Bug 52623 - code compilation with Roslyn fails with code -2146232797
Summary: code compilation with Roslyn fails with code -2146232797
Alias: None
Product: Android
Classification: Xamarin
Component: MSBuild ()
Version: unspecified
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: dean.ellis
Depends on:
Reported: 2017-02-19 23:07 UTC by Eric Liu
Modified: 2017-10-21 00:48 UTC (History)
5 users (show)

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

Solution (15.63 KB, application/x-zip-compressed)
2017-02-19 23:07 UTC, Eric Liu

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Description Eric Liu 2017-02-19 23:07:28 UTC
Created attachment 19881 [details]

Windowns 10 Pro x64
Visual Studio 2017
Xamarin.Android (c9880f9)

[Code to repro]
using Android.App;
using Android.OS;
using System.Threading.Tasks;

namespace App2
    [Activity(Label = "App2", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : Activity
        protected override void OnCreate(Bundle bundle)
            var method = GetType().GetMethod(string.Empty);
            Task.Run(async () =>
                dynamic task = method.Invoke(this, new object[] { 10 });
                dynamic result = await task; // with this line it fails

[Excepted behaviour]
Compile successfully.

[Actual behaviour]
Compilation fails:
error MSB6006: "csc.exe" exited with code -2146232797.
Comment 1 Eric Liu 2017-02-19 23:16:11 UTC
+ And it's working if we cast it.
Task.Run(async () =>
   Task<int> task = (Task<int>)method.Invoke(this, new object[] { 10 });
   dynamic result = await task;

(+ the non-casted code is fine with other frameworks with Roslyn)
Comment 2 Jon Douglas [MSFT] 2017-09-08 19:41:01 UTC
I am seeing the following using 15.3.3:

Error	CS0656	Missing compiler required member 'Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create'

On 15.4 builds, I'm seeing the same thing.

Given your version information, I feel it's safe to say you're on a very old build. Xamarin Android is currently on 7.4 on stable versions and 8.0 on preview versions.

The error seems to stem from your sample project not having a reference to "Microsoft.CSharp.dll". Including this allows the sample to build successfully. Setting this bug to NEEDINFO for the time being.
Comment 3 Eric Liu 2017-10-21 00:48:56 UTC
Yeah it was in 2017 February. Can be closed, pretty much resolved since then.