bjoernager/rust
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implement the skeleton of the updated trait solver

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This commit is contained in:
lcnr 2022-12-04 03:19:10 +00:00
parent 4653c93e44
commit a213bb36c9
21 changed files with 1569 additions and 87 deletions
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59
compiler/rustc_trait_selection/src/traits/project.rs
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@ -25,7 +25,6 @@ use rustc_data_structures::sso::SsoHashSet;
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_errors::ErrorGuaranteed;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
use rustc_infer::infer::at::At;
use rustc_infer::infer::resolve::OpportunisticRegionResolver;
@ -1553,7 +1552,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
// NOTE: This should be kept in sync with the similar code in
// `rustc_ty_utils::instance::resolve_associated_item()`.
let node_item =
assoc_def(selcx, impl_data.impl_def_id, obligation.predicate.def_id)
specialization_graph::assoc_def(selcx.tcx(), impl_data.impl_def_id, obligation.predicate.def_id)
.map_err(|ErrorGuaranteed { .. }| ())?;
if node_item.is_final() {
@ -2113,7 +2112,7 @@ fn confirm_impl_candidate<'cx, 'tcx>(
let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap();
let param_env = obligation.param_env;
let Ok(assoc_ty) = assoc_def(selcx, impl_def_id, assoc_item_id) else {
let Ok(assoc_ty) = specialization_graph::assoc_def(tcx, impl_def_id, assoc_item_id) else {
return Progress { term: tcx.ty_error().into(), obligations: nested };
};
@ -2210,7 +2209,7 @@ fn confirm_impl_trait_in_trait_candidate<'tcx>(
let mut obligations = data.nested;
let trait_fn_def_id = tcx.impl_trait_in_trait_parent(obligation.predicate.def_id);
let Ok(leaf_def) = assoc_def(selcx, data.impl_def_id, trait_fn_def_id) else {
let Ok(leaf_def) = specialization_graph::assoc_def(tcx, data.impl_def_id, trait_fn_def_id) else {
return Progress { term: tcx.ty_error().into(), obligations };
};
if !leaf_def.item.defaultness(tcx).has_value() {
@ -2347,58 +2346,6 @@ fn assoc_ty_own_obligations<'cx, 'tcx>(
}
}
/// Locate the definition of an associated type in the specialization hierarchy,
/// starting from the given impl.
///
/// Based on the "projection mode", this lookup may in fact only examine the
/// topmost impl. See the comments for `Reveal` for more details.
fn assoc_def(
selcx: &SelectionContext<'_, '_>,
impl_def_id: DefId,
assoc_def_id: DefId,
) -> Result<specialization_graph::LeafDef, ErrorGuaranteed> {
let tcx = selcx.tcx();
let trait_def_id = tcx.impl_trait_ref(impl_def_id).unwrap().def_id;
let trait_def = tcx.trait_def(trait_def_id);
// This function may be called while we are still building the
// specialization graph that is queried below (via TraitDef::ancestors()),
// so, in order to avoid unnecessary infinite recursion, we manually look
// for the associated item at the given impl.
// If there is no such item in that impl, this function will fail with a
// cycle error if the specialization graph is currently being built.
if let Some(&impl_item_id) = tcx.impl_item_implementor_ids(impl_def_id).get(&assoc_def_id) {
let item = tcx.associated_item(impl_item_id);
let impl_node = specialization_graph::Node::Impl(impl_def_id);
return Ok(specialization_graph::LeafDef {
item: *item,
defining_node: impl_node,
finalizing_node: if item.defaultness(tcx).is_default() {
None
} else {
Some(impl_node)
},
});
}
let ancestors = trait_def.ancestors(tcx, impl_def_id)?;
if let Some(assoc_item) = ancestors.leaf_def(tcx, assoc_def_id) {
Ok(assoc_item)
} else {
// This is saying that neither the trait nor
// the impl contain a definition for this
// associated type. Normally this situation
// could only arise through a compiler bug --
// if the user wrote a bad item name, it
// should have failed in astconv.
bug!(
"No associated type `{}` for {}",
tcx.item_name(assoc_def_id),
tcx.def_path_str(impl_def_id)
)
}
}
pub(crate) trait ProjectionCacheKeyExt<'cx, 'tcx>: Sized {
fn from_poly_projection_predicate(
selcx: &mut SelectionContext<'cx, 'tcx>,