Resolver output is now validated and converted for typed nodes

This is related to omry#488

news/445.api_change.2

@@ -0,0 +1 @@
+If the value of a typed node is computed by a resolver (including `env`), it is now validated (and possibly converted) based on the type

omegaconf/base.py

@@ -463,13 +463,20 @@ def _evaluate_custom_resolver(
     ) -> Optional["Node"]:
         from omegaconf import OmegaConf
 
-        from .nodes import ValueNode
+        from .nodes import AnyNode, ValueNode
 
         resolver = OmegaConf.get_resolver(inter_type)
         if resolver is not None:
             root_node = self._get_root()
             try:
                 value = resolver(root_node, inter_args, inter_args_str)
+
+                # Ensure the resolver output is compatible with the node's type.
+                if key is not None:
+                    node = self._get_node(key)
+                    if isinstance(node, ValueNode) and not isinstance(node, AnyNode):
+                        value = node.validate_and_convert(value)
+
                 return ValueNode(
                     value=value,
                     parent=self,

tests/test_interpolation.py

@@ -10,6 +10,7 @@
 
 from omegaconf import (
     II,
+    SI,
     Container,
     DictConfig,
     IntegerNode,
@@ -30,6 +31,8 @@
     UnsupportedInterpolationType,
 )
 
+from . import User
+
 # file deepcode ignore CopyPasteError: there are several tests of the form `c.k == c.k`
 # (this is intended to trigger multiple accesses to the same config key)
 
@@ -1082,3 +1085,24 @@ def _check_is_same_type(value: Any, expected: Any) -> None:
         assert expected is None
     else:
         raise NotImplementedError(type(value))
+
+
+def test_custom_resolver_return_validated(restore_resolvers: Any) -> Any:
+    def cast(t: Any, v: Any) -> Any:
+        if t == "str":
+            return str(v)
+        if t == "int":
+            return int(v)
+        assert False
+
+    OmegaConf.new_register_resolver("cast", cast)
+    cfg = OmegaConf.structured(User(name="Bond", age=SI("${cast:int,'7'}")))
+    assert cfg.age == 7
+
+    # converted to int per the dataclass age field
+    cfg = OmegaConf.structured(User(name="Bond", age=SI("${cast:str,'7'}")))
+    assert cfg.age == 7
+
+    cfg = OmegaConf.structured(User(name="Bond", age=SI("${cast:str,seven}")))
+    with pytest.raises(ValidationError):
+        cfg.age

tests/test_matrix.py

@@ -173,7 +173,7 @@ def test_none_construction(self, node_type: Any, values: Any) -> None:
     def test_interpolation(
         self, node_type: Any, values: Any, restore_resolvers: Any
     ) -> None:
-        resolver_output = 9999
+        resolver_output = "9999"
         OmegaConf.new_register_resolver("func", lambda: resolver_output)
         values = copy.deepcopy(values)
         for value in values: