Simplify handling of sourcefiles in Tasty info

Instead of separate source file sections, pickle SourceFile as an
annotation of all toplevel classes.

We represent it like this anyway when reading back Tasty-defined classes.

Author: odersky

src/dotty/tools/dotc/FromTasty.scala

@@ -86,8 +86,8 @@ object FromTasty extends Driver {
               case info: ClassfileLoader =>
                 info.load(clsd) match {
                   case Some(unpickler: DottyUnpickler) =>
-                    val (List(unpickled), source) = unpickler.body(readPositions = true)
-                    val unit1 = new CompilationUnit(source)
+                    val List(unpickled) = unpickler.body(readPositions = true)
+                    val unit1 = new CompilationUnit(new SourceFile(clsd.symbol.sourceFile, Seq()))
                     unit1.tpdTree = unpickled
                     unit1.unpicklers += (clsd.classSymbol -> unpickler.unpickler)
                     force.traverse(unit1.tpdTree)

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

@@ -6,7 +6,6 @@ package tasty
 import Contexts._, SymDenotations._, Symbols._
 import dotty.tools.dotc.ast.tpd
 import TastyUnpickler._, TastyBuffer._
-import dotty.tools.dotc.core.tasty.DottyUnpickler.{SourceFileUnpickler, TreeSectionUnpickler, PositionsSectionUnpickler}
 import util.Positions._
 import util.{SourceFile, NoSource}
 import PositionUnpickler._
@@ -18,13 +17,6 @@ object DottyUnpickler {
   /** Exception thrown if classfile is corrupted */
   class BadSignature(msg: String) extends RuntimeException(msg)
 
-  class SourceFileUnpickler extends SectionUnpickler[SourceFile]("Sourcefile") {
-    def unpickle(reader: TastyReader, tastyName: TastyName.Table) = {
-      val TastyName.Simple(sourceName) = tastyName(reader.readNameRef())
-      new SourceFile(sourceName.toString, Seq())
-    }
-  }
-
   class TreeSectionUnpickler extends SectionUnpickler[TreeUnpickler]("ASTs") {
     def unpickle(reader: TastyReader, tastyName: TastyName.Table) =
       new TreeUnpickler(reader, tastyName)
@@ -41,27 +33,24 @@ object DottyUnpickler {
  */
 class DottyUnpickler(bytes: Array[Byte]) extends ClassfileParser.Embedded {
   import tpd._
+  import DottyUnpickler._
 
   val unpickler = new TastyUnpickler(bytes)
   private val treeUnpickler = unpickler.unpickle(new TreeSectionUnpickler).get
-  private val source = unpickler.unpickle(new SourceFileUnpickler).getOrElse(NoSource)
 
   /** 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])(implicit ctx: Context): Unit = {
+  def enter(roots: Set[SymDenotation])(implicit ctx: Context): Unit =
     treeUnpickler.enterTopLevel(roots)
-    if (source.exists)
-      for (root <- roots) root.addAnnotation(Annotation.makeSourceFile(source.path))
-  }
 
   /** The unpickled trees, and the source file they come from
    *  @param readPositions if true, trees get decorated with position information.
    */
-  def body(readPositions: Boolean = false)(implicit ctx: Context): (List[Tree], SourceFile) = {
+  def body(readPositions: Boolean = false)(implicit ctx: Context): List[Tree] = {
     if (readPositions)
       for ((totalRange, positions) <- unpickler.unpickle(new PositionsSectionUnpickler))
         treeUnpickler.usePositions(totalRange, positions)
-    (treeUnpickler.unpickle(), source)
+    treeUnpickler.unpickle()
   }
 }

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

@@ -184,8 +184,6 @@ Note: Tree tags are grouped into 5 categories that determine what follows, and t
   Category 4 (tags 112-127):  tag Nat AST
   Category 5 (tags 128-255):  tag Length <payload>
 
-Standard Section: "Sourcefile" sourcefile_NameRef
-
 Standard Section: "Positions" sourceLength_Nat Assoc*
 
   Assoc         = addr_Delta offset_Delta offset_Delta?

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

@@ -11,7 +11,6 @@ import Periods._
 import Phases._
 import Symbols._
 import Flags.Module
-import util.SourceFile
 import collection.mutable
 
 /** This phase pickles trees */
@@ -48,8 +47,6 @@ class Pickler extends Phase {
       treePkl.pickle(tree :: Nil)
       pickler.addrOfTree = treePkl.buf.addrOfTree
       pickler.addrOfSym = treePkl.addrOfSym
-      if (unit.source.exists)
-        pickleSourcefile(pickler, unit.source)
       if (tree.pos.exists)
         new PositionPickler(pickler, treePkl.buf.addrOfTree).picklePositions(tree :: Nil, tree.pos)
 
@@ -65,12 +62,6 @@ class Pickler extends Phase {
     }
   }
 
-  private def pickleSourcefile(pickler: TastyPickler, source: SourceFile): Unit = {
-    val buf = new TastyBuffer(10)
-    pickler.newSection("Sourcefile", buf)
-    buf.writeNat(pickler.nameBuffer.nameIndex(source.file.path).index)
-  }
-
   override def runOn(units: List[CompilationUnit])(implicit ctx: Context): List[CompilationUnit] = {
     val result = super.runOn(units)
     if (ctx.settings.YtestPickler.value)
@@ -89,16 +80,16 @@ class Pickler extends Phase {
       }
     pickling.println("************* entered toplevel ***********")
     for ((cls, unpickler) <- unpicklers) {
-      val (unpickled, source) = unpickler.body(readPositions = true)
-      testSame(i"$unpickled%\n%", beforePickling(cls), cls, source)
+      val unpickled = unpickler.body(readPositions = true)
+      testSame(i"$unpickled%\n%", beforePickling(cls), cls)
     }
   }
 
-  private def testSame(unpickled: String, previous: String, cls: ClassSymbol, source: SourceFile)(implicit ctx: Context) =
+  private def testSame(unpickled: String, previous: String, cls: ClassSymbol)(implicit ctx: Context) =
     if (previous != unpickled) {
       output("before-pickling.txt", previous)
       output("after-pickling.txt", unpickled)
-      ctx.error(s"""pickling difference for ${cls.fullName} in $source, for details:
+      ctx.error(s"""pickling difference for ${cls.fullName} in ${cls.sourceFile}, for details:
                    |
                    |  diff before-pickling.txt after-pickling.txt""".stripMargin)
     }

src/dotty/tools/dotc/transform/PostTyper.scala

@@ -36,6 +36,8 @@ import Symbols._, TypeUtils._
  *
  *  (8) Replaces self references by name with `this`
  *
+ *  (9) Adds SourceFile annotations to all top-level classes and objects
+ *
  *  The reason for making this a macro transform is that some functions (in particular
  *  super and protected accessors and instantiation checks) are naturally top-down and
  *  don't lend themselves to the bottom-up approach of a mini phase. The other two functions
@@ -224,7 +226,11 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
           transformMemberDef(tree)
           val sym = tree.symbol
           val tree1 =
-            if (sym.isClass) tree
+            if (sym.isClass) {
+              if (sym.owner.is(Package) && ctx.compilationUnit.source.exists)
+                sym.addAnnotation(Annotation.makeSourceFile(ctx.compilationUnit.source.file.path))
+              tree
+            }
             else {
               Checking.typeChecker.traverse(tree.rhs)
               cpy.TypeDef(tree)(rhs = TypeTree(tree.symbol.info))