Blazor Web App template - bug in ChangePassword.razor

[Andrzej-W]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Create a new Blazor Web App with authentication enabled in dotnet 10.0.0-preview.7.25380.108. Open Components\Account\Pages\Manage\ChangePassword.razor file. Line 9 in this file should be removed.

The interesting thing is that we can compile and run a program with such an error and it works correctly.

Expected Behavior

No response

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

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Anything else?

No response

[javiercn]

@ilonatommy can you take a quick look at this?

[ilonatommy]

That's true, this line got added by mistake in #61633, is in the template code and should be removed. The intention was to use IdentityRedirectManager.

Thank you, @Andrzej-W for spotting it.

[Andrzej-W]

Should we have another issue for bug in the compiler? Why can we compile this program without any errors?

[ilonatommy]

I found external docs from net5 confirming that this behavior was present in Razor files for some releases already:
https://jakeydocs.readthedocs.io/en/latest/mvc/views/layout.html

@inject: for each property, the closest one to the view overrides any others with the same property name

This code skips duplicated @inject properties:
https://github.com/dotnet/razor/blob/c150d2096536ce3e0fb5b1007d4e39663f22bcaa/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Mvc/InjectDirective.cs#L81

We don't have it documented, though. I think it makes sense to make an issue in https://github.com/dotnet/razor and ask if it is by design and if so, document it or to change that code to something like:

if (hasMemberName && !properties.Add(memberName))
{
    // Emit a diagnostic error here
    var diagnostic = RazorDiagnostic.Create(
        new RazorDiagnosticDescriptor(
            "RZ9999",
            () => $"Duplicate @inject property name '{memberName}'.",
            RazorDiagnosticSeverity.Error),
        memberSpan ?? directive.Source?.GetZeroWidthEndSpan());

    codeDocument.Diagnostics.Add(diagnostic);

    continue; // Optionally, or break out depending on behavior desired
}