Merge pull request #11126 from dotty-staging/fix-8022

Fix #8022: Refactor MoveStatics

Author: odersky

compiler/src/dotty/tools/dotc/reporting/messages.scala

@@ -1943,7 +1943,7 @@ import transform.SymUtils._
   }
 
   class StaticFieldsOnlyAllowedInObjects(member: Symbol)(using Context) extends SyntaxMsg(StaticFieldsOnlyAllowedInObjectsID) {
-    def msg = em"${hl("@static")} $member in ${member.owner} must be defined inside an ${hl("object")}."
+    def msg = em"${hl("@static")} $member in ${member.owner} must be defined inside a static ${hl("object")}."
     def explain =
       em"${hl("@static")} members are only allowed inside objects."
   }

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

@@ -34,7 +34,7 @@ class CheckStatic extends MiniPhase {
     var hadNonStaticField = false
     for (defn <- defns)
       if (defn.symbol.isScalaStatic) {
-        if (!ctx.owner.is(Module))
+        if (!ctx.owner.isStaticOwner)
           report.error(StaticFieldsOnlyAllowedInObjects(defn.symbol), defn.srcPos)
           defn.symbol.resetFlag(JavaStatic)
 
@@ -59,23 +59,6 @@ class CheckStatic extends MiniPhase {
 
     tree
   }
-
-  override def transformSelect(tree: tpd.Select)(using Context): tpd.Tree =
-    if (tree.symbol.hasAnnotation(defn.ScalaStaticAnnot)) {
-      val symbolWhitelist = tree.symbol.ownersIterator.flatMap(x => if (x.is(Flags.Module)) List(x, x.companionModule) else List(x)).toSet
-      def isSafeQual(t: Tree): Boolean = // follow the desugared paths created by typer
-        t match {
-          case t: This => true
-          case t: Select => isSafeQual(t.qualifier) && symbolWhitelist.contains(t.symbol)
-          case t: Ident => symbolWhitelist.contains(t.symbol)
-          case t: Block => t.stats.forall(tpd.isPureExpr) && isSafeQual(t.expr)
-          case _ => false
-        }
-      if (isSafeQual(tree.qualifier))
-        ref(tree.symbol)
-      else tree
-    }
-    else tree
 }
 
 object CheckStatic {

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

@@ -1,26 +1,29 @@
-package dotty.tools.dotc.transform
+package dotty.tools.dotc
+package transform
 
-import dotty.tools.dotc.ast.{Trees, tpd}
-import dotty.tools.dotc.core.Annotations.Annotation
-import dotty.tools.dotc.core.Contexts._
-import dotty.tools.dotc.core.DenotTransformers.SymTransformer
-import dotty.tools.dotc.core.SymDenotations.SymDenotation
-import dotty.tools.dotc.core.NameOps._
-import dotty.tools.dotc.core.Flags
-import dotty.tools.dotc.core.Names.Name
-import dotty.tools.dotc.core.StdNames.nme
-import dotty.tools.dotc.core.Symbols._
-import dotty.tools.dotc.core.Types.MethodType
-import dotty.tools.dotc.transform.MegaPhase.MiniPhase
+import core._
+import Flags._
+import Contexts._
+import Symbols._
+import Decorators._
+import DenotTransformers.SymTransformer
+import Types.MethodType
+import Annotations.Annotation
+import SymDenotations.SymDenotation
+import Names.Name
+import StdNames.nme
+import NameOps._
 
-object MoveStatics {
-  val name: String = "moveStatic"
-}
+import reporting._
+import ast._
+
+import SymUtils._
+import MegaPhase._
 
 /** Move static methods from companion to the class itself */
 class MoveStatics extends MiniPhase with SymTransformer {
+  import ast.tpd._
 
-  import tpd._
   override def phaseName: String = MoveStatics.name
 
   def transformSym(sym: SymDenotation)(using Context): SymDenotation =
@@ -38,8 +41,6 @@ class MoveStatics extends MiniPhase with SymTransformer {
       val pairs = classes.groupBy(_.symbol.name.stripModuleClassSuffix).asInstanceOf[Map[Name, List[TypeDef]]]
 
       def rebuild(orig: TypeDef, newBody: List[Tree]): Tree = {
-        if (orig eq null) return EmptyTree
-
         val staticFields = newBody.filter(x => x.isInstanceOf[ValDef] && x.symbol.hasAnnotation(defn.ScalaStaticAnnot)).asInstanceOf[List[ValDef]]
         val newBodyWithStaticConstr =
           if (staticFields.nonEmpty) {
@@ -61,21 +62,30 @@ class MoveStatics extends MiniPhase with SymTransformer {
         assert(companion != module)
         if (!module.symbol.is(Flags.Module)) move(companion, module)
         else {
-          val allMembers =
-            (if (companion != null) {companion.rhs.asInstanceOf[Template].body} else Nil) ++
-            module.rhs.asInstanceOf[Template].body
-          val (newModuleBody, newCompanionBody) = allMembers.partition(x => {assert(x.symbol.exists); x.symbol.owner == module.symbol})
-          Trees.flatten(rebuild(companion, newCompanionBody) :: rebuild(module, newModuleBody) :: Nil)
+          val moduleTmpl = module.rhs.asInstanceOf[Template]
+          val companionTmpl = companion.rhs.asInstanceOf[Template]
+          val (staticDefs, remainingDefs) = moduleTmpl.body.partition {
+            case memberDef: MemberDef => memberDef.symbol.isScalaStatic
+            case _ => false
+          }
+
+          rebuild(companion, companionTmpl.body ++ staticDefs) :: rebuild(module, remainingDefs) :: Nil
         }
       }
       val newPairs =
         for ((name, classes) <- pairs)
           yield
-            if (classes.tail.isEmpty)
-              if (classes.head.symbol.is(Flags.Module)) move(classes.head, null)
-              else List(rebuild(classes.head, classes.head.rhs.asInstanceOf[Template].body))
+            if (classes.tail.isEmpty) {
+              val classDef = classes.head
+              val tmpl = classDef.rhs.asInstanceOf[Template]
+              rebuild(classDef, tmpl.body) :: Nil
+            }
             else move(classes.head, classes.tail.head)
       Trees.flatten(newPairs.toList.flatten ++ others)
     }
     else trees
 }
+
+object MoveStatics {
+  val name: String = "moveStatic"
+}

tests/neg/i11100.scala

@@ -0,0 +1,14 @@
+import scala.annotation.static
+
+class C {
+  val a: Int = 3
+  class D
+  object D {
+    @static def foo: Int = a * a // error
+  }
+}
+
+@main
+def Test =
+  val c = new C
+  println(c.D.foo)

tests/run/statics.scala

@@ -1,30 +1,29 @@
 import scala.annotation.static
 
-class Foo{
+class Foo {
   class Bar {
     def qwa =
-     Bar.field
+      Bar.field
          // 0: invokestatic  #31                 // Method Foo$Bar$.field:()I
          // 3: ireturn
   }
   object Bar {
-     @static
      val field = 1
    }
 }
 
-object Foo{
- @static
- def method = 1
+object Foo {
+  @static
+  def method = 1
 
- @static
- val field = 2
+  @static
+  val field = 2
 
- @static
- var mutable = 3
+  @static
+  var mutable = 3
 
- @static
- def accessor = field
+  @static
+  def accessor = field
 }
 
 object Test {
@@ -34,7 +33,7 @@ object Test {
  }
 }
 
-class WithLazies{
+class WithLazies {
   lazy val s = 1
   //         98: getstatic     #30                 // Field WithLazies$.OFFSET$0:J
 }