Nullable dereference in collection expressions not raising any warning at build time #45643
Open
Description
Describe the bug
"CS8602 - Dereference of a possibly null reference" isn't raised at build time (with dotnet build) when the error is in a collection expression.
To Reproduce
List<string>? a = null;
string[]? c = [.. a];In VS Code (with C# extension) I can see a yellow squiggly line under a at line 2, but when running dotnet build, there's no warning raised.
When <WarningsAsErrors>nullable</WarningsAsErrors> is set on the project, the build should fail, but doesn't.
Further technical details
dotnet --info output:
.NET SDK:
Version: 8.0.404
Commit: 7b190310f2
Workload version: 8.0.400-manifests.b1234fe1
MSBuild version: 17.11.9+a69bbaaf5
Runtime Environment:
OS Name: Windows
OS Version: 10.0.19045
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\8.0.404\
.NET workloads installed:
Configured to use loose manifests when installing new manifests.
There are no installed workloads to display.
Host:
Version: 9.0.0
Architecture: x64
Commit: 9d5a6a9aa4
.NET SDKs installed:
8.0.404 [C:\Program Files\dotnet\sdk]
9.0.101 [C:\Program Files\dotnet\sdk]
.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.33 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 8.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Other architectures found:
None
Environment variables:
Not set
global.json file:
C:\Users\cbao\Downloads\cstest\hello\global.json
Learn more:
https://aka.ms/dotnet/info
Download .NET:
https://aka.ms/dotnet/download
IDE: VS Code with C# extension (no C# Dev Kit)