Support method arg name remapping in @ModifyVariable

src/main/java/net/fabricmc/tinyremapper/LocalInstance.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2016, 2018, Player, asie
+ * Copyright (c) 2026, FabricMC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.fabricmc.tinyremapper;
+
+import net.fabricmc.tinyremapper.api.TrLocal;
+import net.fabricmc.tinyremapper.api.TrMethod;
+
+public class LocalInstance implements TrLocal {
+	public LocalInstance(TrMethod owner, String name, String desc, int index) {
+		this.owner = owner;
+		this.name = name;
+		this.desc = desc;
+		this.index = index;
+	}
+
+	@Override
+	public String getName() {
+		return this.name;
+	}
+
+	@Override
+	public String getDesc() {
+		return this.desc;
+	}
+
+	@Override
+	public int getIndex() {
+		return this.index;
+	}
+
+	@Override
+	public TrMethod getOwner() {
+		return this.owner;
+	}
+
+	final TrMethod owner;
+	final String name;
+	final String desc;
+	final int index;
+}

src/main/java/net/fabricmc/tinyremapper/MemberInstance.java

@@ -25,6 +25,7 @@
 import net.fabricmc.tinyremapper.TinyRemapper.MrjState;
 import net.fabricmc.tinyremapper.api.TrClass;
 import net.fabricmc.tinyremapper.api.TrField;
+import net.fabricmc.tinyremapper.api.TrLocal;
 import net.fabricmc.tinyremapper.api.TrMember;
 import net.fabricmc.tinyremapper.api.TrMethod;
 
@@ -68,6 +69,11 @@ public int getIndex() {
 		return index;
 	}
 
+	@Override
+	public TrLocal[] getLocals() {
+		return this.locals.clone();
+	}
+
 	public MrjState getContext() {
 		return cls.getContext();
 	}
@@ -113,6 +119,10 @@ public void forceSetNewName(String name) {
 		newName = name;
 	}
 
+	public void setLocals(TrLocal[] locals) {
+		this.locals = locals.clone();
+	}
+
 	@Override
 	public String toString() {
 		return String.format("%s/%s%s", cls.getName(), name, desc);
@@ -151,6 +161,7 @@ public static String getNameFromId(TrMember.MemberType type, String id, boolean
 	final String desc;
 	final int access;
 	final int index;
+	TrLocal[] locals;
 	private volatile String newName;
 	private volatile String newBridgedName;
 	String newNameOriginatingCls;

src/main/java/net/fabricmc/tinyremapper/TinyRemapper.java

@@ -57,6 +57,7 @@
 import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.FieldVisitor;
+import org.objectweb.asm.Label;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.RecordComponentVisitor;
@@ -67,9 +68,11 @@
 import net.fabricmc.tinyremapper.IMappingProvider.Member;
 import net.fabricmc.tinyremapper.api.TrClass;
 import net.fabricmc.tinyremapper.api.TrEnvironment;
+import net.fabricmc.tinyremapper.api.TrLocal;
 import net.fabricmc.tinyremapper.api.TrLogger;
 import net.fabricmc.tinyremapper.api.TrMember;
 import net.fabricmc.tinyremapper.api.TrMember.MemberType;
+import net.fabricmc.tinyremapper.extension.mixin.common.data.Constant;
 
 public class TinyRemapper {
 	public static class Builder {
@@ -643,10 +646,25 @@ public void visit(int version, int access, String name, String signature, String
 
 			@Override
 			public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
-				MemberInstance prev = ret.addMember(new MemberInstance(TrMember.MemberType.METHOD, ret, name, desc, access, ret.getMembers().size()));
+				MemberInstance member = new MemberInstance(MemberType.METHOD, ret, name, desc, access, ret.getMembers().size());
+				MemberInstance prev = ret.addMember(member);
 				if (prev != null) throw new RuntimeException(String.format("duplicate method %s/%s%s in inputs", ret.getName(), name, desc));
 
