Syntax errors caused by JS file

[Aqours]

TypeScript Version: 2.5.2

** example code **

Sorry, I cannot provide more code

// a.min.js file
... // compress code
export default n;

// b.js file
import * as N from './a.min';
...
export default {
  // ...
};

// c.ts file
import Re from './b';
...

tsconfig.json

{
  "compilerOptions": {
    "allowJs": true,
    "sourceMap": true,
    "declaration": false,
    "skipLibCheck": true,
    "noImplicitAny": false,
    "strictNullChecks": false,
    "module": "es2015",
    "moduleResolution": "node",
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "dom",
      "es5",
      "scripthost",
      "es2015"
    ]
  },
  "include": [
    "src/**/*.ts"
  ],
  "exclude": [
    "node_modules"
  ]
}

There 34 Syntax errors caused by JS file when compile TS file(use tsc command) without module bundler. Actually, those errors should not be hinted by TS.

[Aqours]

Those errors would be disappeared if I refomat code compressed in a.min.js.

[mhegazy]

your tsconfig.json has "allowJs": true, and i am guessing you have an import to a.min, and does not seem to be a.min.d.ts or a.min.ts available.

so either 1. do not use allowJs, 2. create a new file for a.min.d.ts

[mhegazy]

Also can you share the section of the .js file that is causing the errrors? looks like we have a parser error we need to fix.

[Aqours]

@mhegazy https://github.com/Aqours/Sample-Issues/tree/typescript/18306 I create a min repo which can reproduce this issue,

[mhegazy]

@sandersn looks like another lambda/ternary parsing issue.

[sandersn]

Still repros on master/2.5.3. I'll take a look.

[sandersn]

#18294 fixes this. Interestingly, this is not a dupe of #18158. Bisecting tracked down d796bf1 as the buggy commit, a couple of weeks after the commits that caused #18158.

@Aqours did you try this code on older versions of Typescript to see if it also fails? I am very suspicious that two people hit 3-year-old bugs within two weeks right after I made parsing changes in the last version.

[sandersn]

Here's a small repro that I believe still has the essential parse failure:

{L:function(a){ return true ? (a/8) : true },ka:function(
 ){},
};

[Aqours]

@sandersn
version tested:

• 2.4.2 failed
• 2.3.4 failed
• 2.1.6 failed
• 1.8.10 failed

[sandersn]

#18417 is a better fix than #18294 that works by requiring speculatively parsed arrow functions to have an = for their parameter's initalisers. Currently (x y) { } is parsed as if the user intended to write (x = y) => { }. This is true sometimes, but often it is not, especially when we parse y incorrectly, as is the case with this bug. (Reminder: here y = /8) : true },ka:function()