3 files changed, 15 insertions, 4 deletions
diff --git a/src/ir/type-updating.cpp b/src/ir/type-updating.cpp
index b9bbf7a03..b08cca295 100644
--- a/src/ir/type-updating.cpp
+++ b/src/ir/type-updating.cpp
@@ -32,6 +32,15 @@ void GlobalTypeRewriter::update() {
   }
   typeBuilder.grow(indexedTypes.types.size());
 
+  // All the input types are distinct, so we need to make sure the output types
+  // are distinct as well. Further, the new types may have more recursions than
+  // the original types, so the old recursion groups may not be sufficient any
+  // more. Both of these problems are solved by putting all the new types into a
+  // single large recursion group.
+  // TODO: When we properly analyze which types are external and which are
+  // internal to the module, only optimize internal types.
+  typeBuilder.createRecGroup(0, typeBuilder.size());
+
   // Create the temporary heap types.
   for (Index i = 0; i < indexedTypes.types.size(); i++) {
     auto type = indexedTypes.types[i];
diff --git a/src/passes/SignatureRefining.cpp b/src/passes/SignatureRefining.cpp
index 8a8c45872..11df83f4d 100644
--- a/src/passes/SignatureRefining.cpp
+++ b/src/passes/SignatureRefining.cpp
@@ -51,8 +51,9 @@ struct SignatureRefining : public Pass {
     if (!module->features.hasGC()) {
       return;
     }
-    if (getTypeSystem() != TypeSystem::Nominal) {
-      Fatal() << "SignatureRefining requires nominal typing";
+    if (getTypeSystem() != TypeSystem::Nominal &&
+        getTypeSystem() != TypeSystem::Isorecursive) {
+      Fatal() << "SignatureRefining requires nominal/hybrid typing";
     }
 
     if (!module->tables.empty()) {
diff --git a/src/passes/TypeRefining.cpp b/src/passes/TypeRefining.cpp
index c755c1af6..258feae32 100644
--- a/src/passes/TypeRefining.cpp
+++ b/src/passes/TypeRefining.cpp
@@ -81,8 +81,9 @@ struct TypeRefining : public Pass {
     if (!module->features.hasGC()) {
       return;
     }
-    if (getTypeSystem() != TypeSystem::Nominal) {
-      Fatal() << "TypeRefining requires nominal typing";
+    if (getTypeSystem() != TypeSystem::Nominal &&
+        getTypeSystem() != TypeSystem::Isorecursive) {
+      Fatal() << "TypeRefining requires nominal/hybrid typing";
     }
 
     // Find and analyze struct operations inside each function.