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, 5 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 391ef9e337..7417c5364e 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -4881,10 +4881,11 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
             (// this -> Foo.this
             if (sym.isThisSym)
               typed1(This(sym.owner) setPos tree.pos, mode, pt)
-          // Inferring classOf type parameter from expected type.  Otherwise an
-          // actual call to the stubbed classOf method is generated, returning null.
-            else if (isPredefClassOf(sym) && pt.typeSymbol == ClassClass && pt.typeArgs.nonEmpty)
-            typedClassOf(tree, TypeTree(pt.typeArgs.head))
+            else if (isPredefClassOf(sym) && pt.typeSymbol == ClassClass && pt.typeArgs.nonEmpty) {
+              // Inferring classOf type parameter from expected type.  Otherwise an
+              // actual call to the stubbed classOf method is generated, returning null.
+              typedClassOf(tree, TypeTree(pt.typeArgs.head).setPos(tree.pos.focus))
+            }
           else {
               val pre1  = if (sym.isTopLevel) sym.owner.thisType else if (qual == EmptyTree) NoPrefix else qual.tpe
               val tree1 = if (qual == EmptyTree) tree else atPos(tree.pos)(Select(atPos(tree.pos.focusStart)(qual), name))