Always print parentheses around arrow function parameters #13202
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I have an alternate version of this change that tries to retain no-parens in some cases, and instead just tries to make the logic simpler and more robust. But I like the idea of just always spending two characters to guarantee correct output. |
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Looking at the output, maybe we could still keep the single identifier param, no async, no comments, no types case (which is one of the most common ones) parens-less, or at least do it when the compact: true option is set.
It should still be safe, since it doesn't need to check loc and accidental line breaks don't cause problems.
| (x): %checks => x !== null; |
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OK, I'll polish up the version that tries to keep the no-parens in simple cases, and see what that looks like. |
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I opened a separate PR for the alternate version at #13204, to avoid having to force-push back and forth between the two versions. |
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PR: Bug Fix 🐛
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Closed in favour of #13204. |
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Some arrow functions can safely be printed without parentheses around a single identifier parameter.
However, there are many factors that can make this unsafe (e.g. type annotations, comments), and several generator features that can silently introduce edge cases (
retainLines,auxiliaryCommentBefore/auxiliaryCommentAfter). These make it hard to be confident that printing the bare identifier really is safe.This PR therefore makes the generator always print the parentheses, even when they aren't strictly necessary, greatly simplifying the implementation.