Add attributes section to TASTy

The `Attributes` section contains a list of UTF-8 string that represent
the attributes.

compiler/src/dotty/tools/dotc/core/tasty/AttributePickler.scala

@@ -0,0 +1,25 @@
+package dotty.tools.dotc.core.tasty
+
+import dotty.tools.dotc.ast.{tpd, untpd}
+
+import dotty.tools.tasty.TastyBuffer
+import dotty.tools.tasty.TastyFormat.AttributesSection
+
+import java.nio.charset.StandardCharsets
+
+object AttributePickler:
+
+  def pickleAttributes(
+    attributes: List[String],
+    pickler: TastyPickler,
+    buf: TastyBuffer): Unit =
+      if attributes != Nil then
+        pickler.newSection(AttributesSection, buf)
+        for attribute <- attributes do
+          val bytes = attribute.getBytes(StandardCharsets.UTF_8).nn
+          val length = bytes.length
+          buf.writeNat(length)
+          buf.writeBytes(bytes, length)
+  end pickleAttributes
+
+end AttributePickler

compiler/src/dotty/tools/dotc/core/tasty/AttributeUnpickler.scala

@@ -0,0 +1,26 @@
+package dotty.tools.dotc
+package core.tasty
+
+import scala.language.unsafeNulls
+
+import dotty.tools.tasty.{TastyReader, TastyBuffer}
+
+import java.nio.charset.StandardCharsets
+
+class AttributeUnpickler(reader: TastyReader):
+  import reader._
+
+  private[tasty] lazy val attributes: List[String] = {
+    val attributesBuilder = List.newBuilder[String]
+    while (!isAtEnd) {
+      val length = readNat()
+      if (length > 0) {
+        val bytes = readBytes(length)
+        val attribute = new String(bytes, StandardCharsets.UTF_8)
+        attributesBuilder += attribute
+      }
+    }
+    attributesBuilder.result()
+  }
+
+end AttributeUnpickler

compiler/src/dotty/tools/dotc/core/tasty/DottyUnpickler.scala

@@ -13,17 +13,17 @@ import Names.SimpleName
 import TreeUnpickler.UnpickleMode
 
 import dotty.tools.tasty.TastyReader
-import dotty.tools.tasty.TastyFormat.{ASTsSection, PositionsSection, CommentsSection}
+import dotty.tools.tasty.TastyFormat.{ASTsSection, PositionsSection, CommentsSection, AttributesSection}
 
 object DottyUnpickler {
 
   /** Exception thrown if classfile is corrupted */
   class BadSignature(msg: String) extends RuntimeException(msg)
 
-  class TreeSectionUnpickler(posUnpickler: Option[PositionUnpickler], commentUnpickler: Option[CommentUnpickler])
+  class TreeSectionUnpickler(posUnpickler: Option[PositionUnpickler], commentUnpickler: Option[CommentUnpickler], attributeUnpickler: Option[AttributeUnpickler])
   extends SectionUnpickler[TreeUnpickler](ASTsSection) {
     def unpickle(reader: TastyReader, nameAtRef: NameTable): TreeUnpickler =
-      new TreeUnpickler(reader, nameAtRef, posUnpickler, commentUnpickler)
+      new TreeUnpickler(reader, nameAtRef, posUnpickler, commentUnpickler, attributeUnpickler)
   }
 
   class PositionsSectionUnpickler extends SectionUnpickler[PositionUnpickler](PositionsSection) {
@@ -35,6 +35,10 @@ object DottyUnpickler {
     def unpickle(reader: TastyReader, nameAtRef: NameTable): CommentUnpickler =
       new CommentUnpickler(reader)
   }
+  class AttributesSectionUnpickler extends SectionUnpickler[AttributeUnpickler](AttributesSection) {
+    def unpickle(reader: TastyReader, nameAtRef: NameTable): AttributeUnpickler =
+      new AttributeUnpickler(reader)
+  }
 }
 
 /** A class for unpickling Tasty trees and symbols.
@@ -48,16 +52,21 @@ class DottyUnpickler(bytes: Array[Byte], mode: UnpickleMode = UnpickleMode.TopLe
   val unpickler: TastyUnpickler = new TastyUnpickler(bytes)
   private val posUnpicklerOpt = unpickler.unpickle(new PositionsSectionUnpickler)
   private val commentUnpicklerOpt = unpickler.unpickle(new CommentsSectionUnpickler)
-  private val treeUnpickler = unpickler.unpickle(treeSectionUnpickler(posUnpicklerOpt, commentUnpicklerOpt)).get
+  private val attributeUnpicklerOpt = unpickler.unpickle(new AttributesSectionUnpickler)
+  private val treeUnpickler = unpickler.unpickle(treeSectionUnpickler(posUnpicklerOpt, commentUnpicklerOpt, attributeUnpicklerOpt)).get
 
   /** Enter all toplevel classes and objects into their scopes
    *  @param roots          a set of SymDenotations that should be overwritten by unpickling
    */
   def enter(roots: Set[SymDenotation])(using Context): Unit =
     treeUnpickler.enter(roots)
 
