Inner class mappings are broken on pre-1.8 versions

[makamys]

On 1.7.10 (and I assume any previous versions), inner classes use intermediary names despite there existing yarn mappings for them. This is ostensibly because the tooling assumes official inner class names start with <parent_name>$, which is only true starting from 1.8.

Example (1.7.10)

class_1253$class_1254 is mapped as MineshaftPieces$MineshaftCorridor...

yarn/mappings/net/minecraft/structure/MineshaftPieces.mapping

Line 21 in 297efef

CLASS class_1254 MineshaftCorridor

But in minecraft-merged-named.jar after importing the example mod, the intermediary name is used, and the class is not an inner class:

StructurePieceManager.registerPiece(class_1254.class, "MSCorridor");

Examining mappings.tiny in the Gradle cache (~/.gradle/caches/fabric-loom/1.7.10/net.legacyfabric.yarn.1_7_10.1.7.10+build.458-v2/mappings.tiny), we can see the following weirdness:

c	asy	net/minecraft/class_1254	net/minecraft/structure/class_1254

The class is missing the yarn name. And later in the file, the class appears again, this time with the intermediary name where the official name should be:

c	net/minecraft/class_1253$class_1254	net/minecraft/class_1253$class_1254	net/minecraft/structure/MineshaftPieces$MineshaftCorridor

The class is also treated like a non-inner class in the intermediary mapping:

CLASS	asy	net/minecraft/class_1254

Example (1.8.9)

Let's compare this with 1.8.9, which works correctly.

        StructurePieceManager.registerPiece(MineshaftCorridor.class, "MSCorridor");

In mappings.tiny, there is only a single class containing class_1254 in its name:

c	aqg$a	net/minecraft/class_1253$class_1254	net/minecraft/structure/MineshaftPieces$MineshaftCorridor

We can see that its official name contains the parent class's name before a $ character. This is aqg for reference:

c	aqg	net/minecraft/class_1253	net/minecraft/structure/MineshaftPieces

Intermediary also correctly shows the class as an inner class:

CLASS	aqg$a	net/minecraft/class_1253$class_1254

Fixing it

Fixing this will possibly require changes in Enigma, since it ignores what comes before $ in yarn names, and establishes the parent class relationship by checking the name that comes before the $ in the official name (which, in 1.7.10's case, does not exist). I wasn't able to fix the issue by manually changing the intermediary mapping to CLASS asy net/minecraft/class_1253$class_1254 for this reason.

[thecatcore]

It's because before 1.8.2, Mojang was stripping inner class info from the inner classes so for those versions they appear as independent classes with weird synthetic fields.

[thecatcore]

We may use Ornithe Nests in the future to fix this problem.