Adds basic inline detector supression function

[josh-richardson]

This is a naive approach to integrating a solhint-ignore-like syntax into slither which allows specific rules to be disabled on the next line.

The syntax is as shown in the two slither-disable-next-line statements in the below contract. Each ignore statement must specify a specific rule being ignored by rule check name.

// SPDX-License-Identifier: MIT
//slither-disable-next-line solc-version
pragma solidity >=0.4.22 <0.8.0;

contract Migrations {
  address public owner = msg.sender;
  uint public last_completed_migration;

  modifier restricted() {
    require(
      msg.sender == owner,
      "This function is restricted to the contract's owner"
    );
    _;
  }
  //slither-disable-next-line external-function
  function setCompleted(uint completed) public restricted {
    last_completed_migration = completed;
  }
}

Running slither against this contract (invoking slither . in a new truffle project having replaced Migrations.sol with the above content) should only yield a single warning, rather than the usual three which are produced without the ignore statements.

I'd include tests, but as far as I can see Slither only has tests for the AST and the detectors.

[CLAassistant]

All committers have signed the CLA.

[disconnect3d]

Since the collection is only iterated upon, we should use a generator expression instead of list comprehension.

Also, while it may be counter-intuitive, it's better to use {..} instead of dict(..) for constructing dicts. The dict is a function call and there is an opcode for the dict literal ({}) which ends up being slightly faster. Though, I wouldn't care about it much. A showcase of this below.

In [1]: def foo(): return dict(a=1,b=2)

In [2]: def bar(): return {'a': 1, 'b': 2}

In [3]: %timeit foo()
188 ns ± 6.21 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [4]: %timeit bar()
143 ns ± 0.64 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [5]: import dis

In [6]: dis.dis(foo)
  1           0 LOAD_GLOBAL              0 (dict)
              2 LOAD_CONST               1 (1)
              4 LOAD_CONST               2 (2)
              6 LOAD_CONST               3 (('a', 'b'))
              8 CALL_FUNCTION_KW         2
             10 RETURN_VALUE

In [7]: dis.dis(bar)
  1           0 LOAD_CONST               1 (1)
              2 LOAD_CONST               2 (2)
              4 LOAD_CONST               3 (('a', 'b'))
              6 BUILD_CONST_KEY_MAP      2
              8 RETURN_VALUE

[josh-richardson]

Suggestions implemented.

[disconnect3d]

Please confirm if it works properly, but it seems this three lines above could be changed into:

                ignored_checks = (x.strip() for x in ignore_line_text[match.span()[1] :].split(","))
                matched_ignores = filter(lambda c: r["check"] == c, ignored_checks)
                if any(matched_ignores):

[josh-richardson]

Done

[disconnect3d]

Leaving it here in case someone wonders what this regex matches (via https://regexper.com/#%5E%5Cs*%5C%2F%5C%2F%5Cs*slither-disable-next-line%5Cs*)

[disconnect3d]

Since we match from "Start of line" and then allow only for white spaces the suppress detection feature won't work if the comment is made in a line after code. Not sure if it is fine.

[josh-richardson]

If we want to support comments made on a line after code, I don't think regex is the appropriate tool to find them. I think for now this is by design.

We could perhaps use something like this if we want to match comments made after a line of code, however I'd be more comfortable using a parser:

"[^"]+"(*SKIP)(*FAIL)
|
'[^']+'(*SKIP)(*FAIL)
|
(?|
    //(?P<comment>.+)
)

[josh-richardson]

Will address these comments this evening.

[josh-richardson]

Should all be addressed now, although there's some discussion still to be had about whether we want to support ignore statements placed after a code block.

[montyly]

Thanks again @josh-richardson for your effort.

My changes:

• Added the flag --show-ignored-findings (which will also show the issues triaged with the db)
• slither-disable-next-line all will disable any detector