Actually set the defining use anchor on ObligationCtxt

Author: oli-obk

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -278,7 +278,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         // nested-return-type2-tait3.rs
         let infcx =
             self.tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).build();
-        let ocx = ObligationCtxt::new(&infcx);
+        let ocx = ObligationCtxt::new_with_opaque_type_bubbling(&infcx);
         // Require the hidden type to be well-formed with only the generics of the opaque type.
         // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
         // hidden type is well formed even without those bounds.

compiler/rustc_const_eval/src/util/compare_types.rs

@@ -44,7 +44,7 @@ pub fn is_subtype<'tcx>(
     let mut builder =
         tcx.infer_ctxt().ignoring_regions().with_opaque_type_inference(DefiningAnchor::Bubble);
     let infcx = builder.build();
-    let ocx = ObligationCtxt::new(&infcx);
+    let ocx = ObligationCtxt::new_with_opaque_type_bubbling(&infcx);
     let cause = ObligationCause::dummy();
     let src = ocx.normalize(&cause, param_env, src);
     let dest = ocx.normalize(&cause, param_env, dest);

compiler/rustc_hir_analysis/src/check/check.rs

@@ -417,7 +417,7 @@ fn check_opaque_meets_bounds<'tcx>(
         .infer_ctxt()
         .with_opaque_type_inference(DefiningAnchor::Bind(defining_use_anchor))
         .build();
-    let ocx = ObligationCtxt::new(&infcx);
+    let ocx = ObligationCtxt::new_with_opaque_type_anchor(&infcx, defining_use_anchor);
     let opaque_ty = tcx.mk_opaque(def_id.to_def_id(), substs);
 
     // `ReErased` regions appear in the "parent_substs" of closures/generators.

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -60,7 +60,23 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
         Self {
             infcx,
             engine: RefCell::new(<dyn TraitEngine<'_>>::new(infcx.tcx)),
-            defining_use_anchor: infcx.old_defining_use_anchor,
+            defining_use_anchor: DefiningAnchor::Error,
+        }
+    }
+
+    pub fn new_with_opaque_type_bubbling(infcx: &'a InferCtxt<'tcx>) -> Self {
+        Self {
+            infcx,
+            engine: RefCell::new(<dyn TraitEngine<'_>>::new(infcx.tcx)),
+            defining_use_anchor: DefiningAnchor::Bubble,
+        }
+    }
+
+    pub fn new_with_opaque_type_anchor(infcx: &'a InferCtxt<'tcx>, anchor: LocalDefId) -> Self {
+        Self {
+            infcx,
+            engine: RefCell::new(<dyn TraitEngine<'_>>::new(infcx.tcx)),
+            defining_use_anchor: DefiningAnchor::Bind(anchor),
         }
     }