allow lists of any type as loop variable

vyper/codegen/stmt.py

@@ -17,6 +17,7 @@
 from vyper.codegen.expr import Expr
 from vyper.codegen.return_ import make_return_stmt
 from vyper.codegen.types import BaseType, ByteArrayType, DArrayType, SArrayType, parse_type
+from vyper.codegen.types.convert import new_type_to_old_type
 from vyper.exceptions import CompilerPanic, StructureException, TypeCheckFailure
 
 
@@ -299,13 +300,10 @@ def _parse_For_list(self):
         with self.context.range_scope():
             iter_list = Expr(self.stmt.iter, self.context).lll_node
 
-        # TODO relax this restriction
-        if not isinstance(iter_list.typ.subtype, BaseType):
-            return
-
         # override with type inferred at typechecking time
-        subtype = BaseType(self.stmt.target._metadata["type"]._id)
-        iter_list.typ.subtype = subtype
+        typ = new_type_to_old_type(self.stmt.iter._metadata["type"])
+        iter_list.typ = typ
+        subtype = typ.subtype
 
         # user-supplied name for loop variable
         varname = self.stmt.target.id

vyper/codegen/types/convert.py

@@ -0,0 +1,37 @@
+# transition module to convert from new types to old types
+
+import vyper.codegen.types as old
+import vyper.semantics.types as new
+from vyper.exceptions import InvalidType
+
+
+def new_type_to_old_type(typ: new.BasePrimitive) -> old.NodeType:
+    if isinstance(typ, new.BoolDefinition):
+        return old.BaseType("bool")
+    if isinstance(typ, new.AddressDefinition):
+        return old.BaseType("address")
+    if isinstance(typ, new.Bytes32Definition):
+        return old.BaseType("bytes32")
+    if isinstance(typ, new.BytesArrayDefinition):
+        return old.BytesType(typ.count)
+    if isinstance(typ, new.StringDefinition):
+        return old.StringType(typ.count)
+    if isinstance(typ, new.DecimalDefinition):
+        return old.BaseType("decimal")
+    if isinstance(typ, new.SignedIntegerAbstractType):
+        bits = typ._bits  # type: ignore
+        return old.BaseType("int" + str(bits))
+    if isinstance(typ, new.UnsignedIntegerAbstractType):
+        bits = typ._bits  # type: ignore
+        return old.BaseType("uint" + str(bits))
+    if isinstance(typ, new.ArrayDefinition):
+        return old.SArrayType(new_type_to_old_type(typ.value_type), typ.length)
+    if isinstance(typ, new.DynamicArrayDefinition):
+        return old.DArrayType(new_type_to_old_type(typ.value_type), typ.length)
+    if isinstance(typ, new.TupleDefinition):
+        return old.TupleType(typ.value_type)
+    if isinstance(typ, new.StructDefinition):
+        return old.StructType(
+            {n: new_type_to_old_type(t) for (n, t) in typ.members.items()}, typ._id
+        )
+    raise InvalidType(f"unknown type {typ}")

vyper/semantics/validation/local.py

@@ -32,7 +32,6 @@
     TupleDefinition,
 )
 from vyper.semantics.types.user.event import Event
-from vyper.semantics.types.user.struct import StructDefinition
 from vyper.semantics.types.utils import get_type_from_annotation
 from vyper.semantics.types.value.address import AddressDefinition
 from vyper.semantics.types.value.array_value import StringDefinition
@@ -369,12 +368,6 @@ def visit_For(self, node):
         if not type_list:
             raise InvalidType("Not an iterable type", node.iter)
 
-        if next((i for i in type_list if isinstance(i, ArrayDefinition)), False):
-            raise StructureException("Cannot iterate over a nested list", node.iter)
-
-        if next((i for i in type_list if isinstance(i, StructDefinition)), False):
-            raise StructureException("Cannot iterate over a list of structs", node.iter)
-
         if isinstance(node.iter, (vy_ast.Name, vy_ast.Attribute)):
             # check for references to the iterated value within the body of the loop
             assign = _check_iterator_assign(node.iter, node)