Avoid adding #__PURE__ annotation to .bind(this)() expressions #7043
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Fixes the #__PURE__ annotation getting added to (async () => {})() IIFEs when the arrow function transform is running with spec: true.
Jessidhia
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7.x: regression
PR: Bug Fix 🐛
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I think a proper fix would be to check in the |
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@nicolo-ribaudo that would, unfortunately, then break the not-IIFE case for spec arrow functions ( EDIT: though I guess that could be worked around by specifically whitelisting |
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Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/6231/ |
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@nicolo-ribaudo looks like it's not possible as the |
| ["transform-arrow-functions", { "spec": true }], | ||
| "transform-regenerator", | ||
| "transform-async-to-generator", | ||
| "external-helpers" |
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We could build version accepting NodePaths exclusively on top of the existing helper. |
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I am trying a different approach by wrapping the calls on |
| return _context4.stop(); | ||
| } | ||
| }, _callee4, this); | ||
| })).bind(this); |
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The call to .bind(this) makes this not eligible for DCE by Uglify, even with the #__PURE__ annotation.
Maybe changing this to just check for MemberExpression at all is sufficient; or should we stay optimistic and add the #__PURE__ annotation in this case? 🤔
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Is .bind impure only when the user modifies Function.prototype.bind? If yes, I vote for being optimistic (since Babel has always assumed that builtins are unchanged), otherwise we should remove it.
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I'll merge it just so this bug is not on the next beta anymore, and I'm going to see if using sequence expressions in #7044 instead works out better. |
lock
bot
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the
outdated
This improves on the fix done on #6999.
Fixes the
#__PURE__annotation getting added to(async () => {})()IIFEs when the arrow function transform is running with"spec": true.The arrow function transform will change the function to be wrapped with a call to
.bind(this), which throws off the naïveisIIFEcheck. This adds a fancierisIIFEcheck that will also catch immediately invoking the result of.bind(this).