[java-decompiler] IDEA-246839 Support java records in decompiler

Also: support preview levels in ClsFileImpl
Also fixes: IDEA-247551 Exception on first opening of record .class file

GitOrigin-RevId: 4362d669d1c16b8230d6d8ab803465b6a7476803

src/org/jetbrains/java/decompiler/main/ClassWriter.java

@@ -14,10 +14,7 @@ import org.jetbrains.java.decompiler.modules.decompiler.stats.RootStatement;
 import org.jetbrains.java.decompiler.modules.decompiler.vars.VarTypeProcessor;
 import org.jetbrains.java.decompiler.modules.decompiler.vars.VarVersionPair;
 import org.jetbrains.java.decompiler.modules.renamer.PoolInterceptor;
-import org.jetbrains.java.decompiler.struct.StructClass;
+import org.jetbrains.java.decompiler.struct.*;
-import org.jetbrains.java.decompiler.struct.StructField;
-import org.jetbrains.java.decompiler.struct.StructMember;
-import org.jetbrains.java.decompiler.struct.StructMethod;
 import org.jetbrains.java.decompiler.struct.attr.*;
 import org.jetbrains.java.decompiler.struct.consts.PrimitiveConstant;
 import org.jetbrains.java.decompiler.struct.gen.FieldDescriptor;
@@ -28,6 +25,7 @@ import org.jetbrains.java.decompiler.util.InterpreterUtil;
 import org.jetbrains.java.decompiler.util.TextBuffer;
 
 import java.util.*;
+import java.util.stream.Collectors;
 
 public class ClassWriter {
   private final PoolInterceptor interceptor;
@@ -162,11 +160,19 @@ public class ClassWriter {
 
       dummy_tracer.incrementCurrentSourceLine(buffer.countLines(start_class_def));
 
+      List<StructRecordComponent> components = cl.getRecordComponents();
+
       for (StructField fd : cl.getFields()) {
         boolean hide = fd.isSynthetic() && DecompilerContext.getOption(IFernflowerPreferences.REMOVE_SYNTHETIC) ||
                        wrapper.getHiddenMembers().contains(InterpreterUtil.makeUniqueKey(fd.getName(), fd.getDescriptor()));
         if (hide) continue;
 
+        if (components != null && fd.getAccessFlags() == (CodeConstants.ACC_FINAL | CodeConstants.ACC_PRIVATE) &&
+            components.stream().anyMatch(c -> c.getName().equals(fd.getName()) && c.getDescriptor().equals(fd.getDescriptor()))) {
+          // Record component field: skip it
+          continue;
+        }
+
         boolean isEnum = fd.hasModifier(CodeConstants.ACC_ENUM) && DecompilerContext.getOption(IFernflowerPreferences.DECOMPILE_ENUM);
         if (isEnum) {
           if (enumFields) {
@@ -302,6 +308,13 @@ public class ClassWriter {
       flags &= ~CodeConstants.ACC_FINAL;
     }
 
+    List<StructRecordComponent> components = cl.getRecordComponents();
+
+    if (components != null) {
+      // records are implicitly final
+      flags &= ~CodeConstants.ACC_FINAL;
+    }
+
     appendModifiers(buffer, flags, CLASS_ALLOWED, isInterface, CLASS_EXCLUDED);
 
     if (isEnum) {
@@ -313,6 +326,9 @@ public class ClassWriter {
       }
       buffer.append("interface ");
     }
+    else if (components != null) {
+      buffer.append("record ");
+    }
     else {
       buffer.append("class ");
     }
@@ -324,9 +340,22 @@ public class ClassWriter {
       appendTypeParameters(buffer, descriptor.fparameters, descriptor.fbounds);
     }
 
+    if (components != null) {
+      buffer.append('(');
+      for (int i = 0; i < components.size(); i++) {
+        StructRecordComponent cd = components.get(i);
+        if (i > 0) {
+          buffer.append(", ");
+        }
+        boolean varArgComponent = i == components.size() - 1 && isVarArgRecord(cl);
+        recordComponentToJava(cd, buffer, varArgComponent);
+      }
+      buffer.append(')');
+    }
+
     buffer.append(' ');
 
