Formatter doesn't recognize file type change

[DanielRosenwasser]

Possibly related to #47446.

In VS Code, use an anonymous buffer whose language starts as "TypeScript" and switches to "TypeScript React". The formatter doesn't adapt correctly.

let x = <div>
    <div>
    </div>
</div>;

Format.

Expected

No change

Actual

let x = <div>
    <div>
    </div>
    < /div>;

[RyanCavanaugh]

I couldn't repro this or the other one

[DanielRosenwasser]

Figured it out. If you're in VS Code and have an anonymous buffer whose language starts as "TypeScript" and switches to "TypeScript React", the formatter doesn't adapt correctly. I can't tell if that's a TypeScript or VS Code bug.

[RyanCavanaugh]

The server log should indicate whether TS Server got the message that the file should be treated as TSX

[DanielRosenwasser]

The log does indicate that we got the right updateOpen request.

[Trace  - 02:19:34.109] <semantic> Sending request: updateOpen (4643). Response expected: yes. Current queue length: 2
Arguments: {
    "changedFiles": [],
    "closedFiles": [],
    "openFiles": [
        {
            "file": "^/untitled/Untitled-4",
            "fileContent": "let x = <div>\r\n</div>",
            "projectRootPath": "c:\\Users\\ME\\scratch\\example",
            "scriptKindName": "TSX"
        }
    ]
}

TypeScript also knows to interpret that code as JSX, but the formatter apparently doesn't.