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Revert "Rollup merge of #97346 - JohnTitor:remove-back-compat-hacks, r=oli-obk"

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This reverts commit c703d11dcc, reversing
changes made to 64eb9ab869.
This commit is contained in:
Oli Scherer
2022-07-28 15:22:02 +00:00
parent 05e678ccca
commit a85eb3d9df
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)