-				return super.visitMethod(access, name, desc, signature, exceptions);
+				return new MethodVisitor(Constant.ASM_VERSION, super.visitMethod(access, name, desc, signature, exceptions)) {
+					final List<TrLocal> locals = new ArrayList<>();
+
+					@Override
+					public void visitLocalVariable(String name, String descriptor, String signature, Label start, Label end, int index) {
+						this.locals.add(new LocalInstance(member, name, descriptor, index));
+						super.visitLocalVariable(name, descriptor, signature, start, end, index);
+					}
+
+					@Override
+					public void visitEnd() {
+						member.setLocals(locals.toArray(new TrLocal[0]));
+						super.visitEnd();
+					}
+				};
 			}
 
 			@Override
@@ -662,7 +680,7 @@ public FieldVisitor visitField(int access, String name, String desc, String sign
 			cv = analyzeVisitors.get(i).insertAnalyzeVisitor(isInput, mrjVersion, name, cv, tags);
 		}
 
-		reader.accept(cv, ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES | ClassReader.SKIP_CODE);
+		reader.accept(cv, ClassReader.SKIP_FRAMES);
 
 		return ret;
 	}

src/main/java/net/fabricmc/tinyremapper/api/TrLocal.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2016, 2018, Player, asie
+ * Copyright (c) 2026, FabricMC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.fabricmc.tinyremapper.api;
+
+public interface TrLocal {
+	String getName();
+	String getDesc();
+	int getIndex();
+	TrMethod getOwner();
+}

src/main/java/net/fabricmc/tinyremapper/api/TrMethod.java

@@ -48,4 +48,6 @@ default boolean isAbstract() {
 	default boolean isVirtual() {
 		return getType().equals(MemberType.METHOD) && (getAccess() & (Opcodes.ACC_STATIC | Opcodes.ACC_PRIVATE)) == 0;
 	}
+
+	TrLocal[] getLocals();
 }

src/main/java/net/fabricmc/tinyremapper/extension/mixin/common/data/AnnotationElement.java

@@ -34,6 +34,7 @@ public final class AnnotationElement {
 	public static final String TO = "to";
 	public static final String SLICE = "slice";
 	public static final String METHOD = "method";
+	public static final String NAME = "name";
 	public static final String DEFINITION_METHOD = "method";
 	public static final String DEFINITION_FIELD = "field";
 }

src/main/java/net/fabricmc/tinyremapper/extension/mixin/soft/annotation/injection/CommonInjectionAnnotationVisitor.java

@@ -46,8 +46,8 @@
  * method with the first occurrence in ASM will be remapped.
  */
 class CommonInjectionAnnotationVisitor extends AnnotationVisitor {
-	private final CommonData data;
-	private final List<String> targets;
+	protected final CommonData data;
+	protected final List<String> targets;
 
 	CommonInjectionAnnotationVisitor(CommonData data, AnnotationVisitor delegate, List<String> targets) {
 		super(Constant.ASM_VERSION, Objects.requireNonNull(delegate));

src/main/java/net/fabricmc/tinyremapper/extension/mixin/soft/annotation/injection/ModifyVariableAnnotationVisitor.java

@@ -18,14 +18,151 @@
 
 package net.fabricmc.tinyremapper.extension.mixin.soft.annotation.injection;
 
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.stream.Collectors;
 
 import org.objectweb.asm.AnnotationVisitor;
+import org.objectweb.asm.tree.AnnotationNode;
 
+import net.fabricmc.tinyremapper.api.TrClass;
+import net.fabricmc.tinyremapper.api.TrLocal;
+import net.fabricmc.tinyremapper.api.TrMethod;
+import net.fabricmc.tinyremapper.extension.mixin.common.ResolveUtility;
+import net.fabricmc.tinyremapper.extension.mixin.common.data.Annotation;
+import net.fabricmc.tinyremapper.extension.mixin.common.data.AnnotationElement;
 import net.fabricmc.tinyremapper.extension.mixin.common.data.CommonData;
+import net.fabricmc.tinyremapper.extension.mixin.common.data.Constant;
+import net.fabricmc.tinyremapper.extension.mixin.common.data.Message;
+import net.fabricmc.tinyremapper.extension.mixin.soft.data.MemberInfo;
+
+public class ModifyVariableAnnotationVisitor extends AnnotationNode {
+	private final CommonData data;
+	private final AnnotationVisitor delegate;
+	private final List<String> targets;
+
+	private final List<MemberInfo> methods = new ArrayList<>();
 
