From d542a41475d08817d167c75f2217e28469c33e48 Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Fri, 7 Nov 2025 13:28:58 -0800
Subject: [PATCH 1/2] Properly mark Unsubtyping as closed-world

---
 scripts/fuzz_opt.py        | 3 ++-
 src/passes/Unsubtyping.cpp | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/scripts/fuzz_opt.py b/scripts/fuzz_opt.py
index e5cba2772b5..f4276f58e29 100755
--- a/scripts/fuzz_opt.py
+++ b/scripts/fuzz_opt.py
@@ -2486,7 +2486,8 @@ def write_commands(commands, filename):
                          ("--cfp-reftest",),
                          ("--gsi",),
                          ("--type-ssa",),
-                         ("--type-merging",)}
+                         ("--type-merging",),
+                         ("--unsubtyping",)}
 
 
 def get_random_opts():
diff --git a/src/passes/Unsubtyping.cpp b/src/passes/Unsubtyping.cpp
index ad371d19a28..5bc07467da8 100644
--- a/src/passes/Unsubtyping.cpp
+++ b/src/passes/Unsubtyping.cpp
@@ -446,6 +446,10 @@ struct Unsubtyping : Pass {
       return;
     }
 
+    if (!getPassOptions().closedWorld) {
+      Fatal() << "Unsubtyping requires --closed-world";
+    }
+
     // Initialize the subtype relation based on what is immediately required to
     // keep the code and public types valid.
     analyzePublicTypes(*wasm);

From 60fd544480cf70c723ae680498808d1db9fbec6b Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Fri, 7 Nov 2025 13:42:29 -0800
Subject: [PATCH 2/2] fix random test

---
 test/lit/passes/issue-7087.wast | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/lit/passes/issue-7087.wast b/test/lit/passes/issue-7087.wast
index 096c88e5d45..fab633293d5 100644
--- a/test/lit/passes/issue-7087.wast
+++ b/test/lit/passes/issue-7087.wast
@@ -9,7 +9,7 @@
 ;; module-level code in TypeSSA and fix the validator so it would have caught
 ;; the stale type.
 
-;; RUN: wasm-opt %s -all --type-ssa --unsubtyping -S -o - | filecheck %s
+;; RUN: wasm-opt %s -all --type-ssa --unsubtyping --closed-world -S -o - | filecheck %s
 
 (module
  ;; CHECK:      (rec