Add a compilation test for recursive hash map types

PiperOrigin-RevId: 492535520
Change-Id: I2e58b39bd4ab3064f675474c5e712c76fac02674

absl/container/flat_hash_map_test.cc

@@ -311,6 +311,14 @@ TEST(FlatHashMap, Reserve) {
   }
   }
 }
 }
 
 
+TEST(FlatHashMap, RecursiveTypeCompiles) {
+  struct RecursiveType {
+    flat_hash_map<int, RecursiveType> m;
+  };
+  RecursiveType t;
+  t.m[0] = RecursiveType{};
+}
+
 }  // namespace
 }  // namespace
 }  // namespace container_internal
 }  // namespace container_internal
 ABSL_NAMESPACE_END
 ABSL_NAMESPACE_END

absl/container/node_hash_map_test.cc

@@ -272,6 +272,14 @@ TEST(NodeHashMap, NodeHandleMutableKeyAccess) {
 }
 }
 #endif
 #endif
 
 
+TEST(NodeHashMap, RecursiveTypeCompiles) {
+  struct RecursiveType {
+    node_hash_map<int, RecursiveType> m;
+  };
+  RecursiveType t;
+  t.m[0] = RecursiveType{};
+}
+
 }  // namespace
 }  // namespace
 }  // namespace container_internal
 }  // namespace container_internal
 ABSL_NAMESPACE_END
 ABSL_NAMESPACE_END