Merge pull request #3183 from dotty-staging/fix-3179

fix #3179: bind should be nested in the plan for body

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala

@@ -308,12 +308,12 @@ object PatternMatcher {
           if (scrutinee.info.isNotNull || nonNull(scrutinee)) unappPlan
           else TestPlan(NonNullTest, scrutinee, tree.pos, unappPlan, onFailure)
         case Bind(name, body) =>
-          val body1 = patternPlan(scrutinee, body, onSuccess, onFailure)
-          if (name == nme.WILDCARD) body1
+          if (name == nme.WILDCARD) patternPlan(scrutinee, body, onSuccess, onFailure)
           else {
+            // The type of `name` may refer to val in `body`, therefore should come after `body`
             val bound = tree.symbol.asTerm
             initializer(bound) = ref(scrutinee)
-            LetPlan(bound, body1)
+            patternPlan(scrutinee, body, LetPlan(bound, onSuccess), onFailure)
           }
         case Alternative(alts) =>
           labelAbstract(onSuccess) { ons =>

tests/run/3179.scala

@@ -0,0 +1,8 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    ("": Any) match {
+      case a @ Test => 1
+      case _ => 2
+    }
+  }
+}