Vyper: Unicode characters are allowed to be a part of identifiers

[rohithpr]

Version Information

• vyper Version: Master
• pyethereum Version: x.x.x
• OS: osx/linux/win
• Python Version (python --version):
• Environment (output of pip freeze):

What's your issue about?

In Vyper, Unicode characters are allowed to be a part of identifiers (variable names, method names, etc.). This could lead to Homograph attacks where a piece of code appears to be acting on one variable but is actually acting on some other variable. Unicode characters should probably be disallowed from being a part of identifiers, especially since Vyper aims to be a language that is easy to audit.

---

FWIW, Solidity throws an error when I try to name a variable with a unicode character.

Code:

pragma solidity ^0.4.21;

contract Foo {

    function x(int128 i) public view {
        uint256 Other_Balance = 3; // ASCII O

        // a bunch of code
        if (i>0) {
            uint256 Оther_Balance = 2; // Unicode О
        }

        // a bunch of code
        return Other_Balance; // ASCII O
    }
}

Error:

browser/Untitled5.sol:10:21: ParserError: Expected ';' but got 'ILLEGAL'
            uint256 Оther_Balance = 2; // Unicode О
                    ^

---

Similar code in Vyper, which compiles without throwing any errors:

@public
def foО(i: int128) -> uint256:
    Other_Balance: uint256 = 3 # ASCII O

    # a whole bunch of code
    if i > 0:
        Оther_Balance: uint256 = 2 # Unicode О

    # a whole bunch of code

    return Other_Balance # ASCII O

---

How can it be fixed?

Disallow Unicode characters in identifiers.

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[rohithpr]

I'd like to work on this if it is something that has to be fixed.

[fubuloubu]

Yes, this is a good issue to work on if you're interested in