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Bug Unity will fail to recognize script as MonoBehaviour under specific circumstances

Discussion in '2020.1 Beta' started by SugoiDev, Oct 6, 2019.

  1. SugoiDev

    SugoiDev

    Joined:
    Mar 27, 2013
    Posts:
    315
    Just got this today with 2020.1.0a7

    With a specifically crafted method, Unity will no longer be able to recognize a script as a MonoBehaviour.
    I was bitten by this issue because I have a large number of classes that have methods with this exact structure.

    A class with a method like this will break it:

    Code (CSharp):
    1.  
    2. namespace SomeAssembly {
    3.     using UnityEngine;
    4.     public sealed class MonoBehaviourThatBreaksTheParser: MonoBehaviour {
    5. #if UNITY_EDITOR
    6.         public void SomeMethod() {
    7.             //THIS LINE BREAKS THE PARSER WHEN WE ARE INSIDE #if UNITY_EDITOR BLOCKS
    8.             Utils.HelperMethod(() => $"{Utils.SomeMethodThatReturnsString()}");
    9.             //this line does the same as the above, but the parser will not break
    10.             //Utils.HelperMethod(() => string.Format("Some String: {0}", Utils.SomeMethodThatReturnsString()));
    11.         }
    12. #endif
    13.     }
    14. }
    15.  
    Those Util methods are just this
    Code (CSharp):
    1. namespace SomeAssembly {
    2.     using System;
    3.  
    4.     public static class Utils {
    5.  
    6.         public static string SomeMethodThatReturnsString() {
    7.             return "AA";
    8.         }
    9.  
    10.  
    11.         public static void HelperMethod(Func<string> s) { }
    12.  
    13.     }
    14. }
    15.  

    Any of the following changes makes the issue no longer trigger (it's very specific)

    * Replacing Utils.SomeMethodThatReturnsString() with anything that is not a parameterless method (that returns anything)
    * removing the #if UNITY_EDITOR block
    * using string.format instead of string concatenation ($)


    Anyone else got this? I just submitted a report (case #1189349) with a micro-project that reproduces the issue.

    A bit of extra info: It does not reproduce on a5
     
    Last edited: Oct 6, 2019
  2. Peter77

    Peter77

    QA Jesus

    Joined:
    Jun 12, 2013
    Posts:
    4,637
    Does it output any error message?
     
  3. SugoiDev

    SugoiDev

    Joined:
    Mar 27, 2013
    Posts:
    315
    None.
    I had a few other parser issues before and it's always silent.
    Nothing anywhere.

    I even bind to the actual console writer to see if there's any internal messages that aren't being output to log files, but it's completely silent.

    I had one longstanding with a specific #if usage that was because of a single space after a curly brace.
    It took so long for it to be solved that I just added a rule to my code analysis to break my formatting for that specific case.
    This one would be a bit more annoying to do that because of how involved it is.
     
  4. Ignas83

    Ignas83

    Unity Technologies

    Joined:
    Mar 26, 2013
    Posts:
    27
    There was a bug in interpolated string parser. It wasn't handling ( character immediately followed by ). The fix should be released in the next alpha or the one after that. Thanks for the report!
     
    SugoiDev likes this.
  5. Robert-Acksel

    Robert-Acksel

    Joined:
    Aug 7, 2012
    Posts:
    13
    Isn't unity using the Roslyn c# compiler nowadays?
     
  6. Ignas83

    Ignas83

    Unity Technologies

    Joined:
    Mar 26, 2013
    Posts:
    27
    Not for extracting class names and namespaces from cs files. This might change in the future.
     
  7. SugoiDev

    SugoiDev

    Joined:
    Mar 27, 2013
    Posts:
    315
    Still present in a8 today. I guess it didn't make the cut for a8.
     
  8. Ignas83

    Ignas83

    Unity Technologies

    Joined:
    Mar 26, 2013
    Posts:
    27
    Correct, it's in a9.
     
  9. SugoiDev

    SugoiDev

    Joined:
    Mar 27, 2013
    Posts:
    315
    I'm still seeing this in a9, but under a slightly different scenario. Still related to interpolated strings, though.
    Should I submit a new bug report or update the current one?


    The valid MonoBehaviour below breaks the parser.
    Removing the division (/) makes it work again.
    Removing the #if also makes it work again.
    Using string.Format instead of interpolation as well.


    Code (CSharp):
    1.  
    2. namespace SomeAssembly {
    3.     using UnityEngine;
    4.     public sealed class MonoBehaviourThatBreaksTheParser: MonoBehaviour {
    5. #if UNITY_EDITOR
    6.         public void SomeMethod() {
    7.             this.SomeMethod($"TOOK {100f / 1000f}s");
    8.         }
    9.         public void SomeMethod(
    10.             string message) {
    11.             //nothing
    12.         }
    13. #endif
    14.     }
    15. }
    16.  
    17.  
     
    Peter77 likes this.
  10. SugoiDev

    SugoiDev

    Joined:
    Mar 27, 2013
    Posts:
    315
    QA instructed me to create a new bug report for this one.
    Case is #1193024
     
    LeonhardP likes this.
  11. LeonhardP

    LeonhardP

    Unity Technologies

    Joined:
    Jul 4, 2016
    Posts:
    1,898
    SugoiDev likes this.
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