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Rollup merge of #104594 - compiler-errors:dyn-star-rcvr, r=eholk,estebank

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Properly handle `Pin<&mut dyn* Trait>` receiver in codegen

This ensures we can actually await a `dyn* Future`, which seems important for async fn in dyn trait.

Also, disable `dyn*` trait upcasting. It's not exactly complete right now, and can cause strange ICEs for no reason -- nobody's using it either. I thought it was cute to implement when I did it, but I didn't think about how it interacts structurally with `CoerceUnsized` correctly.

Fixes #104794, presumably removing `dyn*` upcasting and its `CoerceUnsized` issues does the trick.
This commit is contained in:
Matthias Krüger 2022-11-24 08:42:34 +01:00 • committed by GitHub
commit b43c2e7cd9
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14 changed files with 179 additions and 43 deletions
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4
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View file

@ -776,9 +776,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
match (source.kind(), target.kind()) {
// Trait+Kx+'a -> Trait+Ky+'b (upcasts).
(&ty::Dynamic(ref data_a, _, dyn_a), &ty::Dynamic(ref data_b, _, dyn_b))
if dyn_a == dyn_b =>
{
(&ty::Dynamic(ref data_a, _, ty::Dyn), &ty::Dynamic(ref data_b, _, ty::Dyn)) => {
// Upcast coercions permit several things:
//
// 1. Dropping auto traits, e.g., `Foo + Send` to `Foo`

9
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -803,9 +803,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let upcast_trait_ref;
match (source.kind(), target.kind()) {
// TraitA+Kx+'a -> TraitB+Ky+'b (trait upcasting coercion).
(&ty::Dynamic(ref data_a, r_a, repr_a), &ty::Dynamic(ref data_b, r_b, repr_b))
if repr_a == repr_b =>
{
(
&ty::Dynamic(ref data_a, r_a, repr_a @ ty::Dyn),
&ty::Dynamic(ref data_b, r_b, ty::Dyn),
) => {
// See `assemble_candidates_for_unsizing` for more info.
// We already checked the compatibility of auto traits within `assemble_candidates_for_unsizing`.
let principal_a = data_a.principal().unwrap();
@ -831,7 +832,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
.map(ty::Binder::dummy),
);
let existential_predicates = tcx.mk_poly_existential_predicates(iter);
let source_trait = tcx.mk_dynamic(existential_predicates, r_b, repr_b);
let source_trait = tcx.mk_dynamic(existential_predicates, r_b, repr_a);
// Require that the traits involved in this upcast are **equal**;
// only the **lifetime bound** is changed.