Fixes MixinIntermediaryDevRemapper.mapMethodName unable to map ambiguous values

[ishland]

This PR fixes this mixin from lithium unable to be applied cleanly in 1.19.3 devlaunch using 1.19.3+build.2 yarn mappings.

[modmuss50]

LGTM 👍

[sfPlayer1]

brings it in line with the field remapping code, not 100% sure but plausible

[modmuss50]

I was unable to reproduce this 🤔 I think the change is still OK, but I wanted to double check.

I downloaded the latest version of lithium for 1.19.3 and was able to to run in dev without issue?. The refmap contains the full desc for the method you pointed out

"stopAllTasks": "Lnet/minecraft/class_4095;method_18900(Lnet/minecraft/class_3218;Lnet/minecraft/class_1309;)V",

I am unsure how you were able to get into this state? A way to reproduce this and/or a crash log would be useful.

[ishland]

I can reliably reproduce this using this commit of fabric-example-mod (the current version at this point).

Steps to reproduce:

• Download the current lithium release into run/mods
• ./gradlew runClient
• Go into a singleplayer and run /summon villager
• Crashes

Note: it may involve another mixin crashing, this patch for lithium fixes that.

Some analysis copied from caffeine discord lithium dev channel:

im pretty sure this is a loader bug and/or a yarn bug
this is how mixin handles devlaunch environment

1. mixin parses the target and remaps it into intermediary using the refmap provided (success)
   (Lnet/minecraft/entity/ai/brain/task/Task;stop(Lnet/minecraft/server/world/ServerWorld;Lnet/minecraft/entity/LivingEntity;J)V -> Lnet/minecraft/class_7893;method_18925(Lnet/minecraft/class_3218;Lnet/minecraft/class_1309;J)V)
2. mixin tries to remap the intermediary name into the current devlaunch mapped name (failed)

the issue is remapping method names:

fabric-loader/src/main/java/net/fabricmc/loader/impl/util/mappings/MixinIntermediaryDevRemapper.java

Line 103 in 354af34

public String mapMethodName(String owner, String name, String desc) {

according to the debugger this method is for remapping intermediary name to the current devlaunch mapped name

• it attempts to look up in the lookup table but for some reasons the mapping for Lnet/minecraft/class_7893;method_18925(Lnet/minecraft/class_3218;Lnet/minecraft/class_1309;J)V is marked as <ambiguous> (possible mapping bug)
• then it falls back to "querying with additional owner and/or desc info"
• but for some reasons it is trying to use intermediary name to look for classes in a yarn environment (line 141), which will definitely find nothing
• then the remapper thinks the mapping just doesnt exist and gives up checking mappings (line 144)

class names and method descriptors are then remapped successfully
after combining all of them it results in Lnet/minecraft/entity/ai/brain/task/Task;method_18925(Lnet/minecraft/server/world/ServerWorld;Lnet/minecraft/entity/LivingEntity;J)V which is just not valid at all

then mixin just tries to look for methods with this wrong target descriptor and fails

[modmuss50]

Thanks for getting back quickly I was able to reproduce it 👍

This fix works and intented, many thanks.