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Auto merge of #99860 - oli-obk:revert_97346, r=pnkfelix

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Revert "Rollup merge of #97346 - JohnTitor:remove-back-compat-hacks, …

…r=oli-obk"

This reverts commit c703d11dcc, reversing
changes made to 64eb9ab869.

it didn't apply cleanly, so now it works the same for RPIT and for TAIT instead of just working for RPIT, but we should keep those in sync anyway. It also exposed a TAIT bug (see the feature gated test that now ICEs).

r? `@pnkfelix`

fixes #99536
This commit is contained in:
bors 2022-08-18 15:41:30 +00:00
commit 8064a49508
12 changed files with 69 additions and 67 deletions
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14
compiler/rustc_infer/src/infer/opaque_types.rs
View file

@ -40,15 +40,17 @@ pub struct OpaqueTypeDecl<'tcx> {
}
impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
pub fn replace_opaque_types_with_inference_vars(
/// This is a backwards compatibility hack to prevent breaking changes from
/// lazy TAIT around RPIT handling.
pub fn replace_opaque_types_with_inference_vars<T: TypeFoldable<'tcx>>(
&self,
ty: Ty<'tcx>,
value: T,
body_id: HirId,
span: Span,
param_env: ty::ParamEnv<'tcx>,
) -> InferOk<'tcx, Ty<'tcx>> {
if !ty.has_opaque_types() {
return InferOk { value: ty, obligations: vec![] };
) -> InferOk<'tcx, T> {
if !value.has_opaque_types() {
return InferOk { value, obligations: vec![] };
}
let mut obligations = vec![];
let replace_opaque_type = |def_id: DefId| {
@ -56,7 +58,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
.as_local()
.map_or(false, |def_id| self.opaque_type_origin(def_id, span).is_some())
};
let value = ty.fold_with(&mut ty::fold::BottomUpFolder {
let value = value.fold_with(&mut ty::fold::BottomUpFolder {
tcx: self.tcx,
lt_op: |lt| lt,
ct_op: |ct| ct,

18
compiler/rustc_trait_selection/src/traits/project.rs
View file

@ -252,10 +252,20 @@ fn project_and_unify_type<'cx, 'tcx>(
Err(InProgress) => return ProjectAndUnifyResult::Recursive,
};
debug!(?normalized, ?obligations, "project_and_unify_type result");
match infcx
.at(&obligation.cause, obligation.param_env)
.eq(normalized, obligation.predicate.term)
{
let actual = obligation.predicate.term;
// For an example where this is neccessary see src/test/ui/impl-trait/nested-return-type2.rs
// This allows users to omit re-mentioning all bounds on an associated type and just use an
// `impl Trait` for the assoc type to add more bounds.
let InferOk { value: actual, obligations: new } =
selcx.infcx().replace_opaque_types_with_inference_vars(
actual,
obligation.cause.body_id,
obligation.cause.span,
obligation.param_env,
);
obligations.extend(new);
match infcx.at(&obligation.cause, obligation.param_env).eq(normalized, actual) {
Ok(InferOk { obligations: inferred_obligations, value: () }) => {
obligations.extend(inferred_obligations);
ProjectAndUnifyResult::Holds(obligations)