388 lines
18 KiB
Rust
388 lines
18 KiB
Rust
use rustc_errors::ErrorGuaranteed;
|
|
use rustc_hir::LangItem;
|
|
use rustc_hir::def_id::DefId;
|
|
use rustc_infer::infer::TyCtxtInferExt;
|
|
use rustc_middle::bug;
|
|
use rustc_middle::query::Providers;
|
|
use rustc_middle::traits::{BuiltinImplSource, CodegenObligationError};
|
|
use rustc_middle::ty::util::AsyncDropGlueMorphology;
|
|
use rustc_middle::ty::{
|
|
self, ClosureKind, GenericArgsRef, Instance, PseudoCanonicalInput, TyCtxt, TypeVisitableExt,
|
|
};
|
|
use rustc_span::sym;
|
|
use rustc_trait_selection::traits;
|
|
use tracing::debug;
|
|
use traits::translate_args;
|
|
|
|
use crate::errors::UnexpectedFnPtrAssociatedItem;
|
|
|
|
fn resolve_instance_raw<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
key: ty::PseudoCanonicalInput<'tcx, (DefId, GenericArgsRef<'tcx>)>,
|
|
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
|
|
let PseudoCanonicalInput { typing_env, value: (def_id, args) } = key;
|
|
|
|
let result = if let Some(trait_def_id) = tcx.trait_of_item(def_id) {
|
|
debug!(" => associated item, attempting to find impl in typing_env {:#?}", typing_env);
|
|
resolve_associated_item(
|
|
tcx,
|
|
def_id,
|
|
typing_env,
|
|
trait_def_id,
|
|
tcx.normalize_erasing_regions(typing_env, args),
|
|
)
|
|
} else {
|
|
let def = if tcx.intrinsic(def_id).is_some() {
|
|
debug!(" => intrinsic");
|
|
ty::InstanceKind::Intrinsic(def_id)
|
|
} else if tcx.is_lang_item(def_id, LangItem::DropInPlace) {
|
|
let ty = args.type_at(0);
|
|
|
|
if ty.needs_drop(tcx, typing_env) {
|
|
debug!(" => nontrivial drop glue");
|
|
match *ty.kind() {
|
|
ty::Closure(..)
|
|
| ty::CoroutineClosure(..)
|
|
| ty::Coroutine(..)
|
|
| ty::Tuple(..)
|
|
| ty::Adt(..)
|
|
| ty::Dynamic(..)
|
|
| ty::Array(..)
|
|
| ty::Slice(..)
|
|
| ty::UnsafeBinder(..) => {}
|
|
// Drop shims can only be built from ADTs.
|
|
_ => return Ok(None),
|
|
}
|
|
|
|
ty::InstanceKind::DropGlue(def_id, Some(ty))
|
|
} else {
|
|
debug!(" => trivial drop glue");
|
|
ty::InstanceKind::DropGlue(def_id, None)
|
|
}
|
|
} else if tcx.is_lang_item(def_id, LangItem::AsyncDropInPlace) {
|
|
let ty = args.type_at(0);
|
|
|
|
if ty.async_drop_glue_morphology(tcx) != AsyncDropGlueMorphology::Noop {
|
|
match *ty.kind() {
|
|
ty::Closure(..)
|
|
| ty::CoroutineClosure(..)
|
|
| ty::Coroutine(..)
|
|
| ty::Tuple(..)
|
|
| ty::Adt(..)
|
|
| ty::Dynamic(..)
|
|
| ty::Array(..)
|
|
| ty::Slice(..) => {}
|
|
// Async destructor ctor shims can only be built from ADTs.
