[release/9.0-rc1] Fix Type System Equivalence Checks

[github-actions]

Backport of #106498 to release/9.0-rc1

/cc @steveisok @ivdiazsa

Customer Impact

• Customer reported
• Found internally

A customer found a considerable slowdown in their WinForms App when enabling ReadyToRun, as described on issue #96242. Upon investigation, we found that certain methods that were supposed to be precompiled were getting ignored and being deferred to the JIT. This was caused by a new feature added in .NET 8 to add support for type equivalence checks under certain scenarios. However, these checks were interfering in use cases where they were not needed, like our customer's app in this case.

Regression

• Yes
• No

Pull Request: #87899

Testing

Crossgen2 threw an error only viewable through verbose output but did not crash. Tested the fix manually for multiple scenarios ensuring that said error was no longer present. The resulting R2R image also had a larger size, which confirms the method was successfully compiled, as opposed to before implementing the fix.

Risk

Low. This fix corrects an erroneous behavior that could go unnoticed. At worst, with the fix everything will look the same.

[carlossanlop]

Do we have Tactics approval on this @steveisok @ivdiazsa ?

[steveisok]

Do we have Tactics approval on this @steveisok @ivdiazsa ?

Yeah, but we haven't formed the request yet.

[carlossanlop]

Alright. Ping me when ready.

[carlossanlop]

From the Servicing chat, if you can fill out the template and add the servicing-consider label, this PR can be discussed in Tactics today.

[carlossanlop]

From Tactics: Let's retarget this PR to release/9.0.

Either that, or you can close this PR, and run the command again in the original PR but targeting the RC2 branch: /backport to release/9.0 (this would be my preferred option, less mess).

@steveisok @ivdiazsa

[ivdiazsa]

From Tactics: Let's retarget this PR to release/9.0.

Either that, or you can close this PR, and run the command again in the original PR but targeting the RC2 branch: /backport to release/9.0 (this would be my preferred option, less mess).

@steveisok @ivdiazsa

I also think making a new PR when the RC2 branch becomes available is the better option. Closing this PR and will be on the lookout for the RC2 branch. Thanks @carlossanlop.

[carlossanlop]

I also think making a new PR when the RC2 branch becomes available

The release/9.0 branch is currently the RC2 branch. Please send the backport now. There's no point on waiting after the snap, as it would delay the builds.