Avoid compiling the _typeof helper with itself #11049
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nicolo-ribaudo
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PR: Bug Fix 🐛
soryy708
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Jan 23, 2020
| resolvePath(path, (err, path) => (err ? reject(err) : resolve(path))), | ||
| ); | ||
| const readFile = path => | ||
| new Promise((resolve, reject) => |
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Can be refactored using util.promisify
Example:
const readFile = path => util.promisify(fs.readFile)(path, "utf8")
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No, it's not supported by Node 6.
When we'll drop it, we'll directly use fs.promises.
jridgewell
approved these changes
Jan 23, 2020
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If the file is already bundled, then Babel can't reference it and wouldn't introduce a circular dependency but only duplicate the helper. Anyway, I don't think that bundlers strip directives, especially if they are inside a nested function. |
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Don't assume, verify. |
existentialism
approved these changes
Jan 27, 2020
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Hi! when is this getting released? |
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Tomorrow probably 😁 |
rajasekarm
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Feb 17, 2020
* Avoid compiling the typeof helper with itself * Update fixtures
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We already had some logic to prevent the
typeof-symbolplugin from transpiling its own helper. It worked by generating the helper name and checking if the current path is inside a function or a variable declaration with that name.However, it had a few problems:
@babel/runtime, because the generated name is a unique identifier so it's guaranteed not to be equal to the_typeofhelper name._typeof2and_typeof3), causing circular dependencies. This is probably caused by running twice the plugin, but we can avoid failing in that case.I initially hard-coded the helper name in the
isUnderHelperlogic to make it work with@babel/runtime, but:@babel/runtimeis bundled in an app/library byrollup, the function name might changeI then decided to introduce a
"@babel/helpers - typeof"directive, which has a few advantage:@babel/runtime/helpers/typeofThe directive still doesn't work with Terser and UglifyJS because they strip them by default. We could either suggest to whoever finds this bug to set the
directives: falseoption in their minifier settings, or we could ask UglifyJS and Terser's maintainers if they could keep this specific directive in the minified output.This PR makes it safe to transpile
@babel/runtime, which should provide a solution for #9903