oc.create() does not set the readonly flag anymore

The motivation is that otherwise it prevents merging the config with
another one.

omegaconf/resolvers/oc/__init__.py

@@ -13,11 +13,7 @@ def create(obj: Any, _parent_: Container) -> Any:
     from omegaconf import OmegaConf
 
     assert isinstance(_parent_, BaseContainer)
-    ret = OmegaConf.create(obj, parent=_parent_)
-    # Since this node is re-generated on-the-fly, changes would be lost: we mark it
-    # as read-only to avoid mistakes.
-    ret._set_flag("readonly", True)
-    return ret
+    return OmegaConf.create(obj, parent=_parent_)
 
 
 def env(key: str, default: Any = _DEFAULT_MARKER_) -> Optional[str]:

tests/interpolation/built_in_resolvers/test_create_resolver.py

@@ -2,7 +2,7 @@
 
 from pytest import mark, param, raises
 
-from omegaconf import DictConfig, ListConfig, OmegaConf, flag_override
+from omegaconf import DictConfig, ListConfig, OmegaConf
 from omegaconf.errors import InterpolationResolutionError
 
 
@@ -54,7 +54,7 @@ def test_create(cfg: Any, key: str, expected: Any) -> None:
     val = cfg[key]
     assert val == expected
     assert type(val) is type(expected)
-    assert val._get_flag("readonly")
+    assert val._get_flag("readonly") is None
 
 
 def test_create_error() -> None:
@@ -74,14 +74,13 @@ def test_write_into_output() -> None:
         }
     )
     x = cfg.x
-    assert x._get_flag("readonly")
+    assert x._get_flag("readonly") is None
 
-    # "Force-write" into the node generated by `oc.create`.
-    with flag_override(x, "readonly", False):
-        x.a = 1
-        x.b.c = 2
+    # Write into the node generated by `oc.create`.
+    x.a = 1
+    x.b.c = 2
 
-    # The node that we force-wrote into should be modified.
+    # The node that we wrote into should be modified.
     assert x.a == 1
     assert x.b.c == 2
 
@@ -132,3 +131,9 @@ def test_resolver_output_list_to_listconfig(
     assert isinstance(c.x, ListConfig)
     assert c.x == expected
     assert c.x._parent is c
+
+
+def test_merge_into_created_node() -> None:
+    cfg: Any = OmegaConf.create({"x": "${oc.create:{y: 0}}"})
+    cfg = OmegaConf.merge(cfg, {"x": {"z": 1}})
+    assert cfg == {"x": {"y": 0, "z": 1}}