**Description:**
- The option `hoist_props` now does what it's supposed to do.
- Dropping of unused properties now does not drop properties too aggressively.
- The initializer of a dropped variable declaration is now properly visited.
- Indexing with string literals is not marked as a dynamic index anymore. This is required to handle codes like c3f67ceb1e/crates/swc_ecma_minifier/tests/terser/compress/hoist_props/name_collision_1/input.js (L1-L7).
**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:**
This issue is more severe than I originally thought. It raises not in
array indexing, but in function calls and property mutation. We should
treat all function arguments as potentially be property mutated,
otherwise following example
```js
class A {
a = 1
toString() {
return this.a
}
}
const a = new A()
function foo(x) {
x.a++
}
const b = a + 1
foo(a)
console.log(b)
```
would be error(It should log 2, but logs 3 after compress).
As the result, massive regressions is unavoidable, since some of these
optimizations may indeed cause error. Part of them can be mitigated with
following optimization -- allow inline of ident even if its original
value is mutated. Consider
```js
export function foo(x) {
const y = x
x.a = 1
y.b = 2
}
```
If x is a primitive value, all mutations to its properties are ignored;
if x is a object, then y refers to the same object no matter what
mutation is performed.
And there's still room for more, currently following code
```js
export function foo(x) {
const y = Math.floor(x);
g(y);
}
```
But I'd rather do it in a separate PR.
**Related issue:**
- Closes#7402.
**Description:**
This is the groundwork for a parallel analyzer. This PR fixes the ordering issue of the analyzer so that the analyzer works identically regardless of the visit order. This patch contains some improvements because previously, we mixed `.and_modify()` and `.or_default()`.
**Description:**
This PR improves the alias analyzer by distinguishing call and reference, thus reducing the number of identifiers.
---
Co-authored-by: Justin Ridgewell <justin@ridgewell.name>
**Description:**
As our minifier is two-pass by default, this is enough.
At the first pass, we inline all numeric literals using sequential inliner, and minifier can then inline constants correctly in the second pass.
**Description:**
This PR renames `CloningMultiReplacer` to `Finalizer` and makes it handle the removal of unused variables. Also, this PR improves the sequential inliner so we can drop variables within a single pass.
**Description:**
We had two passes for joining variables. This PR removes one in the full optimizer, which is wrong.
**Related issue:**
- Closes https://github.com/swc-project/swc/issues/5989.