-    if (!isEnum && !isInterface && cl.superClass != null) {
+    if (!isEnum && !isInterface && components == null && cl.superClass != null) {
       VarType supertype = new VarType(cl.superClass.getString(), true);
       if (!VarType.VARTYPE_OBJECT.equals(supertype)) {
         buffer.append("extends ");
@@ -362,6 +391,13 @@ public class ClassWriter {
     buffer.append('{').appendLineSeparator();
   }
 
+  private boolean isVarArgRecord(StructClass cl) {
+    String canonicalConstructorDescriptor = 
+      cl.getRecordComponents().stream().map(c -> c.getDescriptor()).collect(Collectors.joining("", "(", ")V"));
+    StructMethod ctor = cl.getMethod(CodeConstants.INIT_NAME, canonicalConstructorDescriptor);
+    return ctor != null && ctor.hasModifier(CodeConstants.ACC_VARARGS);
+  }
+
   private void fieldToJava(ClassWrapper wrapper, StructClass cl, StructField fd, TextBuffer buffer, int indent, BytecodeMappingTracer tracer) {
     int start = buffer.length();
     boolean isInterface = cl.hasModifier(CodeConstants.ACC_INTERFACE);
@@ -452,6 +488,33 @@ public class ClassWriter {
     }
   }
 
+  private static void recordComponentToJava(StructRecordComponent cd, TextBuffer buffer, boolean varArgComponent) {
+    appendAnnotations(buffer, -1, cd, TypeAnnotation.FIELD);
+
+    VarType fieldType = new VarType(cd.getDescriptor(), false);
+
+    GenericFieldDescriptor descriptor = null;
+    if (DecompilerContext.getOption(IFernflowerPreferences.DECOMPILE_GENERIC_SIGNATURES)) {
+      StructGenericSignatureAttribute attr = cd.getAttribute(StructGeneralAttribute.ATTRIBUTE_SIGNATURE);
+      if (attr != null) {
+        descriptor = GenericMain.parseFieldSignature(attr.getSignature());
+      }
+    }
+
+    if (descriptor != null) {
+      buffer.append(GenericMain.getGenericCastTypeName(varArgComponent ? descriptor.type.decreaseArrayDim() : descriptor.type));
+    }
+    else {
+      buffer.append(ExprProcessor.getCastTypeName(varArgComponent ? fieldType.decreaseArrayDim() : fieldType));
+    }
+    if (varArgComponent) {
+      buffer.append("...");
+    }
+    buffer.append(' ');
+
+    buffer.append(cd.getName());
+  }
+
   private static void methodLambdaToJava(ClassNode lambdaNode,
                                          ClassWrapper classWrapper,
                                          StructMethod mt,
@@ -959,7 +1022,13 @@ public class ClassWriter {
         for (AnnotationExprent annotation : attribute.getAnnotations()) {
           String text = annotation.toJava(indent, BytecodeMappingTracer.DUMMY).toString();
           filter.add(text);
-          buffer.append(text).appendLineSeparator();
+          buffer.append(text);
+          if (indent < 0) {
+            buffer.append(' ');
+          }
+          else {
+            buffer.appendLineSeparator();
+          }
         }
       }
     }

src/org/jetbrains/java/decompiler/struct/StructClass.java

@@ -2,6 +2,8 @@
 package org.jetbrains.java.decompiler.struct;
 
 import org.jetbrains.java.decompiler.code.CodeConstants;
+import org.jetbrains.java.decompiler.struct.attr.StructGeneralAttribute;
+import org.jetbrains.java.decompiler.struct.attr.StructRecordAttribute;
 import org.jetbrains.java.decompiler.struct.consts.ConstantPool;
 import org.jetbrains.java.decompiler.struct.consts.PrimitiveConstant;
 import org.jetbrains.java.decompiler.struct.lazy.LazyLoader;
@@ -10,6 +12,7 @@ import org.jetbrains.java.decompiler.util.InterpreterUtil;
 import org.jetbrains.java.decompiler.util.VBStyleCollection;
 
 import java.io.IOException;
+import java.util.List;
 
 /*
   class_file {
@@ -132,6 +135,15 @@ public class StructClass extends StructMember {
     return pool;
   }
 
