How to track down and fix circular dependency detected error?

[ejmurra]

I have a project that is broken into two parts - a "core" package and a CLI that uses the core. Both are authored in Typescript.

While trying to install the core typings for use in the CLI with typings install npm:lede I have been battling a circular dependency error:

typings ERR! message Circular dependency detected using "/Users/emurray/projects/lede-cli/node_modules/babel-register/package.json"

typings ERR! cwd /Users/emurray/projects/lede-cli
typings ERR! system Darwin 14.5.0
typings ERR! command "/Users/emurray/.nvm/versions/node/v6.3.0/bin/node" "/Users/emurray/.nvm/versions/node/v6.3.0/bin/typings" "install" "npm:lede"
typings ERR! node -v v6.3.0
typings ERR! typings -v 1.3.2

My "core" package is dependent on the following:

"dependencies": {
    "archieml": "^0.3.1",
    "aws-sdk": "^2.4.11",
    "babel-preset-es2015": "^6.9.0",
    "babelify": "^7.3.0",
    "browserify": "^13.0.1",
    "fs-extra": "^0.30.0",
    "glob": "^7.0.3",
    "livereload": "^0.4.1",
    "lodash": "^4.4.0",
    "node-sass": "^3.7.0",
    "nunjucks": "^2.4.2",
    "rimraf": "^2.5.2"
  },
  "devDependencies": {
    "ava": "^0.15.2",
    "coveralls": "^2.11.11",
    "nyc": "^7.0.0",
    "typescript": "^1.8.10",
    "typings": "^1.3.2"
  }

In my best effort to figure out what was going on, I added the high-tech debug statements

console.log("Source: " + src)
console.log("Parent: " + JSON.stringify(parent, null, 2))

just above this line in the typings-core source and then reran the command and piped stdout to a file.

The majority of that file is unimportant but the important bit is here at the end:

Source: /Users/emurray/projects/lede-cli/node_modules/babel-core/package.json
Parent: {
  "src": "/Users/emurray/projects/lede-cli/node_modules/babel-register/package.json",
  "raw": "npm:babel-register",
  "main": "lib/node.js",
  "browser": "lib/browser.js",
  "version": "6.11.6",
  "global": false,
  "dependencies": {},
  "devDependencies": {},
  "peerDependencies": {},
  "globalDependencies": {},
  "globalDevDependencies": {},
  "name": "babel-register",
  "parent": {
    "src": "/Users/emurray/projects/lede-cli/node_modules/babel-core/package.json",
    "raw": "npm:babel-core",
    "version": "6.13.2",
    "global": false,
    "dependencies": {},
    "devDependencies": {},
    "peerDependencies": {},
    "globalDependencies": {},
    "globalDevDependencies": {},
    "name": "babel-core",
    "parent": {
      "src": "/Users/emurray/projects/lede-cli/node_modules/babelify/package.json",
      "raw": "npm:babelify",
      "version": "7.3.0",
      "global": false,
      "dependencies": {},
      "devDependencies": {},
      "peerDependencies": {},
      "globalDependencies": {},
      "globalDevDependencies": {},
      "name": "babelify",
      "parent": {
        "src": "/Users/emurray/projects/lede-cli/node_modules/lede/package.json",
        "raw": "npm:lede",
        "main": "dist/index.js",
        "typings": "dist/index.d.ts",
        "version": "0.0.13",
        "global": false,
        "dependencies": {},
        "devDependencies": {},
        "peerDependencies": {},
        "globalDependencies": {},
        "globalDevDependencies": {},
        "name": "lede"
      }
    }
  }
}

So it seems to me that I am depending on a package (babelify) that depends on babel-core which depends on babel-register, which in turn depends on babel-core - thus the circular dependency! However I find it curious that this circular dependency isn't thrown by npm itself and it has me wondering if typings isn't resolving this as it should be or if I have just royally messed something up.

[blakeembrey]

I think this might have been fixed in NPM v3 with flattening, but might not work in v2. That said, this behaviour in Typings may be able to be improved so that during resolution it can reference the parent type and during compilation it re-uses previous paths.

[bsouthga]

I get the same issue on with npm@3.10.3, node@6.3.1, typings@1.3.2, darwin@15.6.0

[blakeembrey]

Anyone is welcome to submit a PR, I haven't had time to fix it. It's be a matter of re-using the pointer during dependencies.ts and then checking for pointers during compile.ts in typings-core.