TypeScript: Support type arguments on tagged templates

[ghost]

Q	A
Fixed Issues?	#7747 (partly)
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?	Yes
Tests Added + Pass?	Yes
Documentation PR
Any Dependency Changes?
License	MIT

@JamesHenry This changes the AST format. CC @DanielRosenwasser for review.
Supports parsing type arguments on tagged template calls.
Should wait on microsoft/TypeScript#23430 to be merged so we're sure we have the final syntax.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/8697/

[existentialism]

LGTM, but will wait for @JamesHenry/@DanielRosenwasser to chime in!

[DanielRosenwasser]

I feel like I commented this before, but I guess not. You need a test like

new foo<A, B>
`hello world`

To show ASI doesn't kick in.

[DanielRosenwasser]

I feel like I commented this before, but I guess not. You need a test like

new foo<A, B>
`hello world`

To show ASI doesn't kick in.
I feel like I commented this before, but I guess not. You need a test like

new foo<A, B>
`hello world`

To show ASI doesn't kick in.
I feel like I commented this before, but I guess not. You need a test like

new foo<A, B>
`hello world`

To show ASI doesn't kick in.
I feel like I commented this before, but I guess not. You need a test like

new foo<A, B>
`hello world`

To show ASI doesn't kick in.

[DanielRosenwasser]

Christ, GitHub on a bad connection can be a real piece of work.

[existentialism]

@DanielRosenwasser well, at least you made your point :)

[DanielRosenwasser]

This looks incorrect. The tagged template should have higher precedence than the NewExpression. As an example, in the following:

new C
``

here's what I currently get:

{
  // ...
  "expression": {
    "type": "NewExpression",
    "start": 0,
    "end": 8,
    "loc": {
      "start": {
        "line": 1,
        "column": 0
      },
      "end": {
        "line": 2,
        "column": 2
      }
    },
    "callee": {
      "type": "TaggedTemplateExpression",
      "start": 4,
      "end": 8,
      "loc": {
        "start": {
          "line": 1,
          "column": 4
        },
        "end": {
          "line": 2,
          "column": 2
        }
      },
      "tag": {
        "type": "Identifier",
        "start": 4,
        "end": 5,
        "loc": {
          "start": {
            "line": 1,
            "column": 4
          },
          "end": {
            "line": 1,
            "column": 5
          },
          "identifierName": "C"
        },
        "name": "C"
      },
      "quasi": {
        "type": "TemplateLiteral",
        "start": 6,
        "end": 8,
        "loc": {
          "start": {
            "line": 2,
            "column": 0
          },
          "end": {
            "line": 2,
            "column": 2
          }
        },
        "expressions": [],
        "quasis": [
          {
            "type": "TemplateElement",
            "start": 7,
            "end": 7,
            "loc": {
              "start": {
                "line": 2,
                "column": 1
              },
              "end": {
                "line": 2,
                "column": 1
              }
            },
            "value": {
              "raw": "",
              "cooked": ""
            },
            "tail": true
          }
        ]
      }
    },
    "arguments": []
  }
}

[kachkaev]

Given that styled-components accept types in template literals (styled-components/styled-components#1798), lot's of people would love to see this merged!

TypeScript is transpiled with babel in Next.js, which is pretty popular and is often used with styled-components. Here is a downstream issue that's pending this PR: vercel/next-plugins#203. 🙏

[EItanya]

Any update on this being merged, Would love to be able to start using this feature!

[existentialism]

@EItanya I made a note to get this rebased and fix the issue above, but if you'd like to tackle it... go for it!

[existentialism]

Finally got around to rebasing/updating this PR.

Changes: fceb066

/cc: @andy-ms @DanielRosenwasser @nicolo-ribaudo

Note, I wound up dropping tsTryParseTypeArgumentsInExpression as the eatNextToken arg seemed misleading since it was just checking via this.match.

[timche]

Is there anything blocking from merging this? Thanks for all ur hard work to support this tho ❤️