Feature related Tech debt

[TilakMaddy]

Feature related technical debt in the codebases
(We'll open another one for refactoring related stuff)

Some points to remember

These were not taken good care of while writing the initial detectors.

1. revert() and revert Error() are different. The former is a function call while the latter is a revert statement. We've skipped cases in many places.
2. type strings can be address or address payable. We should handle both cases where necessary without skipping them.
3. selfdestruct is fine, but we also have to handle suicide
4. It's not enough to check .is_constructor, because for newer versions of solc, even for constructors that returns false, so you should check kind().
5. Use callgraphs

Detectors

• Delegate call in a loop detector should use callgraph, currently doesn't. #689

• Unprotected init function should use callgraph, currently doesn't. #688

• Multiple constructors - Use the modern kind() to cover all solidity versions #687

• Require in string detctor detector fail to follow the 1st point above ^ #685

• Revert and require in loops detector don't account for revert statements #684

• Zero address check should use callgraph (but maybe put on hold, cuz we lose the data-context as we dont have a CFG yet)

Dear open source community, if you are looking at this feel free to pick one up and send PRs :)

[TilakMaddy]

Regarding zero address check I think it's too subjective. Maybe something like, if there is an address parameter, as long as there is some type of binary check on the address it should be okay. What do you think @alexroan ?