Handle @jsx pragmas for TypeScript

[overlookmotel]

We recently added more support for @jsx pragmas in conformance suite (#3553).

I believe some of these should be handled in parser/semantic/transformer (not sure which) instead for TS/TSX files. According to TS docs, they're valid:

https://www.typescriptlang.org/docs/handbook/jsx.html#configuring-jsx

[Boshen]

It should be analyzed in the transformer.

[overlookmotel]

Would it not be useful to add a pragmas field to Program and populate it in the parser, like with Hashbang? I imagine other tools might find this info useful as its meaningful information for interpreting the AST (broadly equivalent to an import React from "whatever"; statement).

[Boshen]

Nope, it's not part of the spec so it can't go into the AST.

[overlookmotel]

But it is part of the TS spec, no? https://www.typescriptlang.org/docs/handbook/jsx.html#configuring-jsx

[Boshen]

That's not an AST spec, it's just documentation 😅

[overlookmotel]

OK, true! But what's the difference? Spec and config are both things which are present in the source text, and alter the meaning of the code.

Therefore I feel it's better to store that useful info in AST. And we have to parse it somewhere, so might as well parse it in the parser. But I don't feel strongly about it - say no one more time, and I'll shut up!

[overlookmotel]

PS It'd also be faster to find these comments in parser while parsing comments anyway, rather than searching through all comments again later.

[Boshen]

You can save them into Trivias if you really want to parse them from the parser.

[Boshen]

In #3553

The lines in https://github.com/microsoft/TypeScript/blob/main/tests/cases/compiler/jsxComplexSignatureHasApplicabilityError.tsx

// @strict: true
// @jsx: react
// @skipLibCheck: true

are compiler settings for the test file, they aren't pragmas.

---

In tsx files, the prgrama

/** @jsxImportSource preact */

<Foo />

produces

import {jsx as _jsx} from 'preact/jsx-runtime';
_jsx(Foo, {});

which is working as intended.