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[no-non-null-asserted-optional-chain] false negative for foo1?.bar!.baz #2412

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xcatliu opened this issue Aug 21, 2020 · 1 comment
Closed
3 tasks done

[no-non-null-asserted-optional-chain] false negative for foo1?.bar!.baz #2412

xcatliu opened this issue Aug 21, 2020 · 1 comment
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documentation Documentation ("docs") that needs adding/updating package: eslint-plugin Issues related to @typescript-eslint/eslint-plugin

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@xcatliu
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xcatliu commented Aug 21, 2020

  • I have tried restarting my IDE and the issue persists.
  • I have updated to the latest version of the packages.
  • I have read the FAQ and my problem is not listed.

Repro

{
  "rules": {
    "@typescript-eslint/no-non-null-asserted-optional-chain": "error"
  }
}
let foo: { bar: any } | undefined;

foo?.bar!.baz;

Expected Result

As the docs described, it should report an error.

Actual Result

No error.

image

Additional Info

foo?.bar!; report an error as expected.

image
image

Versions

package version
@typescript-eslint/eslint-plugin 3.9.1
@typescript-eslint/parser 3.9.1
TypeScript 4.0.2
ESLint 7.7.0
node 12.16.1
@xcatliu xcatliu added package: eslint-plugin Issues related to @typescript-eslint/eslint-plugin triage Waiting for team members to take a look labels Aug 21, 2020
@bradzacher
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The docs are out of date. TS3.9 changed how optional chaining works.

Previously foo?.bar!.baz meant (foo?.bar).baz - which means "assume the result of foo?.bar is non-null.
As of TS3.9, foo?.bar!.baz now just applies the non-null assertion to the property itself.

So it's no longer bad practice to do this.

It is however still bad practice to do foo?.bar.baz!, because that applies the non-null assertion to the entire chain.

@bradzacher bradzacher added documentation Documentation ("docs") that needs adding/updating and removed triage Waiting for team members to take a look labels Aug 21, 2020
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