Merge pull request #5218 from retronym/ticket/9806

SI-9806 Fix incorrect codegen with optimizer, constants, try/catch

2 files changed, 20 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/opt/ConstantOptimization.scala b/src/compiler/scala/tools/nsc/backend/opt/ConstantOptimization.scala
index a7ce7dfa04..eafaf41932 100644
--- a/src/compiler/scala/tools/nsc/backend/opt/ConstantOptimization.scala
+++ b/src/compiler/scala/tools/nsc/backend/opt/ConstantOptimization.scala
@@ -539,14 +539,14 @@ abstract class ConstantOptimization extends SubComponent {
       // number of instructions excluding the last one
       val normalCount = block.size - 1
 
-      val exceptionState = in.cleanStack
+      var exceptionState = in.cleanStack
       var normalExitState = in
       var idx = 0
       while (idx < normalCount) {
         val inst = block(idx)
         normalExitState = interpretInst(normalExitState, inst)
         if (normalExitState.locals ne exceptionState.locals)
-          exceptionState.copy(locals = exceptionState mergeLocals normalExitState.locals)
+          exceptionState = exceptionState.copy(locals = exceptionState mergeLocals normalExitState.locals)
         idx += 1
       }
 
diff --git a/test/files/run/t9806.scala b/test/files/run/t9806.scala
new file mode 100644
index 0000000000..ccde989efe
--- /dev/null
+++ b/test/files/run/t9806.scala
@@ -0,0 +1,18 @@
+object Ex extends Exception
+object Test {
+  def main(args: Array[String]) {
+    try foo catch { case Ex => }
+  }
+
+  def isTrue(b: Boolean) = b
+  def foo = {
+    var streamErrors1 = true
+    try {
+      streamErrors1 = false
+      throw Ex
+    } catch {
+      case ex if streamErrors1 =>
+        assert(isTrue(streamErrors1))
+    }
+  }
+}