Merge pull request #1754 from retronym/ticket/6288

SI-6288 Perfecting positions

3 files changed, 13 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index 068836fe4f..d50d4cd125 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -320,7 +320,12 @@ trait BasicBlocks {
       else
         instrs.zipWithIndex collect {
           case (oldInstr, i) if map contains oldInstr =>
-            code.touched |= replaceInstruction(i, map(oldInstr))
+            // SI-6288 clone important here because `replaceInstruction` assigns
+            // a position to `newInstr`. Without this, a single instruction can
+            // be added twice, and the position last position assigned clobbers
+            // all previous positions in other usages.
+            val newInstr = map(oldInstr).clone()
+            code.touched |= replaceInstruction(i, newInstr)
         }
 
     ////////////////////// Emit //////////////////////
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
index 834c64aaae..fa8aff5cdd 100644
--- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
@@ -801,8 +801,8 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
       protected def spliceApply(binder: Symbol): Tree = {
         object splice extends Transformer {
           override def transform(t: Tree) = t match {
-            case Apply(x, List(Ident(nme.SELECTOR_DUMMY))) =>
-              treeCopy.Apply(t, x, List(CODE.REF(binder)))
+            case Apply(x, List(i @ Ident(nme.SELECTOR_DUMMY))) =>
+              treeCopy.Apply(t, x, List(CODE.REF(binder).setPos(i.pos)))
             case _ => super.transform(t)
           }
         }
@@ -879,7 +879,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
           override def transform(tree: Tree): Tree = {
             def subst(from: List[Symbol], to: List[Tree]): Tree =
               if (from.isEmpty) tree
-              else if (tree.symbol == from.head) typedIfOrigTyped(to.head.shallowDuplicate, tree.tpe)
+              else if (tree.symbol == from.head) typedIfOrigTyped(to.head.shallowDuplicate.setPos(tree.pos), tree.tpe)
               else subst(from.tail, to.tail)
 
             tree match {
diff --git a/src/partest/scala/tools/partest/DirectTest.scala b/src/partest/scala/tools/partest/DirectTest.scala
index 8c18809ad6..483cb491a1 100644
--- a/src/partest/scala/tools/partest/DirectTest.scala
+++ b/src/partest/scala/tools/partest/DirectTest.scala
@@ -39,6 +39,10 @@ abstract class DirectTest extends App {
   // new compiler
   def newCompiler(args: String*): Global = {
     val settings = newSettings((CommandLineParser tokenize ("-d \"" + testOutput.path + "\" " + extraSettings)) ++ args.toList)
+    newCompiler(settings)
+  }
+
+  def newCompiler(settings: Settings): Global = {
     if (settings.Yrangepos.value) new Global(settings, reporter(settings)) with interactive.RangePositions
     else new Global(settings, reporter(settings))
   }