Rollup merge of #116802 - compiler-errors:anchor-opaque-wf, r=oli-obk

Remove `DefiningAnchor::Bubble` from opaque wf check

Set the defining anchor to `DefiningAnchor::Bind(parent_def_id)` where `parent_def_id` is the first parent def-id that isn't an opaque.

This "fixes" some of the nested-return-type wf tests. If we *do* want these to be hard-errors for TAITs, we should probably make those error separately from this check (i.e. via some check like the code in the `OPAQUE_HIDDEN_INFERRED_BOUND` lint). The fact that some of these tests fail but not all of them seems kinda coincidental.

r? oli-obk

1 files changed, 8 insertions, 8 deletions

diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index ff04b0237c2..ee554370305 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -1,5 +1,6 @@
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::OpaqueTyOrigin;
 use rustc_infer::infer::InferCtxt;
@@ -308,20 +309,19 @@ fn check_opaque_type_well_formed<'tcx>(
         return Ok(definition_ty);
     };
     let param_env = tcx.param_env(def_id);
-    // HACK This bubble is required for this tests to pass:
-    // nested-return-type2-tait2.rs
-    // nested-return-type2-tait3.rs
+
+    let mut parent_def_id = def_id;
+    while tcx.def_kind(parent_def_id) == DefKind::OpaqueTy {
+        parent_def_id = tcx.local_parent(parent_def_id);
+    }
+
     // FIXME(-Ztrait-solver=next): We probably should use `DefiningAnchor::Error`
     // and prepopulate this `InferCtxt` with known opaque values, rather than
     // using the `Bind` anchor here. For now it's fine.
     let infcx = tcx
         .infer_ctxt()
         .with_next_trait_solver(next_trait_solver)
-        .with_opaque_type_inference(if next_trait_solver {
-            DefiningAnchor::Bind(def_id)
-        } else {
-            DefiningAnchor::Bubble
-        })
+        .with_opaque_type_inference(DefiningAnchor::Bind(parent_def_id))
         .build();
     let ocx = ObligationCtxt::new(&infcx);
     let identity_args = GenericArgs::identity_for_item(tcx, def_id);