Made Symbol#associatedFile always return non-null

So we don't have to clutter everything with null checks.

Author: paulp

src/compiler/scala/tools/nsc/doc/base/MemberLookupBase.scala

@@ -88,7 +88,7 @@ trait MemberLookupBase {
         // (4) if we still haven't found anything, create a tooltip
         Tooltip(query)
       case List(l) => l
-      case links => 
+      case links =>
         val chosen = chooseLink(links)
         def linkToString(link: LinkTo) = {
           val chosenInfo =
@@ -203,11 +203,11 @@ trait MemberLookupBase {
   def findExternalLink(sym: Symbol, name: String): Option[LinkToExternal] = {
     val sym1 =
       if (sym == AnyClass || sym == AnyRefClass || sym == AnyValClass || sym == NothingClass) ListClass
-      else if (sym.isPackage) 
+      else if (sym.isPackage)
         /* Get package object which has associatedFile ne null */
         sym.info.member(newTermName("package"))
       else sym
-    Option(sym1.associatedFile) flatMap (_.underlyingSource) flatMap { src =>
+    sym1.associatedFile.underlyingSource flatMap { src =>
       val path = src.path
       settings.extUrlMapping get path map { url =>
         LinkToExternal(name, url + "#" + name)

src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala

@@ -12,7 +12,7 @@ import scala.tools.nsc.util.{ ClassPath }
 import classfile.ClassfileParser
 import scala.reflect.internal.MissingRequirementError
 import scala.reflect.internal.util.Statistics
-import scala.tools.nsc.io.{ AbstractFile }
+import scala.reflect.io.{ AbstractFile, NoAbstractFile }
 
 /** This class ...
  *
@@ -250,7 +250,7 @@ abstract class SymbolLoaders {
     protected def doComplete(root: Symbol) {
       val start = if (Statistics.canEnable) Statistics.startTimer(classReadNanos) else null
       classfileParser.parse(classfile, root)
-      if (root.associatedFile eq null) {
+      if (root.associatedFile eq NoAbstractFile) {
         root match {
           // In fact, the ModuleSymbol forwards its setter to the module class
           case _: ClassSymbol | _: ModuleSymbol =>

src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala

@@ -13,6 +13,7 @@ import scala.reflect.runtime.ReflectionUtils
 import scala.reflect.macros.runtime.AbortMacroException
 import scala.util.control.NonFatal
 import scala.tools.nsc.util.stackTraceString
+import scala.reflect.io.NoAbstractFile
 
 trait ContextErrors {
   self: Analyzer =>
@@ -642,7 +643,7 @@ trait ContextErrors {
         val addendums = List(
           if (sym0.associatedFile eq sym1.associatedFile)
             Some("conflicting symbols both originated in file '%s'".format(sym0.associatedFile.canonicalPath))
-          else if ((sym0.associatedFile ne null) && (sym1.associatedFile ne null))
+          else if ((sym0.associatedFile ne NoAbstractFile) && (sym1.associatedFile ne NoAbstractFile))
             Some("conflicting symbols originated in files '%s' and '%s'".format(sym0.associatedFile.canonicalPath, sym1.associatedFile.canonicalPath))
           else None ,
           if (isBug) Some("Note: this may be due to a bug in the compiler involving wildcards in package objects") else None

src/reflect/scala/reflect/internal/Symbols.scala

@@ -11,7 +11,7 @@ import scala.collection.mutable.ListBuffer
 import util.{ Statistics, shortClassOfInstance }
 import Flags._
 import scala.annotation.tailrec
-import scala.reflect.io.AbstractFile
+import scala.reflect.io.{ AbstractFile, NoAbstractFile }
 
 trait Symbols extends api.Symbols { self: SymbolTable =>
   import definitions._
@@ -1916,8 +1916,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
          (this.rawInfo ne NoType)
       && (this.effectiveOwner == that.effectiveOwner)
       && (   !this.effectiveOwner.isPackageClass
-          || (this.associatedFile eq null)
-          || (that.associatedFile eq null)
+          || (this.associatedFile eq NoAbstractFile)
+          || (that.associatedFile eq NoAbstractFile)
           || (this.associatedFile.path == that.associatedFile.path)  // Cheap possibly wrong check, then expensive normalization
           || (this.associatedFile.canonicalPath == that.associatedFile.canonicalPath)
          )
@@ -2176,17 +2176,16 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       case _      => NoSymbol
     }
 
-    /** Desire to re-use the field in ClassSymbol which stores the source
-     *  file to also store the classfile, but without changing the behavior
-     *  of sourceFile (which is expected at least in the IDE only to
-     *  return actual source code.) So sourceFile has classfiles filtered out.
-     */
-    private def sourceFileOnly(file: AbstractFile): AbstractFile =
-      if ((file eq null) || (file.path endsWith ".class")) null else file
-
-    final def sourceFile: AbstractFile = sourceFileOnly(associatedFile)
+    // Desire to re-use the field in ClassSymbol which stores the source
+    // file to also store the classfile, but without changing the behavior
+    // of sourceFile (which is expected at least in the IDE only to
+    // return actual source code.) So sourceFile has classfiles filtered out.
+    final def sourceFile: AbstractFile =
+      if ((associatedFile eq NoAbstractFile) || (associatedFile.path endsWith ".class")) null else associatedFile
 
-    /** Overridden in ModuleSymbols to delegate to the module class. */
+    /** Overridden in ModuleSymbols to delegate to the module class.
+     *  Never null; if there is no associated file, returns NoAbstractFile.
+     */
     def associatedFile: AbstractFile = enclosingTopLevelClass.associatedFile
     def associatedFile_=(f: AbstractFile) { abort("associatedFile_= inapplicable for " + this) }
 
@@ -2932,7 +2931,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       if (c.isOverloaded) c.alternatives.head else c
     }
 
-    override def associatedFile = if (owner.isPackageClass) _associatedFile else super.associatedFile
+    override def associatedFile = (
+      if (!owner.isPackageClass) super.associatedFile
+      else if (_associatedFile eq null) NoAbstractFile // guarantee not null, but save cost of initializing the var
+      else _associatedFile
+    )
     override def associatedFile_=(f: AbstractFile) { _associatedFile = f }
 
     override def reset(completer: Type): this.type = {
@@ -2981,9 +2984,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
         clone.typeOfThis = typeOfThis
         clone.thisSym setName thisSym.name
       }
-      if (_associatedFile ne null)
-        clone.associatedFile = _associatedFile
-
+      clone.associatedFile = _associatedFile
       clone
     }
 
@@ -3169,7 +3170,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     override def enclosingTopLevelClass: Symbol = this
     override def enclosingPackageClass: Symbol = this
     override def enclMethod: Symbol = this
-    override def associatedFile = null
+    override def associatedFile = NoAbstractFile
     override def ownerChain: List[Symbol] = List()
     override def ownersIterator: Iterator[Symbol] = Iterator.empty
     override def alternatives: List[Symbol] = List()