Storage Variable of Type `ModuleT` and `InterfaceT` Not Prevented

[ritzdorf]

Version Information

• vyper Version (output of vyper --version): commit 4b4e188ba83d28b5dd6ff66479e7448e5b925030

  Issue description

Since ModuleT is a Vyper type, and since ModuleT._invalid_locations does not contain DataLocation.STORAGE, it is possible to use it as a type for a storage variable while this should not be possible.

The contract below will compile, and calling foo() will return (1,2).

# main.vy
import lib

initializes: lib

x:lib
y:lib

@external
def foo() -> (uint256, uint256):
    return (self.x.bar(), self.y.bar())

# lib.vy
a:uint256

@internal
def bar()->uint256:
    self.a += 1
    return self.a

Note that a similar behavior can be observed for InterfaceT.

[charles-cooper]

i think the InterfaceT behavior is on purpose (e.g. you have have a variable of type IERC20), the ModuleT behavior is kind of odd though.

[charles-cooper]

should be fixed in https://github.com/vyperlang/vyper/pull/4088