|
|
_ => return Ok(None),
|
|
}
|
|
debug!(" => nontrivial async drop glue ctor");
|
|
ty::InstanceKind::AsyncDropGlueCtorShim(def_id, Some(ty))
|
|
} else {
|
|
debug!(" => trivial async drop glue ctor");
|
|
ty::InstanceKind::AsyncDropGlueCtorShim(def_id, None)
|
|
}
|
|
} else {
|
|
debug!(" => free item");
|
|
ty::InstanceKind::Item(def_id)
|
|
};
|
|
|
|
Ok(Some(Instance { def, args }))
|
|
};
|
|
debug!("resolve_instance: result={:?}", result);
|
|
result
|
|
}
|
|
|
|
fn resolve_associated_item<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
trait_item_id: DefId,
|
|
typing_env: ty::TypingEnv<'tcx>,
|
|
trait_id: DefId,
|
|
rcvr_args: GenericArgsRef<'tcx>,
|
|
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
|
|
debug!(?trait_item_id, ?typing_env, ?trait_id, ?rcvr_args, "resolve_associated_item");
|
|
|
|
let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_args);
|
|
|
|
let input = typing_env.as_query_input(trait_ref);
|
|
let vtbl = match tcx.codegen_select_candidate(input) {
|
|
Ok(vtbl) => vtbl,
|
|
Err(CodegenObligationError::Ambiguity | CodegenObligationError::Unimplemented) => {
|
|
return Ok(None);
|
|
}
|
|
Err(CodegenObligationError::UnconstrainedParam(guar)) => return Err(guar),
|
|
};
|
|
|
|
// Now that we know which impl is being used, we can dispatch to
|
|
// the actual function:
|
|
Ok(match vtbl {
|
|
traits::ImplSource::UserDefined(impl_data) => {
|
|
debug!(
|
|
"resolving ImplSource::UserDefined: {:?}, {:?}, {:?}, {:?}",
|
|
typing_env, trait_item_id, rcvr_args, impl_data
|
|
);
|
|
assert!(!rcvr_args.has_infer());
|
|
assert!(!trait_ref.has_infer());
|
|
|
|
let trait_def_id = tcx.trait_id_of_impl(impl_data.impl_def_id).unwrap();
|
|
let trait_def = tcx.trait_def(trait_def_id);
|
|
let leaf_def = trait_def
|
|
.ancestors(tcx, impl_data.impl_def_id)?
|
|
.leaf_def(tcx, trait_item_id)
|
|
.unwrap_or_else(|| {
|
|
bug!("{:?} not found in {:?}", trait_item_id, impl_data.impl_def_id);
|
|
});
|
|
|
|
// Since this is a trait item, we need to see if the item is either a trait
|
|
// default item or a specialization because we can't resolve those until we're
|
|
// in `TypingMode::PostAnalysis`.
|
|
//
|
|
// NOTE: This should be kept in sync with the similar code in
|
|
// `rustc_trait_selection::traits::project::assemble_candidates_from_impls()`.
|
|
let eligible = if leaf_def.is_final() {
|
|
// Non-specializable items are always projectable.
|
|
true
|
|
} else {
|
|
// Only reveal a specializable default if we're past type-checking
|
|
// and the obligation is monomorphic, otherwise passes such as
|
|
// transmute checking and polymorphic MIR optimizations could
|
|
// get a result which isn't correct for all monomorphizations.
|
|
match typing_env.typing_mode {
|
|
ty::TypingMode::Coherence
|
|
| ty::TypingMode::Analysis { .. }
|
|
| ty::TypingMode::Borrowck { .. }
|
|
| ty::TypingMode::PostBorrowckAnalysis { .. } => false,
|
|
ty::TypingMode::PostAnalysis => !trait_ref.still_further_specializable(),
|
|
}
|
|
};
|
|
if !eligible {
|
|
return Ok(None);
|
|
}
|
|
|
|
let typing_env = typing_env.with_post_analysis_normalized(tcx);
|
|
let (infcx, param_env) = tcx.infer_ctxt().build_with_typing_env(typing_env);
|
|
let args = rcvr_args.rebase_onto(tcx, trait_def_id, impl_data.args);
|
|
let args = translate_args(
|
|
&infcx,
|
|
param_env,
|
|
impl_data.impl_def_id,
|
|
args,
|
|
leaf_def.defining_node,
|
|
);
|
|
let args = infcx.tcx.erase_regions(args);
|
|
|
|
// HACK: We may have overlapping `dyn Trait` built-in impls and
|
|
// user-provided blanket impls. Detect that case here, and return
|
|
// ambiguity.
|
|
//
|
|
// This should not affect totally monomorphized contexts, only
|
|
// resolve calls that happen polymorphically, such as the mir-inliner
|
|
// and const-prop (and also some lints).
|
|
let self_ty = rcvr_args.type_at(0);
|
|
if !self_ty.is_known_rigid() {
|
|
let predicates = tcx
|
|
.predicates_of(impl_data.impl_def_id)
|
|
.instantiate(tcx, impl_data.args)
|
|
.predicates;
|
|
let sized_def_id = tcx.lang_items().sized_trait();
|
|
// If we find a `Self: Sized` bound on the item, then we know
|
|
// that `dyn Trait` can certainly never apply here.
|
|
if !predicates.into_iter().filter_map(ty::Clause::as_trait_clause).any(|clause| {
|
|
Some(clause.def_id()) == sized_def_id
|
|
&& clause.skip_binder().self_ty() == self_ty
|
|
}) {
|
|
return Ok(None);
|
|
}
|
|
}
|
|
|
|
// Any final impl is required to define all associated items.
