Hardening against nulls for deserialization.

When one attempts to populate data structures via
deserialization, nulls tend to show up in unlikely or
"impossible" places. Now there are a few fewer.

6 files changed, 14 insertions, 7 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index 94fbba8066..16ee40280c 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -38,7 +38,7 @@ trait BasicBlocks {
 
     import BBFlags._
 
-    def code = method.code
+    def code = if (method eq null) NoCode else method.code
 
     private final class SuccessorList() {
       private var successors: List[BasicBlock] = Nil
diff --git a/src/compiler/scala/tools/nsc/backend/icode/analysis/CopyPropagation.scala b/src/compiler/scala/tools/nsc/backend/icode/analysis/CopyPropagation.scala
index 338a07c872..d3016b2d9b 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/analysis/CopyPropagation.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/analysis/CopyPropagation.scala
@@ -541,7 +541,8 @@ abstract class CopyPropagation {
       m.isGetter // abstract getters are still pure, as we 'know'
 
     final override def toString() = (
-      method.blocks map { b =>
+      if (method eq null) List("<null>")
+      else method.blocks map { b =>
         "\nIN(%s):\t Bindings: %s".format(b.label, in(b).bindings) +
         "\nIN(%s):\t Stack: %s".format(b.label, in(b).stack)
       }
diff --git a/src/compiler/scala/tools/nsc/backend/icode/analysis/ReachingDefinitions.scala b/src/compiler/scala/tools/nsc/backend/icode/analysis/ReachingDefinitions.scala
index 26b7bc50d8..fecd48ed27 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/analysis/ReachingDefinitions.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/analysis/ReachingDefinitions.scala
@@ -240,7 +240,8 @@ abstract class ReachingDefinitions {
       findDefs(bb, idx, m, 0)
 
     override def toString: String = {
-      method.code.blocks map { b =>
+      if (method eq null) "<null>"
+      else method.code.blocks map { b =>
         "  entry(%s) = %s\n".format(b, in(b)) +
         "   exit(%s) = %s\n".format(b, out(b))
       } mkString ("ReachingDefinitions {\n", "\n", "\n}")
diff --git a/src/compiler/scala/tools/nsc/backend/opt/ClosureElimination.scala b/src/compiler/scala/tools/nsc/backend/opt/ClosureElimination.scala
index aaf2c55dcd..bde17b28fc 100644
--- a/src/compiler/scala/tools/nsc/backend/opt/ClosureElimination.scala
+++ b/src/compiler/scala/tools/nsc/backend/opt/ClosureElimination.scala
@@ -71,8 +71,10 @@ abstract class ClosureElimination extends SubComponent {
     def name = phaseName
     val closser = new ClosureElim
 
-    override def apply(c: IClass): Unit =
-      closser analyzeClass c
+    override def apply(c: IClass): Unit = {
+      if (closser ne null)
+        closser analyzeClass c
+    }
   }
 
   /**
diff --git a/src/compiler/scala/tools/nsc/backend/opt/DeadCodeElimination.scala b/src/compiler/scala/tools/nsc/backend/opt/DeadCodeElimination.scala
index 1026e95fac..483bff6467 100644
--- a/src/compiler/scala/tools/nsc/backend/opt/DeadCodeElimination.scala
+++ b/src/compiler/scala/tools/nsc/backend/opt/DeadCodeElimination.scala
@@ -33,7 +33,7 @@ abstract class DeadCodeElimination extends SubComponent {
     val dce = new DeadCode()
 
     override def apply(c: IClass) {
-      if (settings.Xdce)
+      if (settings.Xdce && (dce ne null))
         dce.analyzeClass(c)
     }
   }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 875aa5a9d3..04bd342004 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -217,7 +217,10 @@ trait Implicits {
       case _ => false
     }
     override def hashCode = name.## + pre.## + sym.##
-    override def toString = name + ": " + tpe
+    override def toString = (
+      if (tpeCache eq null) name + ": ?"
+      else name + ": " + tpe
+    )
   }
 
   /** A sentinel indicating no implicit was found */