Bug 6178 - Code completion does not take co/contra-variance into account
Summary: Code completion does not take co/contra-variance into account
Alias: None
Product: Xamarin Studio
Classification: Desktop
Component: C# Binding ()
Version: unspecified
Hardware: PC Mac OS
: Normal normal
Target Milestone: ---
Assignee: Mike Krüger
Depends on:
Reported: 2012-07-18 11:58 UTC by Alan McGovern
Modified: 2012-07-19 08:14 UTC (History)
1 user (show)

Is this bug a regression?: ---
Last known good build:

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Description Alan McGovern 2012-07-18 11:58:59 UTC
In this scenario MonoDevelop marks 'ToArray' in red, implying the method does not exist, because it does not take covariance into account. The 'ToArray' extension method's signature is:

T[] ToArray (IEnumerable<T>)

In this example IEnumerable<B> is covariant towards IEnumerable<A>, so it compiles and executes with no error even though we are passing an IEnumerable<B> to a method expecting IEnumerable<A>.

public class A

public class B : A

class Program
    static void Main(string[] args)
        var list = new List<B>().ToArray<A>();
Comment 1 Mike Krüger 2012-07-19 03:50:19 UTC
fixed that one.
Comment 2 Alan McGovern 2012-07-19 08:14:25 UTC
This is not fixed in MD master. Are you sure you committed the change?