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Won't Fix

Fixed in 2020.3.X, 2021.1.X

Votes

1

Found in

2018.4

2019.3.4f1

2020.2

Issue ID

1254522

Regression

No

[IL2CPP] Incorrect results when calling a method from outside Class in a Struct

IL2CPP

-

How to reproduce:
1. Open the attached "MutableStructRepro.zip" Project
2. Make sure the "IL2CPP" is selected in the Project Settings
3. Build and Run the Project
4. Press the only button in the scene

Expected Behavior: Label shows "567" value
Actual Behavior: Label shows "456" value

Reproducible with: 2018.4.24f1, 2019.4.2f1, 2020.1.0b14, 2020.2.0a14

Note: The code is in "NewBahaviorScript.cs". It seems that the code in the 88th line is not executed.

  1. Response avatar

    Resolution Note (2020.2.X):

    Thank you for your bug report. We have reproduced your issue and have confirmed that in the conditions:

    1. A generic class A<T>
    2. A generic mutable struct B<T>
    3. A<T> calls a method on B<T>
    4. The call to B<T> makes a call to code that accesses the B<T> instance from its original location.
    5. That call makes a update a property to B<T>

    The update make step 5 are lost.

    Unfortunately correcting this issue will take some time to fix as it will require changes that will affect all generic method calls. This has been added to our internal issues list and will do plan on fixing it, but I cannot give you a timeframe for that fix will be available.

    Please let us know if you need any assistance with a work around. But changing any of the conditions above would do so. For example if the mutable struct B<T> is not generic then the issue does not occur or if any changes to B<T> in step 4 are made directly using the this pointer then the issue will not occur.

  2. Response avatar

    Resolution Note (fix version 2021.1):

    Fixed in 2021.1.24f1

Comments (2)

  1. 33aa6b963156bf667e514c807a5d4e9f?d=mm

    neuecc

    Sep 27, 2020 16:01

    Currently, UniTask needs a workaround for this problem.

    https://github.com/Cysharp/UniTask/blob/master/src/UniTask/Assets/Plugins/UniTask/Runtime/CompilerServices/StateMachineRunner.cs

    This is not desirable as it is accompanied by an extra steps.

  2. D7940162f34a7b9172c8f321e00faca9?d=mm

    tim_lol

    Sep 26, 2020 09:06

    A fix for this would be very helpful for async method builders. As it is, I have to `#if ENABLE_IL2CPP` to rewrite my entire builders for less efficient versions, just so it will work.

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