Mixin seems to be sending null descriptors to method remappers for some deobf cases

[liach]

See FabricMC/fabric-loader#397

MixinIntermediaryDevRemapper.mapMethodName doesn't seem to handle a null Mixin method target descriptor correctly when the owner class isn't mapped, causing a NullPointerException. See crash log: crash-2021-03-06_01.27.35-client.txt

This is triggered by the mixin @Redirect(method = "performBuild", at = @At(value = "INVOKE", target = "Lme/jellysquid/mods/sodium/client/render/pipeline/context/ChunkRenderContext;renderBlock"), remap = false) in https://github.com/comp500/Indium/blob/7e734bdc90357f132d7a038048e19020537179c7/src/main/java/link/infra/indium/mixin/sodium/MixinChunkRenderRebuildTask.java#L55

Relevant portion:

Caused by: java.lang.NullPointerException: Cannot invoke "String.hashCode()" because "this.desc" is null
	at net.fabricmc.mappings.EntryTriple.hashCode(EntryTriple.java:67)
	at java.base/java.util.HashMap.hash(HashMap.java:340)
	at java.base/java.util.HashMap.getOrDefault(HashMap.java:1144)
	at net.fabricmc.mapping.util.MixinRemapper.mapMethodName(MixinRemapper.java:66)
	at net.fabricmc.loader.util.mappings.MixinIntermediaryDevRemapper.mapMethodNameInner(MixinIntermediaryDevRemapper.java:74)
	at net.fabricmc.loader.util.mappings.MixinIntermediaryDevRemapper.mapMethodName(MixinIntermediaryDevRemapper.java:139)
	at org.spongepowered.asm.obfuscation.RemapperChain.mapMethodName(RemapperChain.java:59)
	at org.spongepowered.asm.mixin.refmap.RemappingReferenceMapper.remapWithContext(RemappingReferenceMapper.java:164)
	at org.spongepowered.asm.mixin.refmap.RemappingReferenceMapper.remap(RemappingReferenceMapper.java:121)
	at org.spongepowered.asm.mixin.injection.struct.MemberInfo.parse(MemberInfo.java:692)
	at org.spongepowered.asm.mixin.injection.selectors.TargetSelector.parse(TargetSelector.java:154)
	at org.spongepowered.asm.mixin.injection.selectors.TargetSelector.parseAndValidate(TargetSelector.java:109)
	at org.spongepowered.asm.mixin.injection.struct.InjectionPointData.getTarget(InjectionPointData.java:273)
	at org.spongepowered.asm.mixin.injection.points.BeforeInvoke.<init>(BeforeInvoke.java:126)

This should at least be documented in the javadoc.

[Chocohead]

It is a little ambiguous how lax targets can be, Mixin lets you do more combinations than it is able to remap correctly, but it's not obvious whether that's because remapping might not produce the correct results or because it's broken

[Wexalian]

So I just stumbled upon the same issue as comp500/Indium#127 and I was just wondering if there is any progress being made on this? It sucks not being able to use Sodium and Indium because my own mod relies on the Fabric Rendering API

[sfPlayer1]

At.target Javadoc:

must be specified as a fully-qualified member path including the class name and signature

So more a case of not rejecting the invalid target cleanly, the root cause is on the mod side though.