Case class copy and apply inherit access modifiers from constructor

Fixes scala/bug#7884

Author: Jasper-M

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

@@ -101,14 +101,16 @@ trait Unapplies extends ast.TreeDSL {
     }
   }
 
+  private def applyShouldInheritAccess(mods: Modifiers) = mods.hasFlag(PRIVATE) || (!mods.hasFlag(PROTECTED) && mods.hasAccessBoundary)
+
   /** The module corresponding to a case class; overrides toString to show the module's name
    */
   def caseModuleDef(cdef: ClassDef): ModuleDef = {
     val params = constrParamss(cdef)
     def inheritFromFun = !cdef.mods.hasAbstractFlag && cdef.tparams.isEmpty && (params match {
       case List(ps) if ps.length <= MaxFunctionArity => true
       case _ => false
-    })
+    }) && !applyShouldInheritAccess(constrMods(cdef))
     def createFun = {
       def primaries = params.head map (_.tpt)
       gen.scalaFunctionConstr(primaries, toIdent(cdef), abstractFun = true)
@@ -146,9 +148,20 @@ trait Unapplies extends ast.TreeDSL {
     )
   }
 
+
+  private def constrMods(cdef: ClassDef): Modifiers = treeInfo.firstConstructorMods(cdef.impl.body)
+
   /** The apply method corresponding to a case class
    */
-  def caseModuleApplyMeth(cdef: ClassDef): DefDef = factoryMeth(caseMods, nme.apply, cdef)
+  def caseModuleApplyMeth(cdef: ClassDef): DefDef = {
+    val inheritedMods = constrMods(cdef)
+    val mods =
+      if (applyShouldInheritAccess(inheritedMods))
+        (caseMods | (inheritedMods.flags & PRIVATE)).copy(privateWithin = inheritedMods.privateWithin)
+      else
+        caseMods
+    factoryMeth(mods, nme.apply, cdef)
+  }
 
   /** The unapply method corresponding to a case class
    */
@@ -231,8 +244,9 @@ trait Unapplies extends ast.TreeDSL {
       val classTpe = classType(cdef, tparams)
       val argss = mmap(paramss)(toIdent)
       val body: Tree = New(classTpe, argss)
+      val inheritedMods = constrMods(cdef)
       val copyDefDef = atPos(cdef.pos.focus)(
-        DefDef(Modifiers(SYNTHETIC), nme.copy, tparams, paramss, TypeTree(), body)
+        DefDef(Modifiers(SYNTHETIC | (inheritedMods.flags & AccessFlags), inheritedMods.privateWithin), nme.copy, tparams, paramss, TypeTree(), body)
       )
       Some(copyDefDef)
     }

src/reflect/scala/reflect/internal/TreeInfo.scala

@@ -529,6 +529,12 @@ abstract class TreeInfo {
     case _                                => Nil
   }
 
+  /** The modifiers of the first constructor in `stats`. */
+  def firstConstructorMods(stats: List[Tree]): Modifiers = firstConstructor(stats) match {
+    case DefDef(mods, _, _, _, _, _) => mods
+    case _                           => Modifiers()
+  }
+
   /** The value definitions marked PRESUPER in this statement sequence */
   def preSuperFields(stats: List[Tree]): List[ValDef] =
     stats collect { case vd: ValDef if isEarlyValDef(vd) => vd }

