SI-9268 Be robust against absent classfiles during signature parsing

When parsing a Java generic signature that references an inner
class `A$B`, we were tripping an assertion if the enclosing class
`A` was absent.

This commit creates a stub symbol for `B` when this happens, rather
than continuing on with `NoSymbol`.

The enclosed test shows that we can instantiate a class containing
a method referring to such an inner class with only a warning
about the absent classfile, and that an error is issued only upon
a subsequent attempt to call the method.

1 files changed, 40 insertions, 0 deletions

diff --git a/test/files/run/t9268/Test.scala b/test/files/run/t9268/Test.scala
new file mode 100644
index 0000000000..813cbe7b60
--- /dev/null
+++ b/test/files/run/t9268/Test.scala
@@ -0,0 +1,40 @@
+import scala.tools.partest._
+import java.io.File
+
+object Test extends StoreReporterDirectTest {
+  def code = ???
+
+  def compileCode(code: String) = {
+    val classpath = List(sys.props("partest.lib"), testOutput.path) mkString sys.props("path.separator")
+    compileString(newCompiler("-cp", classpath, "-d", testOutput.path))(code)
+  }
+
+  def client1 = """
+    class Client1 { def p(p: Partial) = p.toString }
+  """
+
+  def client2 = """
+    class Client2 { def p(p: Partial) = p.waitFor() }
+  """
+
+  def deleteClass(s: String) = {
+    val f = new File(testOutput.path, s + ".class")
+    assert(f.exists)
+    f.delete()
+  }
+
+  def show(): Unit = {
+    deleteClass("Waiter")
+    deleteClass("Waiter$Predicate")
+
+    // Used to crash in Java Generic Signature parsing
+    println("Compiling Client1")
+    compileCode(client1)
+    println(storeReporter.infos.mkString("\n"))
+    storeReporter.reset()
+    println("Compiling Client2")
+    compileCode(client2)
+    println(storeReporter.infos.mkString("\n"))
+  }
+}
+