Suggest renaming file from .ts to .tsx if needed?

## Search Terms ts tsx react jsx rename file errors ## Suggestion When adding JSX elements (React) to a `.ts` file rather than a `.tsx` file, error messages aren't clear that it should be a `.tsx` file. If it's clear the user is intending to write JSX code, such as having multiple JSX-like components and/or components that extend `React.Component`, can a code fix be given (on the file? on individual `<>`-related parsing errors?) to rename to `.tsx`? ## Use Cases There's been some buzz on Twitter lately about how easy it is to forget to rename to `.tsx`. Some users are apparently even used to writing JSX in `.js`, so the need to use `.tsx` is a bit confusing for them. ## Examples Given this `file.ts`: ```ts import * as React from "react"; export class ComponentClass extends React.Component { public render() { return <span />; // index.ts(5,22): error TS1005: '>' expected. // index.ts(5,23): error TS1161: Unterminated regular expression literal. } } export const ComponentArrow = () => <span />; // index.ts(11,43): error TS1005: '>' expected. // index.ts(11,44): error TS1161: Unterminated regular expression literal. ``` Would it be possible to special-case just from these errors to suggest to rename the file? Alternately, if we just have the `ComponentArrow` errors, would it still be possible to suggest to rename the file? ## Checklist My suggestion meets these guidelines: * [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code * [x] This wouldn't change the runtime behavior of existing JavaScript code * [x] This could be implemented without emitting different JS based on the types of the expressions * [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.) * [x] This feature would agree with the rest of [TypeScript's Design Goals](https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals).