fix codegen failure with nonreentrant keys

codegen now fails (stops compiling) as of eae0eaf. This is because
the storage layout is generated correctly but the type metadata is not
updated after the first function that references a nonreentrancy key.

This commit also adds a codegen test to check codegen of repeated
nonreentrancy keys.

Author: charles-cooper

tests/parser/features/decorators/test_nonreentrant.py

@@ -23,6 +23,8 @@ def updated_protected():
 interface Callback:
     def updated(): nonpayable
     def updated_protected(): nonpayable
+interface Self:
+    def protected_function2(val: String[100], do_callback: bool) -> uint256: nonpayable
 
 special_value: public(String[100])
 callback: public(Callback)
@@ -42,6 +44,15 @@ def protected_function(val: String[100], do_callback: bool) -> uint256:
     else:
         return 2
 
+@external
+@nonreentrant('protect_special_value')
+def protected_function2(val: String[100], do_callback: bool) -> uint256:
+    self.special_value = val
+    if do_callback:
+        Self(self).protected_function2(val, False)
+        return 1
+    return 2
+
 @external
 def unprotected_function(val: String[100], do_callback: bool):
     self.special_value = val
@@ -66,6 +77,12 @@ def unprotected_function(val: String[100], do_callback: bool):
 
     assert_tx_failed(lambda: reentrant_contract.protected_function("zzz value", True, transact={}))
 
+    reentrant_contract.protected_function2("another value", False, transact={})
+    assert reentrant_contract.special_value() == "another value"
+
+    assert_tx_failed(lambda: reentrant_contract.protected_function2("zzz value", True, transact={}))
+
+
 
 def test_disallow_on_init_function(get_contract):
     # nonreentrant has no effect when used on the __init__ fn

vyper/semantics/validation/data_positions.py

@@ -38,8 +38,11 @@ def set_storage_slots(vyper_module: vy_ast.Module) -> StorageLayout:
         variable_name = f"nonreentrant.{type_.nonreentrant}"
 
         # a nonreentrant key can appear many times in a module but it
-        # only takes one slot. ignore it after the first time we see it.
+        # only takes one slot. after the first time we see it, do not
+        # increment the storage slot.
         if variable_name in ret:
+            _slot = ret[variable_name]["slot"]
+            type_.set_reentrancy_key_position(StorageSlot(_slot))
             continue
 
         type_.set_reentrancy_key_position(StorageSlot(storage_slot))