Before You File a Bug Report Please Confirm You Have Done The Following...

• I'm using eslint-plugin-svelte. (*.svelte file linting does not work with the parser alone. You should also use eslint-plugin-svelte with it.)
• I'm sure the problem is a parser problem. (If you are not sure, search for the issue in eslint-plugin-svelte repo and open the issue in eslint-plugin-svelte repo if there is no solution.
• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.

What version of ESLint are you using?

None (using parser only)

What version of eslint-plugin-svelte and svelte-eslint-parser are you using?

• svelte-eslint-parser@1.3.1

What did you do?

No configuration.

Code snippet A:

<script lang='ts'></script><input onchange={e => {e; let b;}} />

Code snippet B:

<script lang='ts'></script><input onchange={e => {e; let b: number;}} />

What did you expect to happen?

The _virtualScriptCode returned by svelte-eslint-parser for both A and B should include a type annotation on e.

What actually happened?

The _virtualScriptCode returned by svelte-eslint-parser only includes a type annotation on e for code snippet A.

Link to GitHub Repo with Minimal Reproducible Example

https://github.com/abrahamguo/repro/tree/svelte-typed

Additional comments

In #440, @baseballyama added hasTypeInfo, which recurses downwards through the AST looking for any TypeScript node. If it finds any child TypeScript node, then it skips adding a type.

However, this logic is far too broad. As we can see in this example, adding any TypeScript node anywhere in the descendant AST — even if it's completely unrelated — causes the type annotation on e to be skipped, which then causes downstream problems with typescript-eslint picking it up as any.

I believe that this may be the root cause of some of the other currently open issues in this repo regarding TypeScript.