From 8b531fdc0257849b887022d889b79634088afb3a Mon Sep 17 00:00:00 2001
From: Arthur Cohen <arthur.cohen@embecosm.com>
Date: Wed, 6 Mar 2024 16:19:46 +0100
Subject: [PATCH] [wip] unify never

---
 gcc/rust/typecheck/rust-unify.cc | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/gcc/rust/typecheck/rust-unify.cc b/gcc/rust/typecheck/rust-unify.cc
index d2c3efc701a..029e615da17 100644
--- a/gcc/rust/typecheck/rust-unify.cc
+++ b/gcc/rust/typecheck/rust-unify.cc
@@ -238,11 +238,8 @@ UnifyRules::go ()
 	}
     }
 
-  // The never type should always get coerced to the type it's being matched
-  // against, so in that case, ltype. This avoids doing the same check in all
-  // the `expect_*` functions.
   if (rtype->get_kind () == TyTy::NEVER)
-    return ltype->clone ();
+    return rtype->clone ();
 
   switch (ltype->get_kind ())
     {
@@ -1543,8 +1540,32 @@ UnifyRules::expect_never (TyTy::NeverType *ltype, TyTy::BaseType *rtype)
       }
       break;
 
-    default:
+    case TyTy::NEVER:
       return rtype->clone ();
+
+    case TyTy::PLACEHOLDER:
+    case TyTy::PROJECTION:
+    case TyTy::DYNAMIC:
+    case TyTy::CLOSURE:
+    case TyTy::SLICE:
+    case TyTy::PARAM:
+    case TyTy::POINTER:
+    case TyTy::STR:
+    case TyTy::ADT:
+    case TyTy::REF:
+    case TyTy::ARRAY:
+    case TyTy::FNDEF:
+    case TyTy::FNPTR:
+    case TyTy::TUPLE:
+    case TyTy::BOOL:
+    case TyTy::CHAR:
+    case TyTy::INT:
+    case TyTy::UINT:
+    case TyTy::FLOAT:
+    case TyTy::USIZE:
+    case TyTy::ISIZE:
+    case TyTy::ERROR:
+      return new TyTy::ErrorType (0);
     }
   return new TyTy::ErrorType (0);
 }