Allow omitting "()" in event bindings with no parameters passed about angular HOT 12 CLOSED

This suggests opposite thing to #56293

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This suggests opposite thing to #56293

Yes, i had just thought of tooling diagnostic error detecting this as alternative, but turns out this had already been suggested 18 hours ago.
These are not 100% exclusive.

The quirk suggested there[1], could be treated as suggested there, whereas defaulted calling could come from here.

P.S.
[1]

<button (click)="void incrementAndLaterDecrement()">Increment</button>

<button (click)="incrementAndLaterDecrement();">Increment</button>

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One could even consider combining defaulted calling from here with a diagnostic warning (rather than error suggested in #56293)

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Extended diagnostics are configurable w.r.t. being an error, warning or skipped altogether.

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OK, i updated my comment to mention warning only for now.

P.S. Although info could be another feature. :)

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I updated Alternatives considered section in the OP, to make the issue more legible.

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I think an extended diagnostic is probably the right answer here.

Trying to detect whether an expression in an event listener should be auto-called by the framework is a blurry proposition. For example:

(foo)="bar" // probably meant to call it
(foo)="bar.baz" // probably meant to be a call, but also is a method tearoff if strictly interpreted
(foo)="a && b" // also a side-effect free expression, but did you mean (a && b)() or a() && b()
(foo)="getCallback()" // you probably wanted getCallback()() but that's super hard to infer

Instead, I think it's better to report an error when we detect that an expression evaluates to a callable type but is not called.

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I updated Alternatives considered section in the OP, to make the issue more legible.

Twice.

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That's why i've been saying they are not 100% exclusive. Considering continuum of 4 approaches i listed in Alternatives considered in the OP a few minutes ago:

(foo)="bar" // probably meant to call it

approach 1.

ts (foo)="bar.baz" // probably meant to be a call, but also is a method tearoff if strictly interpreted

iff you are saying we can't reliably conclude that this means bar.baz() (but is there a real use-case of that?), (then it won't be approach 1.,) but (rather can be) approach 4.

(foo)="a && b" // also a side-effect free expression, but did you mean (a && b)() or a() && b()

approach 4.

(foo)="getCallback()" // you probably wanted getCallback()() but that's super hard to infer

That's a separate issue out of scope of this issue (because there are "()"), but mentioned as a quirk previously (#56305 (comment)): it's treatment should be discussed separately (should probably even be split off of #56293, because it's not the main thing discussed there, but a fringe case).

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Although not exactly the same, i'd like to point out that lambda expressions, method calls & just function names can work equivalently in standard JS. E.g.,
a. https://developer.mozilla.org/en-US/docs/Web/API/Document/DOMContentLoaded_event#examples

function doSomething() {
  console.info("DOM loaded");
}

if (document.readyState === "loading") {
  // Loading hasn't finished yet
  document.addEventListener("DOMContentLoaded", doSomething);
} else {
  // `DOMContentLoaded` has already fired
  doSomething();
}

b. https://jsfiddle.net/haqer/8Lpganh5/76/

document.getElementById("add").addEventListener("click", handleNew);

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Different area, but perhaps there is a similarity in this seeming example of approach 2 from gpg domain:

gpg -o test.pdf test.pdf.gpg
gpg: WARNING: no command supplied.  Trying to guess what you mean ...
...
File 'test.pdf' exists. Overwrite? (y/N) y
...

P.S. The similarity is in automated deducted action (in this case with a notification).

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Like it been pointed, we're choosing to go in the opposite direction cf #56293 (WIP implementation #56295).

Also the example about addEventListener is different. It expect a function, not something you could or not invoke.

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