Ensure trait var accessor type is widened

If we don't widen, we'll fail to find the setter when
typing `x = 42`, because `x` is constant-folded to `0`,
as its type is `=> Int(0)`. After widening, `x` is
type checked to `x` and its symbol is the getter in the
trait, which can then be rewritten to the setter.

Regression spotted and test case by szeiger.

1 files changed, 4 insertions, 0 deletions

diff --git a/test/files/pos/fields_widen_trait_var.scala b/test/files/pos/fields_widen_trait_var.scala
new file mode 100644
index 0000000000..0ea9d9629a
--- /dev/null
+++ b/test/files/pos/fields_widen_trait_var.scala
@@ -0,0 +1,4 @@
+// check that the `var x` below is assigned the type `Int`, and not `Constant(0)`,
+// and that we can assign to it (if it gets a constant type, the `x` in `x = 42`
+// is constant-folded to `0` and we can't find a setter..
+trait C { protected final var x = 0; x = 42 }