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use rustc_errors::ErrorGuaranteed;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::traits::CodegenObligationError;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{self, Instance, TyCtxt, TypeVisitable};
use rustc_span::sym;
use rustc_trait_selection::traits;
use traits::{translate_substs, Reveal};
fn resolve_instance<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::ParamEnvAnd<'tcx, (DefId, SubstsRef<'tcx>)>,
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
let (param_env, (did, substs)) = key.into_parts();
if let Some(did) = did.as_local() {
if let Some(param_did) = tcx.opt_const_param_of(did) {
return tcx.resolve_instance_of_const_arg(param_env.and((did, param_did, substs)));
}
}
inner_resolve_instance(tcx, param_env.and((ty::WithOptConstParam::unknown(did), substs)))
}
fn resolve_instance_of_const_arg<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::ParamEnvAnd<'tcx, (LocalDefId, DefId, SubstsRef<'tcx>)>,
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
let (param_env, (did, const_param_did, substs)) = key.into_parts();
inner_resolve_instance(
tcx,
param_env.and((
ty::WithOptConstParam { did: did.to_def_id(), const_param_did: Some(const_param_did) },
substs,
)),
)
}
fn inner_resolve_instance<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::ParamEnvAnd<'tcx, (ty::WithOptConstParam<DefId>, SubstsRef<'tcx>)>,
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
let (param_env, (def, substs)) = key.into_parts();
let result = if let Some(trait_def_id) = tcx.trait_of_item(def.did) {
debug!(" => associated item, attempting to find impl in param_env {:#?}", param_env);
resolve_associated_item(
tcx,
def.did,
param_env,
trait_def_id,
tcx.normalize_erasing_regions(param_env, substs),
)
} else {
let ty = tcx.type_of(def.def_id_for_type_of());
let item_type = tcx.subst_and_normalize_erasing_regions(substs, param_env, ty);
let def = match *item_type.kind() {
ty::FnDef(def_id, ..) if tcx.is_intrinsic(def_id) => {
debug!(" => intrinsic");
ty::InstanceDef::Intrinsic(def.did)
}
ty::FnDef(def_id, substs) if Some(def_id) == tcx.lang_items().drop_in_place_fn() => {
let ty = substs.type_at(0);
if ty.needs_drop(tcx, param_env) {
debug!(" => nontrivial drop glue");
match *ty.kind() {
ty::Closure(..)
| ty::Generator(..)
| ty::Tuple(..)
| ty::Adt(..)
| ty::Dynamic(..)
| ty::Array(..)
| ty::Slice(..) => {}
_ => return Ok(None),
}
ty::InstanceDef::DropGlue(def_id, Some(ty))
} else {
debug!(" => trivial drop glue");
ty::InstanceDef::DropGlue(def_id, None)
}
}
_ => {
debug!(" => free item");
ty::InstanceDef::Item(def)
}
};
Ok(Some(Instance { def, substs }))
};
debug!("inner_resolve_instance: result={:?}", result);
result
}
fn resolve_associated_item<'tcx>(
tcx: TyCtxt<'tcx>,
trait_item_id: DefId,
param_env: ty::ParamEnv<'tcx>,
trait_id: DefId,
rcvr_substs: SubstsRef<'tcx>,
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
debug!(?trait_item_id, ?param_env, ?trait_id, ?rcvr_substs, "resolve_associated_item");
let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
let vtbl = match tcx.codegen_select_candidate((param_env, ty::Binder::dummy(trait_ref))) {
Ok(vtbl) => vtbl,
Err(CodegenObligationError::Ambiguity) => {
let reported = tcx.sess.delay_span_bug(
tcx.def_span(trait_item_id),
&format!(
"encountered ambiguity selecting `{trait_ref:?}` during codegen, presuming due to \
overflow or prior type error",
),
);
return Err(reported);
}
Err(CodegenObligationError::Unimplemented) => return Ok(None),
