Add compilation unit info to ClassSymbol (#19010)

- [x] Add `compilationUnitInfo` to class symbols
- [x] Move `assocFile` into `CompilationUnitInfo`
- [x] Add tasty version to `CompilationUnitInfo`
- [x] Include #18925 to have test for `CompilationUnitInfo`
- [x] Add explicit nulls to `CompilationUnitInfo`

Fixes  #18933

compiler/src/dotty/tools/dotc/core/CompilationUnitInfo.scala

@@ -0,0 +1,31 @@
+package dotty.tools.dotc.core
+
+import dotty.tools.io.AbstractFile
+import dotty.tools.tasty.TastyVersion
+
+/** Information about the compilation unit of a class symbol.
+  *
+  * @param associatedFile The source or class file from which this class or
+  *                       the class containing this symbol was generated,
+  *                       null if not applicable.
+  * @param tastyVersion   The TASTy version (major, minor, experimental)
+  * @param explicitNulls  This compilation unit has explicit nulls enabled?
+  */
+class CompilationUnitInfo(
+  val associatedFile: AbstractFile,
+  val tastyVersion: Option[TastyVersion],
+  val explicitNulls: Boolean
+) {
+
+  override def toString(): String =
+    s"CompilationUnitInfo($associatedFile, $tastyVersion)"
+}
+
+object CompilationUnitInfo:
+  def apply(assocFile: AbstractFile | Null, explicitNulls: Boolean = false): CompilationUnitInfo | Null =
+    if assocFile == null then null
+    else new CompilationUnitInfo(
+      assocFile,
+      tastyVersion = None,
+      explicitNulls = explicitNulls,
+    )

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1409,7 +1409,7 @@ class Definitions {
           ),
           privateWithin = patch.privateWithin,
           coord = denot.symbol.coord,
-          assocFile = denot.symbol.associatedFile
+          compUnitInfo = denot.symbol.compilationUnitInfo
         )
 
       def makeNonClassSymbol(patch: Symbol) =

compiler/src/dotty/tools/dotc/core/Denotations.scala

@@ -298,14 +298,13 @@ object Denotations {
                        name: Name,
                        site: Denotation = NoDenotation,
                        args: List[Type] = Nil,
-                       source: AbstractFile | Null = null,
                        generateStubs: Boolean = true)
                       (p: Symbol => Boolean)
                       (using Context): Symbol =
       disambiguate(p) match {
         case m @ MissingRef(ownerd, name) if generateStubs =>
           if ctx.settings.YdebugMissingRefs.value then m.ex.printStackTrace()
-          newStubSymbol(ownerd.symbol, name, source)
+          newStubSymbol(ownerd.symbol, name)
         case NoDenotation | _: NoQualifyingRef | _: MissingRef =>
           def argStr = if (args.isEmpty) "" else i" matching ($args%, %)"
           val msg =

compiler/src/dotty/tools/dotc/core/NamerOps.scala

@@ -141,7 +141,7 @@ object NamerOps:
         ConstructorCompanionFlags, ConstructorCompanionFlags,
         constructorCompanionCompleter(cls),
         coord = cls.coord,
-        assocFile = cls.assocFile)
+        compUnitInfo = cls.compUnitInfo)
     companion.moduleClass.registerCompanion(cls)
     cls.registerCompanion(companion.moduleClass)
     companion
@@ -150,7 +150,7 @@ object NamerOps:
     newSymbol(tsym.owner, tsym.name.toTermName,
         ConstructorCompanionFlags | StableRealizable | Method, ExprType(prefix.select(proxy)), coord = tsym.coord)
 
-  /** Add all necesssary constructor proxy symbols for members of class `cls`. This means:
+  /** Add all necessary constructor proxy symbols for members of class `cls`. This means:
    *
    *   - if a member is a class, or type alias, that needs a constructor companion, add one,
    *     provided no member with the same name exists.

