When a function called from within another function should return uint256 but it returns nothing, the caller is terminated without raise

[michwill]

Version Information

• vyper Version (output of vyper --version): <= 0.1.0-beta9
• OS: linux
• Python Version (output of python --version): 3.6.7
• Environment (output of pip freeze):

asn1crypto==0.24.0
atomicwrites==1.3.0
attrdict==2.0.1
attrs==19.1.0
backcall==0.1.0
certifi==2019.3.9
cffi==1.12.2
chardet==3.0.4
cryptography==2.6.1
cytoolz==0.9.0.1
decorator==4.4.0
eth-abi==2.0.0b8
eth-account==0.3.0
eth-bloom==1.0.3
eth-hash==0.2.0
eth-keyfile==0.5.1
eth-keys==0.2.1
eth-rlp==0.1.2
eth-tester==0.1.0b37
eth-typing==2.0.0
eth-utils==1.4.1
ethpm==0.1.4a13
hexbytes==0.1.0
idna==2.8
ipfsapi==0.4.3
ipython==7.4.0
ipython-genutils==0.2.0
jedi==0.13.3
jsonschema==2.6.0
lru-dict==1.1.6
more-itertools==7.0.0
mypy-extensions==0.4.1
parsimonious==0.8.1
parso==0.3.4
pexpect==4.6.0
pickleshare==0.7.5
pluggy==0.9.0
prompt-toolkit==2.0.9
protobuf==3.7.1
ptyprocess==0.6.0
py==1.8.0
py-ecc==1.4.7
py-evm==0.2.0a39
py-geth==2.1.0
pycparser==2.19
pycryptodome==3.8.0
pyethash==0.1.27
Pygments==2.3.1
pytest==4.4.0
pytest-ethereum==0.1.3a6
requests==2.21.0
rlp==1.1.0
semantic-version==2.6.0
six==1.12.0
toolz==0.9.0
traitlets==4.3.2
trie==1.3.8
urllib3==1.24.1
vyper==0.1.0b9
wcwidth==0.1.7
web3==5.0.0a5
websockets==7.0

What's your issue about?

Take the example contract:

@private
def x(z: uint256) -> uint256:
    if z > 0:
        return z
    else:
        pass

@public
def y():
    self.x(0)
    assert False

Calling y() succeeds without failing.

What I'd expect is either a fail at compile time (because x() can return improper type), or a runtime failure when calling self.x(0). And I certainly wouldn't expect y() to silently terminate when self.x call failed: it should raise

[charles-cooper]

Probably a dup of #590

[charles-cooper]

I wonder if in addition to #1384 the caller should also check that RETURNDATASIZE is the same as expected by the function signature?

[k06a]

Thats why Uniswap/v1-contracts#30 not works. This can be handled by the library or by the compiler. OpenZeppelin re-implemented SafeERC20 to support this kind of tokens: OpenZeppelin/openzeppelin-contracts#1662