|
|
if !leaf_def.item.defaultness(tcx).has_value() {
|
|
let guar = tcx.dcx().span_delayed_bug(
|
|
tcx.def_span(leaf_def.item.def_id),
|
|
"missing value for assoc item in impl",
|
|
);
|
|
return Err(guar);
|
|
}
|
|
|
|
// Make sure that we're projecting to an item that has compatible args.
|
|
// This may happen if we are resolving an instance before codegen, such
|
|
// as during inlining. This check is also done in projection.
|
|
if !tcx.check_args_compatible(leaf_def.item.def_id, args) {
|
|
let guar = tcx.dcx().span_delayed_bug(
|
|
tcx.def_span(leaf_def.item.def_id),
|
|
"missing value for assoc item in impl",
|
|
);
|
|
return Err(guar);
|
|
}
|
|
|
|
let args = tcx.erase_regions(args);
|
|
|
|
// We check that the impl item is compatible with the trait item
|
|
// because otherwise we may ICE in const eval due to type mismatches,
|
|
// signature incompatibilities, etc.
|
|
// NOTE: We could also only enforce this in `PostAnalysis`, which
|
|
// is what CTFE and MIR inlining would care about anyways.
|
|
if trait_item_id != leaf_def.item.def_id
|
|
&& let Some(leaf_def_item) = leaf_def.item.def_id.as_local()
|
|
{
|
|
tcx.ensure_ok().compare_impl_item(leaf_def_item)?;
|
|
}
|
|
|
|
Some(ty::Instance::new(leaf_def.item.def_id, args))
|
|
}
|
|
traits::ImplSource::Builtin(BuiltinImplSource::Object(_), _) => {
|
|
let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_args);
|
|
if trait_ref.has_non_region_infer() || trait_ref.has_non_region_param() {
|
|
// We only resolve totally substituted vtable entries.
|
|
None
|
|
} else {
|
|
let vtable_base = tcx.first_method_vtable_slot(trait_ref);
|
|
let offset = tcx
|
|
.own_existential_vtable_entries(trait_id)
|
|
.iter()
|
|
.copied()
|
|
.position(|def_id| def_id == trait_item_id);
|
|
offset.map(|offset| Instance {
|
|
def: ty::InstanceKind::Virtual(trait_item_id, vtable_base + offset),
|
|
args: rcvr_args,
|
|
})
|
|
}
|
|
}
|
|
traits::ImplSource::Builtin(BuiltinImplSource::Misc | BuiltinImplSource::Trivial, _) => {
|
|
if tcx.is_lang_item(trait_ref.def_id, LangItem::Clone) {
|
|
// FIXME(eddyb) use lang items for methods instead of names.
|
|
let name = tcx.item_name(trait_item_id);
|
|
if name == sym::clone {
|
|
let self_ty = trait_ref.self_ty();
|
|
match self_ty.kind() {
|
|
ty::FnDef(..) | ty::FnPtr(..) => (),
|
|
ty::Coroutine(..)
|
|
| ty::CoroutineWitness(..)
|
|
| ty::Closure(..)
|
|
| ty::CoroutineClosure(..)
|
|
| ty::Tuple(..) => {}
|
|
_ => return Ok(None),
|
|
};
|
|
|
|
Some(Instance {
|
|
def: ty::InstanceKind::CloneShim(trait_item_id, self_ty),
|
|
args: rcvr_args,
|
|
})
|
|
} else {
|
|
assert_eq!(name, sym::clone_from);
|
|
|
|
// Use the default `fn clone_from` from `trait Clone`.
|
|
let args = tcx.erase_regions(rcvr_args);
|
|
Some(ty::Instance::new(trait_item_id, args))
|
|
}
|
|
} else if tcx.is_lang_item(trait_ref.def_id, LangItem::FnPtrTrait) {
|
|
if tcx.is_lang_item(trait_item_id, LangItem::FnPtrAddr) {
|
|
let self_ty = trait_ref.self_ty();
|
|
if !matches!(self_ty.kind(), ty::FnPtr(..)) {
|
|
return Ok(None);
|
|
}
|
|
Some(Instance {
|
|
def: ty::InstanceKind::FnPtrAddrShim(trait_item_id, self_ty),
|
|
args: rcvr_args,
|
|
})
|
|
} else {
|
|
tcx.dcx().emit_fatal(UnexpectedFnPtrAssociatedItem {
|
|
span: tcx.def_span(trait_item_id),
|
|
})
|
|
}
|
|
} else if let Some(target_kind) = tcx.fn_trait_kind_from_def_id(trait_ref.def_id) {
|
|
// FIXME: This doesn't check for malformed libcore that defines, e.g.,
|
|
// `trait Fn { fn call_once(&self) { .. } }`. This is mostly for extension
|
|
// methods.
