Access object with empty-string key

[ikatyang]

TypeScript Version: 2.3.0-dev.20170415

{
  "compilerOptions": {
    "strict": true
  }
}

Code

declare const x: {
  '': string;
  'a': string;
  'a-b': string;
}

x[''] // error TS7017: Element implicitly has an 'any' type because type '{ '': string; 'a': string; 'a-b': string; }' has no index signature.
x['a'] // fine
x['a-b'] // fine

Expected behavior:
no error

Actual behavior:
error TS7017: Element implicitly has an 'any' type because type '{ '': string; 'a': string; 'a-b': string; }' has no index signature.

[HerringtonDarkholme]

May I ask the use case of empty string key? It seems like a strange pattern for me.

[ikatyang]

I just find out this bug accidentally, it looks strange to me too.

But it is still a legal case, so I reported it. 😅