SI-6274 Fix owners when eta-expanding function with byName param

When eta-expanding a function that takes a by-name param the local definition
for the corresponding argument is a function-0

  val eta$1 = () => { argument-to-by-name }

If there are any definitinos in the `argument-to-by-name`, the symbol
owner needs to be changed to the anonymous function's symbol.

To know the function symbol in eta expand, we need to type-check the
function, and therefore pass the `Typer` instance to `etaExpand`.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/files/pos/t6274.scala b/test/files/pos/t6274.scala
new file mode 100644
index 0000000000..cf769fc72d
--- /dev/null
+++ b/test/files/pos/t6274.scala
@@ -0,0 +1,13 @@
+trait Crash {
+
+    def foo(i: => Int) (j: Int): Int
+
+    def t = {
+        // var count = 0
+        foo {
+            var count = 0
+            count
+        } _
+    }
+
+}