Scope of template local variables in Angular @if() block seems wrong

[alcfeoh]

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

compiler

Is this a regression?

Yes

Description

If I declare a local template variable in an @if() block, such variable is available in the @if() block but not in the @else() block, which seems like a bug. See cartContents below is not available in my @else block (see variable name in red below):

Please provide a link to a minimal reproduction of the bug

Screenshot has an example

Please provide the exception or error you saw

No response

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

Angular CLI: 17.3.0
Node: 18.17.1
Package Manager: npm 10.5.1
OS: win32 x64

Angular: 17.3.0
... animations, cli, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1703.0
@angular-devkit/build-angular   17.3.0
@angular-devkit/core            17.3.0
@angular-devkit/schematics      17.3.0
@schematics/angular             17.3.0
rxjs                            7.8.1
typescript                      5.2.2
zone.js                         0.14.4

Anything else?

No response

[JeanMeche]

Hi, this is as designed. Have a look at the RFC. Also note that aliasing is only supported because of the backward compatibility with *ngIf. See also #52103

What you are looking for is the longly awaited template variable declaration #15280.

[alcfeoh]

Ok. Now that the syntax looks like regular if—then—else blocks, my expectation was that this would behave just like in other programming languages. I guess that's one more reason to use Signals instead of Observables.

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