From 3fb317560c7e1220cd51c7f8408cf3db6a84b290 Mon Sep 17 00:00:00 2001
From: Paul Phillips <paulp@improving.org>
Date: Sun, 19 May 2013 03:42:03 -0700
Subject: SI-7427 stop crashing under -Ydebug.

Change "dumpClassesAndAbort" to "devWarning". You can witness
it happen like so.

  % scalac test/files/pos/t7427.scala -Ydebug -Xdev
  ...
  [running phase cleanup on t7427.scala]
  [running phase icode on t7427.scala]
  warning: !!! PJUMP(method matchEnd4)/scala.tools.nsc.backend.icode.GenICode$PJUMP is not a control flow instruction
  warning: !!! PJUMP(method case6)/scala.tools.nsc.backend.icode.GenICode$PJUMP is not a control flow instruction
  [running phase inliner on t7427.scala]
  [running phase inlinehandlers on t7427.scala]

Having now lived with this for months, I have no ambition to
unravel the actual problem, I just want it to stop crashing.
---
 .../tools/nsc/backend/icode/BasicBlocks.scala      | 33 +++++++++++-----------
 .../scala/tools/nsc/backend/icode/GenICode.scala   |  3 +-
 test/files/pos/t7427.flags                         |  1 +
 test/files/pos/t7427.scala                         |  4 +++
 4 files changed, 22 insertions(+), 19 deletions(-)
 create mode 100644 test/files/pos/t7427.flags
 create mode 100644 test/files/pos/t7427.scala

diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index 16ee40280c..26d10d2514 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -8,8 +8,7 @@ package backend
 package icode
 
 import scala.collection.{ mutable, immutable }
-import mutable.{ ListBuffer, ArrayBuffer }
-import scala.reflect.internal.util.{ Position, NoPosition }
+import mutable.ListBuffer
 import backend.icode.analysis.ProgramPoint
 import scala.language.postfixOps
 
@@ -17,8 +16,7 @@ trait BasicBlocks {
   self: ICodes =>
 
   import opcodes._
-  import global.{ settings, debuglog, log, nme }
-  import nme.isExceptionResultName
+  import global._
 
   /** Override Array creation for efficiency (to not go through reflection). */
   private implicit val instructionTag: scala.reflect.ClassTag[Instruction] = new scala.reflect.ClassTag[Instruction] {
@@ -336,9 +334,9 @@ trait BasicBlocks {
            * put into ignore mode so we hear about it if there's a problem.
            */
           instr match {
-            case JUMP(_) | RETURN(_) | THROW(_) | SCOPE_EXIT(_)               => // ok
-            case STORE_LOCAL(local) if isExceptionResultName(local.sym.name)  => // ok
-            case x => log("Ignoring instruction, possibly at our peril, at " + pos + ": " + x)
+            case JUMP(_) | RETURN(_) | THROW(_) | SCOPE_EXIT(_)                  => // ok
+            case STORE_LOCAL(local) if nme.isExceptionResultName(local.sym.name) => // ok
+            case x                                                               => log("Ignoring instruction, possibly at our peril, at " + pos + ": " + x)
           }
         }
       }
@@ -416,7 +414,7 @@ trait BasicBlocks {
         enterIgnoreMode()
       }
     }
-    
+
     /**
      * Same as killIf but with the logic of the condition reversed
      */
@@ -477,16 +475,17 @@ trait BasicBlocks {
 
     def directSuccessors: List[BasicBlock] =
       if (isEmpty) Nil else lastInstruction match {
-        case JUMP(whereto)              => whereto :: Nil
-        case CJUMP(succ, fail, _, _)    => fail :: succ :: Nil
-        case CZJUMP(succ, fail, _, _)   => fail :: succ :: Nil
-        case SWITCH(_, labels)          => labels
-        case RETURN(_)                  => Nil
-        case THROW(_)                   => Nil
-        case _ =>
+        case JUMP(whereto)            => whereto :: Nil
+        case CJUMP(succ, fail, _, _)  => fail :: succ :: Nil
+        case CZJUMP(succ, fail, _, _) => fail :: succ :: Nil
+        case SWITCH(_, labels)        => labels
+        case RETURN(_)                => Nil
+        case THROW(_)                 => Nil
+        case _                        =>
           if (closed)
-            dumpClassesAndAbort("The last instruction is not a control flow instruction: " + lastInstruction)
-          else Nil
+            devWarning(s"$lastInstruction/${lastInstruction.getClass.getName} is not a control flow instruction")
+
+          Nil
       }
 
     /** Returns the predecessors of this block.     */
diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
index 9c9c001f02..cc4d97253f 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@@ -2165,8 +2165,7 @@ abstract class GenICode extends SubComponent  {
      * by a real JUMP instruction when all labels are resolved.
      */
     abstract class PseudoJUMP(label: Label) extends Instruction {
-      override def toString(): String = "PJUMP " + label.symbol
-
+      override def toString = s"PJUMP(${label.symbol})"
       override def consumed = 0
       override def produced = 0
 
diff --git a/test/files/pos/t7427.flags b/test/files/pos/t7427.flags
new file mode 100644
index 0000000000..9c7d6400fc
--- /dev/null
+++ b/test/files/pos/t7427.flags
@@ -0,0 +1 @@
+-Ydebug
diff --git a/test/files/pos/t7427.scala b/test/files/pos/t7427.scala
new file mode 100644
index 0000000000..cca52950d1
--- /dev/null
+++ b/test/files/pos/t7427.scala
@@ -0,0 +1,4 @@
+// Compiles with no options
+// Compiles with -Ydebug -Ydisable-unreachable-prevention
+// Crashes with -Ydebug
+trait Bippy { 3 match { case 3 => } }
-- 
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