Bug 18473 - Mono C# compiler incorrectly emits CS0411
Summary: Mono C# compiler incorrectly emits CS0411
Alias: None
Product: Compilers
Classification: Mono
Component: C# ()
Version: unspecified
Hardware: All All
: --- normal
Target Milestone: ---
Assignee: Marek Safar
Depends on:
Reported: 2014-03-19 15:14 UTC by emoriarty
Modified: 2014-05-06 10:53 UTC (History)
2 users (show)

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

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.

Please create a new report on GitHub or Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:

Description emoriarty 2014-03-19 15:14:34 UTC
The Mono C# compiler does not compile the following code that csc accepts. 

===== Test.cs =====
     1  using System;
     2  using System.Collections.Generic;
     3  using System.Linq;
     4  public interface IA<T> {
     5      void Foo<T2>(IEnumerable<T2> a) where T2 : T;
     6  }
     7  public class B<T, TBase> : IA<T> where T : TBase {
     8      IA<TBase> _d;
     9      Func<TBase, bool> _m;
    10      public B(IA<TBase> d) {
    11          _d = d;
    12          _m = (bo => bo is T);
    13      }
    14      public void Foo<T2>(IEnumerable<T2> a) where T2 : T {
    15          _d.Foo(a.Where(bo => _m(bo)));  
    16      }
    17  }
===== End of Test.cs =====

Command lines:
# From Visual Studio 2013 command prompt
$ csc /target:library Test.cs
Microsoft (R) Visual C# Compiler version 12.0.21005.1
Copyright (C) Microsoft Corporation. All rights reserved.

# From Mono-3.2.6 command prompt
$ mcs /target:library Test.cs
Test.cs(15,30): error CS1594: Delegate `System.Func<TBase,bool>' has some invalid arguments
Test.cs(15,33): error CS1503: Argument `#1' cannot convert `T2' expression to type `TBase'
Test.cs(15,12): error CS0411: The type arguments for method `IA<TBase>.Foo<T2>(System.Collections.Generic.IEnumerable<T2>)' cannot be inferred from the usage. Try specifying the type arguments explicitly
Compilation failed: 3 error(s), 0 warnings

Other Testing:
# Mono fail fail fail fail fail
master/652615f0a22: fail

# csc via developer command prompts.
VS2008: pass
VS2010: pass
VS2013: pass

Edward Moriarty | Junior Engineer
Coverity | The Leader in Development Testing
Comment 1 Marek Safar 2014-05-06 10:53:02 UTC
Fixed in master