SI-8596 Fix rangepos crasher with defaults, poly methods

Regressed in SI-7915 / 3009a525b5

We should be deriving the position of the synthetic `Select`
from `basefun1`, rather than `basefun`. In the new, enclosed
test, the difference amounts to:

    new Container().typeParamAndDefaultArg[Any]()
    `------------ basefun1 --------------'
    `----------------- basefun ---------------'

For monomorphic methods, these are one and the same, which is
why `presentation/t7915` was working. I've extended that test
to a polymorphic method to check that hyperlink resolution works.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/files/pos/t8596.scala b/test/files/pos/t8596.scala
new file mode 100644
index 0000000000..bfed58eadf
--- /dev/null
+++ b/test/files/pos/t8596.scala
@@ -0,0 +1,7 @@
+class TypeTreeObjects {
+  class Container {
+    def typeParamAndDefaultArg[C](name: String = ""): String = ""
+  }
+  // crashed under -Yrangepos
+  new Container().typeParamAndDefaultArg[Any]()
+}