+  /**
+   * @return list of record components; null if this class is not a record
+   */
+  public List<StructRecordComponent> getRecordComponents() {
+    StructRecordAttribute recordAttr = getAttribute(StructGeneralAttribute.ATTRIBUTE_RECORD);
+    if (recordAttr == null) return null;
+    return recordAttr.getComponents();
+  }
+
   public int[] getInterfaces() {
     return interfaces;
   }

src/org/jetbrains/java/decompiler/struct/StructRecordComponent.java

@@ -0,0 +1,47 @@
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.java.decompiler.struct;
+
+import org.jetbrains.java.decompiler.struct.consts.ConstantPool;
+import org.jetbrains.java.decompiler.struct.consts.PrimitiveConstant;
+import org.jetbrains.java.decompiler.util.DataInputFullStream;
+
+import java.io.IOException;
+
+/*
+  record_component_info {
+    u2 name_index;
+    u2 descriptor_index;
+    u2 attributes_count;
+    attribute_info attributes[attributes_count];
+   }
+*/
+public class StructRecordComponent extends StructMember {
+
+  private final String name;
+  private final String descriptor;
+
+
+  public StructRecordComponent(DataInputFullStream in, ConstantPool pool) throws IOException {
+    accessFlags = 0;
+    int nameIndex = in.readUnsignedShort();
+    int descriptorIndex = in.readUnsignedShort();
+
+    name = ((PrimitiveConstant)pool.getConstant(nameIndex)).getString();
+    descriptor = ((PrimitiveConstant)pool.getConstant(descriptorIndex)).getString();
+
+    attributes = readAttributes(in, pool);
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public String getDescriptor() {
+    return descriptor;
+  }
+
+  @Override
+  public String toString() {
+    return name;
+  }
+}

src/org/jetbrains/java/decompiler/struct/attr/StructGeneralAttribute.java

@@ -34,6 +34,7 @@ public class StructGeneralAttribute {
   public static final Key<StructGeneralAttribute> ATTRIBUTE_DEPRECATED = new Key<>("Deprecated");
   public static final Key<StructLineNumberTableAttribute> ATTRIBUTE_LINE_NUMBER_TABLE = new Key<>("LineNumberTable");
   public static final Key<StructMethodParametersAttribute> ATTRIBUTE_METHOD_PARAMETERS = new Key<>("MethodParameters");
+  public static final Key<StructRecordAttribute> ATTRIBUTE_RECORD = new Key<>("Record");
 
   public static class Key<T extends StructGeneralAttribute> {
     private final String name;
@@ -97,6 +98,9 @@ public class StructGeneralAttribute {
     else if (ATTRIBUTE_METHOD_PARAMETERS.getName().equals(name)) {
       attr = new StructMethodParametersAttribute();
     }
+    else if (ATTRIBUTE_RECORD.getName().equals(name)) {
+      attr = new StructRecordAttribute();
+    }
     else {
       // unsupported attribute
       return null;

src/org/jetbrains/java/decompiler/struct/attr/StructRecordAttribute.java

@@ -0,0 +1,38 @@
+// Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.java.decompiler.struct.attr;
+
+import org.jetbrains.java.decompiler.struct.StructRecordComponent;
+import org.jetbrains.java.decompiler.struct.consts.ConstantPool;
+import org.jetbrains.java.decompiler.util.DataInputFullStream;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+/*
+  Record_attribute {
+      u2 attribute_name_index;
+      u4 attribute_length;
+      u2 components_count;
+      record_component_info components[components_count];
+  }
+ */
+public class StructRecordAttribute extends StructGeneralAttribute {
+  List<StructRecordComponent> components;
+  
+  @Override
+  public void initContent(DataInputFullStream data,
+                          ConstantPool pool) throws IOException {
+    int componentCount = data.readUnsignedShort();
+    StructRecordComponent[] components = new StructRecordComponent[componentCount];
+    for (int i = 0; i < componentCount; i++) {
+      components[i] = new StructRecordComponent(data, pool);
+    }
+    this.components = Arrays.asList(components);
+  }
+
+  public List<StructRecordComponent> getComponents() {
+    return Collections.unmodifiableList(components);
+  }
+}

