clear all flags when resetting a symbol

this change is a bit scary because it changes code that's not been
changed in 11 years
https://github.com/scala/scala/commit/7fa7c93#diff-d5789e5ae5061197d782d08324b260dbL214

3 files changed, 12 insertions, 2 deletions

diff --git a/src/reflect/scala/reflect/internal/Flags.scala b/src/reflect/scala/reflect/internal/Flags.scala
index 230d30c74e..e2522ef280 100644
--- a/src/reflect/scala/reflect/internal/Flags.scala
+++ b/src/reflect/scala/reflect/internal/Flags.scala
@@ -235,7 +235,6 @@ class Flags extends ModifierFlags {
   final val AllFlags = -1L
 
   /** These flags can be set when class or module symbol is first created.
-   *  They are the only flags to survive a call to resetFlags().
    */
   final val TopLevelCreationFlags =
     MODULE | PACKAGE | FINAL | JAVA
diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index 6f2d8d802a..ab52a875f8 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -725,7 +725,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     def setFlag(mask: Long): this.type   = { _rawflags |= mask ; this }
     def resetFlag(mask: Long): this.type = { _rawflags &= ~mask ; this }
-    def resetFlags() { rawflags &= TopLevelCreationFlags }
+    def resetFlags() { rawflags = 0 }
 
     /** Default implementation calls the generic string function, which
      *  will print overloaded flags as <flag1/flag2/flag3>.  Subclasses
diff --git a/test/junit/scala/tools/nsc/backend/jvm/DirectCompileTest.scala b/test/junit/scala/tools/nsc/backend/jvm/DirectCompileTest.scala
index f835e9b140..36bdb759a6 100644
--- a/test/junit/scala/tools/nsc/backend/jvm/DirectCompileTest.scala
+++ b/test/junit/scala/tools/nsc/backend/jvm/DirectCompileTest.scala
@@ -88,4 +88,15 @@ class DirectCompileTest extends BytecodeTesting {
   def compileErroneous(): Unit = {
     compileToBytes("class C { def f: String = 1 }", allowMessage = _.msg contains "type mismatch")
   }
+
+  @Test
+  def residentRedefineFinalFlag(): Unit = {
+    val compiler = newCompiler()
+    val a = "final class C { def c1 = 0 }"
+    // for re-defined class symbols (C), the compiler did not clear the `final` flag.
+    // so compiling `D` would give an error `illegal inheritance from final class C`.
+    val b = "class C; class D extends C"
+    compiler.compileToBytes(a)
+    compiler.compileToBytes(b)
+  }
 }