PluginComponent contributes description to -Xshow-phases.

In Global, SubComponent is called a phase descriptor, but it doesn't
actually have a description.  (Phase itself does.)  This fix adds
a description to PluginComponent so that plugins can describe what
they do in -Xshow-phases.

Elliptical descriptions

Exploded archives

Plugged-in partest

Roundup at the Little h!

1 files changed, 21 insertions, 0 deletions

diff --git a/test/files/run/t4351.scala b/test/files/run/t4351.scala
new file mode 100644
index 0000000000..d954d748b7
--- /dev/null
+++ b/test/files/run/t4351.scala
@@ -0,0 +1,21 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    try new BooleanPropImpl().value
+    catch {
+      // was: StackOverflowError
+      case e: RuntimeException => println("runtime exception")
+    }
+  }
+}
+
+trait Prop[@specialized(Boolean) +T] {
+  def value: T
+}
+
+class PropImpl[+T] extends Prop[T] {
+  def value: T = scala.sys.error("")
+}
+
+trait BooleanProp extends Prop[Boolean]
+
+class BooleanPropImpl() extends PropImpl[Boolean] with BooleanProp