fn_subst);
check_that!(table.unify(receiver_ty, &expected_receiver));
}
IsValidCandidate::Yes
})
}
AssocItemId::ConstId(c) => {
check_that!(receiver_ty.is_none());
check_that!(name.map_or(true, |n| db.const_data(c).name.as_ref() == Some(n)));
IsValidCandidate::Yes
}
_ => IsValidCandidate::No,
}
}
#[tracing::instrument(skip_all, fields(name))]
fn is_valid_impl_fn_candidate(
table: &mut InferenceTable<'_>,
impl_id: ImplId,
fn_id: FunctionId,
name: Option<&Name>,
receiver_ty: Option<&Ty>,
self_ty: &Ty,
visible_from_module: Option<ModuleId>,
) -> IsValidCandidate {
let db = table.db;
let data = db.function_data(fn_id);
check_that!(name.map_or(true, |n| n == &data.name));
if let Some(from_module) = visible_from_module {
if !db.function_visibility(fn_id).is_visible_from(db.upcast(), from_module) {
cov_mark::hit!(autoderef_candidate_not_visible);
return IsValidCandidate::NotVisible;
}
}
table.run_in_snapshot(|table| {
let _p = tracing::info_span!("subst_for_def").entered();
let impl_subst =
TyBuilder::subst_for_def(db, impl_id, None).fill_with_inference_vars(table).build();
let expect_self_ty = db.impl_self_ty(impl_id).substitute(Interner, &impl_subst);
check_that!(table.unify(&expect_self_ty, self_ty));
if let Some(receiver_ty) = receiver_ty {
let _p = tracing::info_span!("check_receiver_ty").entered();
check_that!(data.has_self_param());
let fn_subst = TyBuilder::subst_for_def(db, fn_id, Some(impl_subst.clone()))
.fill_with_inference_vars(table)
.build();
let sig = db.callable_item_signature(fn_id.into());
let expected_receiver =
sig.map(|s| s.params()[0].clone()).substitute(Interner, &fn_subst);
check_that!(table.unify(receiver_ty, &expected_receiver));
}
// We need to consider the bounds on the impl to distinguish functions of the same name
// for a type.
let predicates = db.generic_predicates(impl_id.into());
let goals = predicates.iter().map(|p| {
let (p, b) = p
.clone()
.substitute(Interner, &impl_subst)
// Skipping the inner binders is ok, as we don't handle quantified where
// clauses yet.
.into_value_and_skipped_binders();
stdx::always!(b.len(Interner) == 0);
p.cast::<Goal>(Interner)
});
for goal in goals.clone() {
let in_env = InEnvironment::new(&table.trait_env.env, goal);
let canonicalized = table.canonicalize_with_free_vars(in_env);
let solution = table.db.trait_solve(
table.trait_env.krate,
table.trait_env.block,
canonicalized.value.clone(),
);
match solution {
Some(Solution::Unique(canonical_subst)) => {
canonicalized.apply_solution(
table,
Canonical {
binders: canonical_subst.binders,
value: canonical_subst.value.subst,
},
);
}
Some(Solution::Ambig(Guidance::Definite(substs))) => {
canonicalized.apply_solution(table, substs);
}
Some(_) => (),
None => return IsValidCandidate::No,
}
}
for goal in goals {
if table.try_obligation(goal).is_none() {
return IsValidCandidate::No;
}
}
IsValidCandidate::Yes
})
}
pub fn implements_trait(
ty: &Canonical<Ty>,
db: &dyn HirDatabase,
env: &TraitEnvironment,
trait_: TraitId,
) -> bool {
let goal = generic_implements_goal(db, env, trait_, ty);
let solution = db.trait_solve(env.krate, env.block, goal.cast(Interner));
solution.is_some()
}
pub fn implements_trait_unique(
ty: &Canonical<Ty>,
db: &dyn HirDatabase,
env: &TraitEnvironment,
trait_: TraitId,
) -> bool {
let goal = generic_implements_goal(db, env, trait_, ty);
let solution = db.trait_solve(env.krate, env.block, goal.cast(Interner));
matches!(solution, Some(crate::Solution::Unique(_)))
}
/// This creates Substs for a trait with the given Self type and type variables
/// for all other parameters, to query Chalk with it.
#[tracing::instrument(skip_all)]
fn generic_implements_goal(
db: &dyn HirDatabase,
env: &TraitEnvironment,
trait_: TraitId,
self_ty: &Canonical<Ty>,
) -> Canonical<InEnvironment<super::DomainGoal>> {
let binders = self_ty.binders.interned();
let trait_ref = TyBuilder::trait_ref(db, trait_)
.push(self_ty.value.clone())
.fill_with_bound_vars(DebruijnIndex::INNERMOST, binders.len())
.build();
let kinds =
binders.iter().cloned().chain(trait_ref.substitution.iter(Interner).skip(1).map(|it| {
let vk = match it.data(Interner) {
GenericArgData::Ty(_) => VariableKind::Ty(chalk_ir::TyVariableKind::General),
GenericArgData::Lifetime(_) => VariableKind::Lifetime,
GenericArgData::Const(c) => VariableKind::Const(c.data(Interner).ty.clone()),
};
WithKind::new(vk, UniverseIndex::ROOT)
}));
let binders = CanonicalVarKinds::from_iter(Interner, kinds);
let obligation = trait_ref.cast(Interner);
let value = InEnvironment::new(&env.env, obligation);
Canonical { binders, value }
}
fn autoderef_method_receiver(
table: &mut InferenceTable<'_>,
ty: Ty,
) -> Vec<(Canonical<Ty>, ReceiverAdjustments)> {
let mut deref_chain: Vec<_> = Vec::new();
let mut autoderef = autoderef::Autoderef::new(table, ty, false);
while let Some((ty, derefs)) = autoderef.next() {
deref_chain.push((
autoderef.table.canonicalize(ty),
ReceiverAdjustments { autoref: None, autoderefs: derefs, unsize_array: false },
));
}
// As a last step, we can do array unsizing (that's the only unsizing that rustc does for method receivers!)
if let Some((TyKind::Array(parameters, _), binders, adj)) =
deref_chain.last().map(|(ty, adj)| (ty.value.kind(Interner), ty.binders.clone(), adj))
{
let unsized_ty = TyKind::Slice(parameters.clone()).intern(Interner);
deref_chain.push((
Canonical { value: unsized_ty, binders },
ReceiverAdjustments { unsize_array: true, ..adj.clone() },
));
}
deref_chain
}
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