java.lang.IllegalArgumentException: Key xxx:transition was used multiple times on kotlin 2.0.0-RC2 & r8

[qdsfdhvh]

demo: https://github.com/qdsfdhvh/voyager-crash-of-kotlin2

same crash with #410, but i am using kotlin 2.0.0-RC2 and open r8:

Like demo, my home is object HomeScreen, when i open a object DetailScreen, app will be crash this error, but fine with data object DetailScreen;

and if my home is data object HomeScreen, open object DetailScreen is fine, but then open another object XXXScreen, app also crash.

I'm still working on the exact reason for this as well, currently my workaround is replace all object XXScreen to data object XXScreen.

[qdsfdhvh]

I seem to have found the reason that Screen.key was optimised out, I added the following configuration and it solved it.

-keepclassmembers class * implements cafe.adriel.voyager.core.screen.Screen {
    public getKey();
}

Maybe add it to the library's consumer-rules.pro?

[qdsfdhvh]

I used diffuse to compare the differences between the apk's:

OLD: app-debug.apk (signature: V2)
NEW: app-debug-fix.apk (signature: V2)

          │           compressed           │         uncompressed         
          ├───────────┬───────────┬────────┼──────────┬──────────┬────────
 APK      │ old       │ new       │ diff   │ old      │ new      │ diff   
──────────┼───────────┼───────────┼────────┼──────────┼──────────┼────────
      dex │ 604.7 KiB │ 604.5 KiB │ -147 B │  1.2 MiB │  1.2 MiB │  +96 B 
     arsc │  74.3 KiB │  74.3 KiB │    0 B │ 74.2 KiB │ 74.2 KiB │    0 B 
 manifest │   1.8 KiB │   1.8 KiB │    0 B │  5.7 KiB │  5.7 KiB │    0 B 
      res │  36.8 KiB │  36.8 KiB │   -4 B │ 41.8 KiB │ 41.8 KiB │    0 B 
    asset │   3.3 KiB │   3.3 KiB │   +3 B │  3.1 KiB │  3.1 KiB │   +7 B 
    other │    22 KiB │    22 KiB │    0 B │ 32.1 KiB │ 32.1 KiB │    0 B 
──────────┼───────────┼───────────┼────────┼──────────┼──────────┼────────
    total │ 742.8 KiB │ 742.7 KiB │ -148 B │  1.4 MiB │  1.4 MiB │ +103 B 

 DEX     │ old  │ new  │ diff       
─────────┼──────┼──────┼────────────
   files │    1 │    1 │  0         
 strings │ 6692 │ 6693 │ +1 (+2 -1) 
   types │ 2294 │ 2295 │ +1 (+1 -0) 
 classes │ 1759 │ 1760 │ +1 (+1 -0) 
 methods │ 9706 │ 9708 │ +2 (+3 -1) 
  fields │ 5191 │ 5190 │ -1 (+2 -3) 

 ARSC    │ old │ new │ diff 
─────────┼─────┼─────┼──────
 configs │  97 │  97 │  0   
 entries │ 123 │ 123 │  0   

=================
====   APK   ====
=================

     compressed     │   uncompressed   │                                
───────────┬────────┼─────────┬────────┤                                
 size      │ diff   │ size    │ diff   │ path                           
───────────┼────────┼─────────┼────────┼────────────────────────────────
 604.5 KiB │ -147 B │ 1.2 MiB │  +96 B │ ∆ classes.dex                  
   2.8 KiB │   +6 B │ 2.7 KiB │   +6 B │ ∆ assets/dexopt/baseline.prof  
   7.7 KiB │   -4 B │ 7.6 KiB │    0 B │ ∆ res/-6.webp                  
     486 B │   -3 B │   354 B │   +1 B │ ∆ assets/dexopt/baseline.profm 
───────────┼────────┼─────────┼────────┼────────────────────────────────
 615.6 KiB │ -148 B │ 1.2 MiB │ +103 B │ (total)                        


=================
====   DEX   ====
=================

STRINGS:

   old  │ new  │ diff       
  ──────┼──────┼────────────
   6692 │ 6693 │ +1 (+2 -1) 
  
  + Le1/i;
  + ~~R8{"backend":"dex","compilation-mode":"release","has-checksums":false,"min-api":24,"pg-map-id":"79a64e1","r8-mode":"full","version":"8.4.22"}
  
  - ~~R8{"backend":"dex","compilation-mode":"release","has-checksums":false,"min-api":24,"pg-map-id":"cc45031","r8-mode":"full","version":"8.4.22"}
  

TYPES:

   old  │ new  │ diff       
  ──────┼──────┼────────────
   2294 │ 2295 │ +1 (+1 -0) 
  
  + Le1/i;
  

METHODS:

   old  │ new  │ diff       
  ──────┼──────┼────────────
   9706 │ 9708 │ +2 (+3 -1) 
  
  + e1.i <clinit>()
  + e1.i getKey() → String
  + e1.i j(n, int)
  
  - e1.h <init>(int)
  

FIELDS:

   old  │ new  │ diff       
  ──────┼──────┼────────────
   5191 │ 5190 │ -1 (+2 -3) 
  
  + e1.h g: h
  + e1.i g: i
  
  - e1.h g: int
  - e1.h h: h
  - e1.h i: h
  

seem it does possible to lose the Screen.key.

...
  + e1.i getKey() → String
...

mapping.txt

...
com.seiko.demo.voyager_crash_of_kotlin2.HomeScreen -> e1.i:
...

[DevSrSouza]

Thanks for the finding