CA1801 False positive for events

[patriksvensson]

Analyzer package

Microsoft.CodeAnalysis.FxCopAnalyzers

Package Version

Example: v2.9.1

Diagnostic ID

Example: CA1801

Repro steps

I subscribed to an event in XAML (UWP) that generates a event callback in the code-behind file.

<controls:NavigationListView x:Name="MyListView"
    ItemsSource="{x:Bind MenuCommands, Mode=OneWay}"
    ItemInvoked="MyListView_ItemInvoked" />

private void MyListView_ItemInvoked(object sender, ListViewItem e)
{
   // Code here that does not use sender.
}

Expected behavior

I did not expect to get a warning saying that sender is not being used since I cannot remove the parameter without compilation errors.

Actual behavior

I get a warning telling me that not all parameters in the event callback is used (sender).

[mavasani]

@patriksvensson We special case the analyzer to not flag event handler methods that have a special signature:

1. 2 parameters
2. First parameter is of type object
3. Second parameter is of type EventArgs or is a sub-type of EventArgs

It seems that your mentioned signature does not meet the criteria in 3. Did you mean to use ListViewItemEventArgs instead of ListViewItem as the second parameter?

[mavasani]

Kindly refer to the suggestion 1. in #2593 (comment) - you should rename your parameter with one of the allowed discard symbol names to ensure it is not flagged.