test/files/neg/caseclass_private_constructor.check

@@ -0,0 +1,45 @@
+caseclass_private_constructor.scala:4: error: method apply in object A cannot be accessed in object A
+error after rewriting to A.<apply: error>
+possible cause: maybe a wrong Dynamic method signature?
+  def a1: A = A(1) // error: apply is private
+              ^
+caseclass_private_constructor.scala:5: error: method copy in class A cannot be accessed in A
+  def a2: A = a1.copy(2) // error: copy is private
+                 ^
+caseclass_private_constructor.scala:10: error: method apply in object B cannot be accessed in object B
+error after rewriting to B.<apply: error>
+possible cause: maybe a wrong Dynamic method signature?
+  def b1: B = B(1) // error: apply is private
+              ^
+caseclass_private_constructor.scala:11: error: method copy in class B cannot be accessed in B
+  def b2: B = b1.copy(2) // error: copy is private
+                 ^
+caseclass_private_constructor.scala:22: error: method apply in object C cannot be accessed in object qualified_private.C
+error after rewriting to qualified_private.C.<apply: error>
+possible cause: maybe a wrong Dynamic method signature?
+  def c1: C = C(1) // error: apply is private
+              ^
+caseclass_private_constructor.scala:23: error: method copy in class C cannot be accessed in qualified_private.C
+  def c2: C = c1.copy(2) // error: copy is private
+                 ^
+caseclass_private_constructor.scala:25: error: method apply in object D cannot be accessed in object qualified_private.D
+error after rewriting to qualified_private.D.<apply: error>
+possible cause: maybe a wrong Dynamic method signature?
+  def d1: D = D(1) // error: apply is private
+              ^
+caseclass_private_constructor.scala:26: error: method copy in class D cannot be accessed in qualified_private.D
+  def d2: D = d1.copy(2) // error: copy is private
+                 ^
+caseclass_private_constructor.scala:32: error: method copy in class E cannot be accessed in E
+ Access to protected method copy not permitted because
+ enclosing object ETest is not a subclass of
+ class E where target is defined
+  def e2: E = e2.copy(2) // error: copy is protected
+                 ^
+caseclass_private_constructor.scala:41: error: method copy in class F cannot be accessed in qualified_protected.F
+ Access to protected method copy not permitted because
+ enclosing object QProtTest is not a subclass of
+ class F in object qualified_protected where target is defined
+  def f2: F = f2.copy(2) // error: copy is protected
+                 ^
+10 errors found

test/files/neg/caseclass_private_constructor.scala

@@ -0,0 +1,42 @@
+case class A private (i: Int)
+object A
+object ATest {
+  def a1: A = A(1) // error: apply is private
+  def a2: A = a1.copy(2) // error: copy is private
+}
+
+case class B private (i: Int) // no user-defined companion object, should compile
+object BTest {
+  def b1: B = B(1) // error: apply is private
+  def b2: B = b1.copy(2) // error: copy is private
+}
+
+object qualified_private {
+  case class C private[qualified_private] (i: Int)
+  object C
+
+  case class D private[qualified_private] (i: Int) // no user-defined companion object, should compile
+}
+object QPrivTest {
+  import qualified_private._
+  def c1: C = C(1) // error: apply is private
+  def c2: C = c1.copy(2) // error: copy is private
+
+  def d1: D = D(1) // error: apply is private
+  def d2: D = d1.copy(2) // error: copy is private
+}
+
+case class E protected (i: Int)
+object ETest {
+  def e1: E = E(1)
+  def e2: E = e2.copy(2) // error: copy is protected
+}
+
+object qualified_protected {
+  case class F protected[qualified_protected] (i: Int)
+}
+object QProtTest {
+  import qualified_protected._
+  def f1: F = F(1)
+  def f2: F = f2.copy(2) // error: copy is protected
+}

