/**
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* Safari ~11 has an issue where variable declarations in a For statement throw if they shadow parameters.
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* This is fixed by renaming any declarations in the left/init part of a For* statement so they don't shadow.
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* @see https://bugs.webkit.org/show_bug.cgi?id=171041
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*
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* @example
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* e => { for (let e of []) e } // throws
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* e => { for (let _e of []) _e } // works
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*/
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function handle(declaration) {
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if (!declaration.isVariableDeclaration()) return;
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const fn = declaration.getFunctionParent();
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const { name } = declaration.node.declarations[0].id;
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// check if there is a shadowed binding coming from a parameter
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if (
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fn &&
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fn.scope.hasOwnBinding(name) &&
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fn.scope.getOwnBinding(name).kind === "param"
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) {
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declaration.scope.rename(name);
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}
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}
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export default () => ({
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name: "transform-safari-for-shadowing",
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visitor: {
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ForXStatement(path) {
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handle(path.get("left"));
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},
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ForStatement(path) {
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handle(path.get("init"));
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},
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},
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});
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