HMR breaks when using a const enum value inside decorator metadata #59800
Description
Command
serve, build
Is this a regression?
- Yes, this behavior used to work in the previous version
The previous version in which this bug was not present was
No response
Description
When using const enum values inside decorators, in this case in the @Component providers array, you'll get a crash when a hmr change is being applied, likely as it tries to reference it, but it's already been converted to a number and no longer exists.
Assigning it to a variable above the decorator and referencing it works fine.
Using a regular (non const) enum works fine.
We're using tsconfig "preserveConstEnums": false,, but changing it to "preserveConstEnums": true, has no effect on the above.
Minimal Reproduction
import { ChangeDetectionStrategy, Component } from '@angular/core';
import { UI_COMPONENT } from '@app/shared/utils/injection-tokens/ui-component.token';
export const enum Foo {
bar = 0,
baz = 1,
}
const definingTheValueOutsideDecoratorWillWork = Foo.baz;
@Component({
selector: 'app-search-page',
templateUrl: './search-page.component.html',
changeDetection: ChangeDetectionStrategy.OnPush,
// This following syntax won't survive HMR reload.
providers: [
{
provide: UI_COMPONENT,
useValue: Foo.baz,
},
],
// The syntax below works fine.
// providers: [
// {
// provide: UI_COMPONENT,
// useValue: definingTheValueOutsideDecoratorWillWork,
// },
// ],
})
export class SearchPageComponent {}
Exception or Error
zone.js:2227 ReferenceError: Foo is not defined
at SearchPageComponent_UpdateMetadata (search-page.component.ts:4:27)
at Module.ɵɵreplaceMetadata (core.mjs:32363:17)
at search-page.component.ts:30:33
at _ZoneDelegate.invoke (zone.js:339:158)
at ZoneImpl.run (zone.js:110:35)
at zone.js:2428:30
at _ZoneDelegate.invokeTask (zone.js:364:171)
at ZoneImpl.runTask (zone.js:163:37)
at drainMicroTaskQueue (zone.js:535:23)
Your Environment
Angular CLI: 19.1.5
Node: 20.18.0
Package Manager: npm 10.8.1
OS: win32 x64
Angular: 19.1.4
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router
Package Version
---------------------------------------------------------
@angular-devkit/architect 0.1901.5
@angular-devkit/build-angular 19.1.5
@angular-devkit/core 19.1.5
@angular-devkit/schematics 19.1.5
@angular/cdk 19.1.2
@angular/cli 19.1.5
@angular/material 19.1.2
@schematics/angular 19.1.5
rxjs 7.8.1
typescript 5.5.4
zone.js 0.15.0
Anything else relevant?
No response