Merge pull request scala#4125 from retronym/ticket/8944

SI-8944 A more resiliant naming scheme for case accessors

Author: gkossakowski

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

@@ -359,7 +359,14 @@ trait SyntheticMethods extends ast.TreeDSL {
 
       for (ddef @ DefDef(_, _, _, _, _, _) <- templ.body ; if isRewrite(ddef.symbol)) {
         val original = ddef.symbol
-        val newAcc = deriveMethod(ddef.symbol, name => context.unit.freshTermName(name + "$")) { newAcc =>
+        val i = original.owner.caseFieldAccessors.indexOf(original)
+        def freshAccessorName = {
+          devWarning(s"Unable to find $original among case accessors of ${original.owner}: ${original.owner.caseFieldAccessors}")
+          context.unit.freshTermName(original.name + "$")
+        }
+        def nameSuffixedByParamIndex = original.name.append(nme.CASE_ACCESSOR + "$" + i).toTermName
+        val newName = if (i < 0) freshAccessorName else nameSuffixedByParamIndex
+        val newAcc = deriveMethod(ddef.symbol, name => newName) { newAcc =>
           newAcc.makePublic
           newAcc resetFlag (ACCESSOR | PARAMACCESSOR | OVERRIDE)
           ddef.rhs.duplicate

src/reflect/scala/reflect/internal/StdNames.scala

@@ -111,6 +111,7 @@ trait StdNames {
     val PACKAGE: NameType                      = "package"
     val ROOT: NameType                         = "<root>"
     val SPECIALIZED_SUFFIX: NameType           = "$sp"
+    val CASE_ACCESSOR: NameType                = "$access"
 
     // value types (and AnyRef) are all used as terms as well
     // as (at least) arguments to the @specialize annotation.

test/files/run/t8944/A_1.scala

@@ -0,0 +1 @@
+case class A(private val x: String)

test/files/run/t8944/A_2.scala

@@ -0,0 +1,6 @@
+case class Other(private val x: String) // consume a fresh name suffix
+ 
+// the param accessor will now be called "x$2",
+// whereas the previously compiled client expects it to be called
+// x$1
+case class A(private val x: String)

test/files/run/t8944/Test_1.scala

@@ -0,0 +1,3 @@
+object Test extends App {
+  val A("") = new A("")
+}

test/files/run/t8944b.scala

@@ -0,0 +1,9 @@
+case class A(private var foo: Any) {
+  def m = { def foo = 42 /*will be lamba lifted to `A#foo$1`*/ }
+}
+object Test {
+  def main(args: Array[String]): Unit = {
+    val A("") = new A("")  
+    new A("").m
+  }
+}

test/files/run/t8944c.check

@@ -0,0 +1,5 @@
+private java.lang.Object Foo.ant()
+public java.lang.Object Foo.ant$access$0()
+private scala.collection.Seq Foo.cat()
+public scala.collection.Seq Foo.cat$access$2()
+public java.lang.Object Foo.elk()

test/files/run/t8944c.scala

@@ -0,0 +1,8 @@
+case class Foo[A](private val ant: Any, elk: Any, private val cat: A*)
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    def pred(name: String) = Set("ant", "elk", "cat").exists(name contains _)
+    println(classOf[Foo[_]].getDeclaredMethods.filter(m => pred(m.getName)).sortBy(_.getName).mkString("\n"))  
+  }
+}