Mapping format ProGuard not working correctly

[derklaro]

I've written some code to decompile a minecraft client jar file using the official provided mojang mappings (at the time of writing it's client + client mapping 24w07a):

    var enigma = Enigma.create();
    var project = enigma.openJar(this.inputJarFile, new ClasspathClassProvider(), PROGRESS_LISTENER);

    var idx = project.getJarIndex();
    var saveParameters = enigma.getProfile().getMappingSaveParameters();
    var mappingTree = MappingFormat.PROGUARD.read(this.mappingsPath, PROGRESS_LISTENER, saveParameters, idx);
    project.setMappings(mappingTree);

    var jarExport = project.exportRemappedJar(PROGRESS_LISTENER);
    jarExport.write(outputPath, PROGRESS_LISTENER);

The exported jar from this method still has all classes obfuscated (same outcome with the Swing version):

However, when disabling the usage of mapping-io with System.setProperty("enigma.use_mappingio", "false") (or using the Proguard (Legacy) option in the Swing version), the code is deobfuscated correctly:

[NebelNidas]

Hmm, that's due to a disparity between the old reader and Mapping-IO's. The actual mapping file is mojmap -> obfuscated:

net.minecraft.BlockUtil -> l:

Mapping-IO parses this as-is, but since the JAR file's names are obfuscated, nothing gets applied. Enigma's old reader only works because it always inverts the mappings for whatever reason, which is contrary to what you'd expect IMO.

@modmuss50 Should we make the new MIO reader behave like the existing Enigma reader or remove this behavior from the latter? I'd prefer not to auto-invert without prompting the user first.