-  protected def treeSectionUnpickler(posUnpicklerOpt: Option[PositionUnpickler], commentUnpicklerOpt: Option[CommentUnpickler]): TreeSectionUnpickler =
-    new TreeSectionUnpickler(posUnpicklerOpt, commentUnpicklerOpt)
+  protected def treeSectionUnpickler(
+    posUnpicklerOpt: Option[PositionUnpickler],
+    commentUnpicklerOpt: Option[CommentUnpickler],
+    attributeUnpicklerOpt: Option[AttributeUnpickler]
+  ): TreeSectionUnpickler =
+    new TreeSectionUnpickler(posUnpicklerOpt, commentUnpicklerOpt, attributeUnpicklerOpt)
 
   protected def computeRootTrees(using Context): List[Tree] = treeUnpickler.unpickle(mode)
 

compiler/src/dotty/tools/dotc/core/tasty/ScratchData.scala

@@ -10,11 +10,13 @@ class ScratchData:
   val pickledIndices = new mutable.BitSet
 
   val commentBuffer = new TastyBuffer(5000)
+  val attributeBuffer = new TastyBuffer(128)
 
   def reset() =
     assert(delta ne delta1)
     assert(delta.length == delta1.length)
     positionBuffer.reset()
     pickledIndices.clear()
     commentBuffer.reset()
+    attributeBuffer.reset()
 

compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala

@@ -9,7 +9,7 @@ import Contexts._, Decorators._
 import Names.Name
 import TastyUnpickler._
 import util.Spans.offsetToInt
-import dotty.tools.tasty.TastyFormat.{ASTsSection, PositionsSection, CommentsSection}
+import dotty.tools.tasty.TastyFormat.{ASTsSection, PositionsSection, CommentsSection, AttributesSection}
 import java.nio.file.{Files, Paths}
 import dotty.tools.io.{JarArchive, Path}
 
@@ -84,14 +84,16 @@ class TastyPrinter(bytes: Array[Byte]) {
       case Some(s) => sb.append(s)
       case _ =>
     }
-    sb.append("\n\n")
     unpickle(new PositionSectionUnpickler) match {
-      case Some(s) => sb.append(s)
+      case Some(s) => sb.append("\n\n").append(s)
       case _ =>
     }
-    sb.append("\n\n")
     unpickle(new CommentSectionUnpickler) match {
-      case Some(s) => sb.append(s)
+      case Some(s) => sb.append("\n\n").append(s)
+      case _ =>
+    }
+    unpickle(new AttributesSectionUnpickler) match {
+      case Some(s) => sb.append("\n\n").append(s)
       case _ =>
     }
     sb.result
@@ -222,6 +224,20 @@ class TastyPrinter(bytes: Array[Byte]) {
     }
   }
 
+  class AttributesSectionUnpickler extends SectionUnpickler[String](AttributesSection) {
+
+    private val sb: StringBuilder = new StringBuilder
+
+    def unpickle(reader: TastyReader, tastyName: NameTable): String = {
+      sb.append(s" ${reader.endAddr.index - reader.currentAddr.index}")
+      val attributes = new AttributeUnpickler(reader).attributes
+      sb.append(s"  attributes bytes:\n")
+      for attribute <- attributes do
+        sb.append("  ").append(attribute).append("\n")
+      sb.result
+    }
+  }
+
   protected def nameStr(str: String): String = str
   protected def treeStr(str: String): String = str
   protected def lengthStr(str: String): String = str

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -52,11 +52,13 @@ import scala.annotation.internal.sharable
  *  @param reader              the reader from which to unpickle
  *  @param posUnpicklerOpt     the unpickler for positions, if it exists
  *  @param commentUnpicklerOpt the unpickler for comments, if it exists
+ *  @param attributeUnpicklerOpt the unpickler for attributes, if it exists
  */
 class TreeUnpickler(reader: TastyReader,
                     nameAtRef: NameTable,
                     posUnpicklerOpt: Option[PositionUnpickler],
-                    commentUnpicklerOpt: Option[CommentUnpickler]) {
+                    commentUnpicklerOpt: Option[CommentUnpickler],
+                    attributeUnpicklerOpt: Option[AttributeUnpickler]) {
   import TreeUnpickler._
   import tpd._
 

compiler/src/dotty/tools/dotc/transform/Pickler.scala

@@ -108,6 +108,9 @@ class Pickler extends Phase {
                 pickler, treePkl.buf.addrOfTree, treePkl.docString, tree,
                 scratch.commentBuffer)
 
+          val attributes = Nil // TODO add attributes here
+          AttributePickler.pickleAttributes(attributes, pickler, scratch.attributeBuffer)
+
           val pickled = pickler.assembleParts()
 
           def rawBytes = // not needed right now, but useful to print raw format.

tasty/src/dotty/tools/tasty/TastyFormat.scala

@@ -267,6 +267,9 @@ Standard Section: "Comments" Comment*
 ```none
   Comment       = Length Bytes LongInt      // Raw comment's bytes encoded as UTF-8, followed by the comment's coordinates.
 ```
+
+Standard Section: "Attributes" UTF8*
+
 **************************************************************************************/
 
 object TastyFormat {
@@ -361,6 +364,7 @@ object TastyFormat {
   final val ASTsSection = "ASTs"
   final val PositionsSection = "Positions"
   final val CommentsSection = "Comments"
+  final val AttributesSection = "Attributes"
 
   /** Tags used to serialize names, should update [[TastyFormat$.nameTagToString]] if a new constant is added */
   class NameTags {