-public class ModifyVariableAnnotationVisitor extends CommonInjectionAnnotationVisitor {
 	public ModifyVariableAnnotationVisitor(CommonData data, AnnotationVisitor delegate, List<String> targets) {
-		super(data, delegate, targets);
+		super(Constant.ASM_VERSION, Annotation.MODIFY_VARIABLE);
+		this.data = Objects.requireNonNull(data);
+		this.delegate = Objects.requireNonNull(delegate);
+		this.targets = Objects.requireNonNull(targets);
+	}
+
+	@Override
+	public AnnotationVisitor visitArray(String name) {
+		AnnotationVisitor av = super.visitArray(name);
+
+		if (name.equals(AnnotationElement.METHOD)) {
+			return new AnnotationVisitor(Constant.ASM_VERSION, av) {
+				@Override
+				public void visit(String name, Object value) {
+					MemberInfo info = MemberInfo.parse(Objects.requireNonNull((String) value).replaceAll("\\s", ""));
+
+					if (info != null && (info.getOwner().isEmpty() || ModifyVariableAnnotationVisitor.this.targets.contains(info.getOwner()))) {
+						ModifyVariableAnnotationVisitor.this.methods.add(info);
+					}
+
+					super.visit(name, value);
+				}
+			};
+		}
+
+		return av;
+	}
+
+	@Override
+	public void visitEnd() {
+		this.accept(new ModifyVariableSecondPassAnnotationVisitor(this.data, this.delegate, this.targets, this.methods));
+
+		super.visitEnd();
+	}
+
+	private static class ModifyVariableSecondPassAnnotationVisitor extends CommonInjectionAnnotationVisitor {
+		private final List<MemberInfo> methods;
+		private final List<TrClass> targets;
+
+		ModifyVariableSecondPassAnnotationVisitor(CommonData data, AnnotationVisitor delegate, List<String> targets, List<MemberInfo> methods) {
+			super(data, delegate, targets);
+			this.methods = methods;
+			this.targets = Objects.requireNonNull(targets).stream()
+					.map(data.resolver::resolveClass)
+					.filter(Optional::isPresent)
+					.map(Optional::get)
+					.collect(Collectors.toList());
+		}
+
+		@Override
+		public AnnotationVisitor visitArray(String name) {
+			AnnotationVisitor av = super.visitArray(name);
+
+			if (name.equals(AnnotationElement.NAME)) {
+				return new AnnotationVisitor(Constant.ASM_VERSION, av) {
+					@Override
+					public void visit(String name, Object value) {
+						String localName = Objects.requireNonNull((String) value).replaceAll("\\s", "");
+
+						List<String> collection = targets.stream()
+								.flatMap(target -> methods.stream().map(info -> resolvePartial(target, info.getName(), info.getDesc())))
+								.filter(Optional::isPresent)
+								.map(Optional::get)
+								.map(m -> {
+									TrLocal[] localVariables = m.getLocals();
+
+									if (localVariables == null || localVariables.length == 0) {
+										return localName;
+									}
+
+									Map<String, Integer> lvtName2Index = new HashMap<>();
+
+									for (TrLocal variable : localVariables) {
+										if (!lvtName2Index.containsKey(variable.getName())) {
+											lvtName2Index.put(variable.getName(), variable.getIndex());
+										} else {
+											lvtName2Index.put(variable.getName(), -1); // TODO actually generate lvt for injection points, currently only handles unique names
+										}
+									}
+
+									if (!lvtName2Index.containsKey(localName)) {
+										return localName;
+									}
+
+									int lvIndex = lvtName2Index.get(localName);
+
+									if (lvIndex < 0) {
+										return localName;
+									}
+
+									return data.mapper.asTrRemapper().mapMethodArg(m.getOwner().getName(), m.getName(), m.getDesc(), lvIndex, localName);
+								})
+								.distinct().collect(Collectors.toList());
+
+						if (collection.size() > 1) {
+							data.getLogger().error(Message.CONFLICT_MAPPING, localName, collection);
+						} else if (collection.isEmpty()) {
+							data.getLogger().warn(Message.NO_MAPPING_NON_RECURSIVE, localName, targets);
+						}
+
+						super.visit(name, collection.stream().findFirst().orElse(localName));
+					}
+				};
+			}
+
+			return av;
+		}
+
+		private Optional<TrMethod> resolvePartial(TrClass owner, String name, String desc) {
+			Objects.requireNonNull(owner);
+
+			name = name.isEmpty() ? null : name;
+			desc = desc.isEmpty() ? null : desc;
+
+			return data.resolver.resolveMethod(owner, name, desc, ResolveUtility.FLAG_FIRST | ResolveUtility.FLAG_NON_SYN).map(m -> m);
+		}
 	}
 }

