/**
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* Fixes block-shadowed let/const bindings in Safari 10/11.
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* https://kangax.github.io/compat-table/es6/#test-let_scope_shadow_resolution
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*/
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export default function({ types: t }) {
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return {
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name: "transform-safari-block-shadowing",
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visitor: {
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VariableDeclarator(path) {
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// the issue only affects let and const bindings:
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const kind = path.parent.kind;
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if (kind !== "let" && kind !== "const") return;
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// ignore non-block-scoped bindings:
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const block = path.scope.block;
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if (t.isFunction(block) || t.isProgram(block)) return;
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const bindings = t.getOuterBindingIdentifiers(path.node.id);
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for (const name of Object.keys(bindings)) {
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let scope = path.scope;
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// ignore parent bindings (note: impossible due to let/const?)
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if (!scope.hasOwnBinding(name)) continue;
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// check if shadowed within the nearest function/program boundary
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while ((scope = scope.parent)) {
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if (scope.hasOwnBinding(name)) {
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path.scope.rename(name);
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break;
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}
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if (t.isFunction(scope.block) || t.isProgram(scope.block)) {
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break;
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}
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}
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}
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},
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},
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};
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}
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