Merge pull request #6058 from hrhino/bugfix/t6934

Classes can access `protected static` members of their Java superclasses

Author: adriaanm

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

@@ -1,5 +1,5 @@
 /* NSC -- new Scala compiler
- * Copyright 2005-2013 LAMP/EPFL
+ * Copyright 2005-2017 LAMP/EPFL
  * @author  Martin Odersky
  */
 
@@ -647,10 +647,16 @@ trait Contexts { self: Analyzer =>
     // Accessibility checking
     //
 
-    /** Is `sub` a subclass of `base` or a companion object of such a subclass? */
+    /** True iff...
+      * - `sub` is a subclass of `base`
+      * - `sub` is the module class of a companion of a subclass of `base`
+      * - `base` is a Java-defined module class (containing static members),
+      *   and `sub` is a subclass of its companion class. (see scala/bug#6394)
+      */
     private def isSubClassOrCompanion(sub: Symbol, base: Symbol) =
       sub.isNonBottomSubClass(base) ||
-    sub.isModuleClass && sub.linkedClassOfClass.isNonBottomSubClass(base)
+        (sub.isModuleClass && sub.linkedClassOfClass.isNonBottomSubClass(base)) ||
+        (base.isJavaDefined && base.isModuleClass && sub.isNonBottomSubClass(base.linkedClassOfClass))
 
     /** Return the closest enclosing context that defines a subclass of `clazz`
      *  or a companion object thereof, or `NoContext` if no such context exists.
@@ -702,10 +708,10 @@ trait Contexts { self: Analyzer =>
         val c = enclosingSubClassContext(sym.owner)
         if (c == NoContext)
           lastAccessCheckDetails =
-            "\n Access to protected "+target+" not permitted because"+
-            "\n "+"enclosing "+this.enclClass.owner+
-            this.enclClass.owner.locationString+" is not a subclass of "+
-            "\n "+sym.owner+sym.owner.locationString+" where target is defined"
+            sm"""
+                | Access to protected $target not permitted because
+                | enclosing ${this.enclClass.owner}${this.enclClass.owner.locationString} is not a subclass of
+                | ${sym.owner}${sym.owner.locationString} where target is defined"""
         c != NoContext &&
         {
           target.isType || { // allow accesses to types from arbitrary subclasses fixes #4737
@@ -715,9 +721,10 @@ trait Contexts { self: Analyzer =>
               isSubClassOrCompanion(pre.widen.typeSymbol, c.owner.linkedClassOfClass)
             if (!res)
               lastAccessCheckDetails =
-                "\n Access to protected "+target+" not permitted because"+
-                "\n prefix type "+pre.widen+" does not conform to"+
-                "\n "+c.owner+c.owner.locationString+" where the access take place"
+                sm"""
+                    | Access to protected $target not permitted because
+                    | prefix type ${pre.widen} does not conform to
+                    | ${c.owner}${c.owner.locationString} where the access takes place"""
               res
           }
         }

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

@@ -1398,13 +1398,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
       newNonClassSymbol(name, pos, newFlags)
 
     /**
-     * The class or term up to which this symbol is accessible, or RootClass if it is public. As
-     * Java protected statics are otherwise completely inaccessible in Scala, they are treated as
-     * public (scala/bug#1806).
+     * The class or term up to which this symbol is accessible, or else
+     * `enclosingRootClass` if it is public.
      */
     def accessBoundary(base: Symbol): Symbol = {
       if (hasFlag(PRIVATE) || isLocalToBlock) owner
-      else if (hasAllFlags(PROTECTED | STATIC | JAVA)) enclosingRootClass
       else if (hasAccessBoundary && !phase.erasedTypes) privateWithin // Phase check needed? See comment in Context.isAccessible.
       else if (hasFlag(PROTECTED)) base
       else enclosingRootClass

test/files/neg/t3871b.check

@@ -4,7 +4,7 @@ t3871b.scala:61: error: not found: value protOT
 t3871b.scala:77: error: method prot in class A cannot be accessed in E.this.A
  Access to protected method prot not permitted because
  prefix type E.this.A does not conform to
- class B in class E where the access take place
+ class B in class E where the access takes place
       a.prot    // not allowed, prefix type `A` does not conform to `B`
         ^
 t3871b.scala:79: error: value protT is not a member of E.this.B
@@ -19,7 +19,7 @@ t3871b.scala:81: error: value protT is not a member of E.this.A
 t3871b.scala:91: error: method prot in class A cannot be accessed in E.this.A
  Access to protected method prot not permitted because
  prefix type E.this.A does not conform to
- object B in class E where the access take place
+ object B in class E where the access takes place
       a.prot    // not allowed
         ^
 t3871b.scala:93: error: value protT is not a member of E.this.B

test/files/neg/t3934.check

@@ -7,7 +7,7 @@ t3934.scala:15: error: method f2 in class J cannot be accessed in test.J
 t3934.scala:20: error: method f2 in class J cannot be accessed in test.J
  Access to protected method f2 not permitted because
  prefix type test.J does not conform to
- class S2 in package nest where the access take place
+ class S2 in package nest where the access takes place
   def g2(x: J) = x.f2()
                    ^
 two errors found

test/files/neg/t4541.check

@@ -1,7 +1,7 @@
 t4541.scala:11: error: variable data in class Sparse cannot be accessed in Sparse[Int]
  Access to protected variable data not permitted because
  prefix type Sparse[Int] does not conform to
- class Sparse$mcI$sp where the access take place
+ class Sparse$mcI$sp where the access takes place
     that.data
          ^
 one error found

test/files/neg/t4541b.check

@@ -1,7 +1,7 @@
 t4541b.scala:13: error: variable data in class SparseArray cannot be accessed in SparseArray[Int]
  Access to protected variable data not permitted because
  prefix type SparseArray[Int] does not conform to
- class SparseArray$mcI$sp where the access take place
+ class SparseArray$mcI$sp where the access takes place
     use(that.data.clone)
              ^
 one error found

test/files/neg/t6934.check

@@ -0,0 +1,7 @@
+ScalaMain.scala:6: error: variable STATIC_PROTECTED_FIELD in object JavaClass cannot be accessed in object test.JavaClass
+ Access to protected variable STATIC_PROTECTED_FIELD not permitted because
+ enclosing object ScalaMain in package test2 is not a subclass of
+ object JavaClass in package test where target is defined
+    val a = test.JavaClass.STATIC_PROTECTED_FIELD
+                           ^
+one error found

test/files/neg/t6934/JavaClass.java

@@ -0,0 +1,8 @@
+package test;
+
+public class JavaClass {
+
+    protected static int STATIC_PROTECTED_FIELD = 4;
+
+}
+

test/files/neg/t6934/ScalaClass.scala

@@ -0,0 +1,6 @@
+package test
+
+class ScalaClass {
+  /* double-checking that we can still do this */
+  def hmm = JavaClass.STATIC_PROTECTED_FIELD
+}

test/files/neg/t6934/ScalaMain.scala

@@ -0,0 +1,9 @@
+package test2
+
+object ScalaMain {
+
+  def main(args: Array[String]) {
+    val a = test.JavaClass.STATIC_PROTECTED_FIELD
+  }
+
+}