diff --git a/flang/include/flang/Optimizer/Dialect/FIRType.h b/flang/include/flang/Optimizer/Dialect/FIRType.h
--- a/flang/include/flang/Optimizer/Dialect/FIRType.h
+++ b/flang/include/flang/Optimizer/Dialect/FIRType.h
@@ -22,6 +22,11 @@
 class FIROpsDialect;
 class KindMapping;
 using KindTy = unsigned;
+
+namespace detail {
+struct RecordTypeStorage;
+} // namespace detail
+
 } // namespace fir
 
 //===----------------------------------------------------------------------===//
diff --git a/mlir/include/mlir/IR/BuiltinAttributes.h b/mlir/include/mlir/IR/BuiltinAttributes.h
--- a/mlir/include/mlir/IR/BuiltinAttributes.h
+++ b/mlir/include/mlir/IR/BuiltinAttributes.h
@@ -31,6 +31,12 @@
 class Operation;
 class RankedTensorType;
 
+namespace detail {
+struct DenseIntOrFPElementsAttrStorage;
+struct DenseStringElementsAttrStorage;
+struct StringAttrStorage;
+} // namespace detail
+
 //===----------------------------------------------------------------------===//
 // Elements Attributes
 //===----------------------------------------------------------------------===//
diff --git a/mlir/include/mlir/IR/BuiltinTypes.h b/mlir/include/mlir/IR/BuiltinTypes.h
--- a/mlir/include/mlir/IR/BuiltinTypes.h
+++ b/mlir/include/mlir/IR/BuiltinTypes.h
@@ -32,6 +32,12 @@
 class StringAttr;
 class TypeRange;
 
+namespace detail {
+struct FunctionTypeStorage;
+struct IntegerTypeStorage;
+struct TupleTypeStorage;
+} // namespace detail
+
 //===----------------------------------------------------------------------===//
 // FloatType
 //===----------------------------------------------------------------------===//
diff --git a/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp b/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
--- a/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
+++ b/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
@@ -67,7 +67,7 @@
   DefGen(const AttrOrTypeDef &def);
 
   void emitDecl(raw_ostream &os) const {
-    if (storageCls) {
+    if (storageCls && def.genStorageClass()) {
       NamespaceEmitter ns(os, def.getStorageNamespace());
       os << "struct " << def.getStorageClassName() << ";\n";
     }