RequestDelegateGenerator fails to detect route pattern that uses a constant for its value

[martincostello]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

If a Map*() method references a constant for the route pattern, an RDG001 error is emitted for the endpoint and no code is generated.

Unable to statically resolve route pattern for endpoint. Compile-time endpoint generation will skip this endpoint and the endpoint will be generated at runtime. For more information, please see https://aka.ms/aot-known-issues	

I checked the known issues and this specific problem doesn't appear to be listed.

For example, this code references constants for the paths so that they can be reused with configuring OAuth:

private const string DeniedPath = "/denied";
private const string SignInPath = "/sign-in";
private const string SignOutPath = "/sign-out";

public static IEndpointRouteBuilder MapAuthenticationRoutes(this IEndpointRouteBuilder builder)
{
    builder.MapGet(DeniedPath, () => Results.Redirect(RootPath + "?denied=true"))
           .ExcludeFromDescription();

    builder.MapGet(SignOutPath, () => Results.Redirect(RootPath))
           .ExcludeFromDescription();

    builder.MapPost(SignInPath, () => Results.Challenge(new() { RedirectUri = RootPath }, new[] { GitHubAuthenticationDefaults.AuthenticationScheme }))
           .ExcludeFromDescription();

    builder.MapPost(SignOutPath, () => Results.SignOut(new() { RedirectUri = RootPath }, new[] { CookieAuthenticationDefaults.AuthenticationScheme }))
           .ExcludeFromDescription()
           .RequireAuthorization();

    return builder;
}

Expected Behavior

The source generator acquires the static value of the constant to obtain the route template.

Steps To Reproduce

1. Clone martincostello/dotnet-minimal-api-integration-testing@774c5a4
2. Add the following to src/TodoApp/TodoApp.csproj: <EnableRequestDelegateGenerator>true</EnableRequestDelegateGenerator>
3. Build the TodoApp project

Exceptions (if any)

No response

.NET Version

8.0.100-preview.4.23260.5

Anything else?

No response

[captainsafia]

@martincostello Thanks for trying out the RDG and reporting this issue!

Yes, at the moment, we don't support resolving non-literal parameter values. I think we may be able to get rid of the check for the static route handler all-together since we only use it for capturing the MapFallback pattern and we don't do any static analysis on the actual route pattern itself...

[captainsafia]

PR open at #48320

[captainsafia]

@martincostello I've just merged a PR for this for release into preview5.

I'd love for you to try the RequestDelegateGenerator in any other projects you have and report bugs 🙇🏽

[martincostello]

Sure - I'll try it out in some more next week. That was the (unlucky?) first one 😄