Angular 17 @empty block not working in nested propagated component

[WarGreyGon]

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

core

Is this a regression?

No

Description

When I try to display some HTML within an @empty block is not rendering anything whereas if I am using a @if approach is working fine.

Bellow snippet belongs to a nested HTML propagated using Angular projections (the main attribute is a projection area)

	<plc-box main *ngrxLet="games$ as games">
		@for (game of games; track game._id) {
		<plc-game-row main [game]="game"></plc-game-row>
		} @empty {                               <!-- <=== This line FAILS-->
		<!-- } @if(games.length === 0) { -->     <!-- <=== This line WORKS-->
		<ng-container main>
			<plc-icon [name]="'landscape'" ></plc-icon>
			<plc-label class="plc-search-game__no-record-label">
				{{ 'pages.search-game.no-results' | translate }}
			</plc-label>
		</ng-container>
		}
	</plc-box>

Same code outside of a propagation based component works fine (e.g. inside a regular <div></div>)

Please provide a link to a minimal reproduction of the bug

Minimal reproduction in StackBlitz

Please provide the exception or error you saw

I see a blank spot where a HTML should be displayed instead

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

Angular CLI: 17.0.7
Node: 18.18.2
Package Manager: npm 9.8.1
OS: win32 x64

Angular: 17.0.7
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1700.7
@angular-devkit/build-angular   17.0.7
@angular-devkit/core            17.0.7
@angular-devkit/schematics      17.0.7
@angular/cdk                    16.0.1
@angular/material               16.0.1
@schematics/angular             17.0.7
ng-packagr                      17.0.2
rxjs                            7.8.1
typescript                      5.2.2
zone.js                         0.14.2

Anything else?

No response

[JoostK]

Please provide a minimum, runnable reproduction.

[WarGreyGon]

@JoostK updated description with reproduction link 🙂

[JoostK]

Thanks, that has been very helpful. It seems like the empty template is not considered for projection, as was done for the primary blocks of if and for in #52414.

[crisbeto]

This is currently "working as intended". The problem is that we use the main @for block as the insertion point both for the loop contents and the @empty contents.

[pkozlowski-opensource]

The problem is that we use the main @for block as the insertion point both for the loop contents and the @empty contents.

There was a refactoring at some point with which the main loop content and the empty blocks have their separate insertion containers. Capturing a tag name based on the empty block content (as we do for if, for etc.) should do the trick for the empty block as well.