SI-9273 Avoid unpositioned error for bare classOf

A bare identifier `classOf` in a position wth an expected type of
`Class[_]` was leading to an unpositioned error.

This is due to special treatment of bare `classOf` in `typedIdent`
creating an ephemeral, but unpositioned, `TypeTree`.

This commit positions that tree and tests that the error is
issued at a sensible position.

There is still an irregularity between `classOf` and `Predef.classOf`,
but that seems esoteric enough to leave alone for now.

1 files changed, 9 insertions, 0 deletions

diff --git a/test/files/neg/t9273.scala b/test/files/neg/t9273.scala
new file mode 100644
index 0000000000..3f99dff17f
--- /dev/null
+++ b/test/files/neg/t9273.scala
@@ -0,0 +1,9 @@
+class MissingLineNumbers {
+  val foo: Class[_] = classOf            // error without position, line or file
+  val foo1: Class[_] = classOf[X]        // good error, all info contained
+  val foo2 = classOf                     // Infers  T=Nothing
+
+  val foo3: Class[_] = Predef.classOf    // Infers  T=Nothing. Irregular wrt typedIdent.
+  val foo4: Class[_] = Predef.classOf[X] // good error, all info contained
+  val foo5 = Predef.classOf              // Infers  T=Nothing
+}