ASP0023 Ambiguous route warning when targeting .NET 8 and using both [Http*] and [Route] attributes

[adammorr]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When targeting .NET 8 preview 1 and using both [Http*] and [Route("/my/path/template")] attributes on a controller method, an ASP0023 warning is emitted which is a new behaviour that wasn't observed in .NET 7.

If you ignore the warnings, the code will run and the endpoints can be called and return the expected responses for their respective verbs.

Expected Behavior

No warning generated if a controller method can use both [Http*] and [Route] attributes and can be used as expected

Steps To Reproduce

using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers();

var app = builder.Build();
app.MapControllers();
app.Run();

public class MyController : Controller
{
    [HttpGet]
    [Route("Person")]
    public IActionResult Get() => Ok("You GET me");
    
    [HttpPut]
    [Route("Person")]
    public IActionResult Put() => Ok("You PUT me");
}

Exceptions (if any)

No response

.NET Version

8.0.100-preview.1.23115.2

Anything else?

dotnet --info

.NET SDK:
 Version:   8.0.100-preview.1.23115.2
 Commit:    913e4679b3

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19045
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\8.0.100-preview.1.23115.2\

Host:
  Version:      8.0.0-preview.1.23110.8
  Architecture: x64
  Commit:       7deac7d6da

.NET SDKs installed:
  7.0.200 [C:\Program Files\dotnet\sdk]
  8.0.100-preview.1.23115.2 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.0-preview.1.23112.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.0-preview.1.23110.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.0-preview.1.23112.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[captainsafia]

When targeting .NET 8 preview 1 and using both [Http*] and [Route("/my/path/template")] attributes on a controller method, an ASP0023 warning is emitted which is a new behaviour that wasn't observed in .NET 7.

We introduced a new set of analyzers in this preview that might be causing this issue. It looks like the analyzers don't account for differing HTTP methods on actions that use the same route.

The analyzer does have a check to detect matching HTTP methods in a action controller (ref). We don't have test coverage for this though (ref) so there might be a bug here.

@JamesNK Hunches on what might be going on here?

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[JamesNK]

Thanks, some improvements are needed to the analyzer: #47106

This fix should be in .NET 8 preview 3.