Use parent function WfCheckingContext to check RPITIT.

Author: cjgillot

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1544,7 +1544,7 @@ fn check_fn_or_method<'tcx>(
     check_where_clauses(wfcx, span, def_id);
 
     check_return_position_impl_trait_in_trait_bounds(
-        tcx,
+        wfcx,
         def_id,
         sig.output(),
         hir_decl.output.span(),
@@ -1580,13 +1580,14 @@ fn check_fn_or_method<'tcx>(
 
 /// Basically `check_associated_type_bounds`, but separated for now and should be
 /// deduplicated when RPITITs get lowered into real associated items.
-#[tracing::instrument(level = "trace", skip(tcx))]
+#[tracing::instrument(level = "trace", skip(wfcx))]
 fn check_return_position_impl_trait_in_trait_bounds<'tcx>(
-    tcx: TyCtxt<'tcx>,
+    wfcx: &WfCheckingCtxt<'_, 'tcx>,
     fn_def_id: LocalDefId,
     fn_output: Ty<'tcx>,
     span: Span,
 ) {
+    let tcx = wfcx.tcx();
     if let Some(assoc_item) = tcx.opt_associated_item(fn_def_id.to_def_id())
         && assoc_item.container == ty::AssocItemContainer::TraitContainer
     {
@@ -1596,22 +1597,20 @@ fn check_return_position_impl_trait_in_trait_bounds<'tcx>(
                 && tcx.def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder
                 && tcx.impl_trait_in_trait_parent(proj.item_def_id) == fn_def_id.to_def_id()
             {
-                // Create a new context, since we want the opaque's ParamEnv and not the parent's.
                 let span = tcx.def_span(proj.item_def_id);
-                enter_wf_checking_ctxt(tcx, span, proj.item_def_id.expect_local(), |wfcx| {
-                    let bounds = wfcx.tcx().explicit_item_bounds(proj.item_def_id);
-                    let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| {
-                        let normalized_bound = wfcx.normalize(span, None, bound);
-                        traits::wf::predicate_obligations(
-                            wfcx.infcx,
-                            wfcx.param_env,
-                            wfcx.body_id,
-                            normalized_bound,
-                            bound_span,
-                        )
-                    });
-                    wfcx.register_obligations(wf_obligations);
+                let bounds = wfcx.tcx().explicit_item_bounds(proj.item_def_id);
+                let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| {
+                    let bound = ty::EarlyBinder(bound).subst(tcx, proj.substs);
+                    let normalized_bound = wfcx.normalize(span, None, bound);
+                    traits::wf::predicate_obligations(
+                        wfcx.infcx,
+                        wfcx.param_env,
+                        wfcx.body_id,
+                        normalized_bound,
+                        bound_span,
+                    )
                 });
+                wfcx.register_obligations(wf_obligations);
             }
         }
     }

src/test/ui/async-await/in-trait/async-generics-and-bounds.stderr

@@ -4,11 +4,11 @@ error[E0311]: the parameter type `U` may not live long enough
 LL |     async fn foo(&self) -> &(T, U) where T: Debug + Sized, U: Hash;
    |                            ^^^^^^^
    |
-note: the parameter type `U` must be valid for the anonymous lifetime as defined here...
+note: the parameter type `U` must be valid for the anonymous lifetime defined here...
   --> $DIR/async-generics-and-bounds.rs:12:18
    |
 LL |     async fn foo(&self) -> &(T, U) where T: Debug + Sized, U: Hash;
-   |                  ^
+   |                  ^^^^^
 note: ...so that the reference type `&(T, U)` does not outlive the data it points at
   --> $DIR/async-generics-and-bounds.rs:12:28
    |
@@ -21,11 +21,11 @@ error[E0311]: the parameter type `T` may not live long enough
 LL |     async fn foo(&self) -> &(T, U) where T: Debug + Sized, U: Hash;
    |                            ^^^^^^^
    |
-note: the parameter type `T` must be valid for the anonymous lifetime as defined here...
+note: the parameter type `T` must be valid for the anonymous lifetime defined here...
   --> $DIR/async-generics-and-bounds.rs:12:18
    |
 LL |     async fn foo(&self) -> &(T, U) where T: Debug + Sized, U: Hash;
-   |                  ^
+   |                  ^^^^^
 note: ...so that the reference type `&(T, U)` does not outlive the data it points at
   --> $DIR/async-generics-and-bounds.rs:12:28
    |

src/test/ui/async-await/in-trait/async-generics.stderr

@@ -4,11 +4,11 @@ error[E0311]: the parameter type `U` may not live long enough
 LL |     async fn foo(&self) -> &(T, U);
    |                            ^^^^^^^
    |
-note: the parameter type `U` must be valid for the anonymous lifetime as defined here...
+note: the parameter type `U` must be valid for the anonymous lifetime defined here...
   --> $DIR/async-generics.rs:9:18
    |
 LL |     async fn foo(&self) -> &(T, U);
-   |                  ^
+   |                  ^^^^^
 note: ...so that the reference type `&(T, U)` does not outlive the data it points at
   --> $DIR/async-generics.rs:9:28
    |
@@ -21,11 +21,11 @@ error[E0311]: the parameter type `T` may not live long enough
 LL |     async fn foo(&self) -> &(T, U);
    |                            ^^^^^^^
    |
-note: the parameter type `T` must be valid for the anonymous lifetime as defined here...
+note: the parameter type `T` must be valid for the anonymous lifetime defined here...
   --> $DIR/async-generics.rs:9:18
    |
 LL |     async fn foo(&self) -> &(T, U);
-   |                  ^
+   |                  ^^^^^
 note: ...so that the reference type `&(T, U)` does not outlive the data it points at
   --> $DIR/async-generics.rs:9:28
    |

src/test/ui/async-await/in-trait/async-lifetimes-and-bounds.rs

@@ -1,5 +1,4 @@
-// check-fail
-// known-bug: #102682
+// check-pass
 // edition: 2021
 
 #![feature(async_fn_in_trait)]

src/test/ui/async-await/in-trait/async-lifetimes-and-bounds.stderr

@@ -1,5 +1,4 @@
-// check-fail
-// known-bug: #102682
+// check-pass
 // edition: 2021
 
 #![feature(async_fn_in_trait)]

src/test/ui/async-await/in-trait/async-lifetimes.rs

@@ -0,0 +1,13 @@
+// check-pass
+// edition: 2021
+
+#![feature(async_fn_in_trait)]
+#![allow(incomplete_features)]
+
+trait TcpStack {
+    type Connection<'a>: Sized where Self: 'a;
+    fn connect<'a>(&'a self) -> Self::Connection<'a>;
+    async fn async_connect<'a>(&'a self) -> Self::Connection<'a>;
+}
+
+fn main() {}

src/test/ui/async-await/in-trait/async-lifetimes.stderr

@@ -0,0 +1,24 @@
+// check-pass
+// edition: 2021
+
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::fmt::Debug;
+
+trait Foo<Item> {
+    fn foo<'a>(&'a self) -> impl Debug
+    where
+        Item: 'a;
+}
+
+impl<Item, D: Debug + Clone> Foo<Item> for D {
+    fn foo<'a>(&'a self) -> impl Debug
+    where
+        Item: 'a,
+    {
+        self.clone()
+    }
+}
+
+fn main() {}