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

compiler

Is this a regression?

Yes

Description

Between version 19.2.1 and 19.2.2 the keys of several nodes returned from parseTemplate have changed.

Parsing this template: <div></div> returns:

• "Element$1" in 19.2.1
• "Element" in 19.2.2

For a reproduction, I built two stackblitz demos. You can run both with node index.js:

• 19.2.1: https://stackblitz.com/edit/stackblitz-starters-nuft1yx9?file=index.js
• 19.2.2: https://stackblitz.com/edit/stackblitz-starters-zbklt9nu?file=index.js

This change led to this PR in angular-eslint: angular-eslint/angular-eslint#2320
@JamesHenry In the description, you mention that this could be a sign that a node is now considered stable. However, I think this was an unintentional change. I can't actually find something like "$1" anywhere in the Angular code.
But I did find that in a case like Element, there are two classes with the same name in the compiler package:

• angular/packages/compiler/src/ml_parser/ast.ts

  Line 98 in 98bf4d5

  export class Element extends NodeWithI18n {

• angular/packages/compiler/src/render3/r3_ast.ts

  Line 159 in 98bf4d5

  export class Element implements Node {

And between 19.2.1 and 19.2.2 the dependency rollup was increased by two major versions (from 2 to 4): 044dac9#diff-7ae45ad102eab3b6d7e7896acd08c427a9b25b346470d7bc6507b6481575d519R133

And in rollup I found an issue mentioning that "$1" is added to names: rollup/rollup#4637 which was fixed in 3.2.1.

I think this leads to a change in the bundled compiler code:

• 19.2.1: https://www.unpkg.com/browse/@angular/[email protected]/fesm2022/compiler.mjs Line 4986 - The class has the name "Element$1"
• 19.2.2: https://www.unpkg.com/browse/@angular/[email protected]/fesm2022/compiler.mjs Line 4950 - The class has the name "Element" but is assigned to a variable named "Element$1"

So I think this change in key names was accidental due to the update of rollup. I am not sure if the compiler API on that level is part of Semantic versioning?
Triggered by the angular-eslint change, we spent a couple of hours today wondering why the key names in the AST would change during a patch update of the Angular Compiler which would prompt us to adjust some of our custom rules. I hope my theory that rollup could play a role here and was adding the "$1" is correct. In which case I just wanted to make everyone aware of this (maybe unnoticed and unintentional) change.

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

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

Angular CLI: 19.2.5
Node: 22.14.0
Package Manager: npm 11.2.0
OS: darwin arm64

Angular: 19.2.4
... common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.1902.5
@angular-devkit/core         19.2.5
@angular-devkit/schematics   19.2.5
@angular/build               19.2.5
@angular/cdk                 19.2.7
@angular/cli                 19.2.5
@schematics/angular          19.2.5
rxjs                         7.8.2
typescript                   5.8.2
zone.js                      0.15.0

Anything else?

No response