test/org/jetbrains/java/decompiler/SingleClassesTest.java

@@ -129,6 +129,11 @@ public class SingleClassesTest {
   @Test public void testSuspendLambda() { doTest("pkg/TestSuspendLambdaKt"); }
   @Test public void testNamedSuspendFun2Kt() { doTest("pkg/TestNamedSuspendFun2Kt"); }
   @Test public void testGenericArgs() { doTest("pkg/TestGenericArgs"); }
+  @Test public void testRecordEmpty() { doTest("records/TestRecordEmpty"); }
+  @Test public void testRecordSimple() { doTest("records/TestRecordSimple"); }
+  @Test public void testRecordVararg() { doTest("records/TestRecordVararg"); }
+  @Test public void testRecordGenericVararg() { doTest("records/TestRecordGenericVararg"); }
+  @Test public void testRecordAnno() { doTest("records/TestRecordAnno"); }
 
   private void doTest(String testFile, String... companionFiles) {
     ConsoleDecompiler decompiler = fixture.getDecompiler();

testData/results/TestRecordAnno.dec

@@ -0,0 +1,66 @@
+package records;
+
+public record TestRecordAnno(@RC @TA int x, int y) {
+   public TestRecordAnno(@TA int x, @P int y) {
+      this.x = x;
+      this.y = y;
+   }
+
+   public final String toString() {
+      return this.toString<invokedynamic>(this);
+   }
+
+   public final int hashCode() {
+      return this.hashCode<invokedynamic>(this);
+   }
+
+   public final boolean equals(Object o) {
+      return this.equals<invokedynamic>(this, o);
+   }
+
+   @TA
+   public int x() {
+      return this.x;
+   }
+
+   @M
+   public int y() {
+      return this.y;// 5
+   }
+}
+
+class 'records/TestRecordAnno' {
+   method '<init> (II)V' {
+      6      4
+      b      5
+      e      6
+   }
+
+   method 'toString ()Ljava/lang/String;' {
+      1      9
+      6      9
+   }
+
+   method 'hashCode ()I' {
+      1      13
+      6      13
+   }
+
+   method 'equals (Ljava/lang/Object;)Z' {
+      2      17
+      7      17
+   }
+
+   method 'x ()I' {
+      1      22
+      4      22
+   }
+
+   method 'y ()I' {
+      1      27
+      4      27
+   }
+}
+
+Lines mapping:
+5 <-> 28

testData/results/TestRecordEmpty.dec

@@ -0,0 +1,35 @@
+package records;
+
+public record TestRecordEmpty() {
+   public final String toString() {
+      return this.toString<invokedynamic>(this);
+   }
+
+   public final int hashCode() {
+      return this.hashCode<invokedynamic>(this);
+   }
+
+   public final boolean equals(Object o) {
+      return this.equals<invokedynamic>(this, o);// 3
+   }
+}
+
+class 'records/TestRecordEmpty' {
+   method 'toString ()Ljava/lang/String;' {
+      1      4
+      6      4
+   }
+
+   method 'hashCode ()I' {
+      1      8
+      6      8
+   }
+
+   method 'equals (Ljava/lang/Object;)Z' {
+      2      12
+      7      12
+   }
+}
+
+Lines mapping:
+3 <-> 13

testData/results/TestRecordGenericVararg.dec

@@ -0,0 +1,66 @@
+package records;
+
+public record TestRecordGenericVararg<T>(T first, T... other) {
+   @SafeVarargs
+   public TestRecordGenericVararg(T first, T... other) {
+      this.first = first;// 5
+      this.other = other;
+   }
+
+   public final String toString() {
+      return this.toString<invokedynamic>(this);
+   }
+
+   public final int hashCode() {
+      return this.hashCode<invokedynamic>(this);
+   }
+
+   public final boolean equals(Object o) {
+      return this.equals<invokedynamic>(this, o);
+   }
+
+   public T first() {
+      return this.first;
+   }
+
+   public T[] other() {
+      return this.other;// 3
+   }
+}
+
+class 'records/TestRecordGenericVararg' {
+   method '<init> (Ljava/lang/Object;[Ljava/lang/Object;)V' {
+      6      5
+      b      6
+      e      7
+   }
+
+   method 'toString ()Ljava/lang/String;' {
+      1      10
+      6      10
+   }
+
+   method 'hashCode ()I' {
+      1      14
+      6      14
+   }
+
+   method 'equals (Ljava/lang/Object;)Z' {
+      2      18
+      7      18
+   }
+
+   method 'first ()Ljava/lang/Object;' {
+      1      22
+      4      22
+   }
+
+   method 'other ()[Ljava/lang/Object;' {
+      1      26
+      4      26
+   }
+}
+
+Lines mapping:
+3 <-> 27
+5 <-> 6

