[release/8.0] Fix ambiguous route analyzer false positive with switch

[JamesNK]

[release/8.0] Fix ambiguous route analyzer false positive with switch

The ambiguous route analyzer excludes comparing routes that are in different code paths because there is no way to know which code path is used at runtime.

The current logic doesn't correctly exclude routes in switch statements and expressions. The following will flag the two routes:

using System;
using Microsoft.AspNetCore.Builder;
var app = WebApplication.Create();
_ = Random.Shared.Next() switch
{
    0 => app.MapGet(""/"", () => Hello()),
    1 => app.MapGet(""/"", () => Hello()),
    _ => throw new Exception()
};
void Hello() { }

The fix separates routes in switch statements into different code paths for analysis.

Fixes #51285

Customer Impact

Without this fix, ASP.NET Core apps could get false positive warnings about duplicate routes.

Customers can workaround the bad warnings by disabling the analyzer.

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Fix is to an analyzer. No runtime impact.

Verification

• Manual (required)
• Automated

Before:

After:

Packaging changes reviewed?

• Yes
• No
• N/A

[ghost]

Hi @JamesNK. If this is not a tell-mode PR, please make sure to follow the instructions laid out in the servicing process document.
Otherwise, please add tell-mode label.

[ghost]

Hey @dotnet/aspnet-build, looks like this PR is something you want to take a look at.

[ghost]

Hi @JamesNK. Please make sure you've updated the PR description to use the Shiproom Template. Also, make sure this PR is not marked as a draft and is ready-to-merge.

To learn more about how to prepare a servicing PR click here.

[ghost]

Hi @JamesNK. This PR was just approved to be included in the upcoming servicing release. Somebody from the @dotnet/aspnet-build team will get it merged when the branches are open. Until then, please make sure all the CI checks pass and the PR is reviewed.

[JamesNK]

Email approval