**Description:**
Regarding https://github.com/vercel/next.js/issues/55682, I made a mistake while investigating. I assumed it's `swcMinify`-only but it seems like `node-fetch` is fundamentally incompatible with our minification options.
I thought `node-fetch` works with terser, but it did not, and it **should not**. But as I thought `terser` works, I assumed that `terser` has a hack for `AbortSignal`. And that's how I fixed `swcMinify: true`. The correct fix is `keep_classnames: true` but it will result in +~10% bundle size bloat.
At first, I used the correct way (`keep_classnames: true`), but it resulted in the bundle size bloat, so I mimicked the hack of terser with https://github.com/vercel/next.js/pull/57904.
While working on other minification issues, I found that there's no such hack in `terser` and I need to remove the hack in the SWC minifier.
The repro in https://github.com/vercel/next.js/issues/55682 does not work with `swcMinify: false`, even with next@14. The problem of minifier and node-fetch was not exploited before `serverMinification: true`.
**Related issue:**
- https://github.com/brix/crypto-js/issues/415
**Description:**
Note: Preserving native names is a hack, but it's used by `terser` and it's the only way to preserve the name of `class AbortSignal` while mangling without `keep_classnames: true`. We can special case `AbortSignal`, but let's just follow `terser`.
**Related issue:**
- https://github.com/vercel/next.js/pull/57904
**Description:**
The problem arises in L235 of swc_ecma_transforms_base/src/rename/mod.rs
```rs
unit!(visit_mut_fn_decl, FnDecl, true);
```
which calls `get_map` and evals to
```rs
node.visit_children_with(&mut v);
```
with `FnDecl` and `Analyzer` in L132. However, in `Analyzer`, a visit to raw function was not overloaded, so function arguments and function body are considered different scopes.
**Related issue:**
- Closes#7261.
Safety:
For a function-local variable, an expression with side-effects would be a call, including an indirect one with a member expression.
- If the call is function-local, it will be analyzed by the analyzer and inliner will not work.
- If the call is not a function-local one, it cannot modify the local variable.
- We don't need a list of bindings to check if an identifier is unresolved.
- Checking if an identifier is unresolved is now one CPU instruction.
- Previously it was one hashmap operation.
- This PR also improves performance, by removing the hashmaps mentioned above.
