Merge remote-tracking branch 'origin/2.10.x' into pr/merge-2.10

* origin/2.10.x:
  SI-6969, mishandling of SoftReferences in method cache.
  SI-7011 Fix finding constructor type in captured var definitions
  SI-6987 Tests fsc verbose output
  SI-6987 Fixes fsc compile server verbose output
  SI-6231 Report unsupported free var capture by a trait.
  SI-6666 Restrict hidden `this` access in self/super calls.
  SI-6902 Check unreachability under @unchecked
  SI-6976 Fix value class separate compilation crasher.
  Closes SI-6952: add correct error positions for Dynamic feature check.

Conflicts:
	src/compiler/scala/tools/nsc/CompileServer.scala
	src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala

1 files changed, 17 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index 6a253a98b1..3e5ac6922e 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -1214,9 +1214,24 @@ abstract class Mixin extends InfoTransform with ast.TreeDSL {
           // refer to fields in some implementation class via an abstract
           // getter in the interface.
           val iface  = toInterface(sym.owner.tpe).typeSymbol
-          val getter = sym getter iface orElse abort("No getter for " + sym + " in " + iface)
+          val ifaceGetter = sym getter iface
+
+          def si6231Restriction() {
+            // See SI-6231 comments in LamdaLift for ideas on how to lift the restriction.
+            val msg = sm"""Implementation restriction: local ${iface.fullLocationString} is unable to automatically capture the
+                |free variable ${sym} on behalf of ${currentClass}. You can manually assign it to a val inside the trait,
+                |and refer that that val in ${currentClass}. For more details, see SI-6231."""
+            reporter.error(tree.pos, msg)
+          }
 
-          typedPos(tree.pos)((qual DOT getter)())
+          if (ifaceGetter == NoSymbol) {
+            if (sym.isParamAccessor) {
+              si6231Restriction()
+              EmptyTree
+            }
+            else abort("No getter for " + sym + " in " + iface)
+          }
+          else typedPos(tree.pos)((qual DOT ifaceGetter)())
 
         case Assign(Apply(lhs @ Select(qual, _), List()), rhs) =>
           // assign to fields in some implementation class via an abstract