Fix #1335: Generate null checks for extractors

1 files changed, 7 insertions, 3 deletions

diff --git a/src/dotty/tools/dotc/transform/PatternMatcher.scala b/src/dotty/tools/dotc/transform/PatternMatcher.scala
index 30b94623d..490feb7d0 100644
--- a/src/dotty/tools/dotc/transform/PatternMatcher.scala
+++ b/src/dotty/tools/dotc/transform/PatternMatcher.scala
@@ -253,9 +253,13 @@ class PatternMatcher extends MiniPhaseTransform with DenotTransformer {
               )
           } else {
             assert(defn.isProductSubType(prev.tpe))
-            Block(
-              List(ValDef(b.asTerm, prev)),
-              next //Substitution(b, ref(prevSym))(next)
+            val nullCheck: Tree = prev.select(defn.Object_ne).appliedTo(Literal(Constant(null)))
+            ifThenElseZero(
+              nullCheck,
+              Block(
+                List(ValDef(b.asTerm, prev)),
+                next //Substitution(b, ref(prevSym))(next)
+              )
             )
           }
         }