Add heuristics to detect type aliases that has complex typeparameters #10901
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| typeParams.length > 1 && | ||
| !!getLast(typeParams).default && | ||
| typeParams.every((param) => !!param.constraint) | ||
| ) { |
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Right now we only have the condition to fix just #10857, but I think we can improve here based on feedback in the future.
src/language-js/print/assignment.js
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| Boolean(getLast(typeParams).default) && | ||
| typeParams.every((param) => Boolean(param.constraint)) |
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Why check .default only for the last type parameter?
| Boolean(getLast(typeParams).default) && | |
| typeParams.every((param) => Boolean(param.constraint)) | |
| typeParams.some((param) => param.constraint || param.bound || param.default) |
param.bound is for Flow (playground).
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I forgot about param.bound, thank you.
Why check .default only for the last type parameter?
Because the default value of type parameters can only appear on last param.
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Because the default value of type parameters can only appear on last param
It's not the case.
update: oh, sorry, you were right
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Like this?
type Bar<T = string, S> = {}There was a problem hiding this comment.
You're right, TS doesn't accept that. I thought S in that situation would default to any, but it doesn't work that way.
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Still, I think it's better to break the LHS even if at least one type parameter has a constraint or a default (some, not every).
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Okay, I have no strong opinion
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Please add a changelog entry |
| @@ -0,0 +1 @@ | |||
| run_spec(__dirname, ["flow", "babel"]); | |||
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Let's run flow test with babel-flow instead of babel.
Description
Fixes #10857
Checklist
changelog_unreleased/*/XXXX.mdfile followingchangelog_unreleased/TEMPLATE.md.✨Try the playground for this PR✨