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Auto merge of #113215 - compiler-errors:rpitit-predicates-tweaks, r=spastorino

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Make RPITITs assume/require their parent method's predicates

Removes a FIXME from the `param_env` query where we were manually adding the parent function's predicates to the RPITIT's assumptions.

r? `@spastorino`
This commit is contained in:
bors 2023-07-04 04:24:24 +00:00
commit 0130c3a06e
8 changed files with 76 additions and 41 deletions
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19
compiler/rustc_hir_analysis/src/collect/predicates_of.rs
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@ -63,7 +63,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
use rustc_hir::*;
match tcx.opt_rpitit_info(def_id.to_def_id()) {
Some(ImplTraitInTraitData::Trait { opaque_def_id, .. }) => {
Some(ImplTraitInTraitData::Trait { opaque_def_id, fn_def_id }) => {
let opaque_ty_id = tcx.hir().local_def_id_to_hir_id(opaque_def_id.expect_local());
let opaque_ty_node = tcx.hir().get(opaque_ty_id);
let Node::Item(&Item { kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping, .. }), .. }) = opaque_ty_node else {
@ -71,6 +71,18 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
};
let mut predicates = Vec::new();
// RPITITs should inherit the predicates of their parent. This is
// both to ensure that the RPITITs are only instantiated when the
// parent predicates would hold, and also so that the param-env
// inherits these predicates as assumptions.
let identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
predicates.extend(
tcx.explicit_predicates_of(fn_def_id).instantiate_own(tcx, identity_substs),
);
// We also install bidirectional outlives predicates for the RPITIT
// to keep the duplicates lifetimes from opaque lowering in sync.
compute_bidirectional_outlives_predicates(
tcx,
def_id,
@ -89,12 +101,13 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
Some(ImplTraitInTraitData::Impl { fn_def_id }) => {
let assoc_item = tcx.associated_item(def_id);
let trait_assoc_predicates = tcx.predicates_of(assoc_item.trait_item_def_id.unwrap());
let trait_assoc_predicates =
tcx.explicit_predicates_of(assoc_item.trait_item_def_id.unwrap());
let impl_assoc_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
let impl_def_id = tcx.parent(fn_def_id);
let impl_trait_ref_substs =
tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder().substs;
tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity().substs;
let impl_assoc_substs =
impl_assoc_identity_substs.rebase_onto(tcx, impl_def_id, impl_trait_ref_substs);