fixup! Fix to TypeOptimizer to allow literal structs.

llvm/lib/CheerpUtils/TypeOptimizer.cpp

@@ -290,7 +290,10 @@ bool TypeOptimizer::isUnsafeDowncastSource(StructType* st)
 bool TypeOptimizer::canCollapseStruct(llvm::StructType* st, llvm::StructType* newStruct, llvm::Type* newType)
 {
 	if (newStruct == nullptr)
+	{
+		assert(st->isLiteral());
 		return false;
+	}
 	// Stop if the element is just a int8, we may be dealing with an empty struct
 	// Empty structs are unsafe as the int8 inside is just a placeholder and will be replaced
 	// by a different type in a derived class
@@ -447,7 +450,8 @@ TypeOptimizer::TypeMappingInfo TypeOptimizer::rewriteType(Type* t)
 			return CacheAndReturn(newType, TypeMappingInfo::BYTE_LAYOUT_TO_ARRAY);
 		}
 
-		// Generate a new type inconditionally, it may end up being the same as the old one
+		// Generate a new type if it's not a literal struct. It may end up being the same as the old one
+		// In case of literal, it will be created as a literal at the end.
 		StructType* newStruct=nullptr;
 		if (!st->isLiteral())
 			newStruct=StructType::create(st->getContext());