fix: Deleting super property should throw

[SuperSodaSea]

Q	A
Fixed Issues?	Fixes #15169
Patch: Bug Fix?	👍
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?	👍
License	MIT

Spec Compliance

delete super.prop and delete super[expr] should throw ReferenceError. Now they are transformed into:

// `delete super.prop` =>
function () { throw new ReferenceError("'delete super.prop' is invalid"); }()

// `delete super[expr]` =>
(
    babelHelpers.toPropertyKey(expr),
    function () { throw new ReferenceError("'delete super[expr]' is invalid"); }()
)

Thanks @Jack-Works and @nicolo-ribaudo for providing the correct transform.

Tests

• babel-plugin-proposal-class-properties/test/fixtures/public/delete-super-property
• babel-plugin-transform-classes/test/fixtures/spec/delete-super-property
• babel-plugin-transform-classes/test/fixtures/spec/delete-super-property-to-property-key

test262

ok 7187 test/language/expressions/delete/super-property-method.js default # (success)

ok 7188 test/language/expressions/delete/super-property-method.js strict mode # (success)

ok 7189 test/language/expressions/delete/super-property-null-base.js default # (success)

ok 7190 test/language/expressions/delete/super-property-null-base.js strict mode # (success)

ok 7191 test/language/expressions/delete/super-property.js default # (success)

ok 7193 test/language/expressions/delete/super-property.js strict mode # (success)

# 0 new failures, 6 new successes

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/53578/

[liuxingbaoyu]

This should need to be a peer dependency, though I'm not sure, see what other people think.

[SuperSodaSea]

It seems that other packages use this:

"peerDependencies": {
  "@babel/core": "^7.0.0-0"
},
"devDependencies": {
  "@babel/core": "workspace:^"
},

[liuxingbaoyu]

Thanks!

[nicolo-ribaudo]

In theory adding a peer dependency is a breaking change, however this is an internal package only used by other packages that already depend on @babel/core, so it should be fine.

Could you remove the @babel/traverse and @babel/types dependencies, and import them from @babel/core? Or as an alternative, we could just add @babel/template as a dependency and avoid adding @babel/core.

[SuperSodaSea]

Now template is imported directly from @babel/template.

By the way, it seems that the original code (on main branch) of @babel/helper-replace-supers have an import type { File } from "@babel/core"; without declaring @babel/core dependency in package.json. Does it matter?

babel/packages/babel-helper-replace-supers/src/index.ts

Line 19 in 65c8496

import type { File } from "@babel/core";

[nicolo-ribaudo]

It doesn't matter because we remove type-only imports before publishing, so the published code is fine.

[nicolo-ribaudo]

This logic should be moved in a different place: instead of special-casing delete here, we should add an optional delete handler to

babel/packages/babel-helper-member-expression-to-functions/src/index.ts

Line 537 in 65c8496

export interface Handler<State> {

, and implement it in

babel/packages/babel-helper-replace-supers/src/index.ts

Line 121 in 65c8496

const specHandlers: SpecHandler = {

[SuperSodaSea]

Done in 38dcf9d :)