acorn-typescript

See #49 (I used AI to find and fix this) This bluntly but correctly avoids emitting duplicate comments. It looks like an architecturally cleaner fix would be to buffer comments and flush at commit, but that's a bit more code and subtly changes the timing, so I think this is the simplest and least-disruptive fix. I'm happy to do the deeper, arguably more-correct version. The fixture system doesn't handle so I added tests instead. (9 failing before the fix) I can wire that up if fixtures are preferred.

There's a systemic issue where comments can be emitted to more than once. As a result the Svelte parser can end up with exact duplicate comments in its AST. To reproduce where and are locally installed: Output: This affects TypeScript syntax that gets speculatively re-parsed, including arrow return types, computed class keys, index signatures, function-type parameters, and method return types.

I'm quite sure this is a bug. Note: The following is written by Codex but I have done what I could to verify. Discovered when trying to parse this actual file: https://github.com/yassernasc/streamx/blob/7990e4cbad36e2e6ad84ccb43f8403ab631abf73/index.d.ts Reproduction Expected The file parses successfully. In a .d.ts file, an ambient function declaration introduces an exportable declaration name, so export { pipeline } is valid TypeScript. Actual Parsing fails with: Notes Tested against @sveltejs/acorn-typescript@1.0.10 and current main; both fail. This looks related to export validation/scope handling for bodiless declarations. Similar issue #32 was fixed for abstract methods / overload signatures, but this case still fails for top-level declare function in dts mode. The plugin parses declare function pipeline(): void as TSDeclareFunction, but the name doesn’t appear to be registered with Acorn’s top-level module scope / undefinedExports tracking, so Acorn later rejects the named export.