change HIR typeck unification handling approach

3 files changed, 18 insertions, 11 deletions

diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 3f628d80662..575e0472e0e 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -252,7 +252,9 @@ where
                         // inside of an opaque type, e.g. if there's `Opaque = (?x, ?x)` in the
                         // storage, we can also rely on structural identity of `?x` even if we
                         // later uniquify it in MIR borrowck.
-                        if infcx.in_hir_typeck && obligation.has_non_region_infer() {
+                        if infcx.in_hir_typeck
+                            && (obligation.has_non_region_infer() || obligation.has_free_regions())
+                        {
                             infcx.push_hir_typeck_potentially_region_dependent_goal(obligation);
                         }
                     }
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
index 0ca2d216228..6ce68507d65 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
@@ -1,6 +1,7 @@
 use std::fmt;
 
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::def_id::LocalDefId;
 use rustc_infer::infer::region_constraints::RegionConstraintData;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{TyCtxt, TypeFoldable};
@@ -42,13 +43,14 @@ where
     fn fully_perform(
         self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed> {
         if cfg!(debug_assertions) {
             info!("fully_perform({:?})", self);
         }
 
-        Ok(scrape_region_constraints(infcx, self.closure, self.description, span)?.0)
+        Ok(scrape_region_constraints(infcx, root_def_id, self.description, span, self.closure)?.0)
     }
 }
 
@@ -62,9 +64,10 @@ impl<F> fmt::Debug for CustomTypeOp<F> {
 /// constraints that result, creating query-region-constraints.
 pub fn scrape_region_constraints<'tcx, Op, R>(
     infcx: &InferCtxt<'tcx>,
-    op: impl FnOnce(&ObligationCtxt<'_, 'tcx>) -> Result<R, NoSolution>,
+    root_def_id: LocalDefId,
     name: &'static str,
     span: Span,
+    op: impl FnOnce(&ObligationCtxt<'_, 'tcx>) -> Result<R, NoSolution>,
 ) -> Result<(TypeOpOutput<'tcx, Op>, RegionConstraintData<'tcx>), ErrorGuaranteed>
 where
     R: TypeFoldable<TyCtxt<'tcx>>,
@@ -94,6 +97,8 @@ where
         let errors = ocx.select_all_or_error();
         if errors.is_empty() {
             Ok(value)
+        } else if let Err(guar) = infcx.tcx.check_potentially_region_dependent_goals(root_def_id) {
+            Err(guar)
         } else {
             Err(infcx
                 .dcx()
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
index 018e9748cf0..4b8bf868123 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
@@ -1,6 +1,7 @@
 use std::fmt;
 
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::def_id::LocalDefId;
 use rustc_infer::traits::PredicateObligations;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{ParamEnvAnd, TyCtxt, TypeFoldable};
@@ -37,6 +38,7 @@ pub trait TypeOp<'tcx>: Sized + fmt::Debug {
     fn fully_perform(
         self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed>;
 }
@@ -140,6 +142,7 @@ where
     fn fully_perform(
         self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed> {
         // In the new trait solver, query type ops are performed locally. This
@@ -152,9 +155,10 @@ where
         if infcx.next_trait_solver() {
             return Ok(scrape_region_constraints(
                 infcx,
-                |ocx| QueryTypeOp::perform_locally_with_next_solver(ocx, self, span),
+                root_def_id,
                 "query type op",
                 span,
+                |ocx| QueryTypeOp::perform_locally_with_next_solver(ocx, self, span),
             )?
             .0);
         }
@@ -166,19 +170,15 @@ where
         // 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 (mut output, _) =
+            scrape_region_constraints(infcx, root_def_id, "fully_perform", span, |ocx| {
                 let (output, ei, obligations, _) =
                     Q::fully_perform_into(self, infcx, &mut region_constraints, span)?;
                 error_info = ei;
 
                 ocx.register_obligations(obligations);
                 Ok(output)
-            },
-            "fully_perform",
-            span,
-        )?;
+            })?;
         output.error_info = error_info;
         if let Some(QueryRegionConstraints { outlives, assumptions }) = output.constraints {
             region_constraints.outlives.extend(outlives.iter().cloned());