Should leading ampersands (&) be allowed in intersection types?

[Ailrun]

TypeScript Version: 2.4.2 / playground (2.3.?)

Code

let x: (& number & string);

Expected behavior:
Emits error, since language spec said,

IntersectionType: IntersectionOrPrimaryType & PrimaryType

in the subsection 3.8.7

Actual behavior:
Doesn't emit error and uses it as number & string.

[yortus]

@Ailrun it is by design. See #12386. The spec might need updating though.

[Ailrun]

@yortus Why don't anyone try to fix the spec? Isn't specification of language the most important document?

[yortus]

The spec hasn't been updated since January 2016, so it's likely that a bunch of stuff is missing or outdated. I'm not sure why this is; my guess would be time pressure on the team, and the fact that they don't directly take PRs for the spec. Perhaps a team member can chime in.

[ikatyang]

See #17215 (comment).

[Ailrun]

@yortus Alright... thank you for your answer!
@ikatyang Thank you for information!

[mhegazy]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.