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -2588,7 +2588,7 @@ object SymDenotations {
       for (sym <- scope.toList.iterator)
         // We need to be careful to not force the denotation of `sym` here,
         // otherwise it will be brought forward to the current run.
-        if (sym.defRunId != ctx.runId && sym.isClass && sym.asClass.assocFile == file)
+        if (sym.defRunId != ctx.runId && sym.isClass && sym.asClass.compUnitInfo != null && sym.asClass.compUnitInfo.nn.associatedFile == file)
           scope.unlink(sym, sym.lastKnownDenotation.name)
     }
   }

compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala

@@ -24,10 +24,9 @@ import ast.desugar
 
 import parsing.JavaParsers.OutlineJavaParser
 import parsing.Parsers.OutlineParser
-import dotty.tools.tasty.{TastyHeaderUnpickler, UnpickleException, UnpicklerConfig}
+import dotty.tools.tasty.{TastyHeaderUnpickler, UnpickleException, UnpicklerConfig, TastyVersion}
 import dotty.tools.dotc.core.tasty.TastyUnpickler
 
-
 object SymbolLoaders {
   import ast.untpd.*
 
@@ -52,7 +51,7 @@ object SymbolLoaders {
   def enterClass(
       owner: Symbol, name: PreName, completer: SymbolLoader,
       flags: FlagSet = EmptyFlags, scope: Scope = EmptyScope)(using Context): Symbol = {
-    val cls = newClassSymbol(owner, name.toTypeName.unmangleClassName.decode, flags, completer, assocFile = completer.sourceFileOrNull)
+    val cls = newClassSymbol(owner, name.toTypeName.unmangleClassName.decode, flags, completer, compUnitInfo = completer.compilationUnitInfo)
     enterNew(owner, cls, completer, scope)
   }
 
@@ -64,7 +63,7 @@ object SymbolLoaders {
     val module = newModuleSymbol(
       owner, name.toTermName.decode, modFlags, clsFlags,
       (module, _) => completer.proxy.withDecls(newScope).withSourceModule(module),
-      assocFile = completer.sourceFileOrNull)
+      compUnitInfo = completer.compilationUnitInfo)
     enterNew(owner, module, completer, scope)
     enterNew(owner, module.moduleClass, completer, scope)
   }
@@ -213,7 +212,7 @@ object SymbolLoaders {
   /** Load contents of a package
    */
   class PackageLoader(_sourceModule: TermSymbol, classPath: ClassPath) extends SymbolLoader {
-    override def sourceFileOrNull: AbstractFile | Null = null
+    def compilationUnitInfo: CompilationUnitInfo | Null = null
     override def sourceModule(using Context): TermSymbol = _sourceModule
     def description(using Context): String = "package loader " + sourceModule.fullName
 
@@ -317,7 +316,7 @@ abstract class SymbolLoader extends LazyType { self =>
   /** Load source or class file for `root`, return */
   def doComplete(root: SymDenotation)(using Context): Unit
 
-  def sourceFileOrNull: AbstractFile | Null
+  def compilationUnitInfo: CompilationUnitInfo | Null
 
   /** Description of the resource (ClassPath, AbstractFile)
    *  being processed by this loader
@@ -328,7 +327,7 @@ abstract class SymbolLoader extends LazyType { self =>
    *  but provides fresh slots for scope/sourceModule/moduleClass
    */
   def proxy: SymbolLoader = new SymbolLoader {
-    export self.{doComplete, sourceFileOrNull}
+    export self.{doComplete, compilationUnitInfo}
     def description(using Context): String = s"proxy to ${self.description}"
   }
 
@@ -405,7 +404,8 @@ abstract class SymbolLoader extends LazyType { self =>
 
 class ClassfileLoader(val classfile: AbstractFile) extends SymbolLoader {
 
-  override def sourceFileOrNull: AbstractFile | Null = classfile
+  def compilationUnitInfo: CompilationUnitInfo | Null = CompilationUnitInfo(classfile)
+
 
   def description(using Context): String = "class file " + classfile.toString
 
@@ -417,38 +417,55 @@ class ClassfileLoader(val classfile: AbstractFile) extends SymbolLoader {
 
