Fixed initial variable binding for method param...

Fixed initial variable binding for method parameters, that caused the
inliner to infer wrong types for tail recursive methods

3 files changed, 37 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/icode/analysis/TypeFlowAnalysis.scala b/src/compiler/scala/tools/nsc/backend/icode/analysis/TypeFlowAnalysis.scala
index 0dadd8980d..32a6037d41 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/analysis/TypeFlowAnalysis.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/analysis/TypeFlowAnalysis.scala
@@ -126,6 +126,12 @@ abstract class TypeFlowAnalysis {
           in(b)  = typeFlowLattice.bottom
           out(b) = typeFlowLattice.bottom
         }
+
+        // start block has var bindings for each of its parameters
+        val entryBindings = new VarBinding
+        m.params.foreach(p => entryBindings += ((p, p.kind)))
+        in(m.code.startBlock) = lattice.IState(entryBindings, typeStackLattice.bottom)
+
         m.exh foreach { e =>
           in(e.startBlock) = lattice.IState(in(e.startBlock).vars, typeStackLattice.exceptionHandlerStack)
         }
diff --git a/test/files/run/inliner-infer.check b/test/files/run/inliner-infer.check
new file mode 100644
index 0000000000..d702bd602d
--- /dev/null
+++ b/test/files/run/inliner-infer.check
@@ -0,0 +1,2 @@
+non-empty
+empty
diff --git a/test/files/run/inliner-infer.scala b/test/files/run/inliner-infer.scala
new file mode 100644
index 0000000000..107b9508ee
--- /dev/null
+++ b/test/files/run/inliner-infer.scala
@@ -0,0 +1,29 @@
+
+
+/** Test that the inliner is not inferring that `xs' is
+ *  always Nil, removing the call to isEmpty.
+ */
+object Test extends Application {
+
+  @annotation.tailrec
+  def walk(xs: MyList): Unit = {
+    if (xs.isEmpty)
+      println("empty")
+    else {
+      println("non-empty")
+      walk(MyNil)
+    }
+  }
+
+  walk(new MyList)
+}
+
+class MyList {
+  def isEmpty = false
+}
+
+object MyNil extends MyList {
+  override def isEmpty = true
+}
+
+