From 42945fc1e225821f4eea61a8529c624a3d43b415 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Mon, 13 Nov 2023 11:27:15 +0000
Subject: [PATCH] args~~_ref~~_may_unify

---
 compiler/rustc_middle/src/ty/fast_reject.rs               | 8 ++++----
 .../rustc_trait_selection/src/solve/project_goals/mod.rs  | 2 +-
 compiler/rustc_trait_selection/src/solve/trait_goals.rs   | 4 +---
 compiler/rustc_trait_selection/src/traits/coherence.rs    | 2 +-
 .../src/traits/select/candidate_assembly.rs               | 2 +-
 5 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/fast_reject.rs b/compiler/rustc_middle/src/ty/fast_reject.rs
index 75ea53195a3..f95ceeff150 100644
--- a/compiler/rustc_middle/src/ty/fast_reject.rs
+++ b/compiler/rustc_middle/src/ty/fast_reject.rs
@@ -189,14 +189,14 @@ pub struct DeepRejectCtxt {
 }
 
 impl DeepRejectCtxt {
-    pub fn args_refs_may_unify<'tcx>(
+    pub fn args_may_unify<'tcx>(
         self,
         obligation_args: GenericArgsRef<'tcx>,
         impl_args: GenericArgsRef<'tcx>,
     ) -> bool {
         iter::zip(obligation_args, impl_args).all(|(obl, imp)| {
             match (obl.unpack(), imp.unpack()) {
-                // We don't fast reject based on regions for now.
+                // We don't fast reject based on regions.
                 (GenericArgKind::Lifetime(_), GenericArgKind::Lifetime(_)) => true,
                 (GenericArgKind::Type(obl), GenericArgKind::Type(imp)) => {
                     self.types_may_unify(obl, imp)
@@ -231,7 +231,7 @@ impl DeepRejectCtxt {
             | ty::Never
             | ty::Tuple(..)
             | ty::FnPtr(..)
-            | ty::Foreign(..) => {}
+            | ty::Foreign(..) => debug_assert!(impl_ty.is_known_rigid()),
             ty::FnDef(..)
             | ty::Closure(..)
             | ty::Coroutine(..)
@@ -260,7 +260,7 @@ impl DeepRejectCtxt {
             },
             ty::Adt(obl_def, obl_args) => match k {
                 &ty::Adt(impl_def, impl_args) => {
-                    obl_def == impl_def && self.args_refs_may_unify(obl_args, impl_args)
+                    obl_def == impl_def && self.args_may_unify(obl_args, impl_args)
                 }
                 _ => false,
             },
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals/mod.rs b/compiler/rustc_trait_selection/src/solve/project_goals/mod.rs
index 240141065dc..7fb550aa3e0 100644
--- a/compiler/rustc_trait_selection/src/solve/project_goals/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/project_goals/mod.rs
@@ -160,7 +160,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
         let goal_trait_ref = goal.predicate.projection_ty.trait_ref(tcx);
         let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
         let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::ForLookup };
-        if !drcx.args_refs_may_unify(goal_trait_ref.args, impl_trait_ref.skip_binder().args) {
+        if !drcx.args_may_unify(goal_trait_ref.args, impl_trait_ref.skip_binder().args) {
             return Err(NoSolution);
         }
 
diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
index a0e2ad6e202..84baec4ff4c 100644
--- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
@@ -43,9 +43,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
 
         let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
         let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::ForLookup };
-        if !drcx
-            .args_refs_may_unify(goal.predicate.trait_ref.args, impl_trait_ref.skip_binder().args)
-        {
+        if !drcx.args_may_unify(goal.predicate.trait_ref.args, impl_trait_ref.skip_binder().args) {
             return Err(NoSolution);
         }
 
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index dcf5fd86929..787d8063005 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -100,7 +100,7 @@ pub fn overlapping_impls(
     let impl1_ref = tcx.impl_trait_ref(impl1_def_id);
     let impl2_ref = tcx.impl_trait_ref(impl2_def_id);
     let may_overlap = match (impl1_ref, impl2_ref) {
-        (Some(a), Some(b)) => drcx.args_refs_may_unify(a.skip_binder().args, b.skip_binder().args),
+        (Some(a), Some(b)) => drcx.args_may_unify(a.skip_binder().args, b.skip_binder().args),
         (None, None) => {
             let self_ty1 = tcx.type_of(impl1_def_id).skip_binder();
             let self_ty2 = tcx.type_of(impl2_def_id).skip_binder();
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index f4b6d3bcfda..c1d44601891 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -375,7 +375,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // consider a "quick reject". This avoids creating more types
                 // and so forth that we need to.
                 let impl_trait_ref = self.tcx().impl_trait_ref(impl_def_id).unwrap();
-                if !drcx.args_refs_may_unify(obligation_args, impl_trait_ref.skip_binder().args) {
+                if !drcx.args_may_unify(obligation_args, impl_trait_ref.skip_binder().args) {
                     return;
                 }
                 if self.reject_fn_ptr_impls(