 class TastyLoader(val tastyFile: AbstractFile) extends SymbolLoader {
 
-  override def sourceFileOrNull: AbstractFile | Null = tastyFile
+  private val unpickler: tasty.DottyUnpickler =
+    handleUnpicklingExceptions:
+      val tastyBytes = tastyFile.toByteArray
+      new tasty.DottyUnpickler(tastyBytes) // reads header and name table
+
+  val compilationUnitInfo: CompilationUnitInfo | Null =
+    val tastyHeader = unpickler.unpickler.header
+    val tastyVersion = TastyVersion(
+      tastyHeader.majorVersion,
+      tastyHeader.minorVersion,
+      tastyHeader.experimentalVersion,
+    )
+    val attributes = unpickler.tastyAttributes
+    new CompilationUnitInfo(
+      tastyFile,
+      tastyVersion = Some(tastyVersion),
+      explicitNulls = attributes.explicitNulls,
+    )
 
   def description(using Context): String = "TASTy file " + tastyFile.toString
 
   override def doComplete(root: SymDenotation)(using Context): Unit =
-    try
+    handleUnpicklingExceptions:
+      checkTastyUUID()
       val (classRoot, moduleRoot) = rootDenots(root.asClass)
-      val tastyBytes = tastyFile.toByteArray
-      val unpickler = new tasty.DottyUnpickler(tastyBytes)
       unpickler.enter(roots = Set(classRoot, moduleRoot, moduleRoot.sourceModule))(using ctx.withSource(util.NoSource))
       if mayLoadTreesFromTasty then
         classRoot.classSymbol.rootTreeOrProvider = unpickler
         moduleRoot.classSymbol.rootTreeOrProvider = unpickler
-      checkTastyUUID(tastyFile, tastyBytes)
+
+  private def handleUnpicklingExceptions[T](thunk: =>T): T =
+    try thunk
     catch case e: RuntimeException =>
       val message = e match
         case e: UnpickleException =>
-          i"""TASTy file ${tastyFile.canonicalPath} could not be read, failing with:
-            |  ${Option(e.getMessage).getOrElse("")}"""
+          s"""TASTy file ${tastyFile.canonicalPath} could not be read, failing with:
+            |  ${Option(e.getMessage).getOrElse("")}""".stripMargin
         case _ =>
-          i"""TASTy file ${tastyFile.canonicalPath} is broken, reading aborted with ${e.getClass}
-            |  ${Option(e.getMessage).getOrElse("")}"""
-      if (ctx.debug) e.printStackTrace()
-      throw IOException(message)
+          s"""TASTy file ${tastyFile.canonicalPath} is broken, reading aborted with ${e.getClass}
+            |  ${Option(e.getMessage).getOrElse("")}""".stripMargin
+      throw IOException(message, e)
 
 
-  private def checkTastyUUID(tastyFile: AbstractFile, tastyBytes: Array[Byte])(using Context): Unit =
+  private def checkTastyUUID()(using Context): Unit =
     val classfile =
       val className = tastyFile.name.stripSuffix(".tasty")
       tastyFile.resolveSibling(className + ".class")
     if classfile != null then
-      val tastyUUID = new TastyHeaderUnpickler(TastyUnpickler.scala3CompilerConfig, tastyBytes).readHeader()
+      val tastyUUID = unpickler.unpickler.header.uuid
       new ClassfileTastyUUIDParser(classfile)(ctx).checkTastyUUID(tastyUUID)
     else
       // This will be the case in any of our tests that compile with `-Youtput-only-tasty`
@@ -460,15 +477,15 @@ class TastyLoader(val tastyFile: AbstractFile) extends SymbolLoader {
 
 class SourcefileLoader(val srcfile: AbstractFile) extends SymbolLoader {
   def description(using Context): String = "source file " + srcfile.toString
-  override def sourceFileOrNull: AbstractFile | Null = srcfile
+  def compilationUnitInfo: CompilationUnitInfo | Null = CompilationUnitInfo(srcfile)
   def doComplete(root: SymDenotation)(using Context): Unit =
     ctx.run.nn.lateCompile(srcfile, typeCheck = ctx.settings.YretainTrees.value)
 }
 
 /** A NoCompleter which is also a SymbolLoader. */
 class NoLoader extends SymbolLoader with NoCompleter {
   def description(using Context): String = "NoLoader"
-  override def sourceFileOrNull: AbstractFile | Null = null
+  def compilationUnitInfo: CompilationUnitInfo | Null = null
   override def complete(root: SymDenotation)(using Context): Unit =
     super[NoCompleter].complete(root)
   def doComplete(root: SymDenotation)(using Context): Unit =