Scrape extraneous regions from instantiate_nll_query_response_and_region_obligations

compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs

@@ -159,11 +159,19 @@ where
             .0);
         }
 
+        let mut error_info = None;
         let mut region_constraints = QueryRegionConstraints::default();
-        let (output, error_info, mut obligations, _) =
-            Q::fully_perform_into(self, infcx, &mut region_constraints, span).map_err(|_| {
-                infcx.dcx().span_delayed_bug(span, format!("error performing {self:?}"))
-            })?;
+
+        // HACK(type_alias_impl_trait): When moving an opaque type to hidden type mapping from the query to the current inferctxt,
+        // we sometimes end up with `Opaque<'a> = Opaque<'b>` instead of an actual hidden type. In that case we don't register a
+        // hidden type but just equate the lifetimes. Thus we need to scrape the region constraints even though we're also manually
+        // collecting region constraints via `region_constraints`.
+        let (mut output, _) = scrape_region_constraints(
+            infcx,
+            |_ocx| {
+                let (output, ei, mut obligations, _) =
+                    Q::fully_perform_into(self, infcx, &mut region_constraints, span)?;
+                error_info = ei;
 
                 // Typically, instantiating NLL query results does not
                 // create obligations. However, in some cases there
@@ -192,20 +200,29 @@ where
                         }
                     }
                     if !progress {
-                infcx
-                    .dcx()
-                    .span_bug(span, format!("ambiguity processing {obligations:?} from {self:?}"));
+                        infcx.dcx().span_bug(
+                            span,
+                            format!("ambiguity processing {obligations:?} from {self:?}"),
+                        );
                     }
                 }
-
-        Ok(TypeOpOutput {
-            output,
-            constraints: if region_constraints.is_empty() {
+                Ok(output)
+            },
+            "fully_perform",
+            span,
+        )?;
+        output.error_info = error_info;
+        if let Some(constraints) = output.constraints {
+            region_constraints
+                .member_constraints
+                .extend(constraints.member_constraints.iter().cloned());
+            region_constraints.outlives.extend(constraints.outlives.iter().cloned());
+        }
+        output.constraints = if region_constraints.is_empty() {
             None
         } else {
             Some(infcx.tcx.arena.alloc(region_constraints))
-            },
-            error_info,
-        })
+        };
+        Ok(output)
     }
 }

tests/ui/inference/issue-80409.no-compat.stderr

@@ -1,4 +1,4 @@
-error: internal compiler error: error performing ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: UserFacing }, value: ImpliedOutlivesBounds { ty: &'?2 mut StateContext<'?3, usize> } }
+error: internal compiler error: error performing operation: fully_perform
   --> $DIR/issue-80409.rs:49:30
    |
 LL |     builder.state().on_entry(|_| {});