The comment for isCoDefinedWith has long said

  Is this symbol defined in the same scope
  and compilation unit as `that' symbol?

But "same scope" was never checked, only "same compilation unit."
Presumably other layers of logic kept this from being noticed until now,
but it has been crashing sbt. Added check to isCoDefinedWith. Closes
#4220, review by odersky.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/files/pos/bug4220.scala b/test/files/pos/bug4220.scala
new file mode 100644
index 0000000000..98f2649767
--- /dev/null
+++ b/test/files/pos/bug4220.scala
@@ -0,0 +1,7 @@
+// don't know if our half-working sbt build is meaningfully
+// tested for #4220 with this, but it can't hurt.
+class Boo(a: Int = 0)
+
+object test {
+	class Boo
+}