test/files/pos/caseclass_private_constructor.scala

@@ -0,0 +1,47 @@
+case class A private (i: Int)
+object A {
+  def a = A(1).copy(2) // apply and copy are accessible in companion
+}
+
+case class B private (i: Int) { // no user-defined companion object, should compile
+  def b = B(1).copy(2) // apply and copy are accessible
+}
+
+object qualified_private {
+  case class A private[qualified_private] (i: Int)
+  object A {
+    def a = A(1).copy(2) // apply and copy are accessible in companion
+  }
+
+  def a = A(1).copy(2) // apply and copy are accessible in qualified_private object
+
+  case class B private[qualified_private] (i: Int) { // no user-defined companion object, should compile
+    def b = B(1).copy(2) // apply and copy are accessible
+  }
+
+  def b = B(1).copy(2) // apply and copy are accessible in qualified_private object
+}
+
+case class C protected (i: Int)
+class CSub extends C(1) {
+  def c = copy(2) // copy is accessible in subclass
+}
+object CTest {
+  def c = C(1) // apply is public
+}
+
+object qualified_protected {
+  case class C protected[qualified_protected] (i: Int)
+  class CSub extends C(1) {
+    def c = copy(2) // copy is accessible in subclass
+  }
+  object CTest {
+    def c = C(1) // apply is public
+    def checkExtendsFunction: Int => C = C // companion extends (Int  => C)
+  }
+
+  def c = C(1).copy(2)
+}
+object CQualifiedTest {
+  def c = qualified_protected.C(1) // apply is public
+}

test/files/pos/t6734.scala

@@ -6,7 +6,7 @@ package object p
 
 package p {
   import scala.concurrent.Future
-  case class C private[p] (value: Future[Int])   // private to avoid rewriting C.apply to new C
+  case class C protected[p] (value: Future[Int])   // protected to avoid rewriting C.apply to new C
 }
 
 package client {

test/files/pos/userdefined_apply.scala

@@ -1,27 +1,27 @@
 // NOTE: the companion inherits a public apply method from Function1!
-case class NeedsCompanion private (x: Int)
+case class NeedsCompanion protected (x: Int)
 
 object ClashNoSig { // ok
   private def apply(x: Int) = if (x > 0) new ClashNoSig(x) else ???
 }
-case class ClashNoSig private (x: Int)
+case class ClashNoSig protected (x: Int)
 
 
 object Clash {
   private def apply(x: Int) = if (x > 0) new Clash(x) else ???
 }
-case class Clash private (x: Int)
+case class Clash protected (x: Int)
 
 object ClashSig {
   private def apply(x: Int): ClashSig = if (x > 0) new ClashSig(x) else ???
 }
-case class ClashSig private (x: Int)
+case class ClashSig protected (x: Int)
 
 object ClashOverload {
   private def apply(x: Int): ClashOverload = if (x > 0) new ClashOverload(x) else apply("")
   def apply(x: String): ClashOverload = ???
 }
-case class ClashOverload private (x: Int)
+case class ClashOverload protected (x: Int)
 
 object NoClashSig {
   private def apply(x: Boolean): NoClashSig = if (x) NoClashSig(1) else ???
@@ -33,7 +33,7 @@ object NoClashOverload {
   private def apply(x: Boolean): NoClashOverload = if (x) NoClashOverload(1) else apply("")
   def apply(x: String): NoClashOverload = ???
 }
-case class NoClashOverload private (x: Int)
+case class NoClashOverload protected (x: Int)
 
 
 
@@ -43,12 +43,12 @@ class BaseNCP[T] {
 }
 
 object NoClashPoly extends BaseNCP[Boolean]
-case class NoClashPoly private(x: Int)
+case class NoClashPoly protected(x: Int)
 
 
 class BaseCP[T] {
   // error: overloaded method apply needs result type
   def apply(x: T): ClashPoly = if (???) ClashPoly(1) else ???
 }
 object ClashPoly extends BaseCP[Int]
-case class ClashPoly private(x: Int)
+case class ClashPoly protected(x: Int)

test/files/run/t9425.scala

@@ -1,8 +1,8 @@
-class C { case class Foo private (x: Int); Foo.apply(0) }
+class C { case class Foo protected (x: Int); Foo.apply(0) }
 
 object Test {
   def test(c: C) = {import c.Foo; Foo.apply(0)}
   def main(args: Array[String]): Unit = {
     test(new C)
-  }  
+  }
 }

test/files/run/t9546e.scala

@@ -1,5 +1,5 @@
-case class A private (x: Int)
-case class B private (x: Int)(y: Int)
+case class A protected (x: Int)
+case class B protected (x: Int)(y: Int)
 
 class C {
   def f = A(1)