Fix Other Type Parameters than the First One not Being Read

src/main/java/net/fabricmc/loom/configuration/ifaceinject/InterfaceInjectionProcessor.java

@@ -242,7 +242,7 @@ public static List<InjectedInterface> fromMod(FabricModJson fabricModJson) {
 						name = ifaceInfo.substring(0, ifaceInfo.indexOf("<"));
 						generics = ifaceInfo.substring(ifaceInfo.indexOf("<"));
 
-						// First Generics Check, if there are generics, are them correctly written?
+						// First Generics Check, if there are generics, are they correctly written?
 						SignatureReader reader = new SignatureReader("Ljava/lang/Object" + generics + ";");
 						CheckSignatureAdapter checker = new CheckSignatureAdapter(CheckSignatureAdapter.CLASS_SIGNATURE, null);
 						reader.accept(checker);
@@ -313,6 +313,7 @@ public void visit(int version, int access, String name, String signature, String
 				// Second Generics Check, if there are passed generics, are all of them present in the target class?
 				GenericsChecker checker = new GenericsChecker(Constants.ASM_VERSION, injectedInterfaces);
 				reader.accept(checker);
+				checker.check();
 
 				var resultingSignature = new StringBuilder(signature);
 
@@ -345,7 +346,7 @@ public void visitInnerClass(final String name, final String outerName, final Str
 		@Override
 		public void visitEnd() {
 			// inject any necessary inner class entries
-			// this may produce technically incorrect bytecode cuz we don't know the actual access flags for inner class entries
+			// this may produce technically incorrect bytecode cuz we don't know the actual access flags for inner class entries,
 			// but it's hopefully enough to quiet some IDE errors
 			for (final InjectedInterface itf : injectedInterfaces) {
 				if (this.knownInnerClasses.contains(itf.ifaceName())) {
@@ -402,8 +403,8 @@ public void visitFormalTypeParameter(String name) {
 			super.visitFormalTypeParameter(name);
 		}
 
-		@Override
-		public void visitEnd() {
+		// Ensures that injected interfaces only use collected type parameters from the target class
+		public void check() {
 			for (InjectedInterface injectedInterface : this.injectedInterfaces) {
 				if (injectedInterface.generics() != null) {
 					SignatureReader reader = new SignatureReader("Ljava/lang/Object" + injectedInterface.generics() + ";");
@@ -416,8 +417,6 @@ public void visitEnd() {
 					reader.accept(confirm);
 				}
 			}
-
-			super.visitEnd();
 		}
 
 		public static class GenericsConfirm extends SignatureVisitor {

src/test/groovy/net/fabricmc/loom/test/unit/processor/InterfaceInjectionProcessorTest.groovy

@@ -24,6 +24,9 @@
 
 package net.fabricmc.loom.test.unit.processor
 
+import net.fabricmc.loom.test.unit.processor.classes.DoublePassingGenericInterface
+import net.fabricmc.loom.test.unit.processor.classes.DoublePassingGenericTargetClass
+
 import java.nio.file.Path
 import java.util.function.Consumer
 
@@ -137,6 +140,12 @@ class InterfaceInjectionProcessorTest extends Specification {
 			loadedClass.interfaces.first().name == "net/fabricmc/loom/test/unit/proessor/classes/SelfGenericInterface"
 			loadedClass.constructors.first().newInstance().selfGenericInjectedMethod() == null
 		}
+
+		// Class using double generics and passing them to the interface
+		"class_9" | "net/fabricmc/loom/test/unit/processor/classes/DoublePassingGenericInterface<TF;TS;>" | DoublePassingGenericTargetClass.class | { Class<?> loadedClass ->
+			loadedClass.interfaces.first().name == "net/fabricmc/loom/test/unit/processor/classes/DoublePassingGenericTargetClass"
+			loadedClass.constructors.first().newInstance().doublePassingGenericInjectedMethod().getClass() == DoublePassingGenericTargetClass.Pair.class
+		}
 	}
 
 	def "nothing to inject"() {
@@ -230,7 +239,10 @@ class InterfaceInjectionProcessorTest extends Specification {
 		FirstGenericInterface.class,
 		SecondGenericInterface.class,
 		SelfGenericTargetClass.class,
-		SelfGenericInterface.class
+		SelfGenericInterface.class,
+		DoublePassingGenericTargetClass.class,
+		DoublePassingGenericTargetClass.Pair.class,
+		DoublePassingGenericInterface.class
 	]
 
 	private static final String MAPPINGS = """
@@ -243,5 +255,7 @@ c\tclass_5\tnet/fabricmc/loom/test/unit/processor/classes/AdvancedGenericTargetC
 c\tclass_5\$class_6\tnet/fabricmc/loom/test/unit/processor/classes/AdvancedGenericTargetClass\$Pair
 c\tclass_7\tnet/fabricmc/loom/test/unit/processor/classes/DoubleGenericTargetClass
 c\tclass_8\tnet/fabricmc/loom/test/unit/processor/classes/SelfGenericTargetClass
+c\tclass_9\tnet/fabricmc/loom/test/unit/processor/classes/DoublePassingGenericTargetClass
+c\tclass_9\$class_10\tnet/fabricmc/loom/test/unit/processor/classes/DoublePassingGenericTargetClass\$Pair
 """.trim()
 }

src/test/java/net/fabricmc/loom/test/unit/processor/classes/DoublePassingGenericInterface.java

@@ -0,0 +1,7 @@
+package net.fabricmc.loom.test.unit.processor.classes;
+
+public interface DoublePassingGenericInterface<F, S> {
+	default DoublePassingGenericTargetClass.Pair<F, S> doublePassingGenericInjectedMethod() {
+		return new DoublePassingGenericTargetClass.Pair<>(null, null);
+	}
+}

src/test/java/net/fabricmc/loom/test/unit/processor/classes/DoublePassingGenericTargetClass.java

@@ -0,0 +1,8 @@
+package net.fabricmc.loom.test.unit.processor.classes;
+
+public class DoublePassingGenericTargetClass<F, S> {
+	public static class Pair<F, S> {
+		Pair(F ignoredF, S ignoredS) {
+		}
+	}
+}