Err(CodegenObligationError::FulfillmentError) => return Ok(None),
};
Ok(match vtbl {
traits::ImplSource::UserDefined(impl_data) => {
debug!(
"resolving ImplSource::UserDefined: {:?}, {:?}, {:?}, {:?}",
param_env, trait_item_id, rcvr_substs, impl_data
);
assert!(!rcvr_substs.needs_infer());
assert!(!trait_ref.needs_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);
});
let infcx = tcx.infer_ctxt().build();
let param_env = param_env.with_reveal_all_normalized(tcx);
let substs = rcvr_substs.rebase_onto(tcx, trait_def_id, impl_data.substs);
let substs = translate_substs(
&infcx,
param_env,
impl_data.impl_def_id,
substs,
leaf_def.defining_node,
);
let substs = infcx.tcx.erase_regions(substs);
let eligible = if leaf_def.is_final() {
true
} else {
if param_env.reveal() == Reveal::All {
!trait_ref.still_further_specializable()
} else {
false
}
};
if !eligible {
return Ok(None);
}
if !leaf_def.item.defaultness(tcx).has_value() {
let guard = tcx.sess.delay_span_bug(
tcx.def_span(leaf_def.item.def_id),
"missing value for assoc item in impl",
);
return Err(guard);
}
let substs = tcx.erase_regions(substs);
if leaf_def.item.kind == ty::AssocKind::Const
&& trait_item_id != leaf_def.item.def_id
&& let Some(leaf_def_item) = leaf_def.item.def_id.as_local()
{
tcx.compare_assoc_const_impl_item_with_trait_item((
leaf_def_item,
trait_item_id,
))?;
}
Some(ty::Instance::new(leaf_def.item.def_id, substs))
}
traits::ImplSource::Generator(generator_data) => Some(Instance {
def: ty::InstanceDef::Item(ty::WithOptConstParam::unknown(
generator_data.generator_def_id,
)),
substs: generator_data.substs,
}),
traits::ImplSource::Future(future_data) => Some(Instance {
def: ty::InstanceDef::Item(ty::WithOptConstParam::unknown(
future_data.generator_def_id,
)),
substs: future_data.substs,
}),
traits::ImplSource::Closure(closure_data) => {
let trait_closure_kind = tcx.fn_trait_kind_from_def_id(trait_id).unwrap();
Instance::resolve_closure(
tcx,
closure_data.closure_def_id,
closure_data.substs,
trait_closure_kind,
)
}
traits::ImplSource::FnPointer(ref data) => match data.fn_ty.kind() {
ty::FnDef(..) | ty::FnPtr(..) => Some(Instance {
def: ty::InstanceDef::FnPtrShim(trait_item_id, data.fn_ty),
substs: rcvr_substs,
}),
_ => None,
},
traits::ImplSource::Object(ref data) => {
if let Some(index) = traits::get_vtable_index_of_object_method(tcx, data, trait_item_id)
{
Some(Instance {
def: ty::InstanceDef::Virtual(trait_item_id, index),
substs: rcvr_substs,
})
} else {
None
}
}
traits::ImplSource::Builtin(..) => {
if Some(trait_ref.def_id) == tcx.lang_items().clone_trait() {
let name = tcx.item_name(trait_item_id);
if name == sym::clone {
let self_ty = trait_ref.self_ty();
let is_copy = self_ty.is_copy_modulo_regions(tcx, param_env);
match self_ty.kind() {
_ if is_copy => (),
ty::Generator(..)
| ty::GeneratorWitness(..)
| ty::Closure(..)
| ty::Tuple(..) => {}
_ => return Ok(None),
};
Some(Instance {
def: ty::InstanceDef::CloneShim(trait_item_id, self_ty),
substs: rcvr_substs,
})
} else {
assert_eq!(name, sym::clone_from);
let substs = tcx.erase_regions(rcvr_substs);
Some(ty::Instance::new(trait_item_id, substs))
}
} else {
None
}
}
traits::ImplSource::AutoImpl(..)
| traits::ImplSource::Param(..)
| traits::ImplSource::TraitAlias(..)
| traits::ImplSource::TraitUpcasting(_)
| traits::ImplSource::ConstDestruct(_) => None,
})
}
pub fn provide(providers: &mut ty::query::Providers) {
*providers =
ty::query::Providers { resolve_instance, resolve_instance_of_const_arg, ..*providers };
}