Merge pull request #15695 from dotty-staging/zero-init-warnings

Add two tests

Author: liufengyun

tests/init/neg/promotion-segment.scala

@@ -0,0 +1,12 @@
+class Outer:
+  trait A:
+    def foo() = println(m)
+
+  trait B extends A
+
+  class C extends B
+
+  def bar(c: C) = c.foo()
+
+  bar(new C)  // error
+  val m = 10

tests/init/neg/promotion-segment2.scala

@@ -0,0 +1,12 @@
+trait A(o: Outer):
+    def foo() = println(o.m)
+
+class Outer:
+  trait B extends A
+
+  class C extends B with A(this)
+
+  def bar(c: C) = c.foo()
+
+  bar(new C) // error
+  val m = 10