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Planned for 2019.4, 2020.1



Found in



Issue ID




[SerializedField] fields produce "Field is never assigned to..." warning



1. Open the attached project (
2. Observe the warning in the console

Expected: field with SerializeField attribute do not produce the warning

Reproduced in 2018.3.0a1, 2018.3.0b1, 2018.3.0b2, 2019.1.0a1
Did not reproduce in 2018.2.8f1
Regression introduced in 2018.3.0a1

  1. Response avatar


    Nov 06, 2019

    #pragma warning disable 0649
    // your code
    #pragma warning restore 0649

    Or disable it globally by adding a file named csc.rsp to the root of you Assets folder, e.g. Assets/csc.rsp, with the following contents without quotes.


    This will tell the C# compiler to not emit a warning for CS0649 / unused fields.

    If you have .asmdefs with csc.rsp in your project, then you also need to add the "/nowarn:0649" line to those csc.rsp files.

Comments (77)

  1. 03b5422b519c51eb98f03f25678712d8?d=mm


    Mar 05, 2019 18:27

    So Unity's just going to wait for the compiler to fix it? Pretty disappointing considering JetBrains fixed this problem in Rider a long time ago.

  2. D9105352c7a09434ff8fb69b76eb1ad9?d=mm


    Feb 20, 2019 08:41

    Why has this not been fixed yet?

  3. D998d5758d57fa06af2b545cf804fca0?d=mm


    Feb 14, 2019 22:23

    This is fixed for .Net 3.5, but is not fixed for .Net 4.X

  4. F9440774552a4e4217bc66136867b935?d=mm


    Feb 09, 2019 13:51

    Labelling this as "by design" is, frankly, absurd. It actively opposes the purpose of warnings. In this case a warning is issued when the programmer uses good practice, thus discouraging it. Warnings are designed specifically to discourage bad practices.

  5. 42b11a402b6a4c0e2afc8a73172580f9?d=mm


    Feb 01, 2019 06:40

    Boo bad design. Not sure why this could slip through. I guess we want newer Roslyn and this is what we get. Honestly this is a long standing issue that Unity should address in an alternative way. On compile complete if warning cs0649 is field SerializedField... yes? Don't show the stinking warning! Why rely and wait on Roslyn to get fixed? You have control over what is displayed in the console.

  6. 32a15ee3ebf22c352625bb838c7a8b2a?d=mm


    Jan 25, 2019 23:30

    If this is by design, then your design is terrible and you should be ashamed of it.

  7. C35b9264646fd1b72f6ccfca2622c409?d=mm


    Jan 24, 2019 17:01

    I wish to vote for this issue or at least a C# video tutorial in the learning section explaining how to declare my variables now!

  8. 15ff0e0aad9c52ef49fd13d7312e2219?d=mm


    Jan 19, 2019 11:00

    i agree. if this is by design, then the design should be fixed. because the current design either forces you to make everything public which violates the most basic OOP principles, or just live with warnings and hope that you don't miss any actual useful warning within the spam of useless ones. disabling them in every file that has serialized fields is ridiculous.

    this is definitely a design flaw and should be fixed. i just hope someone notices this within a resolved issue...

  9. E440a070914148a6bc803878c27fdcad?d=mm


    Jan 01, 2019 12:42

    If this is by design, then the design has a bug, where do we submit reports for that?

  10. 022c156d76ef8c3212a324c252fa9fbe?d=mm


    Dec 19, 2018 17:41

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