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Always retain lines for async arrow #11836

merged 6 commits into from Jul 15, 2020

Always retain lines for async arrow #11836

merged 6 commits into from Jul 15, 2020


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cwohlman commented Jul 14, 2020

First stab at fixing #11830, fixes the bug but has other issues.

Q                       A
Fixed Issues Fixes #11830
Patch: Bug Fix? Yes
Major: Breaking Change? No - Although the current implementation breaks some tests
Minor: New Feature? No
Tests Added + Pass? No - Added passing tests but breaking other tests
Documentation PR Link
Any Dependency Changes? No
License MIT

Since the fix is to always include parentheses for arrow functions, it breaks the following tests:

  • generation/edgecase › single arg async arrow with retainlines
  • generation/types › ArrowFunctionExpression

I'm not sure what we should do here, ideally I guess we should only wrap the param in parentheses if there's a comment proceeding the param, though I don't have any idea how to do that.

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babel-bot commented Jul 14, 2020

Build successful! You can test your changes in the REPL here:

@@ -109,7 +109,8 @@ export function ArrowFunctionExpression(node: Object) {
if (
node.params.length === 1 &&
t.isIdentifier(firstParam) &&
!hasTypes(node, firstParam)
!hasTypes(node, firstParam) &&
) {
if (
this.format.retainLines &&

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JLHwung Jul 15, 2020 Contributor

We can move node.async to here

this.format.retainLines || node.async

so we are instructing that if async presents, we try to retain lines and print ( if the function body is in different lines with the async arrow.

cwohlman added 2 commits Jul 15, 2020
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cwohlman commented Jul 15, 2020

Thanks @JLHwung, looks like that does the trick.

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@JLHwung JLHwung changed the title Fix 11830 always retain lines for async arrow Jul 15, 2020
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nicolo-ribaudo left a comment


@nicolo-ribaudo nicolo-ribaudo changed the title always retain lines for async arrow Always retain lines for async arrow Jul 15, 2020
@nicolo-ribaudo nicolo-ribaudo merged commit e12caf4 into babel:main Jul 15, 2020
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@cwohlman cwohlman deleted the xolvio:fix-11830 branch Jul 16, 2020
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