Closing soundness hole in variance checking.

See SI-5060.  Review by odersky.

3 files changed, 37 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 3b9cf88a00..b3e1e3feb8 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -762,6 +762,9 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
 
       /** Validate variance of info of symbol `base` */
       private def validateVariance(base: Symbol) {
+        // A flag for when we're in a refinement, meaning method parameter types
+        // need to be checked.
+        var inRefinement = false
 
         def varianceString(variance: Int): String =
           if (variance == 1) "covariant"
@@ -845,12 +848,17 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
             validateVariances(parents, variance)
           case RefinedType(parents, decls) =>
             validateVariances(parents, variance)
+            val saved = inRefinement
+            inRefinement = true
             for (sym <- decls)
               validateVariance(sym.info, if (sym.isAliasType) NoVariance else variance)
+            inRefinement = saved
           case TypeBounds(lo, hi) =>
             validateVariance(lo, -variance)
             validateVariance(hi, variance)
           case MethodType(formals, result) =>
+            if (inRefinement)
+              validateVariances(formals map (_.tpe), -variance)
             validateVariance(result, variance)
           case NullaryMethodType(result) =>
             validateVariance(result, variance)
@@ -887,9 +895,10 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
           // ModuleDefs need not be considered because they have been eliminated already
           case ValDef(_, _, _, _) =>
             validateVariance(tree.symbol)
-          case DefDef(_, _, tparams, vparamss, tpt, rhs) =>
+          case DefDef(_, _, tparams, vparamss, _, _) =>
             validateVariance(tree.symbol)
-            traverseTrees(tparams); traverseTreess(vparamss)
+            traverseTrees(tparams)
+            traverseTreess(vparamss)
           case Template(_, _, _) =>
             super.traverse(tree)
           case _ =>
diff --git a/test/files/neg/t5060.check b/test/files/neg/t5060.check
new file mode 100644
index 0000000000..ab860c9d5b
--- /dev/null
+++ b/test/files/neg/t5060.check
@@ -0,0 +1,7 @@
+t5060.scala:2: error: covariant type T occurs in contravariant position in type => Object with ScalaObject{def contains(x: T): Unit} of value foo0
+  val foo0 = {
+      ^
+t5060.scala:6: error: covariant type T occurs in contravariant position in type => Object with ScalaObject{def contains(x: T): Unit} of method foo1
+  def foo1 = {
+      ^
+two errors found
diff --git a/test/files/neg/t5060.scala b/test/files/neg/t5060.scala
new file mode 100644
index 0000000000..4d934a9a16
--- /dev/null
+++ b/test/files/neg/t5060.scala
@@ -0,0 +1,19 @@
+class A[+T] {
+  val foo0 = {
+    class AsVariantAsIWantToBe { def contains(x: T) = () }
+    new AsVariantAsIWantToBe
+  }
+  def foo1 = {
+    class VarianceIsTheSpiceOfTypes { def contains(x: T) = () }
+    new VarianceIsTheSpiceOfTypes
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val xs: A[String] = new A[String]
+    println(xs.foo0 contains "abc")
+    println((xs: A[Any]).foo0 contains 5)
+    // java.lang.NoSuchMethodException: A$AsVariantAsIWantToBe$1.contains(java.lang.String)
+  }
+}