typescript_strip: option to remove completely unused imports #1060
Conversation
|
I feel this behavior is The import statement For example: // types.ts
windows.a = 1And in other file: |
|
I'm not sure about this.
I agree with you. That's why I implemented it to preserve side effects. But I'm now confused because typescript compiler removes it. |
I think because |
@kdy1 The behaviour you implemented aligns with |
|
The typescript default is |
|
Yeah I guess it makes less sense for swc to be opinionated about that. Can it be a configuration option? |
|
@nayeemrmn I'll add a option to switch behavior, while preserving current semantic as default. |
kdy1
changed the title
| #[derive(Debug, Serialize, Deserialize)] | ||
| #[non_exhaustive] | ||
| pub enum ImportNotUsedAsValues { | ||
| #[serde(rename = "rename")] |
| ImportNotUsedAsValues::Preserve => match entry { | ||
| Some(&DeclInfo { | ||
| has_type: true, | ||
| has_concrete: false, | ||
| .. | ||
| }) => false, | ||
| _ => true, | ||
| }, |
There was a problem hiding this comment.
@kdy1 This is not the behaviour of tsc under "importsNotUsedAsValues": "preserve". The correct behaviour is to never preserve completely unused import identifiers. The above branch should always be used.
I think ImportNotUsedAsValues should be removed since it's a misunderstanding of the equivalent tsc option.
There was a problem hiding this comment.
I'll make a breaking change to fix it.
Current behavior is intended for multiple reason.
import typeare only stripped out if it's used as type.ts 3.8 introduced type-only imports, because the problem I wrote above.
(Note that typescript had a breaking change after it)
swcworks on file-by-file basis, so it cannot know if it's a type-only.I'm considering two options.
Implement emit-only tsc which also handles some special stuffs like const enum within swc_bundler, as it already works by loading multiple file.
Add config to allow user select which behavior should be used.
See: denoland/deno#7413 (comment)