preserveWhitespaces can break defer placeholder detection #61725
Description
Which @angular/* package(s) are the source of the bug?
compiler
Is this a regression?
No
Description
If the element inside the placeholder of a defer is not directly adjacent to the opening brace and preserveWhitespaces is active, the build fails with NG5002: "viewport" trigger with no parameters can only be placed on an @defer that has a @placeholder block with exactly one root element node.
Broken:
template: `
@defer (on viewport) {
<div></div>
} @placeholder {
<div></div>
}
`,
preserveWhitespaces: true,
Working:
template: `
@defer (on viewport) {
<div></div>
} @placeholder {<div></div>}
`,
preserveWhitespaces: true,
Please provide a link to a minimal reproduction of the bug
https://stackblitz.com/edit/stackblitz-starters-3q3h25jf?file=src%2Fmain.ts
Please provide the environment you discovered this bug in (run ng version)
Angular CLI: 19.2.13
Node: 22.15.0
Package Manager: npm 11.3.0
OS: darwin arm64
Angular: 19.2.13
... cli, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router
Package Version
---------------------------------------------------------
@angular-devkit/architect 0.1902.13
@angular-devkit/build-angular 19.2.13
@angular-devkit/core 19.2.13
@angular-devkit/schematics 19.2.13
@schematics/angular 19.2.13
rxjs 7.8.2
typescript 5.7.3
zone.js 0.15.1
Anything else?
This behavior was initially found and filed as an issue in angular-eslint since it calls the compiler with preserveWhitespaces: true: angular-eslint/angular-eslint#2474