src/test/java/net/fabricmc/tinyremapper/extension/mixin/integration/MixinIntegrationTest.java

@@ -42,9 +42,11 @@
 import net.fabricmc.tinyremapper.TinyRemapper;
 import net.fabricmc.tinyremapper.extension.mixin.MixinExtension;
 import net.fabricmc.tinyremapper.extension.mixin.integration.mixins.AmbiguousRemappedNameMixin;
+import net.fabricmc.tinyremapper.extension.mixin.integration.mixins.LvtRemapTargetMixin;
 import net.fabricmc.tinyremapper.extension.mixin.integration.mixins.NonObfuscatedOverrideMixin;
 import net.fabricmc.tinyremapper.extension.mixin.integration.mixins.WildcardTargetMixin;
 import net.fabricmc.tinyremapper.extension.mixin.integration.targets.AmbiguousRemappedNameTarget;
+import net.fabricmc.tinyremapper.extension.mixin.integration.targets.LvtRemapTarget;
 import net.fabricmc.tinyremapper.extension.mixin.integration.targets.NonObfuscatedOverrideTarget;
 import net.fabricmc.tinyremapper.extension.mixin.integration.targets.WildcardTarget;
 
@@ -91,6 +93,22 @@ public void remapAmbiuousRemappedName() throws IOException {
 		assertTrue(remapped.contains("@Lorg/spongepowered/asm/mixin/injection/Inject;(method={\"add(Ljava/lang/String;)V\""));
 	}
 
+	@Test
+	public void remapLvtName() throws IOException {
+		String remapped = remap(LvtRemapTarget.class, LvtRemapTargetMixin.class, out -> {
+			String fqn = "net/fabricmc/tinyremapper/extension/mixin/integration/targets/LvtRemapTarget";
+			out.acceptClass(fqn, "com/example/Remapped");
+			IMappingProvider.Member member = new IMappingProvider.Member(fqn, "target", "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");
+			out.acceptMethod(member, "targetRemapped");
+			out.acceptMethodArg(member, 1, "remappedStr1");
+			out.acceptMethodArg(member, 2, "remappedStr2");
+			out.acceptMethodArg(member, 3, "remappedStr3");
+			out.acceptMethodArg(member, 4, "remappedStr4");
+		});
+
+		assertTrue(remapped.contains("@Lorg/spongepowered/asm/mixin/injection/ModifyVariable;(method={\"targetRemapped\"}, at=@Lorg/spongepowered/asm/mixin/injection/At;(value=\"HEAD\"), name={\"remappedStr3\"})"));
+	}
+
 	private String remap(Class<?> target, Class<?> mixin, IMappingProvider mappings) throws IOException {
 		Path classpath = createJar(target);
 		Path input = createJar(mixin);