support revealing defined opaque post borrowck

6 files changed, 53 insertions, 33 deletions

diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
index adac35b57cd..198ccb000f3 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
@@ -339,7 +339,9 @@ where
 
         match self.typing_mode() {
             TypingMode::Coherence => {}
-            TypingMode::Analysis { .. } | TypingMode::PostAnalysis => {
+            TypingMode::Analysis { .. }
+            | TypingMode::PostBorrowckAnalysis { .. }
+            | TypingMode::PostAnalysis => {
                 self.discard_impls_shadowed_by_env(goal, &mut candidates);
             }
         }
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
index 40d1576256e..70ceb22bfea 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
@@ -644,6 +644,12 @@ where
         }
     }
 
+    pub(super) fn next_region_var(&mut self) -> I::Region {
+        let region = self.delegate.next_region_infer();
+        self.inspect.add_var_value(region);
+        region
+    }
+
     pub(super) fn next_ty_infer(&mut self) -> I::Ty {
         let ty = self.delegate.next_ty_infer();
         self.inspect.add_var_value(ty);
diff --git a/compiler/rustc_next_trait_solver/src/solve/mod.rs b/compiler/rustc_next_trait_solver/src/solve/mod.rs
index 5c54656cc59..ebf1013db1e 100644
--- a/compiler/rustc_next_trait_solver/src/solve/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/mod.rs
@@ -23,7 +23,7 @@ mod trait_goals;
 
 use rustc_type_ir::inherent::*;
 pub use rustc_type_ir::solve::*;
-use rustc_type_ir::{self as ty, Interner};
+use rustc_type_ir::{self as ty, Interner, TypingMode};
 use tracing::instrument;
 
 pub use self::eval_ctxt::{EvalCtxt, GenerateProofTree, SolverDelegateEvalExt};
@@ -321,6 +321,19 @@ where
             Ok(ct)
         }
     }
+
+    fn opaque_type_is_rigid(&self, def_id: I::DefId) -> bool {
+        match self.typing_mode() {
+            // Opaques are never rigid outside of analysis mode.
+            TypingMode::Coherence | TypingMode::PostAnalysis => false,
+            // During analysis, opaques are rigid unless they may be defined by
+            // the current body.
+            TypingMode::Analysis { defining_opaque_types: non_rigid_opaques }
+            | TypingMode::PostBorrowckAnalysis { defined_opaque_types: non_rigid_opaques } => {
+                !def_id.as_local().is_some_and(|def_id| non_rigid_opaques.contains(&def_id))
+            }
+        }
+    }
 }
 
 fn response_no_constraints_raw<I: Interner>(
diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
index 33bd1cf2f56..f5b1b23b8e9 100644
--- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
@@ -6,7 +6,7 @@ mod weak_types;
 use rustc_type_ir::fast_reject::DeepRejectCtxt;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::lang_items::TraitSolverLangItem;
-use rustc_type_ir::{self as ty, Interner, NormalizesTo, TypingMode, Upcast as _};
+use rustc_type_ir::{self as ty, Interner, NormalizesTo, Upcast as _};
 use tracing::instrument;
 
 use crate::delegate::SolverDelegate;
@@ -71,21 +71,10 @@ where
                 Ok(())
             }
             ty::AliasTermKind::OpaqueTy => {
-                match self.typing_mode() {
-                    // Opaques are never rigid outside of analysis mode.
-                    TypingMode::Coherence | TypingMode::PostAnalysis => Err(NoSolution),
-                    // During analysis, opaques are only rigid if we may not define it.
-                    TypingMode::Analysis { defining_opaque_types } => {
-                        if rigid_alias
-                            .def_id
-                            .as_local()
-                            .is_some_and(|def_id| defining_opaque_types.contains(&def_id))
-                        {
-                            Err(NoSolution)
-                        } else {
-                            Ok(())
-                        }
-                    }
+                if self.opaque_type_is_rigid(rigid_alias.def_id) {
+                    Ok(())
+                } else {
+                    Err(NoSolution)
                 }
             }
             // FIXME(generic_const_exprs): we would need to support generic consts here
diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs
index 336bcb9df33..26a8a22d77e 100644
--- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs
@@ -2,6 +2,7 @@
 //! behaves differently depending on the current `TypingMode`.
 
 use rustc_index::bit_set::GrowableBitSet;
+use rustc_type_ir::fold::fold_regions;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::{self as ty, Interner, TypingMode};
 
@@ -95,6 +96,26 @@ where
                 );
                 self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
             }
+            TypingMode::PostBorrowckAnalysis { defined_opaque_types } => {
+                let Some(def_id) = opaque_ty.def_id.as_local() else {
+                    return Err(NoSolution);
+                };
+
+                if !defined_opaque_types.contains(&def_id) {
+                    return Err(NoSolution);
+                }
+
+                let actual = cx.type_of(opaque_ty.def_id).instantiate(cx, opaque_ty.args);
+                // FIXME: Actually use a proper binder here instead of relying on `ReErased`.
+                //
+                // This is also probably unsound or sth :shrug:
+                let actual = fold_regions(cx, actual, |re, _dbi| match re.kind() {
+                    ty::ReErased => self.next_region_var(),
+                    _ => re,
+                });
+                self.eq(goal.param_env, expected, actual)?;
+                self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+            }
             TypingMode::PostAnalysis => {
                 // FIXME: Add an assertion that opaque type storage is empty.
                 let actual = cx.type_of(opaque_ty.def_id).instantiate(cx, opaque_ty.args);
diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
index 096dc32ccc9..6641d2bf924 100644
--- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
@@ -69,7 +69,9 @@ where
             // it's not a real impl.
             (ty::ImplPolarity::Reservation, _) => match ecx.typing_mode() {
                 TypingMode::Coherence => Certainty::AMBIGUOUS,
-                TypingMode::Analysis { .. } | TypingMode::PostAnalysis => return Err(NoSolution),
+                TypingMode::Analysis { .. }
+                | TypingMode::PostBorrowckAnalysis { .. }
+                | TypingMode::PostAnalysis => return Err(NoSolution),
             },
 
             // Impl matches polarity
@@ -174,20 +176,7 @@ where
         // ideally we want to avoid, since we can make progress on this goal
         // via an alias bound or a locally-inferred hidden type instead.
         if let ty::Alias(ty::Opaque, opaque_ty) = goal.predicate.self_ty().kind() {
-            match ecx.typing_mode() {
-                TypingMode::Coherence | TypingMode::PostAnalysis => {
-                    unreachable!("rigid opaque outside of analysis: {goal:?}");
-                }
-                TypingMode::Analysis { defining_opaque_types } => {
-                    if opaque_ty
-                        .def_id
-                        .as_local()
-                        .is_some_and(|def_id| defining_opaque_types.contains(&def_id))
-                    {
-                        return Err(NoSolution);
-                    }
-                }
-            }
+            debug_assert!(ecx.opaque_type_is_rigid(opaque_ty.def_id));
         }
 
         ecx.probe_and_evaluate_goal_for_constituent_tys(