Doesn't resolve correct blazor component usings/imports

Issue Description

Steps to Reproduce

1. Create a new dotnet blazor server project (dotnet new blazorserver -o test)
2. Open the project in Visual Studio Code, with the C# extension installed
3. Open any file which uses components (such as Shared/MainLayout.razor) and the _Imports.razor file

(Note that this does not happen in Visual Studio 2019)

Expected Behavior

This extension doesn’t show any errors for the generated code

Actual Behavior

All components used in Blazor html markup and in C# @code sections (not present in the generated code) are highlighted in blue or red (info/error) because the extension fails to identify and resolve correct @using directives in the top-level _Imports.razor file

Update

I have disabled all extensions except for the OmniSharp C# one and it is still reporting every single component usage as an error.

Logs

OmniSharp log

OmniSharp log

Starting OmniSharp server at 29.5.2021, 21:14:17
    Target: c:\Users\user\Documents\test\test
OmniSharp server started.
Path: c:\Users\user.vscode\extensions\ms-dotnettools.csharp-1.23.12.omnisharp\1.37.10\OmniSharp.exe
PID: 11868
    Starting OmniSharp on Windows 6.2.9200.0 (x64)

    DotNetPath set to dotnet

    Located 2 MSBuild instance(s)
        1: Visual Studio Community 2019 16.9.31205.134 - "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin"
        2: StandAlone 16.11.0 - "c:\Users\user\.vscode\extensions\ms-dotnettools.csharp-1.23.12\.omnisharp\1.37.10\.msbuild\Current\Bin"

    Registered MSBuild instance: Visual Studio Community 2019 16.9.31205.134 - "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin"

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.CSharpFormattingWorkspaceOptionsProvider, Order: 0

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.Completion.CompletionOptionsProvider, Order: 0

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.RenameWorkspaceOptionsProvider, Order: 100

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.ImplementTypeWorkspaceOptionsProvider, Order: 110

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.BlockStructureWorkspaceOptionsProvider, Order: 140

    Detecting Cake files in 'c:\Users\user\Documents\test\test'.

    Could not find any Cake files

    No solution files found in 'c:\Users\user\Documents\test\test'

    Queue project update for 'c:\Users\user\Documents\test\test\test.csproj'

    Detecting CSX files in 'c:\Users\user\Documents\test\test'.

    Could not find any CSX files

    Configuration finished.

    Omnisharp server running using Stdio at location 'c:\Users\user\Documents\test\test' on host 7776.

    Loading project: c:\Users\user\Documents\test\test\test.csproj

    Successfully loaded project file 'c:\Users\user\Documents\test\test\test.csproj'.

    Adding project 'c:\Users\user\Documents\test\test\test.csproj'

    Update project: test

C# log

C# log

*empty log*

Environment information

VSCode version: 1.56.2 C# Extension: 1.23.12

Dotnet Information

.NET SDK: Version: 5.0.202 Commit: db7cc87d51

Runtime: OS Name: Windows OS Version: 10.0.19042 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\5.0.202\

Host (useful for support): Version: 5.0.5 Commit: 2f740adc14

.NET SDKs installed: 3.1.408 [C:\Program Files\dotnet\sdk] 5.0.202 [C:\Program Files\dotnet\sdk]

.NET runtimes installed: Microsoft.AspNetCore.All 2.1.27 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.27 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.1.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 5.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.27 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.1.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 5.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 3.1.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 5.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs: https://aka.ms/dotnet-download

Visual Studio Code Extensions

Extension	Author	Version
aspnetcorerazor-html-css-class-completion	kevin-chatham	1.0.3
auto-close-tag	formulahendry	0.5.10
auto-complete-tag	formulahendry	0.1.0
auto-rename-tag	formulahendry	0.1.6
auto-using	Fudge	0.7.15
autoimport	steoates	1.5.4
blazorwasm-companion	ms-dotnettools	1.1.0
bracket-pair-colorizer-2	CoenraadS	0.2.0
browserslist	webben	1.1.0
code-spell-checker	streetsidesoftware	1.10.2
codespaces	GitHub	0.10.4
comment-ts	salbert	1.0.21
csharp	ms-dotnettools	1.23.12
csharp-colors	logerfo	0.1.8
cshtml	fireside21	0.1.3
debugger-for-chrome	msjsdiag	4.12.12
docfx-assistant	tintoy	0.1.5
docomment	k–kato	0.1.20
dotenv	mikestead	1.0.1
easyzoom	NabeelValley	0.1.0
EditorConfig	EditorConfig	0.16.4
fluent-icons	miguelsolorio	0.0.11
format-selection-as-html	adrianwilczynski	2.3.0
git-graph	mhutchie	1.30.0
github-markdown-preview	bierner	0.0.2
github-vscode-theme	GitHub	4.1.1
gitignore	codezombiech	0.7.0
gitlens	eamodio	11.4.1
headwind	heybourn	1.7.0
html-css-class-completion	Zignd	1.20.0
html-slim-scss-css-class-completion	gencer	1.7.8
JSDocTagComplete	HookyQR	0.0.2
markdown-checkbox	bierner	0.1.3
markdown-emoji	bierner	0.1.0
markdown-preview-github-styles	bierner	0.2.0
markdown-yaml-preamble	bierner	0.0.4
material-icon-theme	PKief	4.7.0
material-product-icons	PKief	1.0.4
material-theme	zhuangtongfa	3.10.14
npm-intellisense	christian-kohler	1.3.1
postcss	csstools	1.0.9
prettier-vscode	esbenp	6.4.0
quokka-vscode	WallabyJs	1.0.369
razor-plus	austincummings	0.1.4
remote-containers	ms-vscode-remote	0.177.2
remote-wsl	ms-vscode-remote	0.56.3
svelte-autoimport	pivaszbs	1.0.4
svelte-extractor	proverbialninja	0.0.3
svelte-intellisense	ardenivanov	0.7.1
svelte-vscode	svelte	105.0.0
tailwind-docs	austenc	1.4.0
tailwind-sass-syntax	macieklad	1.3.0
theme-dracula	dracula-theme	2.22.3
vscode-docker	ms-azuretools	1.13.0
vscode-dotnet-runtime	ms-dotnettools	1.1.0
vscode-eslint	dbaeumer	2.1.20
vscode-firefox-debug	firefox-devtools	2.9.4
vscode-html-css	ecmel	1.10.2
vscode-html-scss	P-de-Jong	0.0.42
vscode-language-babel	mgmcdermott	0.0.31
vscode-npm-script	eg2	0.3.21
vscode-pull-request-github	GitHub	0.26.0
vscode-sqlite	alexcvzz	0.12.0
vscode-stylelint	stylelint	0.86.0
vscode-tailwindcss	bradlc	0.6.6
vscode-versionlens	pflannery	1.0.9
vscode-yaml	redhat	0.19.2
vscodeintellicode	VisualStudioExptTeam	1.2.14
zoombar-vscode	wraith13	1.4.0

[deanchalk]

Hi All, had the same issue. I found a work-around in VS Code by downgrading the C# extension from the current version 1.23.12 to 1.23.11. You can do this in the the extensions panel by clicking on the config button for the C# extension and click ‘Install another version’, then select the previous version. Version 1.23.12 was released about 12 days ago, and obviously has broken razor intellisense

[Xeevis]

Oddly enough downgrading to 1.23.11 fixed the issue, but then I upgraded back to 1.23.12 and it keeps working. 😵