SI-8549 Honour the @SerialVersionUID annotatation

In PR #1673 / 4267444, the annotation `SerialVersionId` was
changed from a `StaticAnnotation` to `ClassFileAnnotation` in
order to avoid silently ignoring non-literal UIDs like:

    @SerialVersionUID(0 - 12345L) class C

And to flag non-constant UIDs:

    @SerialVersionUID("!!!".length)

While this indeed was fold constants, the change was incomplete.
The compiler API for reading the argument from a `ClassFileAnnoation`
is different, on must look for a `LiteralAnnotArg`, rather than a
`Literal`.

This commit:

  - amends the backend accordingly
  - removes relevant duplication between `GenASM` and `GenBCode`
  - tests that the static field is generated accordingly

This will mean that we will break deserialization of objects from
Scalal 2.11.0 that use this annotation.

3 files changed, 24 insertions, 10 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
index 359e5d6c29..f800dbf9cd 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
@@ -239,6 +239,13 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
   }
 
   /*
+   *  must-single-thread
+   */
+  def serialVUID(csym: Symbol): Option[Long] = csym getAnnotation definitions.SerialVersionUIDAttr collect {
+    case AnnotationInfo(_, _, (_, LiteralAnnotArg(const)) :: Nil) => const.longValue
+  }
+
+  /*
    * Populates the InnerClasses JVM attribute with `refedInnerClasses`.
    * In addition to inner classes mentioned somewhere in `jclass` (where `jclass` is a class file being emitted)
    * `refedInnerClasses` should contain those inner classes defined as direct member classes of `jclass`
@@ -881,13 +888,6 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
     val MIN_SWITCH_DENSITY = 0.7
 
     /*
-     *  must-single-thread
-     */
-    def serialVUID(csym: Symbol): Option[Long] = csym getAnnotation definitions.SerialVersionUIDAttr collect {
-      case AnnotationInfo(_, Literal(const) :: _, _) => const.longValue
-    }
-
-    /*
      *  Add public static final field serialVersionUID with value `id`
      *
      *  can-multi-thread
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
index a389816caf..b7f9b30e19 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
@@ -1142,9 +1142,7 @@ abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
 
     def isParcelableClass = isAndroidParcelableClass(clasz.symbol)
 
-    def serialVUID: Option[Long] = clasz.symbol getAnnotation SerialVersionUIDAttr collect {
-      case AnnotationInfo(_, Literal(const) :: _, _) => const.longValue
-    }
+    def serialVUID: Option[Long] = genBCode.serialVUID(clasz.symbol)
 
     private def getSuperInterfaces(c: IClass): Array[String] = {
 
diff --git a/test/files/run/t8549b.scala b/test/files/run/t8549b.scala
new file mode 100644
index 0000000000..1e1bf2c0bc
--- /dev/null
+++ b/test/files/run/t8549b.scala
@@ -0,0 +1,16 @@
+
+@SerialVersionUID(42)
+class C
+
+@SerialVersionUID(43 - 1)
+class D
+
+
+object Test extends App {
+  def checkId(cls: Class[_]) {
+    val id = cls.getDeclaredField("serialVersionUID").get(null)
+    assert(id == 42, (cls, id))  
+  }
+  checkId(classOf[C])
+  checkId(classOf[D])
+}