From 945b31e07fe0e2366c44a2cb03276933d38ac3c4 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Mon, 8 Jun 2020 14:32:05 +0200
Subject: [PATCH] Fix #9115: Make Java-defined fields effectively final

---
 compiler/src/dotty/tools/dotc/core/Flags.scala          | 2 +-
 compiler/src/dotty/tools/dotc/core/SymDenotations.scala | 1 +
 tests/neg/i9115/A.java                                  | 3 +++
 tests/neg/i9115/B.scala                                 | 3 +++
 4 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 tests/neg/i9115/A.java
 create mode 100644 tests/neg/i9115/B.scala

diff --git a/compiler/src/dotty/tools/dotc/core/Flags.scala b/compiler/src/dotty/tools/dotc/core/Flags.scala
index 0b8eb22034b0..d0ace2318974 100644
--- a/compiler/src/dotty/tools/dotc/core/Flags.scala
+++ b/compiler/src/dotty/tools/dotc/core/Flags.scala
@@ -308,7 +308,7 @@ object Flags {
   val (Given @ _, _, _) = newFlags(29, "given")
 
   /** Symbol is defined by a Java class */
-  val (JavaDefined @ _, _, _) = newFlags(30, "<java>")
+  val (JavaDefined @ _, JavaDefinedVal @ _, _) = newFlags(30, "<java>")
 
   /** Symbol is implemented as a Java static */
   val (JavaStatic @ _, JavaStaticTerm @ _, JavaStaticType @ _) = newFlags(31, "<static>")
diff --git a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
index f51aec15c45d..ad8ca5eacfc2 100644
--- a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -1158,6 +1158,7 @@ object SymDenotations {
     final def isEffectivelyFinal(implicit ctx: Context): Boolean =
       isOneOf(EffectivelyFinalFlags)
       || is(Inline, butNot = Deferred)
+      || is(JavaDefinedVal, butNot = Method)
       || !owner.isExtensibleClass
 
     /** A class is effectively sealed if has the `final` or `sealed` modifier, or it
diff --git a/tests/neg/i9115/A.java b/tests/neg/i9115/A.java
new file mode 100644
index 000000000000..2c039ddf2693
--- /dev/null
+++ b/tests/neg/i9115/A.java
@@ -0,0 +1,3 @@
+public class A {
+  public String foo = "A";
+}
diff --git a/tests/neg/i9115/B.scala b/tests/neg/i9115/B.scala
new file mode 100644
index 000000000000..a82c8e10a198
--- /dev/null
+++ b/tests/neg/i9115/B.scala
@@ -0,0 +1,3 @@
+class B extends A {
+  override val foo: String = "B" // error
+}
\ No newline at end of file