getDeclarationOfAliasSymbol assert with shortid npm module in 2@next

[seanmiddleditch]

TypeScript Version: 2.1.0 / nightly (2.1.0-dev.20160821)

Error Message

G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:37610                                                            
                throw e;                                                                                                            
                ^                                                                                                                   

Error: Debug Failure. False expression:                                                                                             
    at Object.assert (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:1289:23)                                   
    at Object.fail (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:1294:19)                                     
    at Object.findMap (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:211:15)                                   
    at getDeclarationOfAliasSymbol (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:13927:23)                    
    at checkExternalModuleExports (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:26428:39)                     
    at checkSourceFileWorker (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:26635:21)                          
    at checkSourceFile (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:26610:13)                                
    at Object.forEach (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:185:30)                                   
    at getDiagnosticsWorker (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:26659:16)                           
    at getDiagnostics (G:\Sean\Documents\Projects\test\node_modules\typescript\lib\tsc.js:26647:24)                                 

package.json

{
  "name": "test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "typings": "typings",
    "tsc": "tsc"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "shortid": "^2.2.6",
    "typescript": "^2.1.0-dev.20160821",
    "typings": "^1.3.2"
  }
}

tsconfig.json

{
    "compileOnSave": true,
    "compilerOptions": {
        "module": "commonjs",
        "moduleResolution": "node",
        "target": "es6",
        "noImplicitAny": true,
        "strictNullChecks": true,
        "sourceMap": true,
        "allowJs": true,
        "outDir": "bin"
    },
    "files": ["index.ts"]
}

typings.json

{
  "globalDependencies": {
    "shortid": "registry:dt/shortid#0.0.0+20160316155526"
  }
}

index.ts

import * as shortid from 'shortid';

Reproduction Steps

npm install
npm run typings -- install
npm run tsc

Note

Removing the Object.fail in Object.findMap results in a crash-free compilation with no ill-effects that I can observe, including on a somewhat larger project.

shortid is not the only module that causes this. I've also observed debug causing this. I'm not sure how many others my app might be hitting since I can't see latter failures until somehow avoiding former ones.

[bipycxp]

Removing "allowJs": true from tsconfig.json solved problem for me. Try it!

[mhegazy]

@sandersn can you take a look

[sandersn]

So there are actually two problems here.

1. when compiling JS files with allowJs, module.exports = ... is treated like export = ... in TS files. But the predicate that getDeclarationOfAliasSymbol doesn't know about this, so it skips that module.exports = ... declaration, then fails when it can't find an export.
2. The compiler shouldn't be compiling .js files at all — the intent is to use the typings/.../shortid/shortid.d.ts, not the actual files in node_modules/shortid. Module resolution is wrong in this case.

I think I can fix (1) but that doesn't fix the module resolution in (2).

[sandersn]

That means, as @bipycxp points out, allowJs: false is a workaround if you don't have any .js in your project. Module resolution will find shortid.d.ts.

[sandersn]

@mhegazy gives an even better workaround: maxNodeModuleJsDepth: 0. This avoids compilation of JS files in node_modules while still allowing compilation of your own JS files. We decided to make this the default for tsconfig.json, although jsconfig.json will keep a default of maxNodeModuleJsDepth: 2.

[sandersn]

Fix for the crash is up at #10538. However @seanmiddleditch, for a real fix, you actually need to add to your files entry in tsconfig: "files": ["index.ts", "typings/index.d.ts"].

The reason you see this crash in the first place is that the compiler misses index.d.ts entirely and then tries to compile the actual JS for shortid. This will not crash after my fix, but it's slower (more compiling) and the intellisense will not be very good.

[seanmiddleditch]

@sandersn excellent, thank you. I have indeed heavily updated my tsconfig file and everything has been fast and crash-free since.