control flow migration: ngIf else error

[e-oz]

Which @angular/* package(s) are the source of the bug?

core

Is this a regression?

No

Description

Was:

<span *ngIf="instance.name else unnamed">{{instance.name}}</span>

<ng-template #unnamed>
    <span i18n>Unnamed Instance</span>
  </ng-template>

After migration:

@if (b.name else unnamed) {
  <span>{{b.name}}</span>
}

<ng-template #unnamed>
    <span i18n>Unnamed Instance</span>
  </ng-template>

it gives error: NG5002: Parser Error: Unexpected token 'else'

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

NG5002: Parser Error: Unexpected token 'else'

Please provide the environment you discovered this bug in (run ng version)

"@angular/core": "^17.0.4"

Anything else?

I have to say, that this migration right now works much better - thank you for all bugfixes!

[e-oz]

After fixing cases like this manually, a few observations:

• Sometimes it is possible to replace such cases by inserting a template into the @else block, but sometimes, when the template is being used more than in one place, it's better to leave the template and use <ng-container *ngTemplateOutlet>;
• The most difficult case is nested ngIf else template;
• Migration can remove "CommonModule" from imports, despite the ngTemplateOutlet directive being used.

[jessicajaniuk]

@e-oz Thanks for the report! You found this error before my PR got approved / merged. It'll be fixed in #53076. The main issue here is that typically we expect else statements to be preceded by a ;. The migration hadn't accounted for it being omitted, which as it turns out is valid syntax. And yeah, your described situation is exactly the case I handled. It will remove the template outlet and template in the case that there's only one usage.

[jessicajaniuk]

#53076 has now been merged. Marking this as fixed. Feel free to try it out when 17.0.0.5 releases tomorrow.

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}