Remove dependency on keccak NPM module.

[MicahZoltu]

The keccak NPM module is a native module which requires node-gyp to properly install. This means the developer needs a fully Python dev-env setup, which can be problematic with Python 2.7 vs 3.0. Please use a native JS sha3 library rather than keccak so users don't need to install Python just to use solc without error.

A good alternative library for keccak hashing is https://github.com/emn178/js-sha3. It has no dependencies and works in node and browser.

PS > npm install

> [email protected] install C:\...\node_modules\keccak
> npm run rebuild || echo "Keccak bindings compilation fail. Pure JS implementation will be used."


> [email protected] rebuild C:\...\node_modules\keccak
> node-gyp rebuild


C:\...\node_modules\keccak>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\node_modules\npm-lifecycle\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node "C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\bin\node-gyp.js" rebuild )
gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack     at PythonFinder.failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:484:19)
gyp ERR! stack     at PythonFinder.<anonymous> (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:509:16)
gyp ERR! stack     at C:\Program Files\nodejs\node_modules\npm\node_modules\graceful-fs\polyfills.js:284:29
gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:154:21)
gyp ERR! System Windows_NT 10.0.17763
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\...\node_modules\keccak
gyp ERR! node -v v10.15.0
gyp ERR! node-gyp -v v3.8.0
gyp ERR! not ok
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] rebuild: `node-gyp rebuild`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] rebuild script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm WARN Local package.json exists, but node_modules missing, did you mean to install?

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\...\AppData\Local\npm\npmrc\_logs\2019-05-05T02_48_08_179Z-debug.log

[axic]

The keccak NPM module is a native module which requires node-gyp to properly install.

I don't think this is correct. It is a module providing both native and JS-only bindings.

It would be nice to consider fixing keccak if you are experiencing issues with it. Have you reached out to the authors yet?

[MicahZoltu]

@axic Yeah, there is a long thread in ethereumjs-utils and keccak and secp256k1 GitHub issues IIRC. Keccak is against going JS only, as they believe the purpose of their library is to wrap both native and JS into a single library, and if users don't like that then they should switch to depending on one or the other directly (which is exactly what I propose here).

The problem is node-gyp, it is notorious for causing problems on build infrastructure, Windows, and elsewhere. It isn't that keccak is doing anything wrong specifically other than they depend on node-gyp, which causes no end of trouble.

In the case of this library (solc) there is no need to use keccak instead of js-sha3, and as seen in #357 removing that dependency is quite easy.