SI-9390 Emit local defs that don't capture this as static

This avoids unnecessary memory retention, and allows lambdas
that call the local methods to be serializable, regardless of
whether or not the enclosing class is serializable.

The second point is especially pressing, given that the enclosing
class for local methods defined in a used to be the (serializable)
anonymous function class, but as of Scala 2.12 will be the enclosing
class of the lambda.

This change is similar in spirit to SI-9408 / 93bee55e.

5 files changed, 105 insertions, 7 deletions

diff --git a/test/files/run/t5652.check b/test/files/run/t5652.check
index a0fb6fe9b4..7c65ba6698 100644
--- a/test/files/run/t5652.check
+++ b/test/files/run/t5652.check
@@ -1,7 +1,7 @@
-public default int T1.T1$$g$1()
 public default int T1.f0()
 public default void T1.$init$()
-public final int A1.A1$$g$2()
+public static int T1.T1$$g$1()
 public int A1.f1()
-public final int A2.A2$$g$1()
+public static final int A1.A1$$g$2()
 public int A2.f2()
+public static final int A2.A2$$g$1()
diff --git a/test/files/run/t5652b.check b/test/files/run/t5652b.check
index ca9d0a74f0..0f4290796f 100644
--- a/test/files/run/t5652b.check
+++ b/test/files/run/t5652b.check
@@ -1,4 +1,4 @@
-private final int A1.g$1()
+private static final int A1.g$1()
 public int A1.f1()
-private final int A2.g$1()
+private static final int A2.g$1()
 public int A2.f2()
diff --git a/test/files/run/t5652c.check b/test/files/run/t5652c.check
index 3b889e066d..5a6d535f02 100644
--- a/test/files/run/t5652c.check
+++ b/test/files/run/t5652c.check
@@ -1,6 +1,6 @@
-public final int A1.A1$$g$1()
-public final int A1.A1$$g$2()
 public int A1.f1()
 public int A1.f2()
+public static final int A1.A1$$g$1()
+public static final int A1.A1$$g$2()
 1
 2
diff --git a/test/files/run/t9390.scala b/test/files/run/t9390.scala
new file mode 100644
index 0000000000..8d7e1be557
--- /dev/null
+++ b/test/files/run/t9390.scala
@@ -0,0 +1,67 @@
+class C {
+  def methodLift1 = {
+    def isEven(c: Int) = c % 2 == 0
+    val f: Int => Boolean = isEven
+    f
+  }
+  def methodLift2 = {
+    def isEven(c: Int) = c % 2 == 0
+    def isEven0(c: Int) = isEven(c)
+    val f: Int => Boolean = isEven0
+    f
+  }
+
+  def methodLift3 = {
+    def isEven(c: Int) = {toString; c % 2 == 0}
+    def isEven0(c: Int) = isEven(c)
+    val f: Int => Boolean = isEven0
+    f
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val c = new C
+
+    {
+      val f = c.methodLift1
+      assert(f(0))
+      assert(!f(1))
+      val f1 = serializeDeserialize(f)
+      assert(f1(0))
+      assert(!f1(1))
+    }
+
+
+    {
+      val f = c.methodLift2
+      assert(f(0))
+      assert(!f(1))
+      val f1 = serializeDeserialize(f)
+      assert(f1(0))
+      assert(!f1(1))
+    }
+
+    {
+      val f = c.methodLift3
+      assert(f(0))
+      assert(!f(1))
+      try {
+        serializeDeserialize(this)
+        assert(false)
+      } catch {
+        case _: java.io.NotSerializableException =>
+          // expected, the closure in methodLift3 must capture C which is not serializable
+      }
+    }
+  }
+
+  def serializeDeserialize[T <: AnyRef](obj: T): T = {
+    import java.io._
+    val buffer = new ByteArrayOutputStream
+    val out = new ObjectOutputStream(buffer)
+    out.writeObject(obj)
+    val in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray))
+    in.readObject.asInstanceOf[T]
+  }
+}
diff --git a/test/files/run/t9390b.scala b/test/files/run/t9390b.scala
new file mode 100644
index 0000000000..439e21e0a0
--- /dev/null
+++ b/test/files/run/t9390b.scala
@@ -0,0 +1,31 @@
+class C { // C is not serializable
+  def foo = (x: Int) => (y: Int) => x + y
+  def bar = (x: Int) => (y: Int) => {toString; x + y}
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val c = new C
+    val f = c.foo
+    assert(f(1)(2) == 3)
+    val f1 = serializeDeserialize(f)
+    assert(f1(1)(2) == 3)
+
+    try {
+      serializeDeserialize(c.bar)
+      assert(false)
+    } catch {
+      case _: java.io.NotSerializableException =>
+        // expected, lambda transitively refers to this
+    }
+  }
+
+  def serializeDeserialize[T <: AnyRef](obj: T): T = {
+    import java.io._
+    val buffer = new ByteArrayOutputStream
+    val out = new ObjectOutputStream(buffer)
+    out.writeObject(obj)
+    val in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray))
+    in.readObject.asInstanceOf[T]
+  }
+}