testData/results/TestRecordSimple.dec

@@ -0,0 +1,64 @@
+package records;
+
+public record TestRecordSimple(int x, int y) {
+   public TestRecordSimple(int x, int y) {
+      this.x = x;
+      this.y = y;
+   }
+
+   public final String toString() {
+      return this.toString<invokedynamic>(this);
+   }
+
+   public final int hashCode() {
+      return this.hashCode<invokedynamic>(this);
+   }
+
+   public final boolean equals(Object o) {
+      return this.equals<invokedynamic>(this, o);
+   }
+
+   public int x() {
+      return this.x;
+   }
+
+   public int y() {
+      return this.y;// 3
+   }
+}
+
+class 'records/TestRecordSimple' {
+   method '<init> (II)V' {
+      6      4
+      b      5
+      e      6
+   }
+
+   method 'toString ()Ljava/lang/String;' {
+      1      9
+      6      9
+   }
+
+   method 'hashCode ()I' {
+      1      13
+      6      13
+   }
+
+   method 'equals (Ljava/lang/Object;)Z' {
+      2      17
+      7      17
+   }
+
+   method 'x ()I' {
+      1      21
+      4      21
+   }
+
+   method 'y ()I' {
+      1      25
+      4      25
+   }
+}
+
+Lines mapping:
+3 <-> 26

testData/results/TestRecordVararg.dec

@@ -0,0 +1,64 @@
+package records;
+
+public record TestRecordVararg(int x, int[]... y) {
+   public TestRecordVararg(int x, int[]... y) {
+      this.x = x;
+      this.y = y;
+   }
+
+   public final String toString() {
+      return this.toString<invokedynamic>(this);
+   }
+
+   public final int hashCode() {
+      return this.hashCode<invokedynamic>(this);
+   }
+
+   public final boolean equals(Object o) {
+      return this.equals<invokedynamic>(this, o);
+   }
+
+   public int x() {
+      return this.x;
+   }
+
+   public int[][] y() {
+      return this.y;// 3
+   }
+}
+
+class 'records/TestRecordVararg' {
+   method '<init> (I[[I)V' {
+      6      4
+      b      5
+      e      6
+   }
+
+   method 'toString ()Ljava/lang/String;' {
+      1      9
+      6      9
+   }
+
+   method 'hashCode ()I' {
+      1      13
+      6      13
+   }
+
+   method 'equals (Ljava/lang/Object;)Z' {
+      2      17
+      7      17
+   }
+
+   method 'x ()I' {
+      1      21
+      4      21
+   }
+
+   method 'y ()[[I' {
+      1      25
+      4      25
+   }
+}
+
+Lines mapping:
+3 <-> 26

testData/src/records/TestRecordAnno.java

@@ -0,0 +1,17 @@
+package records;
+
+import java.lang.annotation.*;
+
+public record TestRecordAnno(@TA @RC int x, @M @P int y) {}
+
+@Target(ElementType.TYPE_USE)
+@interface TA {}
+
+@Target(ElementType.RECORD_COMPONENT)
+@interface RC {}
+
+@Target(ElementType.METHOD)
+@interface M {}
+
+@Target(ElementType.PARAMETER)
+@interface P {}

testData/src/records/TestRecordEmpty.java

@@ -0,0 +1,3 @@
+package records;
+
+public record TestRecordEmpty() {}

testData/src/records/TestRecordGenericVararg.java

@@ -0,0 +1,6 @@
+package records;
+
+public record TestRecordGenericVararg<T>(T first, T... other) {
+  @SafeVarargs
+  public TestRecordGenericVararg {}
+}

testData/src/records/TestRecordSimple.java

@@ -0,0 +1,3 @@
+package records;
+
+public record TestRecordSimple(int x, int y) {}

testData/src/records/TestRecordVararg.java

@@ -0,0 +1,3 @@
+package records;
+
+public record TestRecordVararg(int x, int[]... y) {}