feat: add preserve_imports_with_side_effects option for simplify optimization

[nissy-dev]

Description: Fix #6771

This implementation is still rough, and there are still some implementation decisions that need to be decided on that I mentioned in my comments.

BREAKING CHANGE: Yes

Related issue (if exists):

[nissy-dev]

There was a way to modify the simplify option directly, but I added it in this way to avoid breaking change. What do you think?

[kdy1]

Can you move this to the simplify option?

[kdy1]

I'll merge PRs with breaking changes at once

[kdy1]

Thank you!
As it's a breaking change anyway, we can use correct way.

[kdy1]

Can you move this to the simplify option?

[manucorporat]

I am thinking that it would be soo good, to have a callback to resolve if a indentifier has side effects or not:

So instead of being a bool it could be a function, that is being passed the import source and return a bool

[kdy1]

Nope, it should never be

[kdy1]

Rust-side api is fine, but js api is not fine

[nissy-dev]

@manucorporat Which API do you use, JS API or Rust API?
It is possible to change the simplifier function (in crates/swc_ecma_transforms_optimization/src/simplify/mod.rs) to accept callbacks. If you want to do so, it would be great if you could give me more details about the callback you want to add.

[kdy1]

Why did you touch this? Please revert

[nissy-dev]

@kdy1 Thank you for your reviews. You mean I need to modify simplify option which receive boolean value and json? Like this.

pub struct OptimizerConfig {
    #[serde(default)]
    pub simplify: SimplifyOption,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(untagged)]
pub enum SimplifyOption {
    Bool(bool),
    Json(SimplifyJsonOption),
}

impl Default for SimplifyOption {
    fn default() -> Self {
        SimplifyOption::Bool(true)
    }
}

#[derive(Debug, Default, Clone, Copy, Serialize, Deserialize)]
#[serde(deny_unknown_fields, rename_all = "camelCase")]
pub struct SimplifyJsonOption {
    pub preserve_imports_with_side_effects: bool,
}

If you think so, I will refactor in this way

[kdy1]

Yes, thank you!

[nissy-dev]

I updated!

[kdy1]

I think this should go into Config type

[nissy-dev]

I moved this option to dce config.

[kdy1]

Thank you!

---

swc-bump:

• swc_ecma_transforms_optimization --breaking

[swc-bot]

Automated review comment generated by auto-rebase script