From 4a8edc03653cb0f6b6ed1cdea1779a19df20f8f5 Mon Sep 17 00:00:00 2001 From: Jason Zaugg Date: Tue, 4 Feb 2014 15:55:59 +0100 Subject: SI-8129 Make Object#== override Any#== And the same for != If we tried to declare these signatures in non-fictional classes, we would be chastised about collapsing into the "same signature after erasure". This will have an influence of typing, as the typechecking of arguments is sensitive to overloading: if multiple variants are feasible, the argument will be typechecked with a wildcard expected type. So people inspecting the types of the arguments to `==` before this change might have seen an interesting type for `if (true) x else y`, but now the `If` will have type `Any`, as we don't need to calculate the LUB. I've left a TODO to note that we should really make `Any#{==, !=}` non-final and include a final override in `AnyVal`. But I don't think that is particularly urgent. --- test/files/pos/t8219.scala | 15 +++++++++++++++ 1 file changed, 15 insertions(+) create mode 100644 test/files/pos/t8219.scala (limited to 'test/files/pos/t8219.scala') diff --git a/test/files/pos/t8219.scala b/test/files/pos/t8219.scala new file mode 100644 index 0000000000..e1653b6238 --- /dev/null +++ b/test/files/pos/t8219.scala @@ -0,0 +1,15 @@ +trait Equalizer[T] +trait Gen[A] + +class Broken { + implicit def const[T](x: T): Gen[T] = ??? + implicit def convertToEqualizer[T](left: T): Equalizer[T] = ??? + + def in(a: Any) = () + in { + import scala.None // any import will do.. + "" == "" // this no longer triggers the bug, as Object#== now overrides Any#== + } + + // We can still trigger the bug with a structural type, see pending/neg/t8219.scala +} -- cgit v1.2.3