.NET SDK 8.0.404 ignores <EnablePreviewFeatures>True in dotnet build

[alexandrehtrb]

Description

Hello,

I have a project with the following code line, that requires <EnablePreviewFeatures>True</EnablePreviewFeatures> in the csproj.

if (httpVersion == 3.0m && !(OperatingSystem.IsLinux() || QuicConnection.IsSupported))

When running dotnet build on the pipeline, this error pops up:

Error: D:\a\Pororoca\Pororoca\src\Pororoca.Domain\Features\Common\AvailablePororocaRequestSelectionOptions.cs(42,67): 
error CA2252: Using 'IsSupported' requires opting into preview features. 
See https://aka.ms/dotnet-warnings/preview-features for more information. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca2252) [D:\a\Pororoca\Pororoca\src\Pororoca.Domain\Pororoca.Domain.csproj]
    0 Warning(s)
    1 Error(s)

Even though the .csproj has this flag specified.

Regression?

The bug happens with .NET SDK 8.0.404, but it does not happen with 8.0.403.

Configuration

Win x64 machine. I didn't check on Linux machine.

[alexandrehtrb]

I ran another workflow run and this bug appeared with 8.0.403 too 🤨

[alexandrehtrb]

Should this issue be moved to the dotnet/sdk repo?

[jtschuster]

Yes, I think dotnet/sdk would be the best place for this

[KalleOlaviNiemitalo]

Are you using global.json to make sure that the .NET SDK version is what you expect?

https://github.com/dotnet/designs/blob/main/accepted/2021/preview-features/preview-features.md#sdk-support-of-preview-features says:

The .NET SDK only supports preview features for the current framework. More specifically, <EnablePreviewFeatures> is ignored for all other frameworks.

So if you were somehow accidentally using .NET SDK 9.0.100, but still targeting net8.0, then EnablePreviewFeatures would be ignored.

[alexandrehtrb]

I was setting the SDK version with GitHub Actions and expected to be the only version installed, but .NET 9 SDK was installed too, and it was being used instead.

After adding a global.json, the project started to compile again.

Thanks!