Merge branch 'feat/allow_empty_dicts' into feat/unop_dynamic

opshin/optimize/optimize_const_folding.py

@@ -337,7 +337,7 @@ def generic_visit(self, node: AST):
         if any(
             isinstance(node_eval, t)
             for t in ACCEPTED_ATOMIC_TYPES + [list, dict, PlutusData]
-        ):
+        ) and not (node_eval == [] or node_eval == {}):
             new_node = Constant(node_eval, None)
             copy_location(new_node, node)
             return new_node

opshin/tests/test_misc.py

@@ -2702,3 +2702,16 @@ def validator(_: None) -> Dict[int, int]:
 """
         res = eval_uplc_value(source_code, Unit(), constant_folding=True)
         self.assertEqual(res, {})
+
+    def test_empty_dict_displaced_constant_folding(self):
+        source_code = """
+from typing import Dict, List, Union
+
+VAR: Dict[bytes, int] = {}
+
+def validator(b: Dict[int, Dict[bytes, int]]) -> Dict[bytes, int]:
+    a = b.get(0, VAR)
+    return a
+        """
+        res = eval_uplc_value(source_code, {1: {b"": 0}}, constant_folding=True)
+        self.assertEqual(res, {})

opshin/type_inference.py

@@ -72,7 +72,7 @@ def constant_type(c):
         ), "Constant lists must contain elements of a single type only"
         return InstanceType(ListType(first_typ))
     if isinstance(c, dict):
-        assert len(c) > 0, "Lists must be non-empty"
+        assert len(c) > 0, "Dicts must be non-empty"
         first_key_typ = constant_type(next(iter(c.keys())))
         first_value_typ = constant_type(next(iter(c.values())))
         assert all(
@@ -1085,7 +1085,7 @@ def visit_While(self, node: For) -> bool:
     def visit_Return(self, node: Return) -> bool:
         assert (
             self.func_rettyp >= node.typ
-        ), f"Function '{node.name}' annotated return type does not match actual return type"
+        ), f"Function annotated return type does not match actual return type"
         return True
 
     def check_fulfills(self, node: FunctionDef):