experimentalImportSupport: Fix exported names under relabelling and rest spread (#1772)

[robhogan]

Summary:

Fixes #1460

Fixes two related bugs in Metro's experimentalImportSupport.

Exports with inline relabelling

export const { A: B } = {};

Currently transforms to

const { A: B } = {};
exports.A = A;

Which is invalid: A is a reference error.

After this diff

const { A: B } = {};
exports.A = B;

Exports with spreads

Currently both of these fail to transform:

Object spread

export const {A, ...others} = {A: 'A', B: 'B', C: 'C'};

Plugin throws TypeError: Cannot read properties of undefined (reading 'name') when attempting to iterate over the object for key: val pairs.

Array spread

export const [A, ...others] = ['A', 'B', 'C'];

Plugin throws Property name expected type of string but got undefined after extracting an undefined name and then attempting to use it at as prop of exports.

After this diff

const {A, ...others} = {A: 'A', B: 'B', C: 'C'};
exports.A = A;
exports.others = others;

and

const [A, ...others] = ['A', 'B', 'C'];
exports.A = A;
exports.others = others;

Spec

Almost goes without saying in this case - exported variable declarations should expose the declaration's bound names. ECMA-262 defines those names through Static Semantics: BoundNames, including BindingPattern forms: https://tc39.es/ecma262/#sec-static-semantics-boundnames

Implementation

Metro had naive ObjectPattern/ArrayPattern extraction that read object keys or array elements directly.

This fixes the same issues Expo did in #38058 and #38118, but uses Babel's own getBindingIdentifiers for a simpler implementation.

Changelog

 - **[Experimental]**: experimentalImportSupport: Fix exports renamed by destructuring, and support exports of rest spreads.

Reviewed By: GijsWeterings, huntie

Differential Revision: D111013897

[meta-codesync]

@robhogan has exported this pull request. If you are a Meta employee, you can view the originating Diff in D111013897.

[meta-codesync]

This pull request has been merged in 0dc5030.