|
|
if cfg!(debug_assertions)
|
|
&& ![sym::call, sym::call_mut, sym::call_once]
|
|
.contains(&tcx.item_name(trait_item_id))
|
|
{
|
|
// For compiler developers who'd like to add new items to `Fn`/`FnMut`/`FnOnce`,
|
|
// you either need to generate a shim body, or perhaps return
|
|
// `InstanceKind::Item` pointing to a trait default method body if
|
|
// it is given a default implementation by the trait.
|
|
bug!(
|
|
"no definition for `{trait_ref}::{}` for built-in callable type",
|
|
tcx.item_name(trait_item_id)
|
|
)
|
|
}
|
|
match *rcvr_args.type_at(0).kind() {
|
|
ty::Closure(closure_def_id, args) => {
|
|
Some(Instance::resolve_closure(tcx, closure_def_id, args, target_kind))
|
|
}
|
|
ty::FnDef(..) | ty::FnPtr(..) => Some(Instance {
|
|
def: ty::InstanceKind::FnPtrShim(trait_item_id, rcvr_args.type_at(0)),
|
|
args: rcvr_args,
|
|
}),
|
|
ty::CoroutineClosure(coroutine_closure_def_id, args) => {
|
|
// When a coroutine-closure implements the `Fn` traits, then it
|
|
// always dispatches to the `FnOnce` implementation. This is to
|
|
// ensure that the `closure_kind` of the resulting closure is in
|
|
// sync with the built-in trait implementations (since all of the
|
|
// implementations return `FnOnce::Output`).
|
|
if ty::ClosureKind::FnOnce == args.as_coroutine_closure().kind() {
|
|
Some(Instance::new(coroutine_closure_def_id, args))
|
|
} else {
|
|
Some(Instance {
|
|
def: ty::InstanceKind::ConstructCoroutineInClosureShim {
|
|
coroutine_closure_def_id,
|
|
receiver_by_ref: target_kind != ty::ClosureKind::FnOnce,
|
|
},
|
|
args,
|
|
})
|
|
}
|
|
}
|
|
_ => bug!(
|
|
"no built-in definition for `{trait_ref}::{}` for non-fn type",
|
|
tcx.item_name(trait_item_id)
|
|
),
|
|
}
|
|
} else if let Some(target_kind) = tcx.async_fn_trait_kind_from_def_id(trait_ref.def_id)
|
|
{
|
|
match *rcvr_args.type_at(0).kind() {
|
|
ty::CoroutineClosure(coroutine_closure_def_id, args) => {
|
|
if target_kind == ClosureKind::FnOnce
|
|
&& args.as_coroutine_closure().kind() != ClosureKind::FnOnce
|
|
{
|
|
// If we're computing `AsyncFnOnce` for a by-ref closure then
|
|
// construct a new body that has the right return types.
|
|
Some(Instance {
|
|
def: ty::InstanceKind::ConstructCoroutineInClosureShim {
|
|
coroutine_closure_def_id,
|
|
receiver_by_ref: false,
|
|
},
|
|
args,
|
|
})
|
|
} else {
|
|
Some(Instance::new(coroutine_closure_def_id, args))
|
|
}
|
|
}
|
|
ty::Closure(closure_def_id, args) => {
|
|
Some(Instance::resolve_closure(tcx, closure_def_id, args, target_kind))
|
|
}
|
|
ty::FnDef(..) | ty::FnPtr(..) => Some(Instance {
|
|
def: ty::InstanceKind::FnPtrShim(trait_item_id, rcvr_args.type_at(0)),
|
|
args: rcvr_args,
|
|
}),
|
|
_ => bug!(
|
|
"no built-in definition for `{trait_ref}::{}` for non-lending-closure type",
|
|
tcx.item_name(trait_item_id)
|
|
),
|
|
}
|
|
} else if tcx.is_lang_item(trait_ref.def_id, LangItem::TransmuteTrait) {
|
|
let name = tcx.item_name(trait_item_id);
|
|
assert_eq!(name, sym::transmute);
|
|
let args = tcx.erase_regions(rcvr_args);
|
|
Some(ty::Instance::new(trait_item_id, args))
|
|
} else {
|
|
Instance::try_resolve_item_for_coroutine(tcx, trait_item_id, trait_id, rcvr_args)
|
|
}
|
|
}
|
|
traits::ImplSource::Param(..)
|
|
| traits::ImplSource::Builtin(BuiltinImplSource::TraitUpcasting { .. }, _) => None,
|
|
})
|
|
}
|
|
|
|
pub(crate) fn provide(providers: &mut Providers) {
|
|
*providers = Providers { resolve_instance_raw, ..*providers };
|
|
}
|