C# 8 Using Statement produces compile error

[richardnagle]

What You Are Seeing?

When using the new C#8 using var... statement, the cake script produces compile errors.

What is Expected?

This script should compile successfully.

What version of Cake are you using?

0.35.0

Are you running on a 32 or 64 bit system?

64bit

What environment are you running on? Windows? Linux? Mac?

Windows 10

Are you running on a CI Server? If so, which one?

No

How Did You Get This To Happen? (Steps to Reproduce)

Task("C#8-Using-Statement")
    .Does(() =>
    {
        using var file = System.IO.File.Create(@".\temp.txt");
    });

Output Log

> .\build.ps1 -target C#8-Using-Statement

Preparing to run build script...
Running build script...
(5,11): error CS1002: ; expected
(5,7): error CS0825: The contextual keyword 'var' may only appear within a local variable declaration or in script code
(5,11): error CS0103: The name 'file' does not exist in the current context

[devlead]

I believe this is likely an issue with the script pre-processing.

To unblock you for this specific use case as it's an stream that implements async disposable you can adjust your code to

Task("C#8-Using-Statement")
    .Does(async () =>
    {
        await using var file = System.IO.File.Create(@".\temp.txt");
    });

[devlead]

Just FYI Cake has a built in IO abstraction layer that handles OS/Environment specific things for you. i.e. path normalization. It will also mean you can take advantage of any module that enhances the filesystem i.e. long path, there's a fake file system in Cake.Testing etc.

Utilizing Cake FileSystem could i.e. look something like

Task("C#8-Using-Statement")
    .Does(async context =>
    {
        await using var file = context.FileSystem.GetFile("./temp.txt").OpenWrite();
    });

[gitfool]

I stumbled across this just now while trying the latest shiny C# with Cake version 2.0.0-rc0002: 😞

(Example from using statement (C# Reference))

[devlead]

I stumbled across this just now while trying the latest shiny C# with Cake version 2.0.0-rc0002: 😞

(Example from using statement (C# Reference))

Fix would be somewhere around here https://github.com/cake-build/cake/blob/0de2adc821dd65bc7c003d16c03878971c2698e6/src/Cake.Core/Scripting/Processors/UsingStatementProcessor.cs#L35

Some conditional to return false.

Maybe line contains ( and ) or something similar.

[cake-build-bot]

:tada: This issue has been resolved in version v2.0.0 :tada:

The release is available on:

• GitHub Release
• NuGet Package
• Chocolatey Package
• .Net Global Tool

Your GitReleaseManager bot :package::rocket: