fix[lang]: fix incorrect handling of tuples in nested subscripts

tests/functional/syntax/test_hashmap_container_type.py

@@ -0,0 +1,32 @@
+import pytest
+
+from vyper.compiler import compile_code
+
+valid_list = [
+    """
+d: HashMap[uint256, HashMap[uint256, uint256]]
+
+@external
+def foo() -> uint256:
+    return self.d[0][0]
+    """,
+    """
+d: HashMap[uint256, uint256[10]]
+
+@external
+def foo() -> uint256:
+    return self.d[0][0]
+    """,
+    """
+d: HashMap[uint256, (uint256, uint256)]
+
+@external
+def foo() -> uint256:
+    return self.d[0][0]
+    """,
+]
+
+
+@pytest.mark.parametrize("good_code", valid_list)
+def test_list_success(good_code):
+    assert compile_code(good_code) is not None

vyper/semantics/analysis/local.py

@@ -931,7 +931,13 @@ def visit_Subscript(self, node: vy_ast.Subscript, typ: VyperType) -> None:
             possible_base_types = get_possible_types_from_node(node.value)
 
             for possible_type in possible_base_types:
-                if typ.compare_type(possible_type.value_type):
+                if isinstance(possible_type, TupleT):
+                    assert isinstance(node.slice, vy_ast.Int)  # help mypy
+                    value_type = possible_type.member_types[node.slice.value]
+                else:
+                    value_type = possible_type.value_type
+
+                if typ.compare_type(value_type):
                     base_type = possible_type
                     break
             else: