ngFor over functions causes type error with Ivy

🐞 bug report

Affected Package

@angular/common, maybe? It’s a compile-time error using nothing special except *ngFor

Is this a regression?

This appeared as I was upgrading from Angular 9.1.0, though @JoostK below (https://github.com/angular/angular/issues/39634#issuecomment-725341454) was able to reproduce it on the latest 9.0.x and 9.1.x.

Description

When looping over an array of functions using *ngFor, a strange typing error occurs when calling that function in the template. For example in this template it gives an error like the following:

export class AppComponent  {
  functions = [() => 1, () => 2];
}

<p *ngFor="let fn of functions">
	{{ fn() }}
</p>

Property 'fn' does not exist on type '() => number'.

You’ll see that it somehow is trying to find fn on the function itself? It works fine if you turn off Ivy.

🔬 Minimal Reproduction

https://stackblitz.com/edit/angular-ivy-vttvch?file=src/app/app.component.html

🔥 Exception or Error

Property '__' does not exist on type '___'.

🌍 Your Environment

Angular Version:

Angular CLI: 10.2.0
Node: 12.18.1
OS: win32 x64

Angular: 10.2.2
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router, service-worker
Ivy Workspace: Yes

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1002.0
@angular-devkit/build-angular   0.1002.0
@angular-devkit/core            10.2.0
@angular-devkit/schematics      10.2.0
@angular/cdk                    10.2.7
@angular/cli                    10.2.0
@angular/material               10.2.7
@schematics/angular             10.2.0
@schematics/update              0.1002.0
rxjs                            6.6.3
typescript                      4.0.5

Anything else relevant? Must be using ivy

[ersimont]

@AleksanderBodurri Nice ideas. Thank you, that workaround unblocks me for now!

[angular-automatic-lock-bot[bot]]

This issue has been automatically locked due to inactivity. Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}