2 files changed, 50 insertions, 8 deletions

diff --git a/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java b/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java
index bbbf369..530aff4 100644
--- a/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java
+++ b/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java
@@ -15,6 +15,7 @@ import net.fabricmc.mappingio.tree.VisitOrder;
 import net.fabricmc.mappingio.tree.VisitableMappingTree;
 
 import cuchaz.enigma.ProgressListener;
+import cuchaz.enigma.analysis.index.JarIndex;
 import cuchaz.enigma.translation.mapping.EntryMapping;
 import cuchaz.enigma.translation.mapping.MappingDelta;
 import cuchaz.enigma.translation.mapping.serde.enigma.EnigmaMappingsReader;
@@ -82,7 +83,12 @@ public enum MappingFormat {
                 }
         }
 
+        @Deprecated
         public EntryTree<EntryMapping> read(Path path, ProgressListener progressListener, MappingSaveParameters saveParameters) throws IOException, MappingParseException {
+                return read(path, progressListener, saveParameters, null);
+        }
+
+        public EntryTree<EntryMapping> read(Path path, ProgressListener progressListener, MappingSaveParameters saveParameters, JarIndex index) throws IOException, MappingParseException {
                 if (!useMappingIo()) {
                         if (reader == null) {
                                 throw new IllegalStateException(name() + " does not support reading");
@@ -103,7 +109,7 @@ public enum MappingFormat {
 
                 VisitableMappingTree mappingTree = new MemoryMappingTree();
                 MappingReader.read(path, mappingIoCounterpart, mappingTree);
-                return MappingIoConverter.fromMappingIo(mappingTree, progressListener);
+                return MappingIoConverter.fromMappingIo(mappingTree, progressListener, index);
         }
 
         @Nullable
diff --git a/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingIoConverter.java b/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingIoConverter.java
index 4372585..3843d8e 100644
--- a/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingIoConverter.java
+++ b/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingIoConverter.java
@@ -7,6 +7,9 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.stream.StreamSupport;
 
+import javax.annotation.Nullable;
+
+import org.jetbrains.annotations.ApiStatus;
 import net.fabricmc.mappingio.MappedElementKind;
 import net.fabricmc.mappingio.tree.MemoryMappingTree;
 import net.fabricmc.mappingio.tree.VisitableMappingTree;
@@ -17,6 +20,7 @@ import net.fabricmc.mappingio.tree.MappingTree.MethodMapping;
 import net.fabricmc.mappingio.tree.MappingTree.MethodVarMapping;
 
 import cuchaz.enigma.ProgressListener;
+import cuchaz.enigma.analysis.index.JarIndex;
 import cuchaz.enigma.translation.mapping.EntryMap;
 import cuchaz.enigma.translation.mapping.EntryMapping;
 import cuchaz.enigma.translation.mapping.tree.EntryTree;
@@ -31,6 +35,7 @@ import cuchaz.enigma.translation.representation.entry.LocalVariableEntry;
 import cuchaz.enigma.translation.representation.entry.MethodEntry;
 import cuchaz.enigma.utils.I18n;
 
+@ApiStatus.Internal
 public class MappingIoConverter {
         public static VisitableMappingTree toMappingIo(EntryTree<EntryMapping> mappings, ProgressListener progress) {
                 return toMappingIo(mappings, progress, "intermediary", "named");
@@ -174,20 +179,20 @@ public class MappingIoConverter {
                 mappingTree.visitComment(MappedElementKind.METHOD_VAR, varMapping.javadoc());
         }
 
-        public static EntryTree<EntryMapping> fromMappingIo(VisitableMappingTree mappingTree, ProgressListener progress) {
+        public static EntryTree<EntryMapping> fromMappingIo(VisitableMappingTree mappingTree, ProgressListener progress, @Nullable JarIndex index) {
                 EntryTree<EntryMapping> dstMappingTree = new HashEntryTree<>();
                 progress.init(mappingTree.getClasses().size(), I18n.translate("progress.mappings.converting.from_mappingio"));
                 int steps = 0;
 
                 for (ClassMapping classMapping : mappingTree.getClasses()) {
                         progress.step(steps++, classMapping.getDstName(0) != null ? classMapping.getDstName(0) : classMapping.getSrcName());
-                        readClass(classMapping, dstMappingTree);
+                        readClass(classMapping, dstMappingTree, index);
                 }
 
                 return dstMappingTree;
         }
 
-        private static void readClass(ClassMapping classMapping, EntryTree<EntryMapping> mappingTree) {
+        private static void readClass(ClassMapping classMapping, EntryTree<EntryMapping> mappingTree, JarIndex index) {
                 ClassEntry currentClass = new ClassEntry(classMapping.getSrcName());
                 String dstName = classMapping.getDstName(0);
 
@@ -198,7 +203,7 @@ public class MappingIoConverter {
                 mappingTree.insert(currentClass, new EntryMapping(dstName, classMapping.getComment()));
 
                 for (FieldMapping fieldMapping : classMapping.getFields()) {
-                        readField(fieldMapping, currentClass, mappingTree);
+                        readField(fieldMapping, currentClass, mappingTree, index);
                 }
 
                 for (MethodMapping methodMapping : classMapping.getMethods()) {
@@ -206,9 +211,40 @@ public class MappingIoConverter {
                 }
         }
 
-        private static void readField(FieldMapping fieldMapping, ClassEntry parent, EntryTree<EntryMapping> mappingTree) {
-                mappingTree.insert(new FieldEntry(parent, fieldMapping.getSrcName(), new TypeDescriptor(fieldMapping.getSrcDesc())),
-                                new EntryMapping(fieldMapping.getDstName(0), fieldMapping.getComment()));
+        private static void readField(FieldMapping fieldMapping, ClassEntry parent, EntryTree<EntryMapping> mappingTree, JarIndex index) {
+                String srcDesc = fieldMapping.getSrcDesc();
+                FieldEntry[] fieldEntries;
+
+                if (srcDesc != null) {
+                        fieldEntries = new FieldEntry[] { new FieldEntry(parent, fieldMapping.getSrcName(), new TypeDescriptor(fieldMapping.getSrcDesc())) };
+                } else {
+                        if (index == null) return; // Enigma requires source descriptors, and without an index we can't look them up
+
+                        fieldEntries = index.getChildrenByClass().get(parent).stream()
+                                        .filter(entry -> entry instanceof FieldEntry)
+                                        .filter(entry -> entry.getName().equals(fieldMapping.getSrcName()))
+                                        .toArray(FieldEntry[]::new);
+
+                        if (fieldEntries.length == 0) { // slow path for synthetics
+                                fieldEntries = index.getEntryIndex().getFields().stream()
+                                                .filter(entry -> entry.getParent().getFullName().equals(parent.getFullName()))
+                                                .filter(entry -> {
+                                                        if (entry.getName().equals(fieldMapping.getSrcName())) {
+                                                                return true;
+                                                        } else {
+                                                                System.out.println("Entry name: " + entry.getName() + ", mapping name: " + fieldMapping.getSrcName());
+                                                                return false;
+                                                        }
+                                                })
+                                                .toArray(FieldEntry[]::new);
+                        }
+
+                        if (fieldEntries.length == 0) return; // No target found, invalid mapping
+                }
+
+                for (FieldEntry fieldEntry : fieldEntries) {
+                        mappingTree.insert(fieldEntry, new EntryMapping(fieldMapping.getDstName(0), fieldMapping.getComment()));
+                }
         }
 
         private static void readMethod(MethodMapping methodMapping, ClassEntry parent, EntryTree<EntryMapping> mappingTree) {