Fix S1144 FP: Event with a concrete sender

[IeuanWalker]

Description

If I create an event with a concreate sender it gives the warning S1144 (remove unused code)
i.e. this is gives a warning -

void CustomSwitch_SwitchPanUpdate(CustomSwitch customSwitch, SwitchPanUpdatedEventArgs e)

but this is fine -

void CustomSwitch_SwitchPanUpdate(object customSwitch, SwitchPanUpdatedEventArgs e)

Repro steps

In the CustomSwitch class i have this -

public delegate void CustomSwitchPanUpdatedEventHandler(CustomSwitch customSwitch, SwitchPanUpdatedEventArgs e);
public event CustomSwitchPanUpdatedEventHandler? SwitchPanUpdate;

And I trigger it like this -

SwitchPanUpdate?.Invoke(this, ev);

Then in a consuming class I have this -

void CustomSwitch_SwitchPanUpdate(CustomSwitch customSwitch, SwitchPanUpdatedEventArgs e)
{
	// Logic
}

Expected behaviour

No warning, first parament should be ignored and can be anything not just object

Actual behaviour

Warning

Known workarounds

Setting the first parameter as object

[martin-strecker-sonarsource]

Hello @IeuanWalker,

Thank you for reporting this. Can you please tell if the SwitchPanUpdatedEventArgs class derives from EventArgs? If so, we could relax the exception described in the S1144 rule as Methods with event handler signature void Foo(object, EventArgs) that are declared in partial class to also allow concrete classes for the sender parameter.

[IeuanWalker]

@martin-strecker-sonarsource hi, ye it is - https://github.com/IeuanWalker/Maui.Switch/blob/master/Scr/Switch/Events/SwitchPanUpdatedEventArgs.cs

[martin-strecker-sonarsource]

Hi @IeuanWalker,

We discussed the issue and decided to mark this as a false positive. The S1144 rule exception reads like this now.

Methods with event handler signature void Foo(object, EventArgs) that are declared in partial class

The method signature requirement should be relaxed to

void returning method with two parameters, and the second parameter should derive from EventArgs

We move this issue to our backlog, and you can track our work here.