**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.
