dotnet/roslyn

C# EE: The type of hoisted dynamic variables displayed as object

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#32,492 opened on Jan 15, 2019

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Area-InteractiveInteractive-Debugginghelp wanted

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Description

Step thru Main and M methods. In Main the type of e is displayed as dynamic in Locals window. In M the type of d is object. It should be dynamic as well.

using System;
using System.Linq;
using System.Collections.Generic;

class C
{
    static IEnumerable<int> M()
    {
        dynamic d = 1;
        yield return d;
        Console.WriteLine(d);
    }

    public static void Main()
    {
        dynamic e = 1;
        M().ToArray();
    }
}

We should put DynamicAttribute on the lifted fields, or add and use dynamic variable CDI to the iterator method.

Contributor guide

Research direction
Investigate how the C# compiler generates iterator state machines and ensure DynamicAttribute is applied to lifted fields that store dynamic variables. Look at the SynthesizedLocal or similar classes that create these fields.
Tech stack
csharp
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitC#
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45