Vnext Argument 1: cannot convert from 'string' to 'System.IO.Stream'

Question

I am trying to create a generic serializer withing a Vnext project and when I call the constructor for StreamWriter it throws this compiler error

Error CS1503 Argument 1: cannot convert from 'string' to 'System.IO.Stream' Test.ASP.NET Core 5.0 Helper.cs 14

even though there is a constructor that allows to specify a path to a file as an argument.

this is my class file

using System;
using System.Collections.Generic;
using System.Xml;
using System.Xml.Serialization;
using System.IO;

namespace Test
{
    public static class Helper
    {
        public static void SerializeToXml<T>(string path, T value)
        {
            var serializer = new XmlSerializer(typeof(T));
            using (var stream = new StreamWriter(path)) // ERROR OCCURS HERE
            {
                using (var writer = XmlWriter.Create(stream))
                {
                    serializer.Serialize(writer, value);
                }
            }
        }
    }
}

This is my project.json file

{
    "version": "1.0.0-*",
    "dependencies": {
    },
    "commands": {
        "run": "run"
    },
    "frameworks": {
        "aspnet50": {
            "dependencies": {

            },
            "frameworkAssemblies": {
                "System.Xml": "4.0.0.0"

            }
        },
        "aspnetcore50": {
            "dependencies": {
                "System.Console": "4.0.0-beta-22231",
                "System.Xml.XmlSerializer": "4.0.0-beta-22231",
                "System.Collections": "4.0.10-beta-22422",
                "System.Xml.ReaderWriter": "4.0.10-beta-22231",
                "System.IO": "4.0.10-beta-22231"
            }
        }
    }
}

Answer 1

Here is the Answer from davidfowl

Thats because it's not available on CoreCLR. Use new StringWriter(File.OpenWrite(path)) instead

For future reference where can I check if a function is available or not?

File issues on the https://github.com/dotnet/corefx repository. They will be able to clarify why things are missing in the new framework. I believe the reason this particular overload was removed was because of layering issues between the new packages.

The assembly that contains StreamWriter shouldn't be directly referencing FileStream:

new StreamReader(path)

actually does

new StreamReader(new FileStream(path, options)).