Support TypeScript 4.3 get/set type members

[sosukesuzuki]

Q	A
Fixed Issues?	Fixes #13071
Minor: New Feature?	Y
Tests Added + Pass?	Yes
License	MIT

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[nicolo-ribaudo]

Instead of using lookahead (which is expensive) in tsParseMethodSignatureKind, can we:

• Call this.parsePropertyName
• If not computed, not private, does not have type parameters, and the identifier name is get or set:
  • If tsNextTokenCanFollowModifier, then we are parsing an accessor and we call this.parsePropertyName again
  • Otherwise, it's a method/property named get or set
• Otherwise, it's a method/property

[JLHwung]

Yeah we parse class accessors using the same strategy mentioned above.

[sosukesuzuki]

What the AST babel should return for below code?

interface Foo {
    set foo;
}

In current behaviour, two properties named set and foo are returned (with recoverable error Missing semicolon). If we should keep it, we should detect if the property is a method signature after first this.parsePropertyName call. But then the token is the name of the property, so I don't know how to do that without lookahead...

[nicolo-ribaudo]

It's ok to throw "Expected (":

• It's what we already do for

  class Foo {
    set foo
  }

• It's more likely that someone didn't finish writing a setter, than putting two properties on the same line without ; and that the name of the first one was exactly set.

[nicolo-ribaudo]

Could you rebase this on top of #13098, to avoid the merge conflicts? 🙏

[JLHwung]

Can you add the following test cases?

// 'get' and 'set' accessors cannot declare 'this' parameters.
interface Foo {
  get bar(this: Foo);
  set bar(this: Foo);
}

// A 'set' accessor cannot have an optional parameter.
interface Foo {
  set bar(v?);
}

// A 'set' accessor cannot have rest parameter.
interface Foo {
  set bar(...v);
}

[nicolo-ribaudo]

I rebased feat-7.14.0/parser-updates. Could you rebase this PR removing the commits already in feat-7.14.0/parser-updates? 🙏

[nicolo-ribaudo]

Thanks!