VS Community Preview 16.1.0 - Razor Components intellisense errors

[aford22]

Describe the bug

Regression with VS Community Preview 16.1.0 that was not present in previous Preview release. When authoring Razor Components the "Errors" window and Intellisense both show the same compilation "errors" that are not errors. The project still builds and runs despite those errors. See screenshot of error window:

These false compilation errors were not present in previous VS Community preview release.

To Reproduce

Steps to reproduce the behavior:

1. Install VS Community Preview 16.1.0
2. Use Razor Components "example" project that shipped with previous release of VS Community Preview (the project with the "Counter" page and "Fetch Data" weather forecasts page). I.e. the code:

@page "/counter"
@using WebApplication1.Services
@inject WeatherForecastService ForecastService

<h1>Counter</h1>
<p>Current count: @currentCount</p>
<button class="btn btn-primary" onclick="@IncrementCount">Click me</button>

@functions {
    int currentCount = 0;

    void IncrementCount()
    {
        currentCount++;
    }
}

3. Build the project. You will see the false compilation errors
   
4. Project builds successfully and can be run with no issues

Expected behavior

False compilation errors should not be present in the "Errors" window nor as red wavy lines in the main "Code Editor" window

Additional context

These issues were not present in previous VS Community Preview release

[NTaylorMullen]

@aford22 a few questions to properly diagnose what you're seeing.

• Are you able to reproduce the issue with a new project?
• What's your dotnet --info output?
• Do you see your button tag in Counter.razor as purple?
• Would you mind pasting the contents of your .csproj

[aford22]

Are you able to reproduce the issue with a new project?

Well, unfortunately the "Razor Components" project template has disappeared from the latest VS Comm release... as have the Blazor project templates. This is a problem in itself.

However if I use the "ASP.Net Core Web Application" template then "Web Application" to create a new project, there are lots of files that then need changed to make them work with Razor Components. Like Startup, index, .csproj, etc. Its hacking the whole newly generated project so much that I am not sure what this proves...

What's your dotnet --info output?

.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview3-010431
 Commit:    d72abce213

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100-preview3-010431\

Host (useful for support):
  Version: 3.0.0-preview3-27503-5
  Commit:  3844df9537

.NET Core SDKs installed:
  2.1.500 [C:\Program Files\dotnet\sdk]
  2.1.502 [C:\Program Files\dotnet\sdk]
  2.1.503 [C:\Program Files\dotnet\sdk]
  2.1.504 [C:\Program Files\dotnet\sdk]
  2.1.505 [C:\Program Files\dotnet\sdk]
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.1.700-preview-009597 [C:\Program Files\dotnet\sdk]
  2.2.101 [C:\Program Files\dotnet\sdk]
  3.0.100-preview3-010431 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview3-19153-02 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview3-27503-5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview3-27504-2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Do you see your button tag in Counter.razor as purple?

No, its blue. See screenshot.

You can also see the false error red wavy line...

Would you mind pasting the contents of your .csproj

Surely:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>


  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.0.0-preview3-19153-02" />
  </ItemGroup>

</Project>

[henkmollema]

I'm having the same issue with SDK v3.0.100-preview3-010431 and VS 16.1 Preview 1. I can reproduce it by creating a new Razor Components project with dotnet new razorcomponents and opening it in Visual Studio. I receive errors such as:

CS0428	Cannot convert method group 'IncrementCount' to non-delegate type 'object'. Did you intend to invoke the method? C:\tmp\razorcomponents\Components\Pages\Counter.razor:7

Also the HTML tags don't get their correct colorization:

The csproj looks like this:

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
    <LangVersion>7.3</LangVersion>
    <_RazorComponentInclude>Components\**\*.cshtml</_RazorComponentInclude>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Components.Server" Version="3.0.0-preview3-19153-02" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.0.0-preview3-19153-02" />
  </ItemGroup>
</Project>

[mkArtakMSFT]

Thanks for contacting us folks.
We believe this is now fix in our nightly releases and will be released as part of the next preview release.

[GerritBergen]

@mkArtakMSFT Any idea when the release that fixes this will come out?

[henkmollema]

Updating to Preview 4 fixed this for me, using the same VS 16.1 Preview 1 version.

[GerritBergen]

@henkmollema oh I see. I'm having the same issue with VS 16.0.2 (public release) running core preview 4. Guess they fixed it in VS 16.1. I'll probably just deal with it until 16.1 goes public.