Merge pull request #15109 from dwijnand/fix-unreachable-inhabited-java-enum

Force Java enum children to be queried

Author: odersky

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -1613,7 +1613,7 @@ object SymDenotations {
             c.ensureCompleted()
       end completeChildrenIn
 
-      if is(Sealed) then
+      if is(Sealed) || isAllOf(JavaEnumTrait) then
         if !is(ChildrenQueried) then
           // Make sure all visible children are completed, so that
           // they show up in Child annotations. A possible child is visible if it

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package transform
 package patmat
 

tests/pos/i14807.scala

@@ -0,0 +1,9 @@
+// scalac: -Werror
+enum Foo:
+  case One(value: String)
+  case Two(value: Long, month: java.time.Month)
+
+object Issue:
+  def doSomething(foo: Foo): String = foo match
+    case Foo.One(x)    => s"1 $x"
+    case Foo.Two(x, y) => s"2 $x $y"