catch extcall in for loop iterator

tests/functional/syntax/test_for_range.py

@@ -358,6 +358,21 @@ def bar(t: address):
         None,
         "extcall I(t).bar()",
     ),
+    (
+        """
+interface I:
+    def bar() -> DynArray[uint256, 10]: nonpayable
+
+@external
+def bar(t: address):
+    for i: uint256 in extcall I(t).bar():
+        pass
+    """,
+        StateAccessViolation,
+        "May not call state modifying function for loop iterator.",
+        None,
+        "extcall I(t).bar()",
+    ),
 ]
 
 for_code_regex = re.compile(r"for .+ in (.*):", re.DOTALL)

vyper/semantics/analysis/local.py

@@ -533,6 +533,10 @@ def _analyse_range_iter(self, iter_node, target_type):
     def _analyse_list_iter(self, iter_node, target_type):
         # iteration over a variable or literal list
         iter_val = iter_node.reduced()
+        if isinstance(iter_val, vy_ast.ExtCall):
+            raise StateAccessViolation(
+                "May not call state modifying function for loop iterator.", iter_val
+            )
 
         if isinstance(iter_val, vy_ast.List):
             len_ = len(iter_val.elements)